HBT-EP Archives 2002 - present.

Wednesday December 18 03 58 36492-36513 External Field
During the run I was working with 'high beta' shots that I usually use in my 3/1 experiments. I was trying to develope a model discharge that would be stable to low frequency 3/1 oscilations with the aluminum shells fully inserted and unstable when they're retracted. Due to certain problems with the CAMAC racks and Crunch cabinet I didn't get much run time. Never the less I got several good shots. The data is being analyzed. Regards, Mikhail

Wednesday December 18 05 32 36514-36542 FB setup shots
Developed a "long lived" saturated RWM target mode that lasts about 2 to (sometimes even) 3 ms near the end of the shot. These plasmas were made with the Al shells inserted to suppress higher m/n=4/1 and 3/1 RWMs and 2/1 tearing type modes also. I was successful in bringing the q=2 surface external with a Ip ramp style shot. These shots have an Ip ramp of 2 MA/sec during the first half of the shot and then Ip rolls over somewhat at ~15kA during the last half of the shot when the kink is excited. The kink is of m/n=2/1 helicity instead of our more typical 3/1 variety. The q=2 surface goes out into the vacuum at ~ 4.5ms. The shots typically disrupted at about 8 to 9ms (see shot#35642 as an example). Feedback next.

Thursday December 19 05 38 36543 ICRH
Disappointingly, the large oscillations on the loop voltage now appear not to be related to the plasma after all. Today, in contrast to last week, the oscillation was there even in the absence of plasma. Last week we had one shot, 36486, without plasma, and the loop voltage oscillation was absent. However, today, we took several non-plasma shots, with and without banks firing, 36562, 36564, 36565, where the loop voltage clearly oscillated during the RF. On the bright side, the RF B probe is now absolutely calibrated. The RF B field at the probe is about 1 Gauss, within expectations for vacuum. No clear coupling was seen today, ie. vacuum B fields were basically the same as those when the plasma was around. The calibration factors have all been worked into the MDSPlus tree, so the f_bprobe tag now directly reflects the RF B-field in Gauss. Cory developed some good discharges that would hang around 92-91 cm for a couple of milliseconds. Nonetheless, Q was only observed to dip during inboard disruptions. We did not make significant progress on the triple probe, for lack of time, mostly.

Thursday December 19 05 43 -36603 ICRH Addendum
Two things to add to the report: We just discovered that by mistake, we ran today with the 10% helium mixture instead of the 20% hydrogen. So no chance of heating today. The other thing: I forgot to put in the last shot number of the day. It was 36603.

Friday December 20 04 20 none
Steve Paul was in today and reinstalled a new fiber optic bundle and optics to carry light from the machine to the screen room, as a consequence of that and some work on TS triggering we did not run today. Steve expects a factor of roughly 4 increase in collected light. He also stated he has made progress on fixing the systematic errors in the measurement through calibration improvements. Since the machine will not be running next week we took the opportunity to pump on and bake the Mach and Biased probe bellows and opened them up to the chamber. They should be ready for experiments when we run again. The bake is on.

2003

The lower 12 turn coil has been installed. The OH has been dismantled to facilitate installing the lower 21 turn coil.

Wednesday January 22 05 26 Maurer 36606-36619 shake-down
Finished getting the machine back in order(insulation, TF cooling oil, etc...) today after installation of majority of VF feeback coils during the past two weeks. Took initial OH and VF vacuum shots going in increments up to typical maximun runtime voltages ( e.g. VFEL=200V, OHEL=250V). Observed no problems with new coilsets. Ready for TF and plasma shots tomarrow. Since we are a day behind in getting the machine back together we are planning on moving the run schedule back a day. I will continue tomarrow and check out the TF and get first plasmas and Mikhail will then run on Friday.

Thursday January 23 06 10 Maurer 36620-36656 Clean-up
First plasmas were taken today since prior to Xmas and the new VF coil installation. Plasmas started out short (~2-3ms lifetime) but rather quickly started to last out to ~6ms after about ten shots. Tomarrow we should be able to get some real data. New mounts for the fan array sxr amplifier box were measured out and are being machined. They are needed because of the top middle new VF feedback coil location. The array will hopefully be up and running early next week after the table is installed and an extension is added to the copper bellows(Jim&John). Work on the TS triggering system and the new and repaired u-port adapters also piggy-backed on the run today(Alex&Royce).

Monday January 27 05 26 Mikhail Shilov 36657-36722 External Field
During Fri, Jan 24 and morning of Mon, Jan 27 runs I developed a reproducible discharge type which doesn't have low frequency external kink oscillations in the first phase of the discharge with the aluminum shells all the way in and q*

Monday January 27 05 28 Mikhail Shilov 36657-36722 External Field
During Fri, Jan 24 and morning of Mon, Jan 27 runs I developed a reproducible discharge type which doesn't have low frequency external kink oscillations in the first phase of the discharge with the aluminum shells all the way in and q* less ~ 3. In the afternoon of Mon, Jan 27 I applied external 3/1 corotating, static, static with 180 degree phase flip field to those kind of plasmas. The data is yet to be analyzed. Here is some good natural shots: 36664, 36668, 36671, 36688, 36691, 36703, 36720.

Thursday January 30 06 47 Maurer/Paul 36786-36833 Rotation&TS
Ran some calibrations of the new collection optics to start the day. Working out kinks with new collections optcs (for increased light collection). Ran in 10% and 100% He discharges. Small light levels seen on 100% He discharge cases. Currently not understood why light level is so low. Checking various possibilities. TS triggering progress made. Scope and laser triggered off of jorway pulse stopped pretriggering of scope. Need to AC couple the scope inputs to be able to bump the volts per division to measure TS scattered light.(Alex)

Wednesday February 5 05 31 Cates 36835-36943 Smart Shell RWM Feedback
On Tuesday, several hours were spent testing feedback preamps, and repairing small problems in the system. In the afternoon (shots 36855-65), some target current driven plasmas with 3/1 rwm induced disruptions were tested with and without feedback. Wednesday these current ramp shots were used to do a disruption study with feedback gains changed between full gain, half gain and quarter gain, in order to supplement previous gain studies with only full gain and 0.1 gain. I was also able to test the feedback shots (shots 36878-36891, 36939-43) with these gains against a smaller current ramp which is unstable for a longer period of time, hopefully allowing better observation of mode amplitude growth. As a side note, I have found Mikhail's improved solid_tok code (which now runs every shot automatically) to be a very helpful tool for run time analysis and correlating predicted mode stability with diagnostic signals.

Thursday February 6 05 24 Pedersen 36944-36985 ICRH/triple probe
We exercised the ICRF today and tested the triple probes with some new circuitry. We also took more data with the rf magnetic pickup probe, which was calibrated a while ago. ICRF worked as usual (hardware working fine, but no plasma heating) after a filter replacement. New triple probe circuitry allowed us to take useful data. The ion saturation currents were lower than expected and we changed some resistors to increase the signal levels. We took several good sets of data on the scope; they were stored on floppy and are being analyzed. We can extract a plasma density out of these measurements, and we expect it to be low - how low remains to be seen. Floating potentials were on the order of -40 volts (so Te=10 eV). A higher noise level was observed during the ICRF pulse, but it seems that the signals can still be extracted. RF pickup probe: We noticed small bumps (increases) in the signals when plasmas were inboard limited, but only for those plasmas which were still healthy (the current was still rising and the plasma had not disrupted). Examples: 36978, 83, 84 A typical increase was from 1.1 Gauss to 1.3 Gauss, noticeable but not dramatic.

Thursday February 6 09 33 Maurer 36896-37035 Rotation
... the second shift
Ran plasmas for equilibrium reconstructions for Youhong. Got well centered discharges with essentially constant edge q and major radius over a ~2msec(from about 2 to 4ms during the shot) period with limited MHD that should be good for the VALEN eddy current calculations and Tokamac runs. S. Paul came in for a late night run. We fixed the previous run's problems with signal level and then ran a series of discharges where we systematically varied the puff time to investigate changes in measured intensity levels and effects on the observed rotation rates. More analysis needed, but there were incouraging correlations between mini and major disruptions and the ion velocity being driven to zero. The ions are inferred to rotate in the direction of Ip. Also, TS triggering work was carried out during the ICRH run. There are still some noise issues to sort out with the AC coupled scope inputs. No recognizable scattered light was observed when we did take shots with the plasma. (Alex)

Tuesday February 11 06 08 Pedersen/Maurer etc 37036-45 VF Feedback
The feedback coils are all connected and polarities have been checked. The total series resistance is 32 mOhm, as expected. We pulsed the OH and the VF and looked at the induced voltages in the feedback system. These voltages peak at 2-4 kV. The VF start and the OH breakdown spike each contribute at that level but with opposite polarities. The OH spike induced voltages are roughly in line with expectations, but the VF start was not expected to induce as much voltage as it does. In other words, the coupling between the old VF and the feedback coils must be larger than expected. We consider the voltage level safe for the LANL power supply, which is a 10 kV power supply that will be connected to the FB system through a large transformer.

Thursday February 13 06 16 Maurer/Pedersen none Plasma position feedback
Good news and ...more good news: First, the previously reported induced voltages in the FB systems are off by a factor of 10. The scope probe used was actually a 1:100 divider rather than a 1:1000 divider. Hence the induced voltages were actually on the order of 200 V, which is much more in line with expectations. Nicolai calculated coupling coefficients as follows: Feedback coils - OH coils: c=0.0065 (design value 0.0025) Feedback coils - VF coils: c=0.027 (design value 0.018) No gross discrepancy, in other words. Second, we pulsed the Feedback system with the one LANL power supply. It worked very well with current rise from zero to about 200 A in about 100 microseconds. Data was recorded with the scope for a more precise analysis. The cos theta coil pickup will be recorded on a later run day.

Wednesday February 19 09 07 Nick none
The run-summary page is working again. Upgrading to 10.2.4, rewrote the httpd file without PHP support which is necessary for this script to work.

Wednesday February 19 05 17 Maurer fixing sxrs...
Yesterday and today were spent re-installing the sxr fan array which has been off the machine since the top middle VF feedback coil was installed about two weeks ago. The amplifier box, new table and extended bellows are now setup. The cabling was run differently to help minimize icrh pickup (hopefully) in the future. Initially there were 7 "bad" channels. All appear to be working except for channels 14 and 16 which are open circuit at the vacuum feedthrough. These two channels have been bad for some time. It is not known whether this is due to a bad vacuum side connection or if the diodes are bad (usually diodes fail short when the junction fails). The other channels (1,2,10, 13,15) had either faulty amplifiers or cabling problems that have been fixed except for a small oscillation on 13 and 15. We should be able to get an emissivity centroid out of the array as a check on open loop jog experiments with the new VF feedback coil.

Friday February 21 11 00 Pedersen/Maurer 371??-37206 Radial feedback/triple probe
We did several open loop tests using the LANL into the power supply and operated the triple probe as an ion saturation probe. Open loop tests The open loop test shots were 37190-37206. We found a significant pickup on the cos theta coil when pulsing the FB system. There is a simple proportional pickup but there also seems to be a smaller pick up that looks like it decays exponentially. Not sure about what to do about that one. We have enough data to nail down the calibration factor for the simple linear coupling, and can then proceed to get a believable major radius signal. The LANL worked very well, giving up to 300 A, but the signal generator used to drive the LANL waveforms gave us some problems. It is too early to conclude anything about the efficacy of the new feedback system, since the major radius measurement is contaminated by pickup. The sxr fan array may provide useful independent measurement of the radial position. We can report a preliminary analysis at the Monday meeting.
The triple probe was operated in ion saturation with a 300 V battery to ground, with a 24 Ohm resistor used to measure the ion saturation current. Signals were much better than when operated as a triple probe and the densities are higher too. I suspect that one of the probe leads/connections or the triple probe box is flaky, and I would discard the data taken last week on that basis. One probe tip seemed flaky at first but then started working, the other two were fine. Densities for outboard limited shots start out in the low 10^11 cm^-3 range and gradually increase to about 5*10^11 after about 5 ms. These numbers assume a constant 10 eV electron temperature and that other calibration constants are also accurate. They are a factor of 5 larger than the inboard limited plasma densities reported with the triple probe circuit. Signals are bursty but follow the overall evolution of the plasma well. We need to do inboard limited discharges next. At present, a single probe tip is being digitized in the north rack and a calibrated density (assuming Te=10 eV) is in the tree with the tag ne_inboard

Tuesday February 25 05 21 Maurer MC feedback
Reconfigured crunch amp box and input sensors today for mode control feedback using new gap coils. Checking polarity of signals and magnitude of feedback gains. Initial plasma shots with feedback taken. More of the same tomorrow.

Thursday February 27 05 45 Maurer/Pedersen 37265-37266 VF feedback
Todays run objective was to continue VF open loop jog experiments with the new VF feedback coil. Unfortunantly we did not get very far. The LANL charging supply failed at the start of the run day. The day was spent toubleshooting the supply(Nick has ordered the required parts to fix it). To be able to run we have currently swapped in the charging supply for the other LANL amplifier. Its installation is nearly complete (one dump relay is not working). It should be up and ready tomorrow morning. A calibration error was discovered in analyzing triple probe data. The calculated density form isat measurements is now approximately ~2e18 per cc on the inboard high field side edge plasma. This value is much more in line with other previous outboard Langmuir probe measurements. Also, mode control feedback data was taken yesterday. Analysis is underway. The new u-port adapter checked out OK and is currently installed in the icrh rack. Reminder: Tomorrow we going up to Argon to re-align Thomson scattering.

Friday February 28 05 16 Maurer/Klein
HBT-EP was up to ~200 Torr of Argon today in order to align Thomson scattering. We are currently pumped down using one cryo to 2e-6 Torr with the base pressure comprised of Argon and H2O. The bake has been turned on. Friday February 28 05 20 Maurer/Klein
HBT-EP was up to ~200 Torr of Argon today in order to align Thomson scattering. We are currently pumped down using one cryo to 2e-6 Torr with the base pressure comprised of Argon and H2O. The bake has been turned on. Both cryos were regen'ed during the up to Argon. The TS align had some problems. The stray light level appears to be enhanced over the previous alignment in November. We can discuss this further at the Monday meeting. The LANL supply is back up and running. All the dump-interlocks are now working on the charging supply.

Monday March 3 05 56 Liu 37267-37300 clean up
1. shots 37271-37275 are vacuum shots. When all Krytrons were on and took OH only shot, there was current pickup (about 100-200A) in VF Rogowski coil. However, when VF Krytrons were off, there was no pickup in VF Rogowski coil. This is consistend with prof. Muael's prediction. 2. shots 37276-37300 are clean up shots. plasma lasts 6ms.

Wednesday March 5 06 46 Maurer/Paul 37308-37355 rotation
Doppler rotation data taken using the Thomson scattering viewport to measure the perpendicular plasma He emission. The measured wavelength shift is constant to within 2/100ths of an Angstrom (equivalent to +/- 1km/sec rotation). This constant value will be used to set the baseline of the measurement. There is a baseline shift due to temperature drift that is in the process of being calibrated out now that other systematic errors have been removed. Analysis underway. In taking off the TS collection optics to mount the rotation optics for todays run, a burn spot on the Nikon collection lens was noticed. This might be effecting the position alignment and calibration. Please stop in tomorrow Alex so we can talk. Lastly, we had problems initializing the crates at the end of the day. An unknown RMA error in the action monitor was a sympton. We were unable to correct the problem. cua900 will be rebooted tonight and we will try again tomorrow. This could delay the start of the VF feedback run Thurs.

Thursday March 6 05 27 Maurer/Pedersen 37363-373425 Radial Feedback open loop
Today we did the open loop tests of the radial position control system. It was a very successful day. With the aluminum shells at 8 cm, the plasma moved 2.5 cm in 1.5 msec when we applied a 4 msec square pulse of 250-300 A to the FB coil system. Positive current made the plasmas move inward, negative currents made the plasma move outward. Inward moving plasmas would disrupt early. With the shells at 4 cm, the plasmas were observed to move approximately the same amount but it took about twice as long to get there. The response looks approximately like an exponential decay, consistent with a resistive decay. The outward movements were confirmed by the soft x-ray centroid, which also moved outward. The inward moving plasmas did not have a clear signature on the soft x-ray centroid, presumably because we have several bad channels on the inboard side. Some problems with the LANL control prevented us from doing more fancy waveforms, and will need to be fixed before closed loop feedback can be attempted.

Wednesday March 12 07 07 Paul/Maurer/Cates 37429-37497 Rotation Diagnostic Comissioning
Run was devoted to gaining confidence in the toroidal rotation measurements. Known from earlier runs that the screenroom temperature slightly affects the diagnostic, even though the diagnostic housing is temperature controlled to within 0.2 degrees C. 37429-37445 optimize shots for duration and minimum MHD
37446-37452 track down noise appearing as isolated spikes in rotation diagostic
37453-37464 align detector to look perpendicular to plasma flow; take reproducible shots and record dependence on screenroom temperature
37465-37497 switched to normal toroidal view to look at rotation:
conclusion: 1. once the helium in the plasma is ionized (after 2 msec), the measured value of toroidal velocity is within ±1 km/sec of zero.
2. plasma seen to spin up steadily in the toroidal direction up to 6 km/sec in counter-clockwise (looking from above). Plasma velocity abruptly drops to zero (in < .5 msec) about 1 msec before the end of the shot. Plasma always disrupts subsequent to the locking of the plasma rotation. Sometimes the rotation will drop to near zero, but the plasma recovers and spins up again, only to lock a second time and disrupt fatally.
3. For most shots, plasma rotation increases over the lifetime of the shot, never reaching a steady value, when the locking and disruption occurs. On a few, the rotation appears to saturate. On such shots the SXR signal also saturates and rolls over. On the more common shots, SXR increases steadily and drops suddenly just prior to the disruption.
4. I am fairly confident in the results from the rotation diagnostic once the helium is ionized. The next step is to use various techniques, beginning with the bias probe to alter the plasma rotation and see the effect.

Thursday March 13 04 39 Maurer 37498-37514 Feedback & Setup
Today we ran plasmas in preparation for mode control feedback and started to set up the bias probe and mach probe for future experiments. The capacitor bank for the bais probe was run through a dummy load at the end of the day. It appears to be fine. I had a few problems with the pwr supply and a flakey trigger before it worked. We will re-route cabling tomorrow. We should have both probes in the edge plasma tomorrow(that was the goal for today). As a side note, the LANL unit was tested again on Tuesday with its repaired charging supply. The output is railed at 250A(as it was in last weeks expt) when no input is applied! For the initial VF feedback tests of Feb and early March we ran the unit about once a week for a 6-8 hour period. This output is possibly caused by an offset drift somewhere after the input stage that needs to be tweaked or a bad driver tube on the hot deck. We're flying somewhat blind without schematics for the amplifiers so it may take some time to figure out the actual cause. The output tubes appear to be OK in the sense that they turn on and draw the same filament current. Our attempts at actual position feedback will be stalled until this is fixed.

Tuesday March 25 05 21 Maurer 37588-37627 MC Feedback
Todays run goal was suppression of disruptions induced by 3/1 RWMs using the new mode control coil set in order to compare performance of the new system with smart shell feedback. I had great difficulty getting good RWMs to suppress in making the plasmas. The 3/1 external mode observed today was a short bursty fluctuation (almost delta function like) giving a fast kink that only caused minor disruptions. I am using similar bank settings, etc. that we have used in the past to make good RWMs for the smart shell experiments. Varying the Ip ramp rate and initial q after plasma startup did not have a significant effect. Shilov has agreed to run Friday instead of tomorrow, so I will continue with these experiments on Wednesday!

Thursday March 27 05 15 Pedersen 37640-683 ICRH
We ran the ICRH today. Not much progress to report. Most of the day was spent developing discharges that move inboard without disrupting but the run was cut short because of a water leak that is being fixed now. The ICRF was fired on a small number of shots and appeared to behave as usual.

Thursday April 24 05 42 Maurer 37940-37960 biased probe
Ran plasmas in D2 today. Checked out new triple probe circuitry. The new box is working fine (first actual triple probe operation!). Measured Te~12ev in the high field side edge and densities (a few 10^12 per cc) were similar to those that were measured when the probe was measuring just isat previously. Some minor wiring needs to be done and then we should be able to install the box in the north rack and have it as a day to day diagnostic in the tree (Pedersen). Ran biased probe shots later in the day. Had some problems with the floating potential measurement that need to be fixed. So the run was not too productive. More tomorrow. Ended the day by installing and testing the differential amps in the north rack for real time Ro in the control room for position control. One of the four chs checked out ok, but the other three had clipped square wave outputs with a sine wave input. Not sure why. I will pull the box out and we'll have to test it on the bench to see why. It was working previously. An aside on run summaries... As a group we have been somewhat forgetful as of late in writing up run summaries(myself included). To help in jogging our memories to do so Thomas and I thought it would be useful to remind run operators that writing the summaries is not optional. It is mandatory (similar to the checkout list that must be filled out prior to running hbtep). In the future please submit forgotten run reports the next day or asap. Thanks.

Friday April 25 05 43 Maurer 37961-37967 setup for VF feedback Progress was made on getting real time Ro in the control room today. (I thought this would take the morning, but it consumed the whole day) Pulled the differential amps for real time Ro in the control room out of the north rack this morning and bench tested them. The dip swtiches for the gain stage must have not been been switching properly. I had set them for unity gain yesterday and I must not have pushed down hard enough to engage the switch on the three that were not working. The clipping observed yesterday was due to them still being set for high gain (G=1000). They work fine now. I changed the input integrator on the board to have an RC time of a hundred microseconds so the west rack signals are not so highly attenuated but still low pass filtered for noise. Signals from the north rack and then west rack to the control room checked out ok through the whole isolation system. The differential amp gain was adjusted so that the "system" gain was ~1 at 1kHz. Plasmas were then made with the actual Ip and cos1theta signals form the west rack going over to the north rack and then via the iso-network to the control room. Good news: the data base signals for Ip and Ro look uneffected (recall that the everything looked like a flux loop when previously connected). Not so good news: the observed signals in the control room have features of being correct during the bias and startup phases of plasma operation, but then saturate and are pinned at 4.5V throughout the rest of the discharge. Perhaps there is an extra gain I measured incorrectly.

Tuesday April 29 05 08 Rivera/Maurer none
LANL fix Today we made some progress with fixing the LANLs. The LANL hotdecks were taken apart and tested. It looks like one side of the push-pull output now works. Some history: Previously, problems were fixed in the output stage of the low voltage feedback inputs(input trigger and feedback signal electronics). This had minor effects on the railed LANL output. A bad power supply was then found in one of the hot deck drivers and replaced. After which we were then unable to generate any output at all. Today the trigger and feedback signals were measured at the input to the hot deck and checked out OK. A mosfet that drives the hot deck driver tube on the A-side did not have the same feedback signal superimposed on it as on the B-side (A and B are the push-pull sides). This might still be a culprit in the way it was not working before. We can not say exactly because more than one thing has been fixed prior to being able to measure the output LANL current. We then carefully re-assembled the hot decks and powered the system up. The output is now a half wave rectified version of the input sine wave (with no large offset!). It looks like one side of the push pull configuration is now working. The lack of output after the first hot deck fix was probably due to bad/missed connections or the driver tubes weren't seated properly when it was re-assembled (we think).

Wednesday April 30 04 55 Maurer 37968-37977 biased probe
Ran plasmas in 10% Helium for biased probe rotation studies. Fixed the floating potential measurement box and reinstalled it for the days run. Still could not get a good Vf measurement. The digitizer signal looked essentially like a flux loop. I thought this was due to pickup from my extra long cable runs to the south and then north racks since we've moved the probe 180 degrees around the machine to the microwave interferometer section. Previously when the probe was at the old mach probe stand by the south rack I had no such difficulties with the measurement. After inserting the probe more deeply into the plasma to see some type of plasma potential fluctuation signiture on top of the flux loop pickup on the signal it still looked like a flux loop alone. I then checked continuity to the probe tip mechanically in two different ways. It appears that the feedthrough connections to the probe tip have opened up since it was installed. I believe I'll have to pull it behind the gate valve and check the internal connections out at atmospheric pressure. Too bad. This is now probably a good time to switch the positions of the internal magnetic probe and biased probe stands since I am bringing the bias probe head up to air ( so the new internal magnetic probe is at a chamber section with stainless shells instead of aluminium). We can start this in the background while people run Thurs and Fri.

Thursday May 1 05 05 Cates 37978-38020 RWM Smart Shell Feedback
The Smart Shell Feedback configuration was setup and tested for a RWM run using non disrupting RWM unstable plasmas. shots 37992-38007 were discharges with moderate current ramps which had sizable RWM modes and then large tearing modes later in the shot. Feedback with full gain and coverage was applied to these shots in an attempt to see changes in mode growth rate and rotation frequency. The rest of the shots were an attempt to get a plasma with a mild current ramp which was unstable for a longer period of time, but the plasma was moving around a lot in major radius so I was unable to get a better target plasma to apply feedback to.
ROTATION DIAGNOSTIC
I used the 10% He gas mix and Steve Paul's rotation diagnostic was online - there may have been some offset problems due to the screenroom being warm at the start of the run (shots 37981-37985). For a few shots (eg 38007,38015) the trend of the rotation signal was slowing down with time - the opposite of the normal temporal evolution - this may be due to a changing major radius, but is worth checking out because it is the first time we have seen this trend.
MAJOR RADIUS FEEDBACK
Dave was able to get real time signals of the plasma current and Cos Theta rogowski coils to the control room for use with the dsp.

Thursday May 8 10 43 Cates 38045-38064 RWM Traget Plasma Development
In the morning the Ebara cryo pump adsorber was replaced and the pump was regenerated. The pump temperature was cycling from 8K to ~40K before the change - this symptom was resolved with the new adsorber. Afternoon run was an attempt to create fast startup (high beta) discharges with unstable RWM. I had trouble getting a fast startup and could not drive the initial plasma current above 8 kA. Something seems to have changed in the breakdown. I was running in 100% D2 - last week I attributed this breakdown effect to the introduction of Helium, but maybe something else is going on. Thomas tested the recently modified triple probe box, but did not get good diagnostic signals. The connection of the Cos theta coil to the north rack and control room for use by the dsp for real time radius measurements had to be disconnected because it interfered with the normal digitized signal by introducing a large pickup.

Friday May 9 11 24 Shilov 38067-39106 External Field
I continued with 3/1 external field experiments with current ramps. Running in 100% D2, I experienced the same problem of low initial current as reported by C.Cates in the previous run summary. Raising puff time to 1.7 ms seemed to fix the problem. Something may be wrong with the puff system. I'll check it tomorrow. Data from static and rotating external field application on current ramps was gathered in the afternoon. Still needs to be analyzed.

Tuesday May 13 01 49 Rivera none LANL fix
The LANL amplifier is working again. The output looks the same as it did when first turned on ~2 months ago. However, it should be recalled that at that time there had been an offset in the feedback signal due to a failing tube in the ouput stage. A problem that was not addressed with this fix.

Thursday May 15 01 27 Shilov 38107-38158 External Field
(note: Shilov is referring to krytrons when he writes ignitrons -Nick)
As I expected, the recent problems with plasma start up was due to a half-dead battery in the puff unit. After replacing the battery I was able to reduce the puff time 2 times compared to what I had to set it in the previous run. The reproducibility also improved. Some good data with rotating external field was collected. Later in the day I started having problems with VF CB bias ignitrons (both) firing spontaneously. Nick suggested it was due to ignitrons' age and cut the 'keep alive' wires from the ignitrons. It seemed to fix the problem with the spontaneous firing but produced another problem which was that the bank wouldn't fire ~20% of the shots. That was pretty annoying. The end.

Thursday May 15 04 29 Maurer none fixing cryo
Cates' run was postponed today so we could pump and purge the ebara cryo He supply to see if that stops the temperature cycling that started Monday afternoon (Shilov ran with only the cti cryo Wed). The adsorber that we replaced last Wednesday appears to have only temporarily solved the problem we were having. If this does not fix the problem the seals are mostly likely bad in the expander head and will either have to be replaced or a rebuilt pump head purchased.

Monday May 19 04 36 stillits 38163-38174 Ip signals
Ip raw signals from North rack were tested in DSP. Unfortunately, the output signal from the DSP did not give the correct profile for the plasma current because the raw data received from North rack was influenced by noise (similar to a flux loop). We have to check it out tomorrow (Tuesday).

Thursday May 22 10 35 Maurer none cryo repair
Wednesday was spent taking off the ebara cryo to be sent out and rebuilt. It was FedEx'ed by the end of the day. The gate valve on that pump stand has a through leak at atmospheric pressure. This brought the base pressure in the chamber up to a few times 1e-7Torr while we were taking the cryo off. We blanked off the 10" gate valve and pulled a rough vacuum behind it to stop the through leak. The base pressure in the chamber is now back down to what it was prior to taking the cryo off at 1e-8Torr.

Tuesday June 3 04 43 Pedersen/Stillits/Rivera none LANL/Radial feedback
Today's objective was to control the LANL power supply (driving the feedback coils) directly from the DSP in open loop configuration. We were partly successful: We were able to control the LANL with the DSP but the signals were noisy and distorted to the extent that this problem will need to be fixed. We narrowed the problem down to the optical isolation output having trouble driving the input on the LANL when the LANL is gated on. We are investigating why. Otherwise, the LANL was working well (except tripping too often), there were minimal current offsets, when driven directly by a signal generator. Also, the optical isolation network seems to be fully functional except for its inability to drive the LANL input. Signals looked clean when input into a scope at both 1MOhm and 50 Ohm.

Monday June 9 02 54 meeting time
The weekly HBTEP status meeting shall forthwith be held at 9:30am Monday mornings in the control room.

Thursday June 12 10 24 Muarer none intalling cryo
The rebuilt cryo arrived yesterday and was re-installed in the afternoon. It was cooled down late yesterday and was valved open to the chamber this morning. Base pressure is back down to 6.6 e-9Torr with the rebuilt cryo head a 8K. Shilov is making plasmas today.

Friday June 13 10 45 Shilov 38276-38314
Clean up shots. Plasmas OK

Monday June 16 05 19 Pedersen/Stillits/Rivera none LANL/Radial control
We used the afternoon to check out the LANL some more. A reference signal was reconnected following a conversation between Dave Nadle and Nick Rivera. This did not substantially improve the signals, which were rather noisy. We then tried to use a 1.5 V battery to generate an input signal to the LANL certifiably free of ground loops. The LANL basically ignored this signal and put out a current of -5 Amps regardless of the polarity of the battery, and whether it was hooked up at all, and even when it was connected in parallel with a large capacitor. I now suspect that the input on the LANL is malfunctioning. On the bright side, 5 A of offset is 40 times better than it used to be. An arc inside the LANL stopped the run and will be checked out tomorrow.

Wednesday June 18 10 30 Shilov 38315-38384 RWM, External Field
I spent the morning developing reproducible target discharge with q* approaching 3 slowly from below. It was successfully achieved after a while. Later in the day I applied static and phase flip external fields to the plasmas. The results look promising. The data is yet to be analyzed.

Monday June 23 03 04 Cates 38423-38454 RWM - IP Ramp
Friday 6/20 - Discharge development in an attempt to get a plasma with a RWM which grows slow enough to observe growth rates without disrupting the plasma. By the end of the run, I was able to get plasmas which would work well for a systematic feedback study. These shots (38444-38454) had large 3/1 modes which grew and saturated in .25-.75 ms with frequencies of 4-7 kHz - excellent targets for our smart shell feedback system.

Tuesday June 24 05 29 Cates 38455-38490 RWM Smart Shell Feedback
I continued making the mild current ramp discharges which looked promising from last week. After finding a fairly reproducible shot, I applied full gain smart shell feedback to the plasmas. The feedback clearly alters the rotation frequency of the mode, and sometimes reduces the amplitude. I will need to check the mode structure and growth rates more carefully. I am looking at the RWM in the first 4 ms of the shot - but these plasmas do last to 8-9 ms with significant sxr sawteeth and saturated tearing modes in the second half of the shot.

Tuesday June 24 09 03 Shilov 38385-38422 External Field
I continued with 3/1 external field experiments on the target discharge developed previous day ( ex. Shot #38371 ). The naturally growing RWM was observed with a short unstable time window between ~2.3 – 3 ms. The plasmas lasted for ~ 3-4 ms. I applied static external field with phase flips at 2.5ms and 3 ms. After analyzing the data, it looked like the RWM mode is unstable around q ~ 2.8 and stable above that value which could be related to the error of the edge q measurement. Unfortunately the data collected wasn’t sufficient to make any conclusion on the difference between plasma field phase rearrangement time at 2.5 and 3 ms. I will continue with the experiment this week.

Thursday June 26 11 51 Shilov 38492-38542 External field
Continued with 3/1 external field experiments with the previously developed discharge. Took a lot of phase flip shots with different flip times. The data is being analyzed.

Friday June 27 02 01 Alex Klein n.a. T.S. calibration
HBT-EP was filled to 170 Torr nitrogen. The non-laser wavelength channels showed a signal when laser was fired through the chamber, due to Raman scattering. I checked to note absence of breakdown in laser beam at this pressure. Collection optics were carefully aligned to maximize signal, then I proceeded to pump down and to collect sets of 5 data sets (for averaging) on scope at several pressures. The signals appear to depend linearly on fill pressure (good). Complete dissappearance of signals at pressures below 1 Torr show absence of stray light leakage into non-laser wavelength channels. Ease and accuracy of interpreting T.C. gauge for nitrogen is a plus. Ease of aligning collection optics in the absence of stray light is a great plus.
A minus: Chamber appears to be water logged; it remains to be seen how dirty of an ordeal a nitrogen calibration is. Will analyze todays data and write short report on Thomson Scattering system.

Monday June 30 05 04 cates/stillits 38542-38559 cleanup & ip-signal testing
Cleanup runs were performed. Ip-signals from north rack: signals are looking much better (having almost the right profile), but the signals are too constant - looks almost like a step-function (which gives a linearly increasing plasma current). We have to check that tomorrow.

Tuesday July 1 05 56 Cates 38560-38619 Clean Up
Clean Up shots taken to recover from up to nitrogen for Raman scattering calibration. Current Ramp discharges are fairly consistent, although the loop voltage is still around 10 V for a standard 10kA plasma (compared to around 5 V last week). Royce has been testing the triple probe: We tested the triple probe's electronics circuitry box today using the oscilloscope. Channel V1 and V3 performed as expected. V2 which will indicate the temperature is still saturating the scope so we are reducing the floating potential from 1/5 Vo to about 1/10 or 1/20 to get a complete measurement; Overall a successful test. Remi has noticed a large magnetic pickup on the soft xray tomography channels which is present even when diodes are disconnected and amplifiers are off - he is testing the system to see if he can improve the pickup.

Thursday July 3 01 48 Cates 38620-38656 CLean Up
On Wed. I tried to reproduce earlier RWM discharges, but the machine was not quite clean enough to get reproducible results. As a reference the Loop voltage for 10kA current ramp shots was down to 7-8 V. So half way through the day I switched to taking high current, outboard limited plasmas which lasted as long as possible in an attempt to scrape the limiters clean. These shots improved through the day. Several diagnostics were tested during the day: Yuhong discovered that the flux loops have been disconnected for the month of June (shots 38257-38647). Remi was able to improve the magnetic pickup on the soft xray tomography channels by finding and removing a ground loop in the copper box. The triple probe electronics box was tested by Royce and signals were very noisy.

Tuesday July 8 05 18 Cates 38691-38723 RWM Current Ramps
This morning I took about 15 shots with high current and edge q near 2 in order to help clean up the outboard limiters. These shots were also good for testing the SXT channels. In the afternoon I switched back to mild current ramps in order to produce observable RWM growth rates. I was able to get good target plasmas with Ip and minor radius increasing monotonically and q edge slowly dropping below 3 to induce a 3/1 RWM at around 2-3 ms. See shot 38719 as an example. Unfortunately about the same time that I was able to get reproducible plasmas - the South Rack digitizer signals became flaky and I had serial highway errors almost every shot when storing the South rack data (the feedback sensor coil data). The south rack is being cooled properly and I am not sure what is causing the serial highway errors. Royce, Remi and Nicolai were working on the triple probe, sxt and vf feedback diagnostics respectively throughout the day - no big news for any of those systems.

Thursday July 10 09 58 Shilov 38724 - 38777 Ext. Field I started developing a good discharge for RWM external field experiment in the morning. In the afternoon I started getting reproducible plasmas suitable for the experiment. Around that time the same serial highway error appeared and persisted as it did the day before. After a while it was in every shot. So no signals from the south rack could be digitized. I completed the run.

Friday July 11 05 01 Cates 38823-28870 RWM Smart Shell Feedback
First I examined some shots Mikhail has worked on with edge q going from 2.6 to above 3. After checking to make sure the feedback system was in good shape (one board needed a minor repair - signal 5BS1 was bad) I took full gain feedback shots on these discharges. The best shots are 38848-38859. I then switched back to the more standard current ramp shots I have worked with in the last couple weeks in order to complete a gain scan with feedback. Unfortunately the South rack serial highway problems began around 3:15. I did a few tests trying to eliminate this problem and found out that the problem does not go away after an hour with the south rack crate off, that it is not the crate controller or u-port adapter. It must be a problem with the camac crate itself, it did not occur until the crate had been on for about 6 hours, and did not go away in an hour. The plasmas were well behaved with loop voltages around 5V and the feedback system is working well, so it was a disappointment to quit early due to camac problems.

Tuesday July 15 06 08 Cates 38897-38960 RWM Smart Shell Feedback
I completed a gain scan with relative gain values of 1, .5 and .25 on current ramp plasmas with non-disruptive RWM's.
example shots:
38901 fb off
38902 fb on full gain
38934 fb 0.5 gain
38950 fb 0.25 gain
The plasmas were fairly reproducible and the feedback was working well. -Alex took Thomson scattering data - the laser fired flawlessly - the signal strengths were a little weak - which could be explained by lower density and temperature of plasma during current ramps. -Royce continued testing the triple probe circuitry and Remi tested soft x-ray tomography amplifiers. -Nicolai and Dave tested some buffer amps for getting coil current signals to the control room for use in the radial position feedback system.

Wednesday July 16 12 30 Alex Klein
Hello all: The following is a draft of the Thomson Scattering poster abstract to be submitted to APS. Any comments, suggestions, words of approval, etc. would be greatly appreciated. Thanks very much, Alex "Thomson Scattering on the HBT-EP Tokamak" A. Klein, D.A. Mauer, M.E. Mauel, G.A. Navratil, C. Cates, M. Shilov,??? Thomson Scattering can provide accurate, non-intrusive measurements of the electron density and temperature in a plasma at a spatially and temporally localized point. Thus, this diagnostic represents one of the most attractive methods for measuring essential plasma parameters. We have revived the existing Thomson Scattering system on HBT-EP and improved the resolution and calibration of the instrument. The system is based on a design in use at DIII-D (Carlstrom, et al, Rev. Sci. Instr. 61, 2858, 1990), and uses a 800 mJ pulsed Nd-YAG laser and a five channel interference filter polychromater. Absolute system calibration is achieved using Raman scattering in nitrogen (Yamada, et al, Rev. Sci. Instr. 74, 1675, 2003), because stray light levels have become excessively high and the Raman technique is more accurate than calibrartion based on Raleigh scattering alone. The scattering system is triggered at key times during the 10 msec tokamak discharge; the obtained measurements are compared with conductivity temperature data for several plasma configurations.

Wednesday July 16 06 15 Cates 38961-39009 RWM Smart Shell Feedback
In the morning I took some more feedback data with reduced feedback gain to complete yesterday's gain scan. In the afternoon I ran the feedback at full gain with only the 10 midplane coils activated. I was able to get several good shots with feedback. examples:
38987 fb on
38986 fb off
Unfortunately I lost about two hours due to yet another camac thermal problem - a crate in the west rack has a bad fan on its power supply, and the power supply would shut off every few minutes due to overheating. The crate was stable the rest of the afternoon after adding an external fan to the power supply case. Nicolai and Dave successfully tested a buffer amp to fan out the vfc and ohc signals to the control room for radial position feedback.

Sunday July 20 11 00 Shilov 39010-39133 Ext. Field
I continued with 3/1 external field experiments on "high beta" plasmas. Collected some good phase flip data on Thursday. On Friday I was struggling to get the same reproducible discharge but the plasma s were really disruptive and I couldn't sustained then for more than 4 ms. After a while I realized that the TF bank setting was changed from 6.1 to 5.7 kV some time from Thursday evening to Friday morning without indicating that in the data base. After raising it to regular value the plasmas got much better but unfortunately the south rack camac error appeared at the same time. So I had to finish the run.

Tuesday July 22 04 58 Alex Klein 39137-39195 T.S. parameter space
Rather than run Thomson scattering shots yesterday afternoon, the entire day today was used for that purpose. Yesterday, the biased probe and the internal magnetic probe were installed instead. Todays runs: D. Maurer spent a good bit of time trying to create low temp. high n plasmas, to see the T.S. signals clearly with those kinds of plasmas (Ch. 2,3,4 should vary greatly in the 1-10 eV range). A few shots appear to show low temps according to T.S. data. Fill pressure does correlate with higher n according to T.S. data. Ch. 4 gives generally very hefty signal (up to 250 mV) and correlates well with density for a range of temperatures. The afternoon was devoted to try to achieve max temp and moderate densities, to try to see a signal on channel 5, which is supposed to be sensitive to higher temperature plasmas. Unfortunately, could not see any signal in Ch. 5. Will analyze all data from today more thoroughly later.

Tuesday July 29 05 38 Maurer 39299-39333 cleanup
Cleanup shots only were taken today. As mentioned at the Monday meeting the base pressure was an order of mangitude too high after the weekend bake out and had a N2/O2 ratio characteristic of air. A blown circuit braker and bad pump on a manifold that has a high pressure leak caused the problem. The pump was replaced yesterday and the pressure came down to 1e-8Torr. The manifold that it was connected to contains the limiter piece that we had difficultly sealing after our last up-to-air. This is most likely the location of the leak although we did not leak check separate sections of the manifold to prove it. The first twenty shots taken today were cold with no sxrs and Vloop around 10V. By the end of the day I was seeing some sxrs and the loop voltage was coming back down to 7V. We probably need another morning of cleanup before we get good discharges.

Thursday July 31 04 40 stillits/shilov 39334-39362 testing of signal
The raw and semi-integrated cos1T-signals were finetuned. The signals match the signals on the HBTEP-Tree. PS. CTX has asked us to shot down their camac crate every evening.

Wednesday August 6 12 15 Shilov/S.Pauel 39377-39422 Rot. Diag/RWM The objective of the experiments was to reproduce RWM shots I use in my external field experiments running with 10%He 90%D2 so the Princeton rotation diagnostic can be used to measure ion rotation. As I pointed out before the plasmas were more disruptive compared to those with 100% D2 and it was hard to maintain q* between 2 and 3. In several discharges which parameters were close to those of target plasmas rotation diagnostic showed pretty constant ion rotation rate of 2-4 km/s. Also speculation can be made that the ion rotation is slowed down by the plasma magnetic field fluctuations. Good shot to look at are:
39413
39422
39409
Also, as S. Pauel noted, the ion rotation measurement could be affected by the plasma moving inwards, which was necessary to maintain the desired q* profile. Since the view line of the rotation diagnostic is fixed, the He rotation was measured at different plasma minor radial. On Friday 08/06 I tried reducing the He concentration from 10% to 5% by mixing gases from two bottles in the puff line. After the first attempt of mixing 100%D2 with 10%He and 90%D2. The rotation diagnostic radiation levels stayed the same. After the second attempt the levels went below the level required for rotation measurement. I assumed this technique of mixing wasn’t working properly.

Wednesday August 6 04 00 Maurer/James/Klein 39432-39442 Probes/TS
Fixed offsets on the triple probe today. Fixed cabling and setup Mach probe. Should be able to piggy back and get Mach ignals in the tree tomorrow. Bad news: TS laser alignment was bumped. The laser was realigned through the aperatures on the optical table. Thomson signal was seen with plasma shots. Data analysis underway to see how much realigned signal magnitude differs from last weeks shots.

Thursday August 7 04 02 Maurer/James/Klein none setup
No plasmas made today. Setup the capacitor bank, trigger and cabling for the bias probe. Finished setting up the Mach probe. In the process of installing the internal magnetic probe. Should have new data from all three tomorrow.

Friday August 8 05 28 Mauer/Liu/James 39447-39472 Diagnostic D. Mauer tested the Bias Probe and data was taken. R. James positioned the Mach probe in the plasma (shot 39469), but the signals were weak. We will investigate more next week to improve the signl strength. Y. Liu hooked up the Hall internal magnetic probe system. The whole system is now operational! But there are some things that need to be checked -- channel two is noisy compared to channels one and three; channel four has some problems with the amplifier.

Monday August 11 04 13 stillits/cates 39475-39483 vfc/R - signals
The VFC-signal was fine tuned. Output-signals for major radius, R, was obtained. The maximum difference in major radius from the MDS-scope and the output-signal on the scope is 3-4 mm.

Monday August 11 06 24 James/Cates 39484-39486 Triple Probe
Just a few shots taken. C. Cates gave an instructional session on how to affect changes to the plasma by adjusting various parameters. Unfortunately, we ran out of time. These 3 shots are an initial attempt to produce cold/inboard limited plasmas, ideal for testing the triple probe. We will continue to produce these cold plasmas plus hot, sparse, and dense plasmas for more testing in subsequent runs.

Friday August 15 11 52 Cates --- Power Outage
Due to the power outage yesterday the vacuum chamber went up to a maximum pressure of 2.2 mTorr. It quickly pumped down to 8e-8 Torr with the turbo pump, and is mostly water. Both cryo pumps have been regenerated and are now cooling. The ignitron cooling lines burst this morning when power was restored and flooded the basement. The water is mopped up and should be ok by Monday. The servers (cua900, beta, sherwood) are back up and running normally.

Tuesday August 19 04 36 Maurer/Rivera none none
No plasmas today. TF cooling oil system problems. The pump on the TF cooling oil turned on briefly and then tripped its 20A circuit breaker while getting ready to run. In inspecting the unit the pump motor is drawing 33A(the breaker appears OK). The starting and running capacitors both checked out OK. The bearings on the unit also seem OK. The compressor part of the unit turns on OK. The motor/pump unit does sound like its running loud compared to previous operation. We are not sure if it is the pump itself or the motor that is causing problems at this point. We will remove the motor and pump unit tomorrow and test the motor to sort out what is going on.

Wednesday August 20 10 45 M. Shilov/ S. Paul 39382-39422, 39537-39550 Princeton Rotation
Ion rotation rate in the shots similar to ‘high beta’ 3/1 shots stayed ~ 3 km/s. Natural mode rotation in these shots with 10%He is somewhat less and stays ~ 3-4 kHz whereas the mode rotation in 100% D2 shots is ~ 5-6 kHz.Also S. Paul noted that due to the plasma major radius shift by ~ 1-1.5 cm the rotation measurement could be taken for different minor radia and could not represent the plasma rotation dynamics. Good shots to look at: 39409 & 39412 & 39422 Ion rotation rate starts building up ( upto 8 ms/ in the shots with higher current ramp at ~ 4 ms when significant increase in SXR signals is observed and sawtoothing starts.Ex. Shot: #39538

Wednesday August 20 01 25 Rivera none
The motor was taken out of the TF cooling unit this morning and tested. It is broken. A new motor has been ordered ($350) and sent next day from a distribuor from NJ. If it gets shipped today we will have it Thursday, otherwise it should arrive Friday for installation. We are unable to run until this problem is fixed.

Thursday August 21 04 20 Maurer 39554-39574 clean up
The new motor for the TF chiller was installed this morning. The TF oil pump is working fine now. Clean up shots taken in the afternoon. I had about 0.25V of SXRs on the central fan array channels by the end of the run. The machine cleaned up in about 15 shots. The basement AC is broken. This caused serial highway errors at the start of the run. As a temporary fix until the AC is working, opening the basement rack door and using a fan to cool the rack got rid of the CAMAC errors. Shilov is running tomorrow.

Wednesday August 27 02 14 Maurer 39593-39621 Biased probe
Biased probe experiments were run all day Tues and Wed morning. The probe is up and running. The problems that I had last time with a fraction of the bank voltage appearing on the probe prior to gating the scr appear to be caused by leakage current through the scr itself. I removed a capacitor on the probe side of the scr that was put in place to attenuate high frequency noise on the floating potential measurement. The voltage that now appears on the probe prior to gating only charges the capacitance of the probe shaft which is small and quickly discharges through the plasma during the breakdown phase. I can run this way now, but we'll spec out a new scr for future use. The shots taken were essentially probe clean-up discharges. With V_probe=175V the probe current was maximum of about 60A and changed significantly during the shot. The probe was inserted 2cm into the plasma edge. The plasmas would typically be pushed in by the VF when the probe was pulsed on, most likely due to impurites coming off of the probe itself. I think I will probably need another 1/2 day of cleanup shots.

Wednesday August 27 07 06 Liu 39622-39649 calibrate hall probe
All channels of internal magnetic probe are currently working well. Thanks Nick! VF only shots were taken to check all the channels. From those VF only shots, it's obvious that the vacuum chamber delays the soaking through of the vertical field a lot. A few TF only shots were taken to calibrate the hall sensors and more analysis will come out later on. Plasma shots show that the hall sensor signals are pretty quiet, which are within the bit error (~1Gauss). However, I couldn't see the magnetic field fluctuation, which is about 5 Gausses seeing from SMPs.

Thursday August 28 03 06 stillits/rivera xxxx Lanl
The lanl is working ! Excellent job, Nick ! We triggered the lanl with pulses (from the dsp) of different polarities and durations, and the lanl did what it was supposed to do.

Tuesday September 2 04 48 stillits 39664-39726 Testing Lanl ouput-signal
Lanl's output-signal is on the Tree (hbtep::top.camac.north:L8210_3:input_2). We pulsed (with a square wave) the lanl by the use of the dsp. We did not get perfect, but ok, output-signals. The spikes on the scope (in the control room), however, are gone ! The maximum difference between the output-signal on the mds-scope and the scope (in the control room) is 20-30 A.

Thursday September 4 04 34 Maurer/Liu/Stillts 39746-39768 Bias probe
Ran more bias probe dischages with the probe tip inserted 4cm into the plasma and biased at 150V into electron stauration. Still cleaning up the tip during the first 10 or so shots. Later in the day I saw the first evidence of driving MHD mode rotation to zero and then in the reverse direction. This phase did not last long, maybe 1/2 to 1msec before the modes would re-accelerate in the opposite (natural rotation) direction. There appear to be amplitude effects while this occurs that can be looked at to see what the correlation is between mode rotation and mode amplitude. Facilites workmen finally stopped by and looked at the AC in the bank room. They need a part to fix the unit and said they will be back on Monday to finish the repair. Nicolai worked on radial position control signals during the run and took more shots afterward. They seem to be OK after some problems yesterday with one of the buffer amps. Yuhong also did some Hall probe shots at the end of the day to see how running more than one detector off of a single battery effects noise levels.

Thursday September 4 04 42 stillits/maurer 39726-39743 Signals. From yesterday:
We had hoped to take some open-loop shots, but we experienced some problems with the cos1T-signal. However, this problem was solved today.

Friday September 5 02 17 Maurer none
No shots today. H20 shutdown in Mudd Bldg for plumbing work. Regen'ed Ebara cryo since the compressor was turned off.

Saturday September 6 02 16 Maurer/Liu 39786-39820 Biased probe
Continued biased probe experiments from Thursday. Fixed a pretriggering problem and then slowly increased the bias probe voltage over the course of the run to V_bprobe=250V. The probe appears to be relatively clean now. I was able to reverse mode rotation from the induced Er. In some cases this did appear to effect the external mode amplitude. Hall probe data taken also.

Monday September 8 05 19 stillits/maurer 39821-39860 testing of signals
The cos1T- and Ip- channels on the diff. ampl. have been fixed and are now working. We are getting slightly better values for the major radius; the max. deviation is 3 mm (compared to the mds-scope).

Tuesday September 9 06 25 pedersen/stillits 39861-39884 open- and closed-loop tests
Open-loop tests (39862-39868) were conducted with success. Moreover, closed-loop tests (39883-39884) were conducted. The desired position was R = 93 cm. The lanl was triggered after 1.4 ms, and the closed-loop algorithm gave the correct lanl-current. In both closed-loop runs the plasma moved in to R = 93 cm after 2ms before it moved out to R ~ 93.5 cm. So, fine-tuning of the feedback coefficients needs to be conducted to improve the feedback system.

Wednesday September 10 06 34 Maurer/Pedersen/Stillits 39885-39951 Biased probe/VFFB
Plasmas were ran today for closed loop VFFB tests and biased probe rotation experiments. The biased probe voltage was systematically scanned from 100V up to 400V in a series of current ramp discharges that caused the q=3 surface to go external at about 2ms. The induced rotation appears to stabilize the m=3 mode as it goes out into the vacuum. More data analysis needed though. Also, in monitoring the triple probe density signal there was a systematic density increase with increasing applied bias voltage from 100V to 250V on the probe. Unfortunantly the triple probe stopped working during the run, most likely due to a blown chip, so I was not able to see the increase up to the 400V level. The probe current appears to saturate somewhat once the voltage is up past 150V at 50 to 60A. Tomorrow I will run plasmas with 10% He and the Doppler rotation diagnostic. We made several closed-loop runs today (39891-39906) with different desired positions of the major radius (91, 92, and 93 cm). Some runs were more successfull than others. The biggest problem with the closed-loop runs seems to be the spikes in the dsp-calculation of the major radius, but we have fixed that by using an interpolation of the major radius. Moreover, we also experienced problems with triggering of the DSP; that also needs to be fixed. We will continue the closed-loop runs tomorrow.

Thursday September 11 05 37 Maurer 39952-39991 Biased probe RWM expts
Discharges were made today in 10% He 90% D2 to study the effects of biased probe driven ExB rotation on m=3 RWMs. I setup a control shot similar to Shilov's with an initial edge q of about 2.7 slowly moving inward in major radius. The edge q would go through the 3 surface at about 3ms. This gave me a burst of m=3 RWM that lasted from 2 to 3ms of typically 3G max amplitude and frequency around 2 to 5kHz. To try and keep the RWM stability evolution due to the evolving current profile the same on a shot to shot basis I kept the start up bank settings the same and varied the OHEL a little on a shot to shot basis to always keep the q=3 surface entering the plasma edge at 3ms. I gated the Bprobe on at different times during the wall mode burst with 100V or 200V on the tip. At the lower voltage I was able to torque the RWM frequency to zero and then down to -5 or sometimes -10kHz. The mode was still present at these rotation speeds. There were periods where the RWM amplitude appears modulated and correlated with frequency modulations as the mode rotation changed due to the probe. The most interesting effects were observed at 200V on the tip. Gating the probe on at 1.5ms just prior to the usual onset of the RWM at 2ms spins the plasma enough to essentially suppress the RWM. What MHD is there before the probe is turned on (start up modes/noise) appear to rotate up -20kHz or so. More data analysis needed. To see this effect look at shots 39986 or 39987. A control shot is 39971 to see the typical RWM burst with no probe voltage. Unfortunantly, the Bprobe had some arcing problems at 200V that I don't understand, so I don't have too many shots like these yet. There also was a systematic change at 200V on the rotation diagnostic (although somewhat small maybe?). I will continue the run tomorrow once I cure the arcing problem.

Monday September 15 04 16 Maurer 39998-4007
Attempted to fix the bias probe by conditioning the tip with 1.5KV at 5mA power supply. The probe tip to ground resistance was 85kOhms before conditioning. After high-potting, the resistance to ground was about 5MOhms measured using the 500V meter. Vacuum shots with the probe tip at 350V had the correct RC decay. Plasma shots with the probe tip inserted 4cm into the plasma with 200V on the tip are still arcing unfortunantly. I will take the probe out tommorrow morning. Good news: Triple probe electronics were re-installed and are up and running. Royce also finished bench tests of the differential amp for the Mach probe. We should be able to install it tomorrow. Nicolai re-intalled his differential amp and tested out his signals. Everything is OK.

Tuesday September 16 05 38 stillits/maurer 40008-40030 testing of signals
Biased probe removed this morning. Arcing damage was found from the copper conductor to the stainless steel housing back by the mounting conflate flange. There did not appear to be substantial arcing or tracking on the Alumina itself from the Moly electrode. The probe is already under repair. We are shooting to have it fixed and re-installed by Friday. The Hall probe saw its first kink mode fluctuations! The signals were tested and are now working. Moreover, the new interpolated major radius calculation is also working (max. deviation is 1-2 mm) and without any significiant spikes.

Wednesday September 17 05 38 stillits 40031-40066 Testing of algoritm
I spent most of the day eliminating bugs in the feedback program. They were found and eliminated, and we got very nice and smooth output signals for the major radius. However, the output signal for the plasma velocity is not smooth enough, but that will be fixed tomorrow.

Thursday September 18 06 50 stillits 40067-40090 Testing algoritm
The new feedback algoritm with the velocity term added is working. The major radius has a max. deviation of 2-3 mm, and the calculated plasma velocity is close to the velocity in the scope. Thus, we should be ready to make the first closed-loop run tomorrow morning.

Friday September 19 05 18 stillits 40091-40114 cloased-loop runs and testing
40091-40108: testing of feedback algorithm with derivative gain. closed-loop runs: 40109-40110, we tried to stabilize the plasma at R=93 cm. It was partly successfull. 40111-40114 (except 40112, the dsp was not triggered), the desired position was R=92 cm (40111 is awesome !). In these shots there are small deviations in the actual position, but they are only of a few milimeters. In future runs we will let the lanl be switched on for more than 3 msec because 3 msec is too short, as can be seen in some of the runs.

Monday September 22 06 45 stillits 40123-40146 cloased-loop runs and testing
Today, the lanl was turned on for 6ms (earlier it was 3 ms). Moreover, in all shots the desired major radius was R=93 cm. We were able to stabilize the plasma at ~ 93 cm for almost 7 ms (shot number 40134). So, the lanl is working for 6ms. We are experiencing problems shutting off the lanl when cos1T reaches a certain value. That needs to be fixed. Corey fixed the major radius so that the major radius, which influences q and beta, is automatically recalibrated.

Tuesday September 23 06 36 Liu/Stillits 40147-40202 Feedback + Hall probe
We ran the feedback for R=93 cm (40147-40154), R=92 cm (40155-40165), and R=94 cm (40166-40178). Moreover, the duration of how long the lanl is switched on was increased from 6ms to 9 ms (from shot 40169). Because of that we were able to repeatedly create plasma of 7-8ms duration. However, the shots for R=94 cm are little too volatile, but that can be adjusted by lowering VF (the lanl was not triggered in shot 40170 and 40173). (Stillits) Hall probe was checked for its low measurements on poloidal field. The reason is supposed to be the influence of the high toroidal field. I am trying to figure out if I can fix this problem. (Liu)

Wednesday September 24 05 21 stillits 40203-40229 feedback
Channel 2 (the Ip-signal) on the diff. ampl. was down today. So, shots 40203-40217 are useless. In shots 40218-40222 we tried to stabilize the plasma at R=94 cm, and in 40222 we created a hot plasma that lasted for ~ 8.5 ms. In the rest of the shots we tried R=91 cm, but it was not a huge success. We were able to stabilize the plasma at R=91 cm for max. 1.5 ms (40223 and 40226). But it can probably be improved by changing some of the parameters.

Tuesday September 30 04 51 stillits 40285-40287 testing signals
We tested the Ip-signal (ch. 2). We are getting a signal now, but the signal looks like a ground-loop signal.

Wednesday October 1 05 13 Mauer/James 40288 - 40305 ICRH/Bias Probe
ICRH fired successfully today! We are still waiting for another crate power supply from Princeton or to receive one being repaired to get comprehensive data, but we did see the ICRH fire via an oscilloscope. We also saw pickups on the mach probe from ICRH which fires at about .002 sec. It looks like one of the channels is OOC on the Mach probe again so I am going to trouble shoot it tomorrow [James]. The bias probe is up and running again(only tested at low voltage yet). I had some problems with triggering that are fixed now at the start of the run. The SCR does appear to be going bad that is used to switch the bank voltage on to the probe tip. I was getting about 10V leakage on the tip prior to pulsing it with only 50V total on the bank. Probe cleanup shots tomorrow.

Thursday October 2 05 22 Maurer biased probe
Took biased probe cleanup shots today. The run was cut short because of problems with the TF bank. An eyebolt nut came loose and caused the one side of the rope dump to short the bank while it was being charged (the bank was at about 5kV). This boiled the local dump water resistor and blew its top off. The cupper sulfate H20 blown out of the first dump resistor appears to have then allowed a conductive path from the neighboring dump resistor, which was at whatever residual voltage was left on the bank, and then shorted the rest of the TF charge to ground burning an arc path in the wood shelf that the dump resistors sit on. The H20 has been cleaned up. We still need to cut out the carbonized material on the wooden shelf before we run again. This should be finished tomorrow morning.

Friday October 3 06 07 Maurer/James/Klein 40319 - 40350 Bias probe/ICRH
Tf repair was completed this morning(Nick and Jim). The bank was brought up to full voltage before lunch and tested OK. Plasmas were made in the afternoon and more biased probe clean-up shots taken. The probe tip was biased to 200V by the end of the day. It appears to still be a little dirty. More clean-up tomorrow at higher voltage. The power supply for the ICRH crate was installed and is a permanent member of the serial highway! Took a few shots and worked out some triggering bugs. Now, the signals are in the tree and showing up on the scope but some of the inputs look switched (will diagnose this weekend). The Mach Probe is also installed and the digitizer for one of the channels is the problem and not the electronics; it will be switched to another open channel.[James]

Saturday October 4 01 45 Maurer 40352-40382 biased probe
Continued taking biased probe cleanup shots today. V_probe= 300V with I_probe=30 to 50A. Nothing exciting to report.

Tuesday October 7 05 34 Maurer/Stillits 40383-40422 Biased probe/VFFB
More bias probe clean-up shots and work on the VFFB signal problem today. First hints of a temperature increase on the triple probe were seen in some shots today. Not as dramatic as previously observed but an improvement from Saturdays run. Typical currents with 300V on the probe are about 50A. The probe appears to be clean enough to apply 100 to maybe 200V on the tip without disrupting the plasma. shots taken with 300Vs still cause the plasma to move in and disrupt, probably due to impurity influx. Hopefully the 200V case will be a useful ICRH target for tomorrows run. The feedback system is up and running. Nick solved the problem we have had with ch. 2 on the dsp.

Wednesday October 8 06 36 Mauer/James/Stillits 40423-40461 ICRH/Feedback
It took about half he day to with the scope and signal generator to put the ICRH system back together again. Once that was figured out, we took a few shots before Shilov’s Invited talk dry run. We were unable to perform the ”high density inboard limited” plasmas with the working ICRF because of time restraints, but we were able to get some good baseline ICRF data while tuning the feedback system. If there is time, tomorrow afternoon we will try again with the bias probe (to get high density plasmas). Subsequently, the feedback system has been fixed and all channels are operating normally. The feedback system (and most of the other diagnostics) was greatly affected by the ICRH discharge. Some sort of filter or shielding will have to be explored now that we are actively trying to couple the plasma.[James]

Monday October 13 05 22 James/Stillits 40557 - 40590 Testing (Triple Probe/Feedback)
Shots 40557-40579 Feedback shots to calibrate system with newly installed filters. ICRH Will fire tomorrow to test filters. [Stillits] Shots 405780-40590 Tested the triple probe and mach probe electronics and they are working at spec. on the bench. When installed in the rack, density signal (triple probe) is still erratic and the right channel (mach probe) is flat/no signal. Concentrating on the triple probe (for the ICRH run on wed. and thurs.), I tested the cabling from the probe to the electronics with the high voltage meter and they were good. Next I bypassed the t-probe electronics and used the m-probe’s power supply, rogowski coils, and electronics/o-scope to test the raw t-probe signals. After 10 shots, the probe appears to be working normally, but more testing tomorrow so we hope to lock in a solution. Alex was able to prep Thompson Scattering and get signals into the o-scope. It is ready to go for tomorrows Testing. Thanks to Yuhong for hanging around and babysitting the new plasma shooters! [James]

Tuesday October 14 05 35 Klein/Stillits 40610-40630 Thomson Scattering The plan was to create very hot plasmas which tend to be outboard limited, then use position control to (rapidly) push the plasma inwards into the field of view of the TS collection optics. In preparation yesterday, I (Klein) crudely aligned the laser. Should have done this more critically. Today: Very healthy signals on all channels, including #5, which is supposed to come in to play for hot plasmas, was very encouraging. These signals were present for warm plasmas at r = >94 cm, surprising. Then we made hotter plasmas and pushed them inboards, as planned. Timed TS to coincide with r= 92 cm position. Signals looked the same. Finally, TS was fired after plasmas had long died: signals looked the same. Conclusion: laser beam is poorly aligned, scraping some edge or surface, overwhelming stray light is creeping into each channel. Will re-align laser and try again...

Tuesday October 14 05 50 stillits/klein/james 40592-40649 testing of signal + TS + IRCH
The feedback system is up and running again with the new filters installed. The max. deviation is only a few millimeters. That is also the case when ICRH is turned on. The problem we had getting the lanl to give a zero current when the semi-integrated signal for cos1T is less than zero has been fixed. So, we should be able to run the ICRH with feedback tomorrow.

Wednesday October 15 05 27 stillits/james 40652-40667 feedback + ICRH
40652-40655: The signals were tested with IRCH on.
40657-40669: The feedback was turned on and the plasma was positioned at 92cm.
40660-40662: The feedback was turned on and the plasma was positioned at 91.5cm.
40663: The feedback was turned on and the plasma was positioned at 92 cm. The IRCH was turned on at 2ms.
40663: The feedback was turned on and the plasma was positioned at 91.5 cm. The IRCH was turned on at 2ms.
Rough day at the shop for the triple probe. I was unable to diagnose the problem with the density channel. After making some repairs to the electronics and installing protection, the output was not correct. I was also unable to get the third channel to trigger on the scope and ran out of time before I could try the others. I will try those early tomorrow and if I can’t get the probe to function as a triple probe, then I will run it as an Isat probe or use the mach probe electronics and use it as a double probe for ICRF testing with the Feedback system. [James]

Friday October 17 09 24 Pedersen/Stillits/James 40680-40733 ICRH
Today's objective was to do plasma-RF antenna coupling experiments using the radial feedback system to move the plasmas inboard in a controlled way, and the triple probe to confirm increased densities. Although we did not observe any clear signs of heating, we did see some antenna loading, so the run was successful overall. Transient loading of the ICRF antenna was clearly observed on a number of shots, including on the order of 10 shots where the loading was clearly observed before the plasma disrupted (eg. 40692). Towards the end of the run day, a decent target discharge for further studies was developed. Shots 40720 and 40723 are good examples of this discharge without ICRH. The radial feedback was preprogrammed to move the plasma from outboard limited to inboard limited for 1 msec, then back to being outboard limited. Ion saturation current from the inboard side triple probe (the box is still bad, hence no real density measurement) would increase by 30-80% during these jogs. On a number of shots we hit the plasma with ICRF during this phase. Most of these shots disrupted but a few survived (40728 and 29). These two plasmas were apparently not pushed far enough inboard to couple to the antenna. We will want to continue development of these discharges next week, hopefully with the Bdot probe and the triple probe box up and running.

Monday October 20 07 55 James 40734 - 40749 ICRH-RF Pickup Probe Ran ICRF this afternoon to prepare for tomorrows run. I first used the o-scope to insure that the probe and transmission lines were operational. They did in fact produce a signal, though it seemed a little askew. I then tested multiple digitizers until I was able to get a signal. Finally I was able to reproduce a signal in the tree that resembled the signal in the scope, but not the typical RF B probe in absences of plasma; see shot #40749 (atypical) and compare to #36547 (typical). Also notice that the loop voltages are very different in these two shots, but I am not sure it could cause such a drastic difference in the RF B probe signal. In the morning I will run with a plasma and the ICRF and diagnose the problem if indeed there is one.

Monday October 20 10 32 Nick None Since no runs were scheduled at this morning's meeting we, the technical staff, used the time to modify the ICRH cabinet. The ICRH should not be run until I have time to inspect the cabinet for run readiness!!!

Tuesday November 11 04 31 pedersen/stillits 40751-40758 ICRH + feedback
We did not make any plasmas today because of problems with some of the U-port adapters.

Wednesday November 12 05 38 pedersen/stillits 40760-40802 ICRH + feedback. We tried to create reproducible plasmas that behaved like preprogrammed in feedback:
1.8msec - 2.8msec: R = 93 cm
2.8msec - 3.8msec: R = 91.5 cm
3.8msec - disruption: R = 93 cm
At the end (shot#: 40795-40802), we were finally able to create reproducible plasmas that behaved as preprogrammed in feedback. The ICRH was turned on in shot# 40796, 40798, 40800, and 40802, but turned off in shot# 40795, 40797, 40799, 40801. However, we did not see any heating of the plasma that could be a consequence of ICRH. Next ime we will try to push the plasma farther inboard (to R ~ 90-91 cm).

Thursday November 13 05 23 pedersen/stillits 40803-40836 ICRH/radial feedback
We continued developing discharges for ICRH coupling using the radial position control system. The ICRH rack appears to give serial highway problems so it was bypassed. We (Corey+Dave) suspect the power supply is faulty. The rack was bypassed, so no antenna loading measurements today. On the positive side, the triple probe box works fine, and did so all day yesterday as well, except for some minor offsets on the temperature. Using the triple probe inboard density measurement, we developed discharges that have 3.5-5*10^18 m^-3 density for about 1 msec as the plasma is shoved inboard by the radial control system (used in both closed loop and open loop feedback today). This is a factor of 2 improvement over typical inboard densities (2*10^18), and is close to inboard densities seen during inward disruptions (5 to 8*10^18). The ICRH was pulsed during some of these discharges. No clear effects of heating but we are somewhat limited by several diagnostics being offline (ICRH diagnostics were out due to CAMAC problems and the soft x-rays appear not to be working). Further discharge development will be done when we have ICRH diagnostics available to confirm loading and coupling.

Friday November 14 04 10 stillits 40837-40877 ICRH + feedback
Shot# 40837-40867: We tried to creaty discharges (with 20% H2) with and without ICRH. We were able to obtain inboard edge densities around ~ 5e18 m^-3 (shot# 40863, ICRH turned on at 3.5 msec), and we presumably saw an increase in temperature in shot# 40855 (ICRH turned on at 3ms). Shot# 40868-40877 (Steve):
We tried with He 10% to create discharges that stayed at R = 92 cm for a considerable time. In the last shot we succeed in doing that.

Friday November 21 02 51 steve paul/stillits 40868-40922 rotation + feedback.

Friday December 5 07 37 Rivera/James/Mauer 40923 - 40937 ICRH
We tested the voltage dividers on the ICRF today via the oscilloscope and they performed as expected! Data from the run with voltage and current measurements is being analyzed. We are in the process of setting up the digitizer to make the dividers a permanent diagnostic measurement for the ICRH system. The CAMAC crate and power supply we ordered came in about mid-day and was immediately tested and installed. Preliminary tests show that it is operating normally. Shot # 40936 shows an ICRF only shot through the tree. The B-dot probe is not set up correctly, but the others are performing normally. Soon after this shot, we had some trouble with the dumps not responding to the reset controls in the control room. This problem fixed itself, but we are not sure of the cause or the fix. The air conditioners in the basement also froze causing the CAMAC racks to fail. We shut down in effort to let them cool off with external fans, but they were still over heated by the end of the day. Nick is working on the air conditioner repair, but until that is complete, we may have to revert back to shutting down during lunch and any other periods of extended down time between shots.

Friday December 5 12 24 STILLITS 40939-40941 testing software
Thanks to Mikhail, the software for the feedback system is now up and running. John (study group) put the feedback current cable in the ceiling, and it is working.

Monday December 8 06 27 Maurer/Stillits/James 40949-40967 A little bit of everything
CAMAC problems from last week caused by ICRH rack, possibly due to the fiber optic cable to the u-port adapter. Everything is working OK now. Worked on circiuitry for capacitive dividers for ICRH. (James) Shots taken to check out new control panel operation of radial position feedback setup writing text file to dsp, recompiling the program, and initializing the dsp fro an external trigger. So far so good! (Stillits) Turned up gains for new RWM feedback. Checking out sensor and control coil signals. Real feedback on current ramps tomorrow. (Maurer) S. Paul called and is planning on coming up Friday.

Tuesday December 9 05 15 Maurer/Stillits 40968-41007 testing feedback and software.
Checking, correcting and figuring out some errors in the RWM feedback wiring. Nothing important to discuss yet. (Maurer) The software for the radial position feedback control system is up and running. The feedback system was successfully tested with new software and the new feedback-current cable. So, the feedback system is now operational!!! (Stillits)

Thursday December 11 10 33 Maurer 41007-41021 RWM feedback
Yesterdays run was cut short due to the same intermittent bank problem we had last week. The cap bank dumps were not reseting properly from the panic panel. Nick and I went to work on it this morning but the dumps worked fine. Again, the problem "fixed" itself. So we will have to wait until it breaks again(and stays broken long enough that we can diagnosis whats going on). When problems are about to occur the bias bank dump fails first. If you are taking shots the signature of this to look for is the OH bias bank controller not reaching full charge while the rest of the banks do(red light never goes on). The next time the dump button is hit on the panic panel the dumps will not reset. If this happens let Nick and I know so we can fix try and diagnosis whats going on.

Thursday December 11 12 01
Today at 1pm, I'll show how to use the feedback system. Nicolai

Thursday December 11 03 59 james/pedersen/stillits 41025-41036 ICRH + feedback
We tried to create a discharge that behaved as a square-wave with respect to major radius. We succeeded in doing that when we got problems with the ICRH. The charging power supply in the basement is down.

Monday December 15 06 12 James 41069 - 41099 ICRF
It was slow running today. The CAMAC Serial Highway was down most of the morning and half the afternoon. Apparently there were some access violations that fixed themselves after Cory rebooted the system as the administrator. Some good news, the circuit breaker seems to be holding on between shots. Had trouble with the B-probe as well. The L_8210 did not seem to be working. I replaced it with another and tested it with an fxn generator. Then tested again with new digitizer and both rectified and un-rectified signals. Neither signal was seen via the digitizer or the scope (turns out that the new L_8210 is not 1 mega-ohm, and a new 1mega-ohm will have to be found and installed, but the scope was set for 1 mega-ohm and it did not see a signal). I tested the resistance of the lead wire form the probe coil in the machine to the ICRH crate and there was none. There may be a problem with the wire, connections or the probe itself. I did just get signals from this probe after APS, so the failure is even more peculiar and recent. I checked the connector, and it was tightly fixed so I will have to ‘probe’ deeper to find the solution. I was unable to test the capacitive dividers at high voltage, but further analysis of the low voltage tests performed earlier last week show the frequency to be ~4.505 MHz.

Tuesday December 16 07 01 D. Maurer/S. Paul 41100-41174 bias probe with radial control
We were looking for fluid rotation effects with the bias probe turned on. Typical example without probe is 41124, where the natural rotation is about 5 km/sec in the ion drift direction (toroidally clockwise, when viewed from above HBTEP). Edge MHD measured by the shell probe increases from 5.2 msec onward on that shot, and the mode growth is coincident with the braking of the plasma. The plasma rotation slows to near zero by 5.9 msec, at which time the plasma disrupts. For the most part, the probe seemed to make the plasma cold and difficult to control. Perhaps the reason is lack of conditioning as the probe was last used some time before the APS meeting. The best example of the bias probe's effect the rotation is 41145, where the ion flow was reversed, however that does not occur often. Shot 41142 had the bias probe turned on, yet the results were very similar to shot 41124, as described above. The best correlate with high rotation appears to be a strong SXR signal. A good example is 41109 and 41127, where the edge rotation jumps following each sawtooth crash.

2004

Friday January 9 03 42 Alex Klein n.a. TS calibration
Filled chamber with nitrogen and performed Raman type Thomson Scattering system calibration. Laser was stil aligned through the chamber, needed no adjustment, near perfect burn spot on inboard side. Laser energy still 800 mJ. Inspected optics, all clean and good. Collection lens was aligned carefully. Took 5 shots at each pressure (from 150 to 5 Torr), swapped Ch. 3 and Ch. 5 electronics to calibrate Ch. 5 and repeated. Data was saved in spreadsheet form for more precise analysis. Now will have to calculate gain coefficients for each channel. Water contamination appears to be minimal (RGA says 10^-7 Torr, mostly nitrogen, after 1 hour pump down).

Wednesday January 14 04 06 Maurer 41175-41205 Clean-up
Clean-up shots taken after up to N2 for TS realignment and calibration. Plasmas lasting 5 to 6 msec by the end of the day. SXRs visible after only 10 shots or so. Will continue tomorrow.

Tuesday January 20 06 31 T. Pedersen, R.James, N. Stillits 41242 - 41257 ICRF
We were able to run ICRF (with no B probe) today. We took about 15 shots with the Feedback system on. We did see some signs of loading (comparing shots 41249 vacuum shot to 41256), but were again stopped short by what seems to be more CAMAC problems. This time in the VF current, and it seems to be intermittent. We will look into it more tomorrow. We are planning to try again on next Tuesday. It seems like we are on the right track with the high density plasmas moved into the antenna with the feedback system approach.

Monday January 26 04 16 Maurer 41258-41279 feedback
Took several VF only shots to start the day and check out the VF bank current monitor problems from last week. The digitizer/circuitry behaved correctly the whole run day. I will keep an eye on it this week to see if the problem re-occurs.
The rest of the day was spent taking set-up shots for the weeks feedback runs. I am starting to see some nice m=3 fluctuations as the edge q drops below 3. These are in shots that start with an initially low plasma current, have a rapid Ip ramp and send the q=3 surface into the vacuum anywhere from 2 to 4ms depending upon the bank voltages. I had some difficulty keeping the plasma centered and this would lead to some shot-to-shot variability. I plan to run tomorrow with the radial position control from the start to help keep the major radius from moving out and forcing the edge q too low. Todays run is cut short because I have to go in for my allergy shots at 5pm. I will continue tomorrow.

Tuesday February 17 07 49 Maurer 41477-41506 MC feedback
Todays run goal was to continue the feedback experiments of a week ago using the new mode control coil set with poloidal field sensors. I had some difficulty during the whole run generating target RWMs to feedback on. Started to see small RWM fluctuations near the end of the day. Also had some difficulty breaking down late in the day. The D2 bottle is nearly empty (has been low for awhile) and I plan on changing it before tomorrows run. This might have lead to some of the problems getting a nice fluctuation to feedback on relative to last week where I was adjusted the puff time to change the RWM onset time with qstar. The feedback was turned on during a few shots to check the loop. Things seem to be OK. I will continue again tomorrow.

Wednesday February 18 05 28 Maurer 41507-41531 Feedback
Spent the day trying to setup plasmas for feedback. Still had problems with the breakdown off and on again. Changing the D2 bottle had small effect on the breakdown problems. As an aside the D2 manifold is showing its age. It has to be maxed out to just barely get the fill line pressure above 20 psig(where we usually run). This was one of the reasons I though the bottle was low and the high pressure side gauge might have been reading incorrectly. I now think think the high pressure gauge is OK. Also checked the puff fill pressure and it seemed reasonable at 2.4 e-5 for 1.5ms puff with the puff battery voltage at 223V (the input circuitry for the puffline says it needs 220V). Checked the egun and its working OK with 9A of filament current and 220V bias. Later in the day I replaced the puff line battery with a new one (246V) and the breakdown became more consistent. I was able to get the puff time back down to 1ms and still had it breakdown. It looks like the battery was marginal and giving rise to most of the problems breaking down. Not much progress in setting up target plasmas as a result. More tomorrow.

Thursday February 19 05 55 Maurer 41533-41557 Discharge development
Spent the day trying to develop an Ip ramp down case with nice m=3 RWM fluctuations for feedback. Had no breakdown problems today. Discharges exhibited lots of tearing activity with minor or major disruptions before the q=3 surface went external. Some signs of RWMs but nothing as nice as the target plasma fluctuations of last weeks runs. The change in puff valve pulser battery has changed the machine fill pressure for a given puff valve pulse time. I am adjusting for this to effect to try an reproduce the previous runs RWMs with essentially the same bank settings. It hasn't quite worked out yet. I will continue tommorrow.

Friday February 20 05 17 Maurer
No shots taken today. Planning on Saturday feedback run.

Saturday February 21 12 58 Maurer none none
Came in this morning to run and found the base pressure at 5.5e-5Torr and the Ebara cryo head at 268K. The CTI cryo was still pumping, but the head temp was at 15K(a little warm, should less than 10K). After valving off the Ebara the pressure came down to 3e-7Torr and was composed mostly of water on the RGA readout. I spun up the turbo and switched over to it so I could regen the CTI cryo. The base pressure went up slightly to 5.3e-7Torr. I am currently pumping on the CTI head. I have also pumped out the Ebara cryo head. I turned on the bake to help get rid of the water. The base pressure is now in the low 1e-6 range with the turbo only. I am not sure what happened to the Ebara cryo. After inspecting the compressor it appears to have blown one phase of its 220V, 3phase pwr. I found the cable plug had a blackened pwr pin on it. The circuit breaker appears not to have blown which I find confusing. Hopefully the compressor is not damaged. I will stay until the CTI head has been pumped on fully and turned back on to cool down. This takes 2 to 3 hours to reach final temperature. If someone who lives nearby wants to stop in at 5 or 6PM and switch over pumping to the CTI cryo once it is cold let me know. Otherwise I'll stop in Sunday and do it.

Sunday February 22 03 55 pedersen
I switched over from the turbo to the CTI cryo at ~3:30pm today (Sunday). Pressure was 2.7e-7 before the switchover and started dropping at a good rate when the gate valve was opened to the cryo. It is currently 9.7e-8 and continues to drop.

Monday February 23 03 53 Maurer None
Opened up the Hall probe array bellows to the vacuum chamber after the group meeting. The pressure went up to a few 1e-7 composed mostly of water. Kept the bake on until midafternoon. The base pressure is now in the low 1e-8 range. Nick is currently inspecting the compressor to make sure it has failed. We will try hooking it back up to pwr tomorrow when new plug ends arrive from McMaster. There was no obvious damage inside the compressor housing. Maybe it was just the plug ends that failed. We have a quotation for an advanced exchange with a 2 day turn-around time (they have a matching compressor in stock) from Genesis Vac Tech if it turns out the compressor is bad. The price is $3950. I did not get a chance to take any cleanup shots today. I plan on starting tomorrow morning. After about ten shots or so if the machine still looks dirty I will glow in He. Also, Yuhong is ready to piggy-back and test the four Hall probe channels that she has installed.

Tuesday February 24 04 19 Liu 41560-41573 test Hall array
There were just two shots were caught in today's run and the rest of the day we experienced serial highway failure. Mikhail tried to bypass CTX and ICRH, but it didn't work out. The Hall array was working except they were more noisy than the old array. More shots need to run to analyze the reason.

Wednesday February 25 06 01 Maurer/Liu 41578-41639 Clean-up shots
Took clean-up shots today. Started to see sxrs and tiny sawteeth by the end of the day. The Ebara compressor is OK. The cable end only was damaged in the weekend failure. This is very good news. It has been re-installed and was opened during the last 1/3 of todays run. This helped quite a bit in pumping out stuff knocked off the walls. I had to raise the puff because I had trouble initially breaking down with both cryos pumping. It was after this that I was able to get some sxr signals on the fan array. Yuhong ran piggy back and worked on her Hall sensor signals. The noise problem of the Hall sensors comes from the power of the amplifier. When I used a battery, one of which were used for Hall sensor current source, together with a car battery powered the amplifier, the annoying random noise was gone. Also, G=10/100 were tested for vacuum shots and both worked fine. I will monitor the Hall sensor's behavior when Dave runs tomorrow.

Thursday February 26 05 20 Maurer 41640-41682 Clean-up shots
Took more clean-up shots today. By the end of the day things were looking good enough that I was starting to develop a target plasma for feedback. Vloop was less than 10V at plasma start-up evolving down to 5 or 6V at discharge termination compared to greater than 12V yesterday during most of the run. I am switching to the shot type with a RWM generated by the initial qstar less than 3 and slowly evolving up to 3 (similar to shilov's case) that I used for RWM bias probe experiments this fall. This would typically give a burst of m=3 magnetic fluctuations between 2 to 3 ms. Yuhong also worked on her Hall probe sensor signals. There appears to be high frequency noise on the signals at discharge start-up and termination that might require filtering.

Friday February 27 05 16 Maurer 41683-41691
Only a few shots taken today. Tested out the Hall sensor array. The problems with noise are a result of layout and cabling problems. This is good news in that an input filter will not be needed. The actual layout of the 20 channel array will have to be done very carefully.

Monday March 1 04 12 Maurer 41692-41732 target plasma development
Spent the day trying to generate m/n=3/1 RWM fluctuations. Tried dialing in old shot number bank settings that Shilov used as a target shot. Plasmas generated this way were different from the database case, with typically higher loop voltage and different major radial and qstar evolution. The wall-limiter conditioning must still be not quite up to what we need to generate these plasmas. Spent the rest of the day trying to develop a case with the initial qstar at about 2.7 after discharge start-up evolving toward qstar of 3 by 2 to 3ms into the shot. This would traditionally have a RWM fluctuation from 2 to 2.5ms and a few Gauss amplitude in the past. Was somewhat successful at this but the plasmas did not have a good m=3 fluctuation to feedback on perhaps due to profile effects. I will continue tomorrow and turn the feedback on even if I don't have a mode just to check things out. I am out early today to go and get my allergy shots.

Tuesday March 2 07 15 Maurer 41733-41780 Setting up target
Took more shots today trying to develop target for RWM feedback experiments. I had one clear example of an m/n=3/1 RWM on shot 41744. This can be seen on the smps and ssi Br sensors just around 3ms. I took this shot after the machine sat for 1 hr, so the prior shots residual gas was well pumped away. I was unable to reproduce this plasma by lowering the puff (so far at least). Comments and suggestions welcome. Also, the Ebara cryo head has recently started to make pinging noises most likely due to the seals starting to go bad in the head. It was rebuilt last June so I hope it is under warranty.

Wednesday March 3 05 17 Maurer 41781-41792 target development
Working on target plasmas (still). Trying to adjust puff time and bank settings to generate RWM fluctuation burst as qstart approaches 3. More work to be done tomorrow. Both beta and sherwood had to be restarted this afternoon. I hope this did not disturb peoples work too much. Nick has contacted the company who rebuilt the Ebara cryo head this summer about warranty coverage. Hopefully we'll know by tomorrow or the end of the week what the situation is. As it stands now the head is holding its 8 K temperature. There has been to signs of temperature cycling yet.

Thursday March 4 05 31 Maurer 41781-41826 target development
More of the same. Another day of trying to get a good RWM for feedback studies. I am contemplating going back to the ramp down case. Comments.

Sunday March 7 10 47 Maurer 41728-41778 target development
Took more shots Saturday. After trying to develop target discharges, I switched to a high Ohmic input plasma to generate sxrs and cleanup the limiters and walls.

Tuesday March 9 07 13 Maurer 41881-41891 clean-up
Had a short clean-up run only today. I will try the RWM case tomorrow. In other news the Ebara cryo head has stopped squeaking for at least the last two days (maybe Sunday too). Maybe it will last longer than was first thought after all. I will keep a close watch on it. The FPGA arrived yesterday. Alex is sorting out some software driver issues with NI. The leaking pipe in the bank room is sceduled to be fixed tomorrow morning. The run will commence after that is finished.

Wednesday March 10 05 29 Maurer 41892-41942 Clean Up/Target development
Took 30 clean up shots to start the day. Then switched to target development shots. Started to see a choppy burst of MHD fluctuations as q_star was approaching and going though 3 from below. The fluctuations were of lower frequency than the background MHD nosie. Reproducibility was better than during the last weeks, but still not too robust. These are the first encouraging results in about two weeks! Here's looking forward to tomorrow.

Thursday March 11 12 40 stillits 41953-41960 Testing RPFB
The RPFB is up and running again. Moreover, we have modified the control panel application.

Thursday March 11 04 36 stillits none Modification of Control panel application.
- the control panel application has been modified to use triangles instead of square-wave as input for RPFB.

Monday March 15 06 12 stillits 41962-42017 feedback
Feedback on major radius (with the new application) is now working. Feedback on q* seems to be working, but some more finetuning needs to be done.

Friday March 19 10 11 Maurer 42018-42027
Yesterdays run was cut short by a problem with the TF charging resistor. There was some arcing from the top of the resistor to the water column. The top electrode had broken off from the charging supply lead during the run. A new electode is being manufactured and will be installed asap.

Monday March 22 05 26 stillits 42069-42124 q*-feedback
We tried to perform feedback on q*. The algorithm does the right things, but there are some minor problems with the gains, which need to be finetuned. We'll work on that tomorrow.

Tuesday March 23 04 35 stillits 42125-42154 q*-feedback
We were able to get the feedback on q* up and running today. There are, however, some "small" deviations between q* in the scope and q* we calculate. The max. deviations in q* are approximately 0.2-0.3 and in some cases 0.4. The reason for this is the small value of the minor radius a squared (a^2 ~ q*), which will change q* by 5-10% when the major radius in the scope deviates by, for example, 4 mm compared to the major radius we calculate. When we take into account these deviations, we can still get very nice feedback values on q*:
Shot #42137-42146: We tried to put the plasma at q*=3.5. After having chosen the suitable parameters (which only took a few shots), we were able to get some nice shots #42141 and #42142 (and also #42143).
Shot# 42147-42154: We tried to ramp up the plasma from q*=2.7 at 2.4 msec to q* = 3.1 at 4 msec. Again, it took only at few shots to tune the parameters. The nice shots are #42150, (#42151), and #42154.

Monday March 29 04 12 stillits No shots. Application.
The Control Panel Application has been modified. Control of q* (including q*-ramps) has been included.

Tuesday March 30 07 23 James No Shots Maintenance
At about 9:45 last night I found a large amount of water on the floor in the basement. It was centered on the bias probe electronics and when I looked to find the source I noticed that it was the leak that Jim has been trying to get maintenance to repair. Over the weekend I guess it had filled the drip pan. It was a lot of water and it spread over to the dump, I vacuumed it up with the wet-vac, but before we run today that space (from the wall behind the bias probe to the dump) should be checked again to be sure I didn’t miss anything before it is powered up.

Tuesday March 30 07 26 James No Shots Maintenance
At about 9:45 last night I found a large amount of water on the floor in the basement. It was centered on the bias probe electronics and when I looked to find the source I noticed that it was the leak that Jim has been trying to get maintenance to repair. Over the weekend I guess it had filled the drip pan. It was a lot of water and it spread over to the dump, I vacuumed it up with the wet-vac, but before we run today that space (from the wall behind the bias probe to the dump) should be checked again to be sure I didn’t miss anything before it is powered up.

Wednesday March 31 05 10 Maurer RWM development
News from Tuesday: the leaking pipe in the bank room was finally fixed by facilities. Todays run was cut short by a minor arc on the TF coil set. A nut on one of the coils for the lug connection to the current feedthru had come loose. When the last shot of the day was taken part of the lug was vaporized giving rise to a big flash when the arc occured. The TF current trace looks just like the previous shot, so the full bank current still flowed through the arc to the coils. Nick and Jim have cleaned up the contacts and re-made the lug connection. All other TF connections have been checked also. I will check the resistiance and inductance of the coil and compare it to others before running tomorrow.

Thursday April 1 03 52 Maurer 42176-42185 checking out TF
We had another TF lug arc at the same spot as yesterday. Started the run today by bringing the TF up a kV at a time until we reached 6.1 kV to check out the new lug end. Everything appeared to be fine. Took one plasma shot with full TF, VF and OH banks. On the second plasma shot the lug arced at the TF current feed just like yesterday, blowing off the end of the lug. Apparently, the threads were damaged enough that the nut loosened up again an caused an another arc. We are discussing various possiblities about how to proceed. Input and any comments are welcome. New lugs have to be ordered and should be in tomorrow.

Monday April 5 05 05 Maurer 42185-42205 TF check-out
Checked out the new TF coil lug attachment today that was arcing last week. So far so good. I brought the TF up in kV steps initially checking the lug nuts between every shot. After reaching 6kV with the TF only I took about 5 shots with full banks making plasmas while still checking the lug nuts every shot. They were nice and tight every time. After that the remainder of the plasma shots were taken checking the lug nuts every 2 shots then 3 shots. They were OK the whole afternoon. I will continue to check them tomorrow gradually increasing the number of shots between inspections. Tomorrow I will be attempting to generate RWMs approaching qstar=3 from below using the Ro-qstar equilibrium feedback to help reproducibility.

Wednesday April 14 10 43 D. Maurer, Alex K. 42248-42270 FPGA tests
Yesterdays run summary... Inserted FPGA processor into one poloidal set of sensors/control coils (bottom shell, upper set). Digitized raw sensor signals, filtered signal that reach the FPGA, signals from the FPGA, and current in control coils. Will analyze data to see how it is consistent with mode control algorithm and filters. We tried several gain settings on the analog boards to see at what point crunch amplifiers are overdriven. More work needs to be done, including checking polarity of control coils and current shunts, (spatial) phase shifting of output signals.

Wednesday April 21 02 51 Alex Klein 42271-42315 FPGA testing
Yesterday, fixed polarity issues with current shunts. Also took many shots with sine wave driving things instead of sensors (no plasmas), to measure overall system transfer function. Today, verified control coil polarities and then ran toroidal phase shift scan on bottom-midplane FPGA group with all signals looking very nice. Took shots at 0,45,90,135 and 180 degrees toroidal shift. Will analyze data. Hope to wire in remaining FPGA groups by end of week.

Thursday April 29 09 53 A. Klein 42326-42434 wiring/repair/configure
The FPGA global mode control system is installed and functioning. All analog boards, FPGA wiring details, control coil current shunt polarities, crunch amplifiers, control coil polarities, sensor coil polarities, coil integrities, etc are fixed, configured, functioning, verified. Now ready to apply feedback to RWM plasmas at various spatial phase angles using 20 sensors/coils configured in 4 groups of 5.

Thursday April 29 05 07 D. Maurer, Alex K. 42438-42457 mode control testing
Applied DFT FPGA mode control with all available coils. Only covered 2 spatial phase angles for feedback: 0 and -85 degrees. Will require much analysis to see actual effects on the plasma, and much analysis to see what effects should be acting on the plasma.

Friday April 30 04 33 Maurer none
Bias probe reinstalled and bellows assembly leak checked this week. Opened gate valve to chamber this afternoon. Pressure rise was maximum of about 6e-7 Torr and composed mostly of H2O. The bake has been on for over an hour and the base pressure is already down to 2.8e-8 Torr. We will continue baking over the weekend.

Thursday May 6 04 54 stillits 42464-42519 clean-up shots.
Clean-up shots were taken with RPFB and biased probe turned on.

Friday May 7 04 53 stillits 42520-42591 clean-up shots. Clean-up shots were taken with the biased probe and RPFB (R=94 cm and R=93 cm) turned on.

Monday May 10 03 43 stillits 42592-42605 H-modes (Biased probe + RPFB)
In our attempt to create H-modes, we ran the biased probe with RPFB. However, after a few shots, the biased probe arched. We measured a high-voltage short between the tip of the probe and ground. The probe has been pulled out, and the gate valve has been closed.

Tuesday May 11 05 39 Alex Klein 42607-42630 Global Mode Control
Initially, trouble with basement digitizer. Ch 2 on 8210#2 in basement appears to be out, switched VF bank signal to Ch3. Then, developed discharges to yield q* < 3 at start, then slowly ramp through q*=3.
Ran several shots with FPGA mode control ON at t=2 msec, off at t=3.5 msec for 0 and 180 degree spatial phase shifts.
Did not run radial position control, will do so tomorrow.

Wednesday May 12 05 18 Alex K 42631-42668 FPGA mode control
Performed gain scan on FPGA system: It had been slightly overdriven previously (increasing gain caused no increase in crunch amp current). Reduced FPGA gain setting and found gain setting which causes max crunch amp output (5-7 amperes)for typical plasmas.
Ran with radial position control, with goal of keeping plasmas alive as long as possible while slowly ramping through edge q =3 from below. Found m =2 tearing modes to dominate everything at 4 msec, resulting in disruptions. While FPGA feedback was on at various times for many shots, these may not be too meaningful...
Plans now have changed: perhaps run through edge =3 quickly and from above, to look for RWM before tearing modes dominate ? Did some discharge development in this direction.

Friday May 14 10 15 Alex Klein 42669-42722 FPGA model control
Spent a while developing discharge with aggressive OH ramp, such that edge q runs through 3 from the outside early on in the shot. Got to the point where RWM consistently observed between t=2 and t= 3 msec as edge q dipped below 3.
With this type of shot, then ran with FPGA mode control. Control output gated on between t=1.5 and 3.5 msec. Took data at 45 degree spatial phase shift increments for FPGA output. Have at least two shots at each angle with RWM.
Will have to look at data carefully to be able to say reasonable things about mode control. The RC filters and digital integration, as well as control coil inductances are causing control coil output to be dominated by low frequencies, and phase between sensors and controls highly susceptible to frequency as well.
Puff valve: For unknown reason, puff valve required to be open for 2.2 msec to get comparable gas levels as existed earlier in the day with valve opening only for 1.2 msec. Battery on valve checked out fine (235V), gas lines were all open with adequate pressure….There may be something wrong with the puff valve.

Friday May 21 03 49 Alex Klein 42723-42747 Mode Control
Again used discharges where plasma current ramp = agressive, edge q comes from the outside and rapidly dips below '3', giving rise to RWM early on in the shot. Very clear and reproducible RWM's.
With FPGA mode control algorithm now using much reduced integration time (~15 micro-secs), determined what spatial angle to dial into DFT to have 90 degree spatial phase shift between N=1 sensor mode and N=1 control mode. Took many shots at this setting with and without FPGA running. Consistently had 90 degree phase relationship.
Saw evidence that at "+" 90 degrees, feedback system excites N=1 mode. Fairly reproducible increase in sensor mode amplitude and lower mode rotation rates when FPGA is on, vs. when it is off.
Then, adjusted DFT angle by 180 degrees, to attempt "-" 90 degree feedback, should be suppression of RWM. No clear results. Mode amplitude looks always similar, regardless of wether FPGA is on or not.
Why? -> Consistenly had NO fixed phase relationship between control and sensor coils, i.e. phase is all over the place. Mode rotation rates seem high.
Will now do more rigourous analysis, with some objective method for quantifying data.

Thursday June 3 04 46 Alex K. 42748-42792 FPGA mode control Picked up where we left off 2 weeks ago. Plasma behaved exactly the same, without any tweaking required (edge q comes to 3 quickly, from the outside). Took many shots with spatial phase angle close to 0 degrees, and many shots with phase angle near 180. Cursory glance: RWM looks about the same for the two types. Will require more analysis to say anything meaningful. Then drove control coils with function generator going into analog boards, to explore gain and saturation limits in crunch amplifiers. Then with p[lasmas: began gain scan (at spatial phase angle ~90 degrees), will continue tomorrow and perform gain scan at phase angle ~ -90 degrees.

Friday June 4 04 43 Alex K. 42793-42817 FPGA mode control Hose for ignitron cooling burst, flooded basement. Fixed and cleaned up in the morning. Then continued gain scan from yesterday, at approx. +90 degree spatial phase shift and -90 degree target phase shift. Nearly finished, cua900 computer acting up... Gain scan should be complete after about 20 more shots (to be done next week).

Monday June 7 02 34 Maurer/Rivera
The OHEL bank is back up and running... The fpga is being programed for this weeks latency tests. The run will start tomorrow.

Wednesday June 9 03 56 Alex K. 42829-42871 FPGA mode control
Yesterday, ignitron cooling water hose had burst and flooded basement (again), therefor no runs. Today: With the usual discharge (see past several run reports): Finished gain scan at spatial phase angle which causes mode suppression. Then: Implemented FPGA program which has select-able latency in multiples of 10.2 microseconds, while keeping looprate/sample-rate the same. Took shots at 10, 50, 100, 200 microsecond latencies. It will require lengthy analysis to expose small effect, judging by quick look at the data.

Monday June 21 05 29 stillits 42873-42894 clean-up shots + biased probe
In the first 13 shots the biased probe was not turned on. In these shots the plasma was cold, lasted between 3-4ms, and the plasma current reached 10 kA. The loop voltage was fairly constant ~ 12 in each of these shots. From shot#42887 the biased probe was turned on. The biased probe voltage was increased from 0V to 350 V in 50V-steps. Saturation was reached at 300-350 V in which I_sat = 100-150 A. We saw a few more spikes in the loop voltage (~ 12), and from SXR the plasma was a bit hotter (but not much). However, there is a lot of noice in SXR, for example, so it is not easy to say anything about spikes in SXR. The RPFB was not turned on in any of the shots because of problems with the hot decks on the LANL. Tomorrow we will continue taking clean-up shots with the biased probe on.

Tuesday June 22 05 24 stillits 42895-42931 clean-up shots + biased probe
Clean-up shots were taken. The biased probe (BP) was slowly ramped up to 300V (it looks more like 200 V on the scope), and at 300 V the BP-current was 100 A. The plasmas created lasted for 3-4ms, and the plasma currents were ~10 kA. The signals are very noisy, so it is not very easy - by looking at the SXR-signals - to say anything about how hot the plasmas were, but the spikes in the loop-voltage seem to be absent in some of the last shots. The RPFB was not on because of problems with the LANL, but Nick is working on it. We will continue taking clean-up shots tomorrow.

Wednesday June 23 05 21 stillits 42966-43011 clean-up shots + biased probe
Clean-up shots were taken. The biased probe (BP) was slowly ramped up from 100 V to about 300V, and at 300V the BP-current was ~100 A. The plasmas lasted for ~ 4 ms and plasma current ~ 10kA. There are no spikes in the loop-voltage indicating the BP is clean. Furthermore, as soon as the BP is turned on (at 2ms), the loop-voltage remains constant (~ 10) or decreases indicating the plasma is getting heated (the plasma current ramp is 2.5 MA/s). SXR indicates a hot plasma but it is difficult to say because of noice. The RPFB was not turned on, but Nick is working on the LANL.

Thursday June 24 05 00 Alex K. 43012-43076 FPGA open loop runs
Coerced the machine to produce the types of discharges I have been using for a while now, with agressive current ramp, edgq q approaching 3 from above early in the shot... Spent the day running "open loop" experiments: All 20 control coils were energized with a set of signals that were out of phase with each other such as to drive a m=3, n=1 helical pertubation around the tokamak. At a certain time during the pulse, the polarity of the signals was reversed. (Phase Flip Experiments) Initially (in the morning), I had the pertubation propagate downwards poloidally as the toroidal angle was advanced (along plasma current). Saw little or no mode locking at several frequencies (between 4 and 8 kHz). Then I switched helicity, and found mode locking (between sensor coils and control coils) for a range of frequencies. This means presumably that perturbations are tied to the electron fluid. Can now analyze data to measure plasma response to phase flip of magnetic perturbation, also looks like I can measure plasma amplification of resonant perturbations.

Friday June 25 04 21 Alex K. 43078-43107 open loop, closed loop
The transfer functions of a feedback system seem to be surprisingly important.

Tuesday June 29 04 02 stillits/maurer 4343108-43124 Biased probe
The biased probe (BP) was tested. With BP inserted 3 cm into the plasma, an IV-characteristic was obtained with I_sat = 45-50 A at V = 250 V (the BP voltage was increased to 350 V with no sign of increased BP current). There was no sign of impurities by looking at the loop-voltage (too much noice on SXR). Tomorrow we will perform an IV-scan by obtaining IV-characteristics at different positions of BP in the plasma.

Wednesday June 30 04 50 stillits/maurer 43153-43174 Biased probe
We had BP positioned at 1 cm and 5 cm from the edge of the plasma (it was positioned at 3 cm yesterday) to obtain IV-characteristics. The voltage was increased from 100V to 350 V in 50V-steps. For 1 cm, I_sat was 30 A, and for 5 cm it was 55 A. In the 5 cm case I_sat was reached at 100V-150 V, and in the 1 cm case I_sat was reached at 200V - 250V.

Thursday July 1 04 41 Alex K. 43175-43202 Mode control debugging
Was going to run latency experiments, spent the day chasing down bugs and problems instead. Output signals from the crunch amps on bottom poloidal group are not what they should be. Input signals as seen by digitizer are what they should be. Verified that FPGA module works as it should, and analogboard output stage performs properly as well. Took some plasma shots as part of the bug-chasing work, no good data. Hope to fugure this out tomorrow.

Thursday July 8 05 05 Alex K. 43242-43249 Mode control debugging
The analog boards/rack seem to be fixed after Nick R. worked on it on the bench. All channels are working except for one output signal on one of the bottom control lines (Channel 3B C3). It is a very bizzarre problem that can't easily be diagnosed/explained. Just as I was getting to the bottom this, the CAMAC data aqcuisition failed, presumably because the basement rack is overheating - the air conditioner in the basement is down, Jim A. is on the job of getting it repaired.

Tuesday July 13 05 50 A. Klein 43262-43288 Mode control debugging
Still had problems with one group of output signals - but I think I finally figured out the problem. Will test tomorrow and hopefully everything will be working. Developed discharges also: while the typical type of shot used previously for mode control studies appeared once in a while, it was not as reproducible and robust today as before. Will continue tomorrow, and hopefully run latency experiments.

Wednesday July 14 05 16 A. Klein 43288-43319 latency in mode control
All signals behave properly now. It took a while to get the target plasma, but then the old mode control shot (aggressive current ramp, edge q comes in to 3 and hovers there for a while, slow freq 3-1 oscillations visible) appeared. Ran feedback with 10, 60,110,160,210 microsecond latency in system. Data looks interesting. Every shot from 43302 to 43319 is relevant, no dud shots (which is nice for the operator). Will now have to analyze the data more thoroughly.

Thursday July 15 05 01 stillits 43320-43349 biased probe + RPFB
The LANL and the triple probe are working again. We inserted the biased probe (BP) 5 cm into the plasma, and slowly increased the BP-voltage from 100 V to 300 V. The max. BP-current was 50A-100A. We used RPFB to position the plasma at 94 cm (from 3 to 10 msec), which was fairly successfull. In a couple of shots, for example shot# 43346, we saw huge inboard edge densities up to 6-8*10^18 m^-3. However, we have to smooth the signals before we come to any conclusion. In shot# 43332 we see some interesting stuff. At 4.1 msec to 5.1 msec we see a drop (from 60A to 10-20 A) in BP-current, an increase in SXR from 0 to about 0.1 (the loop-voltage decreases from 12 to 9), and a slowly increasing inboard edge temperature from 5-10eV to 20eV. The inboard edge density seems to be fairly constant. All this could indicate an H-mode.

Friday July 16 08 35 Stillits 43356-43388 Bias Probe +RPFB
Today we ran the biased probe (BP) and RPFB. The BP-voltage was slowly increased from 100V to 250V, and BP was kept at 5cm from the outer limiter. We tried to position the plasma at 93cm and 94cm, but R=93cm seems to be the preferable choise because at R=94 cm we saw huge BP-currents (up to 150A), which could potentially destroy the probe. Beside the noice, we did not really see anything of interest. However, we are getting better at running BP; we were able to create long lasting (8-9 ms) and faily hot plasmas (SXR ~ 0.2-0.3) with BP inserted.

Monday July 19 04 48 stillits 43392-43406 No plasma shots.
We didn't take any shots today. There was water in the basement this morning, and after the basement was dry the OH kryon pulser broke down and some parts had to be replaced. However, everything is working now and as soon we get the D_alpha-meter installed tomorrow we will start taking shots.

Tuesday July 20 05 26 stillits 43407-43447 Bias probe + RPFB
We ran the bias probe (BP) with RPFB on. The plasma was kept at 94cm from 2.5 msec, and BP was inserted 5 cm into the plasma from the outer limiter and voltage was 200 V. In shots# 43411 and 43421 the RPFB and BP were turned off (however, BP was inserted 5 cm, but no voltage on it). We had several very good shots (shot# 43418,43420, 43426, 43428, 43430, 43433, 43438, 43439, 43441, and 43442) in which the BP-current almost dropped to 0 A, SXR increased, loop-voltage decreased, inboard temperature slowly increased, and inboard edge density decreased or stayed constant. Several of these shots (especially shot# 43428, 43433 and 43441) experience an increase in SXR (and a drop in loop-voltage) so soon as the BP current drops to (almost) 0 A, and a decrease in SXR when the BP current increases. These shots could indicate an H-mode. The D_alpha-meter needs to be installed before we can come to a final conclusion about creation of an H-mode. We had expected to install it today but because of APS abstracts we didn't have the time to do it.

Thursday July 22 08 09 James/Stillits 43450 – 43480 ICRF
Spent the morning putting the ICRF back together. There were some minor problems with filling the cooling system reservoir on Monday that were rectified but put us a little behind schedule. ICRF was revived almost without incident. We have a problem with the Jorway trigger and had to run a cable to the one in the west rack so we could run. We were able to take only a few shots bug free (mostly operator error). Shots 43467-43480; our vacuum shot (base line) for comparison with the antenna q ratio for loading investigation was #43478. Most of the shots were not high density, but #43477 looks like a good loading candidate at first glance. The feedback system was not on for this shot (43477) but it was for the others. We hope to spend more time next week with in developing more ideal plasmas and using the bias probe.

Friday July 23 04 32 A. Klein 43481-43532 Mode control phase scan
Ran detailed phase angle scan for FPGA mode control using the 2nd order digital filter, lowest latency, moderate (fixed) gain. I adjusted the toroidal phase of the control field, covered 46 different angles. Found phase of maximum feedback, observed mode frequency increase (substantial) to the "left" of that, and frequency decrease to the "right", implying torques on the modes as expected. It was quite a good day: out of 51 shots, only one is not useful.

Wednesday July 28 08 20 James/Stillits 43533 – 43580 ICRF
Spent the morning developing target plasmas, and fired ICRF in the afternoon. Had to stop running due to difficulty the Jorway timing in the west rack, but fortunately, we were able to get some data and even the data that was time eschewed (baseline vacuum shots) may be salvageable. The bias probe did show increases in the density of close a factor of two, the radial positioning worked like a charm. Thursday we will start with testing the ICRH tree and developing H-mode like plasmas and position them near the ICRF antenna for loading and heating.

Friday July 30 06 14 James/Stillits 43616-43658 ICRF
We fixed the tree problem we were having with the trigger. We were able to basically dial up the plasmas that gave us possible H-modes in the past. We did see some good H-mode candidates during the run (43654-43656), but most were not. However, almost all the plasmas we did develop were ideal for loading studies. We observed loading not just in the initial launch of the ICRF, but also through the shot as well. See the comparison of antenna_q value for shots 43631, 32, 38, 39 (loaded plasma) and 43629, 33, 41 (vacuum) - the vacuum shots are in such good agreement that any of them can be used. I will try to have some print outs available for Monday. More data analysis to come, but we don’t expect to find much evidence of heating. I hope to take more shots like these with the bias probe / RPFB system combination. The densities were close to two orders of magnitude higher than those typically seen without them. So finally we have verified that our theories about positioning densities near the antenna for loading. Next we want to take more shots like these to determine the best density regimes and attempt to heat the plasma!

Tuesday August 3 05 28 stillits 43694-4375 ICRH + BP + RPFB
Today we had the ICRH, BP, and RPFB on. In most of the shots, the RPFB kept the plasma at 94 cm from 2.5msec to 10 msec. BP was kept at 200V in all the shots. With RPFB and BP on, we took shots with and without ICRH. We saw several plasmas that had an "H-mode"-structure (for example shot# 43729). However, there is a problem with the ICRH measurements; the loading is not as high as previously thought, and there is not loading during the whole ICRH shot, as previously claimed.

Monday August 9 04 12 stillits/james 43778-43820 IRCH+RPFB+BP
The LANL is working again, and the D_alpha-meter is installed and working. ICRH: (We ran with Deuterium) The source of the pick-up was found and repaired and the triggering problem was fixed too. We tried all day long to create high inboard densities, but the plasma was pretty "stubborn" today; we never reached above 4*10^19. "H-mode": The D_alpha-meter started working in shot# 43815 (to 43820). In shot# 43820, we see something that could resemble an "H-mode" while we see a (slow) decrease in the D_alpha signal. However, this should probably be taken with a grain of salt since we just got the meter to work.

Wednesday August 11 04 46 Maurer
summary for Tues and Wed... Building power was shut down on Monday night to fix problems with a faulty phase. The cryos where valved off in case they lost power during the shutdown. The base pressure was 1e-4 Torr on Tues morning after not pumping over night and was composed of H20 and some air. After pumping the machine down the base prressure hung at 3e-8 Torr and was mostly H20. We baked in the afternoon and after cooling down the pressure is back down to 3e-9 Torr. Today getting ready to run we had some CAMAC problems that took the afternoon to fix. Yuhong took some VF shots later in the day to test out the Hall amplifier box. We have also been experiencing some problems charging the TF bank recently(last week or so). Nick has checked it out and suspects the charging resistor needs to be cleaned out of Cu debris that fills the bottom of the resistor as the top electrode corrodes. We will take care of this before tomorrows run in the morning. Scheduled runs are still: Thurs ICRH and Fri Biased probe.

Thursday August 12 04 01 Maurer/James/Stillits
More problems today. There was a small flood to start the day off in the bank room. The TF resistor was cleaned out and put back into service. In getting ready to take a shot the TF bank appeared not to charge. Upon going back down into the bank room we found the water leak had opened up again. After fixing this and cleaning up the floor we had more problems charging the TF. After inspecting the bank with Nick and charging it to low voltage locally we found no obvious problems. The problem appears to be intermittant. Several shots in a row at the end of the day were OK. Hopefully the power supply is OK. We are going to see if we can monitor the bank charging current meter on the camera system to actually see what happens when the bank does not reach full charge. No ICRH run as a result.

Friday August 13 05 18 stillits 43853-43908 "H-mode"
We had BP on = 200 V at 5 cm, RPFB = 94 cm from 2.5 msec, and we ran with 20% H_2, 80% D_2. We saw several shot that could indicate an H-mode: for example shot# 43877, 43893, 43895, 43904, and 43906. In shot# 43906, we see a very clear signal of an H-mode: BP-current goes to zero, a drop in the D_alpha-signal, an increase in the floating T-probe potential, and increasing SXR's. The major radius was kept at ~ 94 cm during the whole shot. The T-probe batteries were dead. After we changed the batteries we saw much larger inboard edge densities.That could probably be reason why were not able to make large inboard edge densities last week.

Tuesday August 17 04 52 stillits/james 43917-43972 "H-mode" + ICRH Shot# 43917-43959:
We were able to lower the puff time from 2.0 msec to 0.9 - 1.0 msec and create some hot plasmas; in almost all the shots the loop-voltage started at ~ 9 and decreased to about 5-6 (we saw a lot of SXR's). With these settings we tried to create "H-modes"; in almost all the shots we saw weak and clear signs of an "H-mode" structure. Shot# 43960-43972: In these shots we ran with ICRH turned on. We increased the puff time from 1.0 msec to 2.0 msec to get high-density plasmas. The inboard density reached ~ 8*10^18 m^-3, and the ICRH was triggered at 25 kV - 30 kV. However, we can not say anything about loading; some more analysis is required.

Wednesday August 18 04 54 stillits 43973-44007 "H-mode"
We ran with RPFB (93.5 - 94 cm from 2.5msec to 10 msec) and BP (200 V, 5 cm) on. We saw several signs of an H-mode (especially shot# 43977), but in most of the shots the D_alpha-meter was down because of high temperatures in the screenroom (83 degrees F). We tried to use a fan but it didn't help a lot. By the way, in some of the shots we were able to create very long lasting and hot plasmas: in shot# 43985 the plasma lasted for 9.3 msec, and SXR reached almost 2.0 at 8 msec.

Friday August 20 05 39 stillits/pedersen 44017-44074 ICRH + "H-mode"
"H-mode": We ran with BP = 200 V at 5cm, and RPFB at 93.5 cm from 2.5 msec to 10 msec. We saw several cases with an H-mode structure and a few cases with a "Multi H-mode" structure (2 - 3 "H-modes" (of short duration) in same shot). We also tried to perform density-scans (push the plasma inboard towards the Triple probe during an "H-mode") but it was not a huge success. This was tried in shot# 44050-44074 (the "interesting" shots are 44060, 44061, 44063, and 44065). ICRH: In some of the shots we saw some loading but it requires some more analysis.

Monday August 23 08 08 Y. Liu 44075-44094 VF only vacuum shot
These shots were used to figure out the noise problem of Hall probe array. As prof. Navratil predicted, it is amplifier cross-talk. After keeping on fixing problems, there are two worst channels left now - I can get clean signal by leaving them off. Further analysis needs to be done to have all channels work well. There was water leak in the basement. It was from the old wound of the tube close to TF banks. The ground under TF banks are wet. I mopped the open ground and left the fan on. Hope it will be fine by tomorrow.

Tuesday August 24 05 02 Stillits/Klein 44095-44131 "H-mode" + FPGA
We ran with 20% H_2 + 80% D_2. The RPFB was on and BP =200 V at 5 cm. First we tried to see if we could generate any H-mode structure. When that was achieved we tried to push the plasma inboard towards the triple probe in order to perform a density scan. It was not huge success, but in shot# 44119, 44121, and 44122 we were able push the plasma inboard while the plasma was in some kind of an H-mode. However, we don't see any huge increase in inboard density as we would have expected We tried to do "feedback", i.e. turned on the mode control system to see what effect might be produced by control coils when plasma drops into/out of H-mode and very strong, high freq. MHD modes are present. FPGA algorithm is not at presently designed to deal with 30 kHz modes however, the data is difficult to interpret.

Wednesday August 25 10 25 klein 44132-44137 gain limit scan
Fired vertical field only and ran mode control feedback with various gain settings on analog board to explore limits. Had been running with G=10 for good feedback with plasmas. Now, found strong (saturated) self-oscillations at ~16 kHz for gain settings above 100. (G=100 still OK). Analysis shows oscillations are produced largely as n=1 mode, indicating feedback loop is self oscillating (as opposed to circuitry after FPGA).

Wednesday August 25 04 41 A. Klein 44138-44159 Mode control phase scan
Began filling in more data points for fine phase angle scan, will have data at 5 degree increments (71 shots) by tomorrow. Will then also try to nail down phase angle for positive feedback...

Thursday August 26 11 14 A. Klein 44160-44178 Mode control phase scan
Finished phase angle scan, have data at 5 degree increments for entire torus. Also took some shots around angle where negative feedback is maximized, to try to nail down 90 degree measured phase between control and sensor coil fields. TF charging supply quit for a while, messing with rheostat miraculously fixed the problem.

Friday August 27 02 56 Liu/Maurer 44179-44184
Just very few shots were taken. The amplifer box for Hall sensor has problems. I added filter caps for all the channels, but it didn't get things work better. Instead, some of the chips got hot when the power was turned on for a while. And couldn't see amp outputs even on bench test. Hope to continue to investigate the problem when Nick is back next Monday.

Tuesday August 31 05 08 Liu/Mauer/Nick 44179-44205 Test Hall probe Both VF only and plasma shots were taken on Monday and Tuesday. We current have 19 out of total 20 channels working fine. There is one noisy channel left. We will continue work on it.

Wednesday September 1 04 38 Liu 44207-44241(84-117) Hall array
With 19 channels, we took both vacuum shots and plasma shots. VF only shots with TF sweep were taken to check TF effect; TF only shots with bank voltage from 170V to 320V were taken for calibration purpose. Shots 44234-44242 were plasma shots. All available hall sensor channels detect clear fluctuations. Hall sensor data is currently located on Langmuir with tree name 'my_tree'.

Friday September 10 04 12 Maurer
Due to building power being turned off to fix the main breaker for floors 1 and 2 of the Mudd Bldg the HBT cryos will be valved off and shutdown overnight and also cua900, beta, sherwood and langmuir will be shutdown overnight at 5PM today, Friday Sept. 10. cua900 and the linux machines will be back on tomorrow afternoon.

Tuesday September 14 05 08 A. Klein 44249-44302 Mode control phase scan
With new (and improved) digital filter, which should give flatter phase response for frequency band 1-20 kHz, began detailed phase angle scan... Will cover toroidal angle in 5 degree increments, expect to fibish tomorrow. Plasma type is as always, agressive current ramp bringing the edge q to 3 early in the shot. Good reproducibility, and data looks good at first glance.

Wednesday September 15 03 40 A. Klein 44315-44359 Mode control phase scan
Finished taking data for detailed phase angle scan using the new and improved digital filter. Had to replace puff valve battery midway through. CUA900 is full, Dave Maurer is working on backing up data to tapes, until he is finished no more runs are possible.

Tuesday September 21 05 35 Liu 44373-44412(149-185)
Plasma shots with SMP shell at both 0cm and 4cm out were taken. In each case, SS feedback was turned on to exciting and suppressing modes. So far, it doesn't look it makes a big difference with one pair of Al shells in(0cm) or out(4cm): phase shift to excite/suppress mode stays same; the regular plasma shots with same bank setup look same also. Hall sensor array was recalibrated by moving to different locations (R). Plan to have another run-day this week by moving Al shells in and out. P.S. ICRH crate seemed have some problem (fan made a big noise) when we tried to turn it on. Therefore, we had to bypass it.

Wednesday September 22 05 26 Liu 44413-44442
m=3 mode was investigated by moving Al shells with different combinations. There is no conclusion so far.

Thursday September 23 04 51 Andrello/Stillits installation
We installed and pumped out the new multiprobe. Tomorrow we will leak check it and hopefully open it to the chamber to bake over the weekend.

Friday September 24 04 40 Andrello/Maurer/Stillits installation The multiprobe vacuum installation is complete. The pressure jumped to 10^-7 torr and quickly came back down to 10^-8 torr. Bake is on for the weekend.

Tuesday September 28 04 38 Liu/Maurer Hall probe
Hall probe shroud developed a leak during todays run while it was inserted into the edge plasma bringing the vacuum chamber up to ~50 Torr. Cryos have been regened, the bake is on, and the base pressure is 2 e -6 Torr comprised predominantly of H20 pumping with the Ebara cryo only so far. Glow discharge cleaning planned for tomorrow and continued baking. The Hall probe tubing has been taken off the machine and melting at the tip is clearly seen. We are currently investigating ways to surround it with a refractory material like alumina.

Wednesday September 29 10 23 Liu CPCI digitizer
CPCI digitizer is now integrated into hbtep main tree. I already tested it - working well. If anybody finds any complain please let me know. Joshua Stillerman gave us a lot of help during the whole process.

Friday October 1 04 51 Maurer/Andrello
summary of cleanup details... Tues. up to 50 Torr of air in the machine. Wed. glowed in D2. Prior to glowing machine base pressure was dominated by water. Miniturbo would not turn on and will be sent back for repair quote. Glowed using a static fill of D2 and pumping out with horizontal turbo every half hour. Ebara cryo warmed up spontaneously during the afternoon(cause not understood might be due to incomplete regen on Tues or something more serious). Thurs glowed in He. Fixed roughing pump line accident on regen line for the ebara cryo and started regen. Machined new new alumina tip for Hall probe array and mounted on shaft. Fri finished cryo regen and installed Hall probe tube and bellows and pumped it out and baked it. Opened it to the chamber after the afternoon talk. Base pressure was 7 e-8 Torr composed mostly of He after yesterdays glow. It is not 1 e-7 Torr and mostly water after opening the Hall probe gate valve. The bake willl continue over the weekend.

Tuesday October 5 06 07 maurer/liu
Tried taking cleanup shots today but had problems with the tree and mdsplus when initializing the shot cycle that took the whole afternoon to figure out. Partial fix has been implemented so we should be able to run tomorrow. Not sure what exactly happened to the hbt tree to cause these problems.

Wednesday October 13 07 29 Liu 44523-44558 vacuum shots
Calibration shots for both old and new Hall arrays were taken. I accidently turned off chamber ion guage. Jimmy came back to the lab from home to check the vacuum system to make sure everything is all right.

Friday October 15 02 15 Maurer/Stillits 44559-44570 TP-array
We tested the triple probe array (TPA). The test was conducted by moving the TPA 1cm into the plasma after each shot. Thus, the TPA is now 4 cm into the plasma. All tips, except for one - the third tip on the third TP, are working. The amps need to be checked. Nick did some work on the TF-charger, but we are experiencing some problems with the TF-charger still.

Tuesday October 19 04 46 liu/stillits 44573-44623 clean-up shots
We took clean-up shots all day long. We started with a puff time at 2.2 msec, but when the puff time reached 1.6-1.7 mesec the plasma had problems breaking down. Beside that, we were able to produce up to 4-5 msec plasmas, loop voltage ~12, and major radius at 94 cm. We had problems with the TF-power supply. The power supply was monitored; when the TF bank got stocked at a certain level, the amps on the power supply dropped down to zero. Thus, there seems to be a problem with the power supply.

Wednesday October 20 04 46 liu/stillits 44624-44688 clean-up shots + TPAWe took clean-up shots all day long. The plasma stayed around 94 cm, loop voltage ~11-12, and lasted up to 6 msec. We tried to lower the puff time, but we had problems breaking down the plasma when the puff time was lower than 1.8 msec. We tested the triple probe array (TPA). Thanks to Nick, all 4 triple probes are now working. We will hook up the TPA to the CPCI digitizer tomorrow. The batteries for the triple probe were dead and were replaced. We will continue taking clean-up shots tomorrow.Ă

Thursday October 21 04 23 liu/stillits 44689-44738 clean-up
We continued clean-up shots today. Although we had to increase pufftime instead of decreasing it to breakdown the plasma, the plasma got better comparing with the shots we took yesterday. With VFFB on, plasma typically lasts 5-6ms. Also we saw sawteeth from SXR signal.
. problems: (1) TF bank power supply is getting worse. It failed to charge for most of the afternoon. It's a very high priority for it to get fixed before we could productively run the machine. (2) The first channel of triple probe array still has a problem with the chip - it keeps getting blown - but Nick is looking into it.

Monday October 25 03 11 liu/stillits 44739-44756 clean-up shots
We were only able to take a few shots today before the TF went dead. However, we were able to produce some nice plasmas: loop voltage ~ 8-10, duration ~ 5-6 msec,SXR ~ 0.1 (sawtooth). All four TP's are now working, but we are having problems with blown chips on TP no. 1.

Tuesday October 26 05 03 Stillits/Liu 44757-44785 clean-up
We took clean-up shots all day long. We are beginning to see some very nice plasmas: loop voltage ~ 10, duration ~ 5-6 msec, SXR ~ 0.1-0.2, however, we were not able to lower the puff time below 2.0 msec. The RPFB was on: 94 cm from 2.5 msen till disruption. We checked the puff-battery and it showed 240 V, which should be ok. The triple probe array (TPA) was working well till we blew the board. The second board was installed, and we will continue to test TPA tomorrow. The Hall sensor array is working well and we are expecting to get some useful data if the plasma behaves repeatable tomorrow.

Wednesday October 27 03 54 liu/stillits 44786-44808 hall-probe + TPA
We are beginning to produce plasmas that are behaving very nice: duration more than 6 msec, loop voltage starting at 10-11 and decreasing to ~ 8, SXR ~ 0.1-0.2 and in some cases ~ 0.3-0.4. We ran the triple probe array (TPA) with the new board, and it seems to be working: we are getting very nice signal (one I_sat and two voltage measurements) for TP no. 1. Furthermore, we are not seeing any huge spikes in the signals. We will keep testing TPA tomorrow. The Hall probe array is working normally. We were trying to get some target shots for natural m=3 MHD mode study. The plasmas were quite repeatable. However, we couldn't take enough shots since TF power supply was working part-time. Nick has been working on it - in trying to pin down the problem, he has put light bulbs in parallel at different locations.

Monday November 1 07 14 Liu/Stillits 44809-44850 Mode structure
Good news: Nick has TF power supply fixed! So as we were able to run experiments smoothly today. Although the base pressure is a little bit high (~9*10^(-9)) comparing with the old days, plasmas are quite repeatable. Shots were taken by pulling all the Al shells out. Also, m=3 mode structures were investigated by partially turned on FPGA feedback control (Thanks Alex for adding new fuction on labview control pannel of this purpose). We are looking forward to collecting more data tomorrow.

Tuesday November 2 02 26 Liu/Stillits 44851-44877 Mode structure
We collected most needed data for mode study by investigating m=3 mode with different FPGA feedback scan. However, we had a hard time breaking down the plasma since late morning. PGA showed water and N2 are dominant effect to vacuum at current point. The base pressure is 1.7*10^(-8). TPA has been tested also. Data from the 1st channel is promising.

Monday November 22 02 59 stillits 44924-44939 clean-up shots
We had hoped to take some clean-up shots today, but we were not able to break down the plasma. The pressure was 1.1e-8 and we ran as high as 3.0 msec in puff time, 275 on OH elect, 6.5 on OH start. The e-gun is working and there is gas in the system (a signeficant jump in pressure during a shot). There seems to be a lot of water in the system, which probably stems from a leak.

Wednesday November 24 04 18 stillits 44940-44959 clean-up shots + TPA
The e-gun battery was dead. After having replaced the battery, we were able to break the plasma down. However, we have to run with at a very high puff time = 2.8 msec; if we try to lower the puff time below 2.8 msec, the plasma can't break down. Anyway, with a puff time of 2.8 msec, we were able to create some fairly hot and long-lasting plasmas: SXR ~ 0.3-0.4, duration of 7 msec, loop-voltage ~ 11 down to about 8. The start pressure was 1.2*10^-8. Furthermore, we were able to lower OH_start and OH_elect to 5.5 and 265, respectively. We can probably lower the OH values even further and still get nice plasmas. We will check the puff valve battery on Monday. After Nick fixed the problems we have had with the cable (from the TPA to the digitizer), the TPA signals seem to be working very well (we hooked the cables up to the function generator). On Monday we'll try to insert the TPA into the plasma and get some data. The RGA seems to be indicating that there's some H20/D20 and Nitrogen in the system: 2.5-3*10^-9 for both water and Nitrogen.

Wednesday December 1 07 12 Liu 44968-45040
First, CPCI communication problem has been fixed. The problem probably was caused by network frozen. Today's plasma is repeatable and controllable. With the Hall probe inserteded into plasma 2.5cm (1st channel of the probe at R=1.047), we took shots with current ramps from 4MA/s to 0A/s, et. al. Triple probe array is ready to capture data tomorrow.

Thursday December 2 04 19 stillits 45041-45058 Testing TPA (triple probe array)
We tested the TPA today. There semms to be some problems with the electronic; we are getting saturated signals on all except for one channel - even when we pull the TPA out of the plasma. We will look into the problems tomorrow.

Friday December 3 03 58 stillits 45059-45072 TPA-testing
We tested the TPA today. However, we are still experiencing problems with the TPA-electronic.

Thursday December 16 04 48 David Maurer 45147-45180 Discharge development, bias probe
We've been trying to develop the same shots as used for mode control experiments late in the summer. The puff valve is deteriorating, fresh battery still requires very long puff times to achieve reasonable gas fills. We also experienced a few computer problems, which have been corrected. The discharges now look almost like the target discharge, it may still be a matter of adjusting the gas puff in small increments. Current puff time is 8.5 msec (compared with 2 msec in August to achieve similar densities). We expect to have the traget plasmas by tomorrow morning and turn on the niased probe to affect rotation...

Tuesday December 21 05 26 Maurer/Klein 45198-45235 low kink rotation
By adjusting the fill pressure we were able to generate a plasma similar to those used for the recent feedback studies (see shot 45217 for example, the target shot was 43481). The puff valve response is changing on a daily basis. Current settings are Tpuff=1.15ms gives 3.1 e-5Torr fill pressure. Friday it was Tpuff=4ms for the same fill. In the future, people would be well advised to take static fills of the chamber with the pumps valved off to know their operating point. The biased electrode was inserted approximately 3cm into the edge plasma. Bias voltages of 50, 100, and 300V were applied to the probe tip. The higher settings (100 and 300V) were tried because it was difficult to see any rotational effects at 50V on the MHD. The reason for this is not clear. I plan on trying 5 cm insertion tomorrow and will keep the voltage high until I see an effect on the MHD such as reversal of the rotation direction and then back off the voltage and aim for only slowing the mode down to zero.

2005

Monday January 10 04 46 A. Klein 45292-45337 Gain scan feedback
Performed gain scan with full coverage feedback. Used only two toroidal phase angles (max and min supression). Found feedback effect visible in Rogowski coil signals even at gain 14 times lower than that used previously (although greatly reduced effect). Max gain used was 1.4 times greater than previous setting (distortion of control waveform out of crunch amps limits gain). Pulser for puff valve failed, switched to spare. Nick is repairing the unit. Will continue partial coverage feedback experiments throughout the week.

Tuesday January 11 05 23 A. Klein 45338-45426 gain and partial coverage mode control
Performed gain scan for partial coverage scenarios: midplane only coils activated, and midplane coils de-activated (top and bottom coil sets active). Did detailed gain scan for toroidal phase angle set to max ecxitation and max suppression. Data looks very good (3 shots at each setting) and interesting. Maximum gain (1.4 time greater than previously used) does NOT result in maximum suppression due to distortion of waveforms, high freq. modes excited. Best supression seen when gain is a bit lower than setting used for phase angle scan this summer. Extreme low gains of course diminish feedback effectiveness, and at gains 14 times lower than previously used the kink modes seem unaffected. Puff valve behavior drifted and might require that I re-do the data set for mid-plane only coil sets active, because base shot was a bit different and more varied than usual. The data set for midplane coils turned off case looks very nice though, after I adjusted gas puff time. Problems with the new digitizer (for triple and hall probe arrays) resulted in errors and restarts of cua900, after some time YuHong was able to make the system work. Will continue these types of experiments in the next few days.

Wednesday January 12 03 54 A. Klein 45431-45497 partial coverage mode control gain scan Todays partial coverage scenarios: Toroidal positions de-activated, did gain scan with shells 1,3,4 on but 2 and 5 off, then did gain scan with shells 1,3 on but 2,4,5 off. Cursory glance indicates that such feedback does not work very well. Minor differences between feedback on and no feedback shots, even at high gain, both for exciting and suppressing phase angle setting. Scan was detailed (three shots each setting, 6 gains, both exciting and supressing phase angle). Puff valve drifted again compared with yesterday but periodic checking of puff time on fill pressure made this not an issue. Will continue these types of experiments in the next few days.

Thursday January 13 04 38 A. Klein 45501-45599 gain scan partial coverage mode control Ran more gain scans for various partial coverage scenarios: 1) One toroidal location disabled (pretty successful feedback) 2) Redid midplane only coils active (plasma is much better and cleaner data) 3) Every other coil disabled (fairly successful) As before, 2 phase angles (max suppression and excitation) were used at 6 gain settings, three shots each. In general, plasmas are very reproduceable. The machine has cleaned up considerably since Monday. Exception: When the triple probe array was inserted 6 cm into the plasma, very different discharges were observed. These were very quiescent except for intense sawtoothing on the x-ray, very long lived, very hot, edge q went down to between 1 and 2 and stayed there. All other parameters were the same (intense current ramp). These shots were reproducible (5 times in a row), but then probe was withdrawn and I continued with gain scans on the "old" shot types.

Tuesday January 18 05 31 A. Klein 600-627 gain scan partial coverage mode control Finished taking data for partial coil coverage gain scan. Had some problems with ignitron cooling flowmeter interlocks, but they were resolved. Puff valve was very unpredicteable for the first few shots (50% variability) but then stabilized. Will now analyze the ~400 good shots taken last week.

Wednesday January 19 07 49 Yuhong Liu 45628-45699 It's a long run-day. Current ramp scan was done with all Al shells pulled back.The plasma shot length was not affected by withdrawing Al shells. The puff valve was wavy at the beginning of the run, but it was adjusted from time to time and stayed stable for most of the shots we took taday. Machine behaves well.

Thursday January 20 04 35 stillits 45700-45732 TPA testing We tested the TPA today. We tried to rotate the TPA 180 degrees (at different positions: 2, 3.5, 5, and 6.5 cm) to see if the results (temperature and density) would be the same. There does not seem to be any change in the values. However, we began to experience some problems with the signals from the TPA after we had rotated it, which seem to be related to some of the connectors. We'll look into that tomorrow.

Friday January 21 03 38 stillits 45733

Friday January 21 03 40 stillits 45733-45744 TPA testing We ran the TPA today. However, we are experiencing problems with the electronic (connectors) still. We'll look into that next week.

Monday January 24 04 38 Maurer ICRH Fixed CTS and traverser problems with the ICRH crate Jorway. The trigger is now working fine(several shots at least!). FYI the L8210 does give NOX storage errors in the action monitor and serial crate controller (SSC) errors if the crate cooling is not on and the door is not well closed. The ICRH was turned on and a couple shots taken at 15kV and 25kV to check triggering, etc. The bank fired but the plate currents do not appear in the data base properly yet. I assume this is a cabling and rectifier hookup problem since the digitzers come up with no signals and appear to be storing properly in the data base. I will try to piggy-back and check this out tomorrow or Wed.

Tuesday January 25 04 07 Stillits/Maurer triple probe Started to diagnosis problems with the triple probe array. Did not get too far along due to CAMAC serial highway sync problems and communication problems between cua900 and the CPCI crate that appears to freeze MDSplus during initialization of the serial highway. It was discovered that the basement u-port adaptor is causing the no-sync problem presumably due to over-heating. CTX has been temporarily jumpered out of the highway during trouble-shooting of the system. Will continue tomorrow.

Wednesday January 26 03 23 A. Klein 45760-45802 partial coverage mode control gain scan Had intended to run two more partial coverage scenarios with mode control. Instead, experienced and worked on problems all day: U-port adapter in basement failed, needs repair or replacement. Took adapter from CTX experiment and installed in basement. Fiber optic link to ICRF rack appears to have failed, intermittant link took a while to diagnose. Had to bypass that crate. Experienced CAMAC and initialization problems, needed to back up, but back up disc was full. Yuhang deleted shots, then archived data on cua900. Finally, puff valve was extremely irratic, esp. at first. Sometimes no gas at all was admitted to chamber (perhaps CAMAC failure to trigger), when it did open, the amount of gas varied wildly. This appeared to have stabilized towards the end of the day. However, I was unable to achieve target shot, seems as though OH start is much lower than previously despite match in bank settings. Upped OH start considerably, which improved things, then they became worse and worse again (low initial plasma current). Will try again at later date.

Tuesday February 1 04 46 A. Klein 45815-45860 diagnose problems Had intended to finish partial coverage gain scan for mode control feedback. Instead, dealt with problems. OH Start bank was not providing the voltage one would expect, one of the Klystrons had failed and was replaced by Nick. After that, the OH bank was still not up to par, and produced inconsistent results even for fixed settings. Then determined the OH Start bank is leaking off charge fairly rapidly. Took much of the day to realize this. Played with voltage settings, "refreshing" the charge, adjusting the charge rate so that bank finishes close to when the TF bank is finished charging. This may be moderately succesfull. There must be a capacitor in the bank that is bad. Higher voltage settings result in lower start voltages, it is a mystery and is not explained by leaking capacitors (is it?). Also, had trouble breaking down to form plasma. This may be related to the OH start bank problems, or perhaps not. Checked out e-gun, seems to be working fine. Gas puff also works fine (although long pufftimes are required to get target fil pressure). Formed plasma only 3 times today, which is a bit inexpliceable. The North Rack contiunues to have problems with digitizers for the SMP's.

Wednesday February 2 04 02 Maurer/Rivera Fixed problems with the Ohmic heating circiut today. The OHST bank dump had failed. The ST bank dump oil was almost black in color. The reduced standoff voltage was enough that the bank was continually discharging through it leading to yesterdays problems. The dump oil was changed and some tracking on the dump structure was cleaned up. The dump was then reinstalled. The bank was the checked and is working properly now. FYI: the CTX crate is back in the camac loop and will have to be turned on before running tomorrow. In addition, the ICRH crate is also back and will need to be turned on. Alex will resume Tuesdays incomplete feedback run starting tomorrow. Lets hope the breakdown problems from earlier this week do not occur.

Thursday February 3 04 09 A. Klein 45867-45951 partial coverage mode control gain scan More partial coverage gain scans: Today, had no problems with the banks. Plasmas were good (very first shot was target plasma). SMP's still not being digitized properly. Puff valve failry stable, it drifted a little during the day but I compensated with the puff time. I ran 2 scenarios: top two poloidal groups only, and uppermost (single) poloidal group only. The data is very surprising. Recall that the previous data suggested midplane coils only were not as effective for feedback as top and bottom only, and that perhaps this had to do with not having enough poloidal coverage to grab onto the modes. Well, todays data says:Top group is very effective at suppressing/exciting 3-1 mode, with top-midplane group or even without ! At medium gain, the one lone top poloidal group (which is furthest from the plasma surface since the plasma is shifted down somewhat) is as able to suppress the kink as the entire system (all groups on) is. All the data so far suggests that a) midplane coilsets do not couple as effectively to the external kink mode, or b) what we think is the midpalne is the top, and vice versa. I spoke with M. Shilov, he seemed to be sure of what is what, confirming that what I think is the top/midplane is in fact the top/midplane. Perhaps he has it wrong? Thus far I have the coils numbered 1 assigned to the midplane, and the ones numbered 3 assigned to the top (or bottom). Does anyone have documentation to confirm/refute this? Will analyze the data more formally, we can then decide what it might mean or what other experiments should be run.

Monday February 7 04 43 A. Klein 45973-46015 partial coverage mode control gain scan Investigated partial coverage gain scan for one poloidal group (bottom midplane) only active scenario. Doesn't look like it performed too well. Will keep running these types of experiments tomorrow. ad some trouble due to CPCI data acquisition system, ended up restarting cua900 and disabling the CPCI stuff.

Tuesday February 8 02 30 A. Klein 46015-46100 partial coverage mode control gain scan Completed partial coverage gain scans for top poloidal group only active and top-midplane poloidal group active only. The data conforms to previous data and trends. The puffvalve now requires 35 msec pulse times to give required fill pressure... I think this may conclude the partial coverage gain scan experiments (I hope). Will analyze the data in the coming days...

Monday February 21 05 07 Maurer 46241-46260 Ran initial tests with new vertical poistion bucking coil. The coil was run at 50, 100, 200, 400 and 600A of current. No breakdown problems were experienced even when running at the highest 600A level. Plasmas typically had about 350 to 450A of plasma current in the OH transformer bias phase indicating a medium gas fill level. Initial observations showed the global plasma parameters were not changed significantly until 200 to 400A were run in the new coil. Plasmas were actually pushed in major radius at the 400A level. Perhaps indicating that we are pushing it too high. There is preliminary evidence that the poloidal sensor arrays top-bottom asymmetry is less at the 200 to 400A level. No major jumps in sxrs, loop voltage or other parameters were noticed during the expts. We are still having camac problems with the shell mounted coils. I found what appears to be sin(theta) coil cabling in the west rack. Have not yet been able to check out if it is ok yet due to some afternoon camac-vax problems. Nicolai continued to check out ion saturation current measurements on the triple probe array and will also piggy back tomorrow.

Wednesday February 23 04 31 Maurer 46257-46307 Vertical position Moved top and bottom limiters out yesterday 2cm to allow some wiggle room for the plasma as the vertical position bucking coil experiments continue. Today was a day of problems... shorting stick left on the OHST bank caused some localized arcing and damage to the stainless steel resistor but nothing serious. This was cleaned up in the morning, the bank is OK, and a new shorting stick built and installed. The CPCI crate was taken out of the loop due to a fan failure on the digitizer side of the rack which was extremely noisy and discovered during the mornings run. The company has been contacted about a replacement and the problem fan was removed temporarially and the crate re-installed for tests tomorrow. The polarity of the leads for the vertical bucking coil were reversed (to move the plasma down) as a check on Mondays initial results before proceeding with a more detailed position-current scan. I tried to set up a target plasma but had great difficulty with the puff valve and intial fill pressures. They were widely varying the whole day. So much so that the plasmas were ranging in lifetime from 1.5ms to 6ms. The initial bias phase currents went from about 0 to 1000A. The puff valve pulser was found to be putting out about 100V instead of the 235V battery value when measured on a scope. The input trigger appears solid. The backup pulser was installed but did not give out a pulse when triggered. Nick is checking out the two units. Perhaps the transistors are failing because of the factor of ten to twenty larger puff times that we now require to attain the same fill pressures used in the past (due to puff valve aging?). I would suggest that we take time tomorrow to recalibrate the SMPs, flux loops, etc which has still not been done until the puff pulser is fixed. There is only Mondays data to discuss for Thurs meeting.

Thursday February 24 05 06 maurer Figured out north rack problem with the smps and triple probe diagnostics in the afternoon. The local serial ribbon cable input on the fiber optic uport adapter is failing. This causes information on the store part of the shot cycle in crates 7 and 9 to be lost (or mostly lost). This appears to be the cause of the recent smp and triple probe problems in the database. The ctx uport adapter was borrowed to trouble shoot the problem.

Tuesday March 1 04 32 A. Klein 46369-46433 vertical position shift Collected ample data on vertical shift coils and their effect on one type of discharge. Will analyze in detail. Only with extreme currents in the correcting coils does the plasma behave grossly differently/badly. Hottest plasmas near 200 Amps driving plasma upwards. Tried to digitize Sin-theta Rogowski coil, the coil is not functioning (probable short circuit, 0 Volts).

Wednesday March 2 04 51 Maurer/Liu Calibrations Started calibration checks today on the flux loops, smps, bank currents, etc... work still in progress. Tomorrows run is with the biased probe and triple probes (Stillits). FYI: Dmitry and I will be at PPPL going over VALEN again and in particular learning how to do the partial coverage runs to help in understanding Alex's recent data presented at the last physics meeting.

Sunday March 6 07 11 Maurer 46524-46551 Calibrations Sunday run... tested HFS triple probe. Even with the north rack camac problems fixed the isat measurement is still not working on the triple probe. The digitizer checks out OK with a sine wave input. Pulled the amp out of the north rack and checked the battery is OK. Must be the opamp or other circuit problem. Will have Nick check it tomorrow. Spent rest of the evening running sine and square waves through the shell mounted probe electronics to check for any AC response differences that might give rise to measurement errors. All the working channels looked OK with a 1kHz square wave input. Also checked the flux loop in a similar manner on Wed with Yuhong. All the flux loop channels were OK also. Still have to go over the bank current rogowskis. Did not get the bucking vertical position coil on today due to the calibration checks.

Wednesday March 9 02 46 Jmaes/Stillits 46560 -46603 Beta Enhancement Spent the morning checking equipment, ICRH, Triple Probe, RPFS, & Bias Probe. We were able to get ICRH signals in the tree on Monday. Replaced an op-amp in the triple probe, but signals still seemed strange in the tree; still debugging. In the meantime, we will use a t-probe tip to make an Isat probe for a direct relationship to the inboard density. This will allow us to continue the ICRF studies this Thursday and Friday. We were able to develop plasmas that resemble h-modes with the ICRF and bias probe on and the plasma positioned at ~94 cm. We had some problems with the RPFS, Nicolai and Nick are investigating. Dave Mauer has offered us assistance in rerouting the screen room out of the serial highway for tomorrow and Friday. I am not sure if that affects the RPFS or not but we are confident that we can work it out. We needed the extra u-port adapter to replace the one removed form ICRF a few weeks ago. We borrowed CTX’s U-port, but returned it yesterday afternoon so they can run this week.

Thursday March 10 10 54 Maurer 46607-46638 vertical position shift Yesterdays run... HFS triple probe isat measurement is now working. Found bad opamp chip. Hooked up shell probes and had flux loops, hall array, LFS triple probe, poloidal feedback sensors on for todays vertical shift expt. Ran the vertical shift coil in 50A increments to scan position. Target plasma was outboard limited with Ro = 94 to 95 cm. Took three shoots at each current up to 350A. Coarsened scan to 1 shoot per 50A increment from 350 up to 600A due to limited space on cua900 at the end of the day. Data analysis underway. CTX uport returned. Screen rm jumpered out of camac loop to allow for ICRH run today.

Thursday March 10 06 56 James/Stillits 46643 - 46695 ICRH We bypassed the screen room first thing this morning. We used the bias probe, to increase inboard plasma densities all day, but each time we tried to move the plasma inboard with the RPFS, the densities seemed to fall. We weed to investigate this further, but today, we were just trying to get target ICRH plasmas by whichever tools were available. We left the plasma edge at ~.94 m and found that when the radial current is at 200 A, the edge densities increased noticeably and relatively remained so throughout the plasma lifetime. We then fired the ICRF at lower energy at first (~18 kV) and then up to 28 kV for the final 5 or so shots. I am analyzing the data now, and plans to begin a more systematic sweep tomorrow of edge densities to lock in the ideal parameters for FMSW Coupling.

Tuesday March 15 05 54 Maurer 46765-46829 HFS density optimization Ran plasmas today to otimize the HFS density measurement on the triple probe. Was able to develop target plasma with edge density of around 4 e-12 per cc as measured on the HFS triple probe. This was done by a combination gas puff, vertical shift coil current, and OH bank adjustments. I was able to make a relatively long lived plasma with Ro at 92cm and another target with Ro at 91cm for a 2.5 ms period. This was done so far without the biased probe or radial position control. Late in the day I turned on the baised probe at 250V and expected the density to increase even further, but this was not experimentally seen. The probe current and voltage signals were very noisy. The major radial evolution changes slightly with the probe on. As as a reference case we usually get a factor of two or so increase in edge density with the biased probe (this gives values of about 5 e-12 per cc). So we are getting close to that edge density without the probe just by todays discharge programming with increase gas puffing, but it is not clear why the probe is not enhancing the density even more. There were some Lanl problems during mondays run that hopefully will not impede tomorrows work. I plan to run from the start with the probe in the morning to see if I can increase the density even further. If this shows no promise I'll switch on the ICRH and use the target I have currently going in the afternoon. In todays run I was using 200 to 250A in the vertical shifting coil.

Wednesday March 16 08 32 James 46738 - 46763 Radial Field Scans This from Monday’s runs: We were unable to use the Lanal, seems to be a repeat of a problem experienced last year see Nick, Dave or Nicolai for more information. The bias probe was on for all shots. Nicolai, help me to set the plasma between 93 and 92 cm with lifetimes from 3-5 ms. Once we were able to have a suitably long lifetime, I began a sweep of the vertical positions starting at 175 A radial current and ending at 225 A, at 25 A increments with about five shots for each step. Looking at the 2.3ms-4.1ms window density averages, the largest were shots 46752 (4.18E+18) and 46760 (4.01E+18). From the sweep, it looks like the 225 A current produced the highest densities in that window. I also turned on the ICRH for shots 46761 – 63 and 46764 (vacuum shot) to continue to look for some loading and any other signs of coupling while I everything is still working. I ran out of time before I could try 250 A radial field currents, so it may produce an even higher density measurement.

Thursday March 17 10 32 Maurer 46830-46880 High density plasmas with ICRH Forgot yesterdays run report... I continued making high density plasmas and using the vertical shift coil at 225A. The two target plasmas developed yesterday for ICRH studies are: (1) Ro= 92 cm plasma with edge density of 4 e-12 per cc and (2) Ro= 91 cm inboard limited (on the RF antenna limiter) plasma also with edge density of approximately 4 e-12 per cc. Ran ICRH pulses at 28kV into both of these target plasmas. The sxr fan array has enoungh pickup that it is not useful in diagnosing any temperature rise. I will try to play with cabling to see if it can be reduced. No easily seen signature of loading or heating seen just looking at the data initially during the run. Looking at the Q measurements for subtle loading effects today.

Thursday March 17 04 54 Stillits/Maurer 46881-46948 H-mode + TPA We had problems with the LANL, which we have had for some time now; each time we took a shot the banks got dumped. We were, however, able to create long-lasting (~ 6-7 msec) plasmas without the RPFB. Furthermore, we couldn't get the D_alpha meter to work; we'll look into that tomorrow. The BP (Biased probe) was on at 250 V and 5 cm into the plasma, and the TPA (triple probe array) was inserted 3.5 cm into the plasma. We saw several cases of "H-modes."

Monday March 21 05 08 stillits 46982-47063 H-mode + TPA We ran with BP on at 250 V and inserted 5 cm. The TPA was inserted 3 cm into the plasma. We saw some cases of H-modes, some more interesting than others. Among the interesting shots are shot# 47003, 47026, 47043, and 47044. We'll continue with these kinds of shots tomorrow and perform the BP-TPA test. By the way, the high-field TP is not working.

Tuesday March 22 04 21 stillits 47064-47100 H-mode + TPA We ran with TPA inserted 3.5 cm into the plasma, and BP on at 250 V and inserted 5 cm into the plasma. We saw several cases of H-modes, but the run day was cut short when the TPA stopped working.

Tuesday March 29 04 16 A. Klein 47103-47126 Mode control coverage Ran to tie up loose ends with partial coverage mode control experiments. Previously, Dr. Mauel had suggested two control coils were always highly correlated with feedback effect (magic coils). There is something to this, judging by todays experiments. Toroidal position #3 apparently is close to Rogowski coil used for analysis, and activating coils at that location strongly affects feedback analysis when based on Rogowski coil measurements. Will have to re-evaluate lots of data, using 2nd Rogowski coil, poloidal sensors, and shell mounted probes.

Wednesday March 30 04 38 A. Klein 47126-47182 discharge development Developed discharge with R ~ 93 cm, current ramp, external kink when edge q goes below 3 while vertical shift coil was powered with 260 Amperes. Shot 47182 is the target, I think. Will use such shots to do some mode control feedback experiments.

Friday April 1 04 52 stillits 47184-47201 TPA Thanks to Nick, the TPA is working again. We tried to test how close to the BP we could move the TPA before experiencing any major problems. The BP was on at 150 V and 5 cm into the plasma, and the initial position of the TPA was 3 cm. After having experienced problems with the CPCI digitizer this morning (we couldn't initialize), we got as far as inserting the TPA 4.2 cm into the plasma - 8 mm from the BP - before we again started having problems with the CPCI. Up to that point we didn't have any problems with the TPA getting to close to the BP. Next week we will try to address the problem with the CPCI. On the positive side, the high-field TP is working again and the digitizer for the D_alpha-meter is working again (we will run with the D_alpha-meter next week).

Wednesday April 13 05 15 stillits 47221-47308 H-mode This is run report for Monday, Tuesday, and Wednesday this week. We experienced problems with the CPCI this Monday; we were not able to initialize the TPA channels. However, Yuhong seems to have been able to fix this problem by creating a completely new publicly - for the HBTEP group - accessible CPCI-tree, which will be tested tomorrow. Furthermore, we are having troubles with the D_alpha-meter. The digitizer is working, and we have tested all the cables (which are also working), but we are not able to get any signals from the spectrometer. We will try to fix this problem tomorrow. Since we have had problems with the CPCI, we have no been able to perform the BP-TPA scan. Instead, we tried to create "H-modes" in which we had the BP inserted 2 cm into the plasma with 300 V. It seems that we are able to create "H-mode" structures with this "BP- setting" too; for example shot# 47279 and 47305 are interesting.

Monday April 18 05 06 James 47320 - 47355 ICRF I used the scope to measure the period of the ICRF oscillations – T=2.28x10^-6 s so f= 4.38 MHz (should be 4.5 MHz). I put this into Prof. Maul’s program, but we are still unsure of the toroidal B-field, so it is not clear how significant this change is. We were able to develop some fairly high densities (centered around ~5x10^18 [+- 1.5x10^18]). ICRH was fired at full strength, ~31 kV, and a few shots showed significant loading. After looking at some previous shoots, it seems that the inboard density can be double what I got when the biased probe is inserted 5 cm. Combine this with clearing the toroidal B-field uncertainty so we can adjust the frequency, and we should be able to determine weather or not more drastic measures should be taken.

Monday April 18 02 33 Liu CPCI digitizer status - works well Want to clear that both hardware and software of the cpci digitizer are working well. I spent time last week created a new mdsplus tree on langmuire /home/hbtep, which is accessible for the whole group. The tree's name is 'subtree_cpci'. Anybody who wants to retrieve data from the tree, please just use the standard mdsplus/idl commands/programs. If you want to get data from terminals that are not langmuir, please use "mdsconnect, 'langmuir.ap.columbia.edu' ". The commands "mdsopen, 'subtree_cpci', shot#", "a=mdsvalue('top...')", etc still work the same way as you get data from 'hbtep' tree. Please be sure the correct node name to get data - you can check it using traverser. One thing needs to be mentioned: the problem that cpci digitizer sometimes stops working is quite possibly because the CPU usage on langmuir is more than 99%. If anybody has the idea of limiting user's usage of CPU, it will solve the problem.

Friday April 22 05 18 stillits 47435-47450 BP-TPA scan Thanks to Yuhong - we were able to run the CPCI/TPA today. The BP was position 5 cm into the plasma, and the voltage was 150 V. The initial position of the TPA was 4.2 cm (= the center of the deepest inserted TP was 4.2 cm into the plasma). we then slowly moved - in step of 2 mm - the TPA into the plasma. We stopped taking shots when the deepest inserted TP was inserted 5.8 cm into the plasma. We did not see any spikes - neither on the I_sat or voltage (float or +) for each of the TP - at all at any position.

Monday May 2 04 00 Alex Klein 46504-47538 mode control compass scan Began detailed compass-scan of mode control system and tokamak configured exactly as during August 2004, but with toroidal position #3 control coils de-activated. This is the position near an m = 3 Rogowski coil which otherwise is subject to direct pick up. The plasmas look good, data looks good at first glance, will finish tomorrow (am trying to cover 72 different angles).

Tuesday May 3 02 41 Alex Klein 47539-47589 Mode control compass scan Finished compass scan with mode control system configured as in August 2004, but toroidal position 3 control coils deactivated. Will now analyze data to see how rogowski is affected when nearest control coils are far away.

Tuesday May 10 05 15 stillits 47605-47653 TPA + BP Thanks to Yuhong, we are now able to take data with the TPA. After we had kicked Bialek of langmuir and changed OS to the old version, we were able to take shots without any major problems, except for a few shots in which the CPCI was not able to store data. we ran with BP at 2 cm & +300V and TPA at 3.8 cm (position of the deepest inserted TP). We saw some cases of spikes in SXR while the BP-current was ~ 0A; at the same time we saw drop in I_sat/density on the deepest inserted TP's, so the "barrier" seems to appear deeper inside the plasma than 3.8cm. But some more analysis is required. Next time we'll try to insert the TPA deeper than 3.8 cm.

Wednesday May 11 04 02 Alex Klein 47657-47699 mode control compass scan Performed full coverage mode control control coverage scan, to confirm that the feedback system actually still works as before (there had been a question, as plasmas appear to have slightly faster natural rotation rates compared to previously). At first glance: Mode control works, dramatic exitation/suppression on Rogowski coils as before. Tomorrow, will do phase angle scan with toroidal position #7 (far from either Rogowski) control coils muted.

Thursday May 12 03 05 Alex Klein 47699-47778 partial coverage mode control gain scan Ran detailed compass scan study with mode control coils at toroidal position #1 muted. This is the set of coils near Rogowski m eq 3 coil number two, and also the set mounted on the shells which are partially withdrawn due to Hall probe access. At first glance, it looks like feedback is working, as the Rogowski coil #2 mimicks Rogowski coil #1. Will do analysis to quantify feedback effect.

Friday May 13 02 34 Liu/stillits 47779-47822 Hall probe calibration
Yuhong tried to calibrate the Hall probe today. However, during these shots we had to reboot the CPCI and langmuir several times. We don't know what makes the system so unstable - but we have emailed Josh and Peter about the problems.

Friday May 20 02 08 stillits 47889-47900 TPA calibration 12 shots were taken today (three for each TP). Data was stored on floppy disk, and further analysis will be done in IDL.

Monday May 23 09 56 James 47901 - 47921 B-dot Probe Tested the B-dot probe today, ensured the cable was indeed attached and checked it for shorts. Initially took an ICRH only shot to compare with B-dot readings in the past (see shot #36547), with the rectified probe raw signal in the raw bottom antenna current digitized channel. The signal seemed to just be pickup in the wire (see shot #47902). Then bench tested the Ge rectifier, but sig. gen. only went to 1MHz and at this frequency it was hard to tell if the signal was truly rectified. Went back to the ICRH crate and used the o-scope while firing the ICRH to see both the un-rectified and rectified signals over the lifetime of the ICRH pulse. Seems like the rectified signal oscillates with the carrier as it drops, pointing to a possible capacitor failure, but I ran out of time before I could replace them – will do so next time and start the toroidal B-field scans with ICRH.

Tuesday June 14 03 50 stillits/liu 47952-47982 cpci The CPCI seems to be working now. We took about 30 shots, and in each shot all the data was stored; this even happened while Bialek was running (using more than 99% of CPU).

Thursday June 23 02 46 Stillits_Nick 47987 OH test Tested the OH bank to see if there was any damage from the water leak. It worked fine. Will test triple probe tomorrow.

Friday July 8 05 25 stillits 48192-48218 TPA The TPA is now working. After Nick had cleaned the pins, allocated new channels on the CPCI (we are now using ch. 49-54 for TPA1 and TPA2) and after we had recalibrated - by means of the effective areas - we were able to get the temperature profile we had anticipated. The temperatures were underestimated by: TPA1 (outermost): 3%, TPA2: 11%, TPA3: 13%, TPA4 (innermost): 5% However, we have not taken into account the ~25% - related to the electronic - we are overestimating the temperature on each TP, but it will not change the profile structure. All this will be added in the tree. Furthermore, after we put a fan in front of the CPCI, the CPCI has become more reliable. There are, however, instances in which data is not stored, but the solution to that problem seems to be to turn the CPCI off and on - without rebooting langmuir. We have also changed the sampling rate on the CPCI from 200K to 250K and (almost) gotten rid of the time delay ~200e-6 sec, but there are still some a few minor problems that need to be solved. I'll try to look into these problems and put it all on the tree this weekend.

Tuesday August 2 04 43 Maurer Fixing broken quartz section Summary of Monday 8/1 and Tuesday 8/2. Found the HBT vacuum chamber up to air prior to Mondays group meeting. The quartz piece between the Hall probe and SMP chamber pieces had cracked around the circumference sometime over the weekend. The exact cause of the break is unknown. The failure mode is however similar to the quartz piece that cracked next to the ICRH section about 5 years ago when a cinder block wall was taken down in another part of the lab. It was thought then that floor vibrations due to taking the wall down caused enough of an impulse to start a crack propagating in the quarz. In checking with facilites, there was no scheduled heavy construction on our or ajoining floors so I am not sure what caused it (if that is the cause). The quartz piece was taken out this morning. It took a bit of time to pull the bolts, move the Hall probe stand, pop off its flange and dismantle the connections to the control and sensor coils mounted off of those stainless shells so they could be moved over inside the chamber to allow the quartz piece to be removed (since the gap coils extend over underneath the quartz piece). I broke one wire of the smart shell coils in dismantling them that will have to fixed. Upon inspecting the broken quartz we found a part of the crack that does go over to the edge of the piece and might have been caused by contact with the next door chamber flange. If anyone wants to do more post mortem analysis the pieces are on the table by the door to the control room. We currently intend to install an old single-convolution stainless steel piece in place of the broken quartz. This is being done for ease and quickness of installation. Also, there were no diaganostics at that location that were in use. There is a m/n=2/1 saddle coil that we are planning on not re-installing. The quartz was also jumpered out and not acting as an insulating break either. Using the convolution piece we have a good chance of installing it tomorrow and perhaps even doing an initial pump down and with baking we might be able to run at the end of next week perhaps. If people think this is not the way to go and they want one of the new thick, machined quartz pieces installed (Mike or Thomas?) please email Jerry and I and we will discuss matters since everyone is gone. Right now we are cleaning the spool piece and orings, making new mylar covers to hold the orings in place, and preparing to install the section tomorrow. We have checked the gap between the chambers and the convolution spool piece should fit with its orings and mylar cover, There is a gap of a little less than 0.1 in. flange to flange. We also checked to make sure the bolt circles match alright. In addition to the above, we pulled off the top microwave feedthru that has been broken for some time so that it can be fixed in anticipation of having the interferometer up and running in the future. I will either blank it off or if i can find it install a window and shutter than S. Paul loaned to us in the past. This could perhaps be used for the new Dalpha array temporarily since the microwaves will not be workijng for sometime. I have tried to inspect the SXR Be filter to see if it was damaged by the pressure wave when the quartz cracked by looking through the bottom window opposite the array. I frankly cannot see it well enough to say if it has minor damage or not. It does not appear that there is major cracks or flaking of the Be. If there are other up-to-air tasks that people would like to see done now is the time!

Wednesday August 17 05 32 Hanson/Stillits 48559-48632 clean-up Yesterday there were problems relating to the TF-CB circuit. We chose a new trigger channel and amplifier, and got the circuit to work. This mornining, we still had problems with the TF bank firing for low charging voltages ( < 6.1 kV ). It would seem that the one of the TF ingitrons is no longer good. After achieving solid TF pulses, a clinking noise was heard from inside the machine area. Two loose bolts were found resting on the concrete pad underneath the hbtep near where the quartz piece had been replaced, and were removed. Subsequently, clinking noise was no longer heard. We plan to check again for loose tools and hardware before running tomorrow. Intitial shots (48569-48578) showed little or no ionization. Gas puff time was gradually increased to 3.0 ms, and OHST was gradually increased to 6.5kV. Breakdown was achieved at shot 48580. For the rest of the day, pulse length gradually improved, and was just shy of 3 ms by the end of the day.

Thursday August 18 05 54 Hanson/Stillits 48633-48678 Clean Up Started the day with a second missing tool search as promised in yesterday's run report. Jim Andrello found a small section of hex stock (that was used in losening the socket head cap screws holding the broken quartz piece) on the machine area floor beneath the concrete base pad. Jim still believes that an allen wrench is missing, but no clinking sounds were heard when firing the TF bank. Runs today showed spotty improvements in discharge time. Typical shots lasted 3-4ms, but we had a lovely 8ms shot towards the end of the day (48677). In order to get breakdown, we needed to keep the gas puff time around 3.0ms. In the afternoon, it was increased to 3.5 ms. We plan to continue making clean-up plasmas tomorrow with the hope of making 8.0+ ms discharges consistently. Ideally, we would test ICRH early next week.

Friday August 19 01 30 Hanson/Stillits 48680-48701 Clean Up Before running this morning, we installed a new puff valve pusler box. We did at one point swap the old box back in again, but it did not seem to fire. Then we promptly reinstalled the new box. All shots taken today failed to break down. We tried to explore various settings: increased OHB to 03, increased OHEC and OHST to 280 and 6.5, respectively. VFEC was already at 40 from yesterday. We verified visually that the E-gun lights up, and that gas puffs consistently bring the system to order 10^-4 pressures. We ended up increasing the gas puff time to 20.0 ms. Also tried to adjust the tree setting TOP:CAMAC:TIMING:PUFF_VALVE2 a little bit, but I am not sure about the units, and whether it is the length of time or start time for the puff. We've been using nothing but D2 gas all week. Perhaps the missing quartz piece really does make a difference?? On several occassions yesterday, I noticed strings of shots that had progressively longer discharges. However after building to a 6-8 ms discharge, the following shot would fail to break down at all. I'd say this happened about 3 times yesterday.

Monday August 22 05 34 Hanson/Stillits 48704-48708 Clean Up After poor plasma performance last Friday, the idea for today's shots was to asses the effect of fill pressure on our ability to achieve breakdown. To this end, we scanned gas puff times from 1.0 ms to 10.0 ms with little success. Around mid afternoon, Nic remembered the following: a) there was a small leak in the vacuum chamber which now seems to be fixed. Thus breakdown problems might be due to the chamber being too clean. b) the e-gun has a bias power supply that runs on a battery. We checked the battery on the e-gun bias supply and found that it had about 200 V out of 250. A fresh battery was then inserted. Subsequently, breakdown was achieved when the puff time was set at 20.0 ms. After achieving breakdown and some ~8 ms discharges, the puff time was slowly decreased to 16 ms with no negative result (see shots 48740-48748). Plan tomorrow to keep attempting to lower the puff time and make reproducibly good plasmas.

Tuesday August 23 05 35 Hanson/Stillits/Maurer 48749-48805 Clean-up Smooth progress today. There were some questions about whether the gass lines were clear of He this morning, so they were pumped out. SXR emissions are slowly creeping up, and loop voltage is decreasing. Discharge times are in the neighborhood of 6ms.

Wednesday August 24 05 05 stillits/hanson/maurer 48806-48859 clean-up The plasma is slowly getting cleaner. At the end ot the day we were able to create plasmas with puff time = 1.3-1.4 msec, loop-voltage starting at 12-14 and dropped to ~ 6. The duration of plasmas was on average 8 msec, initial plasma current 5 kA and max. current 7-8 kA (OH elect. = 260 and Oh start = 5.8). By the way, there were signs of increasing SXR's.

Thursday August 25 02 54 maurer none baking After running the past few days with clean up discharges base pressure remains at 2 e -8 Torr. The dominant partial pressure is H20 on the RGA. The ratio of O2 to N2 as about 5 so if there is a leak it is small. I think the easiest way to get rid of the H20 is by baking rather than making plasmas, which is not very efficent at getting rid of the water. The bake is back on and I will see what it pumps down to on Fri morning. I think the fact that some bake controllers are not working appears to have limited our ability to get rid of the H20. The pressure with the bake on is 7 e-8 Torr.

Monday August 29 05 11 Maurer/Hanson 48860-48883 clean-up Dave turned off and removed the bake system this morning, and we started running at about 1:45. Discharge times today seemed to fall pretty consistently in the 6.0-8.0 ms range. Soft x-ray signals are still small or non-existent. Loop voltage seemed to average about 11-13V. Most notably, the major radius seemed pretty bouncy on a 1-2ms time scale.

Wednesday August 31 04 34 A._Klein 48884-48929 Clean Up Took many clean up shots. Plasma still prone to multiple minor disruptions, ended up running shots similar to past several days: large R and repeated "crashes" into outboard side, with hopes of cleaning machine that way. Did NOT adjust TF settings as reproducibility is still sorely lacking. Vertical Field only shot revealed poloidal sensor T1 position had its polarity reversed during the recent repairs.

Tuesday September 6 05 27 Hanson/Stillits 48931-48965 clean-up Took more clean up shots today. Loop voltages averaged 10-15 V; Discharge times, 4-8 ms. Soft x-ray signals were very small. Major radius seemed quite chaotic. Planning to continue clean-up shots tomorrow, and maybe scan the TF a bit in the afternoon.

Wednesday September 7 05 31 Hanson/Maurer 48966-49022 cleanup/tf scan <p>Spent the morning & early afternoon doing cleanup shots, and switched to coarse TF scan later in the afternoon.</p> <p> Regarding cleanup, discharge length seemed to average about 8 ms, loop voltage~13, no soft x-rays to speak of, major radius still quite chaotic. Nearly all of the shots shared some interesting characteristics: plasma current seemed to ramp up for about a 3rd of the flat-top, hit 7-8 kA, and then ramp back down to ~5 kA by the end of the discharge. During this ramp down period, loop voltage decreased to less than 10 and conductivity temp increased to maybe 10-20 eV. See shot 49001, for example.</p> <p> The results of the tf scan (49006-49022) seem encouraging. Scanned the tf voltage from 4.9 kV to 6.3 kV, in steps of 0.2 kV, with a 3 ms puff time. Was able to reproducibly achieve breakdown even at 4.9 kV, but discharge times here were very short since the vf was not adjusted to compensate. Shots taken at between 5.7-6.3 kV all looked quite similar.

Tuesday September 13 04 55 maurer Glowed in D2 on Monday. Ratio of N2 to O2 was about 10 with the bake on this morning. Did a initial D2 glow in the morning and switched to He in the afternoon. Current base pressure is 5.0 e-7 Torr after turning off the glow. Mostly He and H20 products (DHO, D2O). Will take shots starting tomorrow morning.

Thursday September 15 04 57 Maurer Only a few shots taken today. The OH coil started making a louder than usual noise when I was making plasmas. The sound resembles a dull thud. It does not appear to be an arc. It happened quite distinctly on one shot. We are in the process of trying to find out what is loose, moving around and making the noise. It is probably the bottom OH winding that has caused problems in the past. After inspection it does not look like the clamps have broken anywhere. So it is at least not a large scale clamp failure. It is possible that the bolts holding them together are a little loose from pulsing the machine. The clamps we have been able to check so far we finger tight. We will check the rest of the bolts before testing the circiut again. It is somewhat harder than before to access the bolt clamps due to the bottom-middle radial position control coil that is now installed.

Friday September 16 02 12 maurer

Friday September 16 02 21 Maurer We were able to tighten the clamps on the bottom OH coil enough to reduce any noise back to similar levels as before yesterday. In the process of localizing where the coil was loose an arc flash was observed for a few OH only bank shots. This arc is intermitant in occurance. It was not observed with shots taken later in the day. The chamber sections where we believe the arc was localized were inspected as much as possible given the limited access to examine the clamps and cabling. There was no visible damage to either the clamps or cable that i could see or feel with my hand. Currently the VF winding, turnbuckles and other items that where taken off the machine to be able to inspect those clamps are being reinstalled.

Tuesday September 20 09 56 Alex_Klein 000 Dear All, I'm doing a dry run for a talk I am scheduled to give at MIT next week. The talk is an overview of the mode control experiments on HBT in the past 2 years + present status. You're invited. If interested, it will be in the control room on Thursday 9/22/05, 9:30 am. Thanks Alex K.

Wednesday September 21 05 13 stillits 49058-49095 clean-up shots After having installed the Hall probe array this morning, we started to take clean-up shots. The plasma is slowly getting better with small signs of SXR's. The flashes we have been seeing lately were due to a trigger cable from an unused puff valve that was arcing where its connecter was touching the pump stand. It has since been insulated and the probelm has been fixed.

Friday September 23 04 39 stillits 49152-49190 clean-up shots We spent the day taking clean-up shots. Small improvements of the plasma are seen but we probably have to spend at least one more day taking cleaup shots. We had problems charging the OH bias bank; fortunately it was only a water-resistor that needed to be refilled.

Monday September 26 04 29 stillits 49191-49247 clean-up shots No major improvements of the plasma. We ran with OH-start ~ 6.9 and OH-elect ~ 290 but the plasma did not last more than ~ 4-5 msec, loop-voltage ~ 12 and only small values of SXR ~ 0.05.

Tuesday September 27 05 18 hanson 49248-49289 clean-up shots Clean up shots today looked more or less like they did last week. Little or no SXRs, plasma current peaking at 10 kA, loop voltage ~10-15 V, discharge times 4-7 ms. Major radius still seems quite chaotic.

Wednesday September 28 03 14 A._Klein 49291-49359 Clean up/phase flip Tried to reproduce Shilov-type shot with edge q evolving from below 3. Played around in bank settings but as unable to achieve the shot. Generally, plasmas appear to be fairly clean, some discharges had long duration (9 msec) with some soft x-rays and relatively smooth equilibrium evolution. Only, Shilov target shot is difficult to achieve....

Thursday September 29 03 41 stillits 49360-49417 clean up No major progress today. The plasma is still fairly lousy. We ran with puff time ~ 1.7 msec, OH_elect ~280, OH_start ~ 6.8, VF_elect ~ 50-100, and VF_start ~ 2.9-3.8. The major radius is very volatile and loop-voltage ~12. Duration of plasma was ~3-4 msec, and plasma current stayed below 10 KA (~8-9 kA).

Friday September 30 04 39 stillits 49418-49454 Clean-up + Biased Probe No major progress today. We are still faced with a lousy plasma. Max. duration ~ 4-5 msec, no SXR's, loop-voltage ~ 12 even with OH_elect. ~ 280, OH-start ~ 7.0. We tried to insert the biased probe to 3.5 cm with +200 V (biased current ~ 75-80 A) to see if we could see any changes in the plasma. But that was not a success either.

Monday October 3 04 43 stillits 49458-49522 clean up After Dave had removed the straps/jumpers, we were able to get higher initial plasma current (~7 kA) at a lower OH_start: it is now OH_start = 5.2 compared with OH_start = 7.2 earlier. However, the plasma does not really seem to heat up: SXR's very small < 0.05, loop-voltage ~12-13, duration 4-5 msec, and max. plasma current ~ 10 kA. We will (probably) keep taking clean-up shots tomorrow.

Thursday October 6 12 13 A._Klein 49618-49625 test Unable to break down plasma. Checked electron source, filament and bias. Confirmed gas fill. Confirmed bank currents. Unable to breakdown, will try again later after consulting w D. Maurer

Tuesday October 11 05 05 stillits/hanson 49626-49810 clean-up Plasmas seemed very unwilling to breakdown. Nicolai increased the puff time throughout the afternoon to get results. When I took over, puff time was at 15.0 ms, corresponding to a fill pressure of ~2.3E-4 Torr. Shots with 10 ms puff times failed to breakdown. Dave noticed that even with the high fill pressures, plasma current during the bias phase of the shot is more or less zero. Bank traces, however, looked normal.

Monday October 17 03 23 Maurer none Checked out e-gun circuitry. Bias voltage and heating current tested OK. Initially had a hard time measuring the emission current. After testing various parts of the circuit we were able to measure about 30mA of emission current (lots!). Not sure if we bumped a bad or intermittent conection or not that led to the earlier zero emsision current results. Decided not to pull the e-gun and inspect it since it appears OK. Opened up Hall probe gate value to main chamber and turned on bake. Will insert alumia coated probe shaft tomorrow and take shots. Plans in progress for up-to-air installation of quartz piece.

Tuesday October 18 04 16 Maurer Took shots today to make sure breakdown is working well enough to make plasmas for testing the Hall probe shaft coating. Will test shaft tomorrow morning witharound 50 shots.

Friday October 28 03 55 Jim_Andrello Quartz installation The quartz section is installed and sealed. The seals roughed down to 10^-3 Torr. Monday I will leak test it with Helium. The ICRF 10" flange has also been taken off for access to the Faraday shield.

Thursday November 3 05 58 Jeremy_Hanson ICRF hardware work I completed removal of the Faraday screen from the ICRF antenna as planned on Monday. I then replaced the antenna limiters in their original positions. It turns out that it's possible to remove the Faraday shield/antenna limiter assembly without perturbing the antenna straps themselves. Once this assembly is removed, the Faraday screen straps are easily unbolted. I haven't had a chance to really look closely at the B-dot probe yet. It's covered in a little Faraday screen of its own that will be difficult to remove. My current understanding is that the probe circuit is open. I'll check that tomorrow and then see what else can be done.

Wednesday November 16 02 02 Hanson 49716-49732 ICRF testing Yesterday, Nic and I removed all but one of the stages from the ICRF delay line in order to be able to test the ICRF with a short pulse. Today, I took vacuum ICRF shots with increasing voltages. I also added one more stage to the delay line and took more vacuum shots. The current traces in the antenna straps seem to track well with the top tank current (bottom tank ws not digitized). All traces exhibit an exponential RC decay, so I don't suspect any arcing. However, a snapping sound is heard when the antenna fires at higher voltages. The delay line was left in its truncated state because I intend to repeat this experiment with plasmas whenever they are available.

Wednesday November 16 02 52 Pedersen none FYI Just a reminder of the HBT-EP physics meeting tomorrow morning at 9.30 am. I will be talking about our research on bias induced edge transport barriers.

Thursday November 17 01 45 Hanson 49733-49734 icrf testing Today, Nic and I took a couple more ICRF shots to see if we could determine the source of the snapping sound heard yesterday. However, the sound could not be reproduced today.

Tuesday December 13 04 14 hanson/klein 49735 feedback test Alex and I did a vacuum test of the feedback system. We put a sine wave on the control coils using the fpgas and then checked to make sure the sensors picked it up. They did. The feedback system seems to be in working order.

Thursday December 15 05 57 hanson/maurer 49738-49794 clean-up First day of plasma shots since the re-installation of the quartz piece. Plasma currents were ~5 kA, pulse lengths 1-2 ms. Breakdown and the character of the shots seemed quite consistent; much better than the intial clean-up shots taken towards the end of last summer.

Friday December 16 01 03 hanson 49795-49812 clean-up

Friday December 16 01 14 hanson 49795-49812 clean-up Plasma shots today looked more or less like yesterday. Low plasma current: ~6 kA, and short lifetime ~ 2ms. Discharges are quite consistent and there haven't been any big problems breaking down. The vacuum base pressure has been somewhat problematic; I've been waiting 10-15 min for the pressure to return to the 10^-8 range between shots. Fill pressures are ~3E-5 Torr. Around 11:30 this morning, the base pressure began to climb a little while after a shot. The temperature on the cryo head was about 10K, and a look at the RGA showed Dt and H20 to be dominant; ratio of N2 to 02 was about 10. After climbing slowly to 4.5E-7 Torr, the base pressure began to recede. It's now at 1.0E-7, a little more than an hour after the incident.

2006

Monday January 9 04 22 hanson 49813-49822 icrf test Made the first tests of the ICRF system with plasma since the removal of the Faraday shield. The ICRF delay line was trimmed to two sections, as with the previous vacuum tests, making the ICRF pulse about .5 ms. Due to the long pump-down time between shots (30 min - 1 hr), I was not able to complete a scan of ICRF voltage settings. Preliminary results don't show any signs of arcing or misbehavior. The plasmas themselves look much the same as they did two weeks ago: plasma current peaking around 7 kA, ~2 ms pulse lengths. Turning on the ICRF doesn't seem to impact plasma parameters. I plan to resume the voltage scan on Wednesday, and eventually add more sections to the delay line.

Wednesday January 11 04 42 hanson 49823-49862 icrf test Today, I resumed scanning the ICRF bank voltages and added two sections to the delay line. For the most part, the ICRF traces looked normal, and I did not see any big changes in plasma behavior. Evidence of an arc was observed in the ICRF traces for the highest bank setting (20) and 4 sections in the delay line, in the presence of a plasma (49861). No arcing was seen for a vacuum test of the ICRF with an identical configuration. I plan to explore the arcing issue further, with Nick's help.

Tuesday January 17 05 18 hanson 49863-49888 clean-up/icrf test Took clean-up shots and continued testing the ICRF system. I kept the ICRF bank voltage lower (~20) and did not see any signs of arcing. On one shot (49883) the having the ICRF on seemed to correlate with slightly higher conductivity temperature and plasma current. Most shots showed little or no effect. It turned out that the cause of the bottom tank circuit not being digitized was that the digitizer was not connected to the coil. I'll get that fixed up tomorrow.

Wednesday January 18 04 55 hanson 49889-49917 icrf test/clean up Today, I digitized light from the ICRF tests using a photo diode pointed through the quartz window towards the antenna straps. Firing the ICRF introduced noise into the photo diode signal, but didn't cause any DC jumps. There was another arc in the ICRF system (49907), when the charging voltage was set at 30 kV. After this, I went downstairs and noticed that the ICRF cooling water purity light had turned red -- indicating impure water. The light did not turn green afterwards, so the ICRF was not fired again.

Thursday January 19 05 11 hanson 49918-49946 clean-up Took clean-up shots today, without firing the ICRF.

Friday January 20 05 00 hanson 49947-49976 clean-up More clean up shots today. Plasmas seem to slowly be improving. Average loop voltage has been about 11 V; soft x-rays still negligible; pulse lengths are averaging 5 ms. Replacement ICRF cooling water pump has arrived; plan to replace it on Monday morning.

Monday January 23 05 06 stillits 49977-50044 clean-up shots Clean-up shots were taken. Outboard limited plasmas were created R~94-98cm. Loop-voltage ~ 14-6, plasma current ~ 5-8 kA, duration ~ 8 msec, and only weak SXR signals. Puff time ~ 2.0-2.5 msec. Will continue to take clean-up shots tomorrow.

Tuesday January 24 04 57 stillits 50045-50131 clean-up shots Again, clean-up shots were taken. Outboard limited plasmas were created R~94-99cm. Loop-voltage ~ 15-6, plasma current ~ 5-7 kA, duration ~ 7-8 msec, and only weak - but improving - SXR signals. Puff time ~ 2.1-2.5 msec; no break down of plasma when puff time < 2.1 msec.

Wednesday January 25 03 22 maurer/hanson Took about 20 shots and tried to diagnosis why there is no plasma current in the bias phase of the OH transformer. Typical fill pressures to have the plasma breakdown are 1e-4 Torr. Thats about 3 to maybe 5 times what we normally would require. After chasing down a few possibilites iI think its the egun again. Nick and I will check it out.

Friday January 27 05 27 hanson 50153-50222 clean-up/icrf test Took clean-up shots and attempted further testing of the ICRF system. The good news is that we now seem to be seeing some plasma current in the bias phase of the shot (so the e-gun seems to be functioning after yesterday's repairs). However, large fill pressures (~1E-4 Torr) are still required for breakdown. The plasmas seem to be cleaning up slowly but surely: SXRs are becoming more noticable, loop voltage is decreasing, etc. The ICRF system is still suffering water purity problems in spite of the new pump. The indicator light seems to go red after an ICRF shot, and then turn green again later. Firing 3 ICRF shots in close succession resulted in an arc.

Monday January 30 03 44 hanson 50223-50250 clean-up More clean-up shots taken today. Attempted to do current-ramp shots as discussed at this morning's meeting. I was able to ramp up to 9.5 kA plasma current, maximum.

Tuesday January 31 05 05 hanson 50251-50313 clean-up More clean-up shots taken today. I'm now able to get plasma currents up to 10 kA using an agressive ramp. Plan to test run the feedback system tomorrow or Thurs.

Thursday February 2 05 45 hanson 50354-50445 clean-up/feedback tests Made clean-up discharges and fired up the feedback system today, using an FGPA routine written by Alex. The feedback system seems to work inasmuch as nontrivial voltages appear across the control coils. It's hard to say if any modes were suppressed. I did a scan over the toroidal phase-angle input to the FPGA routine.

Friday February 3 05 02 hanson 50446-50502 clean-up/feedback tests Took more clean-up and feedback phase-scan shots today.

Tuesday February 7 05 44 hanson 50503-50586 clean-up/feedback tests Took clean-up shots and attempted to generate magnetic perturbations with the FPGAs in open loop. I had some difficulties getting the FPGAs to generate waveforms on the coils; plan to try again tomorrow.

Wednesday February 8 05 43 hanson 50593-50613 clean-up/phase-flip Took more clean up shots today, and managed to put some 3:1 modes on the control coils. Also, I had a look at the loop voltage voltage divider. It appears to be in working condition, and the gain settings in the tree give accurate results to within 2-4%.

Thursday February 9 05 39 hanson 50614-50696 clean-up/phase-flip Took more clean-up shots and did phase-flip experiments.

Wednesday February 15 05 59 hanson 50726-50777 clean-up Took more clean-up shots. After clearing out the puff-valve lines an switching to pure deuterium, plasma bias current seems to have improved.

Monday February 20 05 12 stillits 50830-50855 New Biased Probe We tested the new biased probe (BP) today. We took a few regular shots in which we had BP inserted 1cm, 2cm, and 4 cm into the the plasma and no voltage. Thereafter, we inserted BP 1 cm into the plasma and at +50 V we measured BP-current ~50 A, +100 V => BP-current ~100-120 A, and +150 V => BP-current ~ 150 A. Tomorrow we'll try to insert BP 2cm - 5cm and V_BP = 50 - 150 V (it will depend on the current drawn). Clean-up shots were taken too. We are able to create plasma with puff time ~1.2-1.3 msec.

Tuesday February 21 05 05 stillits 50856-50896 Biased Probe We finished getting I-V characteristics for the new biased probe (BP). We had BP inserted 1cm to 4-4.25cm (max. insertion) into the plasma and slowly ramped the voltage up from +50V to +150V at each position. The BP current is ~1 A/V and fairly independent of the position. Furthermore, we also took clean-up shots. Small improvements are seen: duration of plasma ~ 6msec, puff time ~ 1.3 msec, max. plasma current ~ 10 kA, weak SXR < 0.1, q* ~ 1.5.

Thursday February 23 05 29 hanson 50897-50938 clean-up Took clean-up shots and experimented with moving the aluminum shells. Putting in the Al shells does not seem to impact breakdown greatly, but does lead to more quiescent discharges. Also, the Ebara cryo-pump has been misbehaving again, oscillating in temperature and causing temporary increases in base pressure.

Friday February 24 05 00 hanson 50939-50981 phase-flip Attempted to drive 3:1 modes rotating at 5 kHz using the control coils in an open-loop configuration on discharges with little ambient 3:1 activity. I didn't see much correlation on the SMPs. Plan to analyze runs and do a frequency scan next week.

Tuesday February 28 03 58 stillits 50982-50988 TPA + BP Most of the day was spent on getting the CPCI to work. Afterwards, we took a few plasma shots with the old TPA, but the cpci is still having some problems storing data. On Thursday we will try to get a few plasma shots with the new BP and old TPA to see what floating potentials and electric fields we are generating with the new BP.

Wednesday March 1 05 09 hanson 50989-50139 clean-up/open loop fpga Took clean-up shots and conducted open-loop fpga tests. I attempted to impose a rotating 3:1 mode on plasmas that had some ambient 3:1 activity. Rotation frequencies varied from 1-8 kHz. Plan to continue frequency scan on Friday. Also, the Ebara cryo pump continues to misbehave, warming up and discharging into the chamber every hour or two.

Friday March 3 05 03 hanson 51069-51110 open-loop fpga Completed a frequency scan of rotating 3:1 magnetic perturbations using the fpgas. Plasma discharges continue to improve, but the Ebara cryo pump still has temperature cycling issues. Bake is on.

Tuesday March 7 04 41 hanson 51111-51156 open-loop fpga Applied more rotating 3:1 perturbations with control coils, at various frequencies. Hopefully, these results will guide phase-flip experiments to be done tomorrow and later in the week. Also, the Ebara cyro pump continues to misbehave.

Wednesday March 8 01 43 hanson 51156-51176 discharge shaping Attempted to create "Shilov style" discharges in which the edqe safety factor slowly crosses 3 from below. These shots seem to be more quiescent than shots with agressive current ramps and may be more suitable for open-loop phase-flip experiments.

Wednesday August 30 01 54 maurer/hanson 51528-51545 systems test Test fired all banks and the puff valves. Monitored the TF coils with the new flux loop sets, and the traces looked fine. We achieved plasma breakdown on shots 51544 and 51545. Plasmas showed low plasma current (max 5 kA). Pumping has been a bit slow and the RGA still shows lots of water. Plan to bake, glow in Dt this afternoon, and maybe regen a cryo or two.

Wednesday October 11 04 27 hanson/maurer/james 51555-51590 clean-up/neutrals This was the first real HBT-EP run day since spring. Plasma currents peaked consistently around 10kA, loop voltages were around 10-13 V, pulse lengths grew as the day went on, reaching about 3 ms. Plasma behavior seemed quite consistent from shot to shot with most discharges experiencing a noticable disruption about halfway through the shot. Used the caemra housing, small filter, and single channels on the PDA to test the amp. Signals without the filter were about 1V on average peaking at about 2V and negative (as expected). the H-alpha filter signals were somewhat more reduced, so it was difficut to seperate them from the noise. This could be a result of the plasmas being cold so we will continue tomorrow. If results are unchaged tomorrow, I will revisit the amp.

Thursday October 12 08 59 James_Hansen 51590 - 51627 Cleanup & Neutrals Cleanup shots continued today, we reached longer lifetimes (about 5.5 -5.75 milliseconds) than yesterday, but we were around 7 kA Ip for most of the day – close to yesterdays. We did notice that we had to raise the fill pressure throughout the day after long breaks between shots as expected after a long pump down. We were able to continue testing the PDA to day as well. Filtered signals with a single channel from the array were still too small to distinguish from the noise. All these shots can be viewed in the tree with the PDA.jscp in the HBTEP directory; shot #51579 is a good example to see this. We then replaced the array with the single diode and same filter. The single diode with an area 4 times that of the array’s single channel showed a clear and smooth twin peaked signal as predicted. Next we put two and finally three adjacent elements from the array in parallel to increase the surface area and finally got a noisy but clearly discernable signal, shot #51627. We will be able to test more channels in this fashion once the larger filter comes in on Monday.

Tuesday November 14 05 42 hanson 51636-51668 clean-up Made clean-up plasmas. Plasma parameters are slowly improving, loop voltage averages around 14 V, plasma current around 10 kA, pulse-length 3-4ms. No soft x-rays yet. Some initial tests were done of the Hall probe hardware and D-alpha amplifier.

Friday November 17 02 56 hanson 51669-51678 clean-up

Friday November 17 02 58 hanson 51669-51678 clean-up More clean-up shots today. Plasma parameters continue to improve. Most notably, loop voltage now stays below 10V for a msec or two on most shots. Pulse lengths are in the neighborhood of 3-4ms.

Monday November 20 04 23 hanson 51690-51716 clean-up More clean-up shots today. Loop voltage averages around 10V, and SXRs are still quite small.

Tuesday November 21 06 04 hanson 51717-51757 clean-up More clean-up shots today. Plasmas are behaving fairly consistently, with loop-voltages a little below 10 V (on the good shots), but no soft x-rays yet.

Wednesday November 22 06 20 _hanson 51758-51796 clean-up More clean-up shots today. Loop voltage seems to be coming down. Plan to bake over the long weekend and resume clean-up shots on Monday.

Tuesday November 28 06 04 hanson 51797-51828 clean-up More clean-up shots today. Attempted to make hot plasmas with lots of ohmic heating input. This was somewhat successful: core soft x-rays in the neighborhood of .15 V were observed, and some shots even had some small saw-teeth.

Wednesday November 29 05 14 James/Hansen 51833 - 51873 Clean-Up/D-alpha More of the same today, clean-up shots mostly, with a mixed with Hall probe and D-alpha testing. The Hall probe seems to be functioning well, calibrations to follow. The D-alpha detector single channel is operating nicely with little gain (about a factor of 2 M-ohms), so the Thompson Scattering port is a good place for collecting light from the plasma. We are still working out bugs in the array amplifier.

Thursday November 30 04 21 hanson 51894-51897 clean-up More clean-up shots today. We continue to see small improvements in the soft x-rays.

Thursday November 30 04 25 hanson 51894-51917 clean-up More clean-up shots today. We continue to see small improvements in the soft x-rays.

Tuesday December 5 06 44 hanson 51919-51983 clean-up More clean-up shots today. Plasmas look a lot like they did last week. Also, the sensor coil digitizers were tested using a function generator, and found to all work. Additionally, OH only and VF only shots (51955,51956) were taken to try to assess whether these effects are corrected for properly in the major radius calculation routine.

Wednesday December 6 05 14 James,_Hansen 51983 - 52030 Clean-Up More clean-up shots today. The cooling oil fixes seem to be holding up well.

Thursday December 7 04 32 hanson 52031-52070 clean-up More clean-up shots today. Plasmas continue to improve, but do not behave consistently from shot to shot.

Monday December 11 05 03 hanson 52071-52109 clean-up More clean-up shots today. The battery in the puff-valve circuit was slightly low, so we replaced it this morning. I did repeated static fills throughout the day to determine if the puff-valve was working consistently -- it is. The minimum fill pressure required for plasma breakdown was about 1.0E-4 T. Plasmas behaved similarly to how they did last week, but did seem a bit more consistent shot-to-shot.

Tuesday December 12 04 04 hanson/james 52115-52123 clean-up A few clean-up shots were taken this afternoon; during the morning, additional hardware related to the D-alpha experiment was installed on HBT-EP. Also, did some troubleshooting on one of the m=2 rogoski coils (which hadn't worked in recent memory). The coil was installed and in good shape; the problem turned out to be a misconfigured AM502 amplifier.

Wednesday December 13 05 09 hanson 52123-52160 clean-up More clean-up shots today. Some testing of the D-alpha hardware (with a tangential view of the plasma) was done as well.

Thursday December 14 05 52 hanson 52161-52205 clean-up More clean-up shots today. There have been problems getting the CPCI to initialize after a restart of langmuir.ap a couple days ago. I've requested help from Yuhong and am waiting to hear back.

2007

Friday January 26 04 26 hanson/maurer 52218-52250 testing Tested all of the banks, looked for tools dropped near the machine, and sorted out some small kinks that had worked their way into the system since the last run (back in Dec). The TF coils were tested with care, and traces from the diamagnetic loops mounted on the coils looked normal. Also, one plasma shot was taken. Plan to take clean-up shots all next week, as everything now seems to be in good working order.

Tuesday January 30 05 17 hanson 52251-52284 clean-up Took clean-up shots today. Plasmas are behaving fairly consistently shot to shot, with loop voltages around 8-10V. The sensor coils were tested and found to work, with the exception of two whose analog boards have not been fixed yet. We looked into getting the optical rotation diagnostic connected to a digitizer, but some of the configuration settings for the 6810 were not transparent. Steve Paul has been contacted for advice. Plan to take clean up shots for the rest of the week and work on getting data from the hall and rotation diagnostics.

Thursday February 1 04 33 hanson/james/maurer clean-up Took more clean up shots. By the end of the day we had nice sawteeth and loop voltages down to about 6 Volts by the end of the shot. The longest lived plasmas lasted about 8 msec. Had problems with the vacuum controller interlocks again (similar problems occured with the main ion gauge last week and caused the vacuum system controller to trip over the MLK day weekend at the start of the semester). It appears that many of the connections on the backside of the gauge controller are starting to fail due to age and fatigue. There might be some problems with the gauge controller itself as well.

Friday February 2 12 07 hanson 52382-52399 clean-up More clean-up shots today. Saw some nice plasmas with lots of soft x-ray/mhd activity and loop voltages descending to around 6V. We're ending early today to fix oil leaks, bake relays, the ion-gauge connection, and the remaining analog feedback boards.

Wednesday February 7 05 19 hanson 52400-52425 clean-up Made more clean-up plasmas today. Plasmas continued to look good, but the RGA showed high water levels after the run. The crunch amplifiers and control coils were tested and seem to be working. The new Kalman filtering routine was run and it seems to produce coil signals similar to those made by Alex's routines. Plan to continue with the clean-up shots with some focus on creating discharges with (m,n)=(3,1) activity.

Thursday February 8 05 06 hanson 52425-52490 clean-up More clean-up shots today. Plasmas continue to look good. Pulses typically last longer than 6 ms and have loop voltages that descend from 10-5 V over the shot.

Monday February 12 04 27 hanson 52491-52528 clean-up More clean-up shots today. Plasmas continue to look good with loop voltages that approach 5V towards the end of the shot and plenty of MHD activity.

Tuesday February 13 02 58 hanson 52528-52556 clean-up More clean-up plasmas today. Plasmas continue to look good. As there seems to now be plenty of mhd activity, the plan for tomorrow is to do some initial testing of the Kalman filter feedback algorithm and a compass scan.

Thursday February 15 04 50 hanson 52557-52622 feedback system testing Did some testing of filter gain and feedback phase settings using both new (Kalman filter with lead-lag compensator) and old (lead-lag compensator only) FPGA routines. Also, more Hall probe calibration data was taken. Plan to do some further FPGA tests tomorrow and think about the results over the weekend. I should be in shape to do some more formal phase scan experiments next week.

Wednesday February 21 05 59 hanson 52654-52672 feedback testing Did some more tests of the feedback system with a slightly re-designed Kalman filter. (An oversight in the program was discovered earlier this week.) Some D-alpha hardware tests were done and some more Hall probe calibration data was taken.

Friday February 23 02 43 hanson 52691-52710 Rotation Diagnostic/Feedback We recorded data for the first time using the rotation diagnostic. 90% He, 10% D2 plasmas were made and signals were seen on both channels. Unfortunately, the gas received for these experiments was mixed incorrectly. It should have been 10% He, 90% D2. The gas supplier has been contacted. Throughout the week, I've been trying to pin down the source of some large DC offsets seen in the control coil traces when the feedback system is on. Tests done today seem indicate that at least some of these are due to hardware problems, not bugs in the FPGA routines (as originally suspected).

Tuesday February 27 04 15 hanson/james 52711-52729 feedback/d-alpha Did more tests of the feedback system today. Some potential problems in the FPGA algorithm were eliminated. I hope to have the rest of the bugs worked out by the end of the week. D-alpha array is working (minus the slit). It turns out that the negative lead to the PDA was borken and has been repaired. I will test with the slit tomorrrow.

Wednesday February 28 04 04 James/Hansen 52730 - 52740 D-alpha Tests I did initial tests on the Photodiode array today. The tests show that we did remove most of the noise from the system and that there is plenty of white light available. We were unable to get specific levels of D-alpha for a single element of the arrray due to problems with the VF-Start control panel. It is unclear if it is just a problem in the Control Panel or in the basement bank system. Nick is investigating. We plan to complete ths D-alpha tests tomorrow whern VF problem is corected. No feedback work was done due to problems with the analog boards. They don't seem to be getting the correct voltages from the power supply anymore. Work to fix this issue is underway.

Friday March 2 04 46 hanson 52772-52796 feedback testing After bench-testing all of the analog boards yesterday (all were in good, working order), the feedback system was reassembled for online testing. (It was suspected at one point that one or more boards might have shorts or bad op-amps.) Replacing the +/- 12 V DC power supply for the analog boards with two large 12 V batteries fixed some of the problems we were seeing during the previous two weeks. These were: DC offsets appearing inconsistently in the control coil signals and incorrect power supply voltages appearing across the boards. In any case, eliminating the power supply seemed to do the trick. A replacement has been ordered.

Wednesday March 7 02 40 James 52827 - 52840 D-alpha Installed a moving mirror setup for the D-alpha array. I used a laser to confirm the angle range to sweep the solid angle from major radius about R=107 inward. The Levels of white light increased as the view was moved in to the center of the plasma, but they were substantially lower than the levels seen with out the mirror, compare shot number 52831 with mirror and 52724 no mirror. When the filter was added the levels drastically dropped to almost zero without the slit even being added yet, compare 52838 with mirror and 52729 no mirror and both no slit. I will print these out for Monday morning meeting. To see the data mentioned look in ICRH_L8210_1:Input_2 in the tree and the signal is negative so it must be multiplied by -1.

Thursday March 8 04 39 hanson 52854-52891 feedback testing Today, a working Kalman filter was tested on plasmas for the first time. However, the filter did not work as expected on all of the FPGAs. One FPGA/poloidal group seemd to work flawlessly, but the others performed strangely. I'm still pondering this. (Other programs have either worked correctly or not on all of the FPGAs.) Also, plasmas looked quite good; I was able to create discharges with lots of m=3 activity.

Friday March 9 02 33 hanson 52892-52905 feedback testing I got the Kalman filter working on all four FPGAs today. (There had been a bug in the software preventing matrix data from being loaded correctly onto some of the FPGAs.) I did a few shots with the filter turned on at a constant feedback phase angle and a few reference shots. The plasmas showed lots of m=3 activity, but it was difficult to tell from the raw signals whether I was driving or suppressing anything. I plan to compare the filter output with my model over the weekend and undertake more elaborate experiments next week.

Tuesday March 13 05 46 hanson 52906-52950 feedback More Kalman filter tests today. I played around with some different proportional gain and phase angle settings. By looking at the time delay in gating on the feedback, I got an estimate for the FPGAs' loop rate. Updating the matrices with this parameter produced control coil currents that were in good agreement with my model for what should happen. Setting the phase angle at 180 degrees (for positive feedback on the kink mode) causes the Kalman filter to blow up. I can even make the FPGAs ring on line noise (with no plasma) at this setting. I Plan to attempt a fine phase scan tomorrow, hardware permitting.

Wednesday March 14 05 50 hanson 52951-53045 feedback phase scan Did the greater part of a feedback phase angle scan today. I took two feedback on and two control (feedback off) shots for each 10 degree step. Plan to finish up the scan tomorrow and start analyzing the retsults.

Thursday March 15 05 45 hanson 53047-53092 feedback phase scan The Kalman filter feedback phase angle scan continued today and is nearly finished. The run day was cut short by a failure in the charging power supply for the OH electrolytic bank. The failure point was a splice connector at the 3-phase power input to the supply. The connector had become loose and was arcing and melting. A substitute connector was made in the shop this afternoon, so we should be ready to run again in the morning.

Friday March 16 12 47 hanson 53093-53127 feedback phase scan Completed the Kalman filter phase angle scan today. The OHEC charging supply was reassembled this morning and appears to be working fine.

Thursday March 22 05 05 hanson/debono 53150-53163 rotation diagnostic tests We tested the Doppler rotation diagnotic using 10% He 90% D2 plasmas. Signals coming from the optics looked like they were in qualitative agreement with earlier results.

Tuesday March 27 05 13 hanson 53176-53132 feedback More feedback tests today. After a numerical error was found in the alorithm last week, the first plasma tests of the corrected filter were done today. The control coil currents seem to track quite well with expectations, but it is difficult to tell yet what the impact of the feedback is on kink modes. Further testing and analysis to come.

Wednesday March 28 04 44 hanson 53233-53298 feedback More feedback testing today. Some time was spent developing a reference discharge with a strong current ramp and lots of m=3 activity. I have not seen any very obvious evidence of suppression yet, but a frequency analysis of the shots has yet to be done. Also, one poloidal group seems to be performing poorly; I hope to be able to address this issue tomorrow.

Friday March 30 04 42 hanson 53299-53310 feedback More feedback testing. Frequency analysis from shots taken earlier this week showed that the filter algorithm drives the control coils at frequenies that are somewhat smaller than the mode. The filter matrices were recalculated for slightly higher frequencies and tested again today. Also some more data was taken using the rotation diagnostic.

Tuesday April 3 06 11 James 53317 - 53325 D-alpha Success! I was able to repeat last Friday's tests in Deuterium (vs the 10 percent He mix). The white light and D-alpha output concurrently increased. I then masked the single diode to 1mm and added the filter and lens and was able to sweep the mirror to find the highest D-alpha levels. Outputs were around the 2.5V level through the shot, after the start-up spike. I also documented the rise and fall of the signal around this peak mirror angle. After these initial tests, I replaced the masked single diode with the array and after some quick repair work on the input connector, D-alpha signals between .7V and 1.3V were achieved! Tomorrow I will vary the PDA elements and mirror angle to try and get a framework to begin mapping the chords.

Wednesday April 4 05 06 hanson 53327-53376 feedback testing I made some changes to the way that the Lead-Lag filter is implemented in the feedback algorithm and tested them piecewise this morning. Initial analysis shows (both in theory and practice) that the lag filter does a good job of flattening the transfer function going into the FPGAs, so that the signal seen by the Kalman filter stage is proportional to B (and not, say, dB/dt). In the afternoon, the algorithm was tested as a whole. Anecdotal evidence of some m=3 suppression and excitation was seen for different feedback phase angles.

Thursday April 5 04 38 hanson 53377-53430 feedback I did a coarse feedback phase angle scan using the algorithm as described yesterday. Analysis is pending.

Friday April 6 01 13 hanson/debono 53431-53442 rotation diagnostic testing Took some data using Steve Paul's rotation diagnostic that will hopefully lead to a better calibration.

Tuesday April 24 04 59 hanson 53468-53501 feedback Two sensor coils that exhibitted signal saturation problems were disconnected from the feedback loop. The analog boards had been eliminated as possible sources of the saturation; there is some suspicion that the shielding on the coils themselves may be damaged. (Recall that the poloidal sensors are mounted on the plasma facing side of the stainless steel shells.) Eliminiting these inputs left the xT_S1 group with only two inputs (a third sensor coil in this set is open-loop). Control coil signals for the xT_S1 group were subsequently much more well behaved, and looked similar to those on other groups. However, I am not yet sure if the spatial DFT coefficients for this group should be modified to compensate for the unevenly sampled data. Plasmas were repeatable, with one or two shots showing signs of possible feedback suppresssion of m=3 modes. I plan to think about the DFT coefficients tonight and continue with feedback experiements tomorrow.

Thursday April 26 05 09 hanson 53524-53566 feedback testing I attempted to make plasmas in the style of M. Shilov for feedback studies. These plasmas break down between edge-q=2 and 3 on the outboard edge and move inwards, pulling in the q=3 surface as they expand. This type of shot seems to be m=3 unstable without perturbing the two "bad" sensor coils as much. I was able to keep these coils plugged in and have the Kalman filter work reasonably well on the xT_S1 set. I found it more difficult to reproduce the Shilov plasmas exactly, shot to shot. However, I believe that I've seen some anecdotal evidence of m=3 suppression. I plan to continue in this vein tomorrow.

Friday April 27 05 01 hanson 53569-53640 feedback More feedback shots today, using the "Shilov shot" described in the run report yesterday. I adjusted the banks a little and was able to achieve better repeatablility. I covered a few feedback phase angles; the rest will be done next week.

Tuesday May 1 05 30 hanson 53672-53750 discharge shaping I've been trying to cultivate a shot with large, low frequency (~5 kHz) m=3 activity. As a model, I'm using shot 43102, from Alex Klein's work. Some important characteristics of this shot are subtle and difficult to reproduce, but I'm making progress. I hope to get back to doing feedback studies tomorrow.

Thursday May 3 04 59 hanson 53823-53875 feedback I've been able to develop a plasma with a more slowly oscillating m=3 mode--in the neighborhood of 5-7 kHz. Initial experiments with the Kalman filter appear to indicate that I can both suppress and drive it.

Friday May 11 04 41 hanson 54163-54213 feedback I spent the week developing a discharge with a robust, current driven m=3 instability. I am not able to exactly reproduce the discharge used by Alex Klein, but I have found one that behaves similarly. I seem to be able to both supress and excite the mode using the feedback system.

Tuesday June 5 05 04 James 54326 - 54385 D-alpha Finally tested the D-alpha prototype amplifier with three signals. The designed board worked perfectly. One of the output connector channels between the CPCI connector and the amp is a little flaky but the amp itself works great. I was able to take a white light shot and get signals that were clipped into the 5 volt region. D-alpha light ranged between .2 V for an inboard view to 1 V in the edge region. These views are not exact but in the general vicinity. The noise was in the .0012 V region and frequency response seems good. Nick and I are working up drawings to submit for a quote on a multi-channel amplifier board made on the economy. Tomorrow morning I will take a few shots with the power supply to check noise levels and hopefully a repaired connector to get rid of the one flaky channel between the CPCI and the amp.

Tuesday June 19 03 01 James 54412 - 54417 D-alpha I was able to conclusively show that the amplifier boards work. I will verify their freq. response on later this week. I was also able to take a picture of the plasma that I will send out or post after I put it in a better format. I will also attempt to create better pictures of the plasma and hopefully use the d-alpha filter in a few shots!

Monday June 25 04 32 James 54437 - 54440 D-alpha Theses were short lived plasmas, ~3.5 ms. The pictures were taken through the ICRH port to get a fairly unobstructed view. Able to see D-alpha Light - the center of the plasma does not seem to be emitting much, but the edge of the plasma and not the chamber wall seems to be the source as would be expected when not looking at a limiter. I have e-mailed out a pdf with pictures in it.

Friday July 6 05 02 Hanson/DeBono 54517-54532 Rotation Diagnostic Tested rotation diagnostic using 10%He, 90%De mix.

Tuesday July 10 06 06 James 54563-54587 D-alpha Did some calculations with Dave Maurer and determined that the transfer fxn roll-off was mostly due to the 15pF cap in the amplifier circuit. I replaced the caps in each of the channels with a 1pF, 3.6pF, and 6.6pF capacitors and did some signal to noise tests on the bench. I then put the PDA on the machine and tested the cabling and CPCI digitizer. I spent the rest of the afternoon attempting to align the lens & PDA with the mirror - with no success. I will continue tomorrow with this process and then determine noise levels and frequency response for each channel.

Thursday July 12 09 57 James 54588 - 54624 D-alpha I was able to calibrate the detector and get D-alpha signals into the 1V range through the shoot lifetime. There are still noise problems from the PDA connector, but they will be rectified in constructing the final unit. There was noticeable smoothing in the 6.6pF and minor smoothing on the 3.6pF channels. The 1pF had some extra wiggles but it was on a channel with an obscured view, so it was hard to compare side by side. Yet the freq response test confirm a 31KHz - 35KHz corner freq for the 1pF channel with 30.6KHz calculated. I didn't test the others yet, but the 3.6pF has a calculated corner freq. of about 10.5KHz which seems a bit low. For now we are going with the 1pF and I will do the freq. response for the other two channels to make a decision on Monday for the final design to be processed.

Thursday July 12 03 37 hanson 54633-54647 kalman filter testing Tested a newly written version of the Kalman filter algorithm today, with actual plasmas. The new algorithm has been optimized for a significantly improved latency: 10-15 microsec, down from 30-40 microsec. Qualitatively, the algorithm performed more or less as expected. Control coil currents seemed to be a bit attenuated on some toroidal sections--this may be due to a numerical error (possibly an underflow) in the algorithm. I plan to check the new algorithm carefully and to work on making plasmas with robust m=3 modes.

Friday July 13 04 23 hanson 54648-54697 discharge development Spent the day trying to fine tune m=3 kink-mode discharges. I plan to pick up where I left off on Monday and spend the rest of next week doing Kalman filter experiments.

Monday July 16 03 19 hanson 54698-54729 kalman filter More discharge development and Kalman filter testing today. I've been able to create a fairly repeatable kink mode. There's a small bug in the Kalman filter algorithm that seems to track with the adjustable phase angle. I think I know what's wrong and will fix it tonight and recompile. I hope to be ready to start compass scan experiments tomorrow.

Tuesday July 17 05 41 hanson 54730-54790 kalman filter This morning, I found and fixed the bug in the Kalman filter (there was some incorrect memory addressing in the inverse DFT step) and was able to start experiments. I completed about a quarter of a feedback phase angle scan. This afternoon, there was some trouble with the TF bank charging electrode: a piece had broken off. With Nick's help, I filled the resistor high enough to submerge what was left of the electrode. Eventually, it will need some attention.

Wednesday July 18 05 39 hanson 54791-54850 kalman filter The feedback phase angle scan continued today. It's nearly halfway finished.

Thursday July 19 07 35 hanson 54851-54930 kalman filter More of the Kalman filter feedback phase angle scan today. I am nearly done; plan to finish up tomorrow morning.

Friday July 20 03 51 hanson 54931-54965 kalman filter The Kalman filter feedback phase scan was completed today. I plan to do initial analysis of the results over the weekend, so we can talk about what to do next on Monday. Also, I managed to overheat the TF charging resistor again: the electrode is now almost gone and needs attention. I'll repair it with guidance from Nick and Dave on Monday.

Tuesday July 24 05 01 hanson 54966-55005 discharge development This morning, I inserted the aluminum shells fully and re-created the shot used for feedback experiments last week. The Al shells were able to suppress the mode about as well as optimally phased feedback (last week), but this suppression was not spectacular. Perhaps the mode I used behaved too ideally. I am now working on developing a more resistive mode.

Thursday July 26 03 39 hanson 55006-55106 discharge development I've spent the last couple days fine tuning my kink mode discharge. I hope to get back to taking feedback data tomorrow.

Friday July 27 04 29 hanson 55107-55151 kalman filter Took some feedback phase scan data today. Much more of the same planned for next week.

Monday July 30 05 05 hanson 55152-55195 discharge shaping Did some work trying to make a better, stronger external kink mode. Plan to continue in this vein tomorrow.

Tuesday July 31 05 12 hanson 55196-55258 discharge development Work on making a better external kink discharge continues. I have a candidate that I'll test with feedback tomorrow.

Wednesday August 1 06 10 hanson 55260-55304 discharge development More discharge development today.

Thursday August 2 05 22 hanson 55308-55379 kalman filter I started a feedback phase scan with a new, stronger kink mode today.

Friday August 3 06 05 hanson 55381-55447 kalman filter More feedback phase scan shots today. Initial results show some promise, but the going is slow.

Monday August 6 04 28 hanson 55448-55506 kalman filter More feedback phase scan data taken today.

Tuesday August 7 04 54 hanson 55507-55579 kalman filter More feedback phase scan shots today. I'm now done with over half of the compass points.

Wednesday August 8 06 09 hanson 55580-55659 kalman filter More feedback phase scan data taken today.

Thursday August 9 05 49 hanson/shiraki 55660-55738 kalman filter/hall probe Finished up the feedback phase scan today. Initial analysis of the data points to some suppression over a decently broad range of phase angles. I'll have some plots for discussion on Monday. aisuke got some hall probe data as well.

Friday August 10 05 00 shiraki/hanson 55739-55781 Hall probe Took some hall probe data, attempting to recreate Yuhong's shots.

Monday August 13 05 09 hanson/shiraki 55782-55834 In the morning, we pulled the Al shells all the way out to try to replicate a shot from Yuhong Liu's thesis. In the afternoon, the shells were fully inserted to see what effect they had on the mode used for feedback experiments last week. Some suppression was seen, but I'd like to take a few more of these shots.

Tuesday August 14 04 37 hanson 55835-55861 discharge development First, the mode from last week's phase scan was re-created with the aluminum shells pushed all the way in. Little suppression was seen. Next, the Al shells were pulled back 4 cm from the plasma surface and an attempt at making a shot similar to the one used in Liu's thesis (45645) was made. The behavior in this shot seems to be a little easier to reproduce than seen in Klein's discharges. I plan to fine tune my reproduction tomorrow.

Wednesday August 15 05 47 hanson 55862-55915 discharge development Attempts to make a better kink mode continue.

Friday August 17 04 50 hanson 55916-55960 discharge development The search for a better kink/rwm continues. Today, I spent a some time attempting to make shots similar to those used by M Shilov (e.g. 38318). One thing that's nice about this shot is that the mode appears much later in the discharge compared to the shots that Klein used--usually around 5 ms. By this time, the plasma has had a chance to heat up more and there is sometimes a good, solid SXR signal. In any case, I feel like I've been having difficulty achieving good soft x-rays, especially early on in a discharge. Loop voltages are usually below 10 V for "usual" plasma currents of 10-20 kA, but I've been finding that I usually need to grow the plasma in major radius to see much of anything in the SXRs. I've played with the fill pressure a little bit, but perhaps some more systematic studies are warranted.

Monday August 20 05 08 hanson 55961-55997 discharge development Friday and today, there were some problems getting the banks to fire. The issue has been intermittent, so I haven't been able to pinpoint the cause yet. Also, the screenroom digitizer did not want to power on this morning. It's bypassed for now. I did have time to make a few plasmas. The idea now is to see if I can get them to heat up better by breaking down a little further out (R~=95cm) and then pulling the plasma in. This does seem to be helpful. I will not run tomorrow in order to allow for Thompson scattering and D-alpha hardware work to be done in the machine area. I'll pick back up again on Wednesday.

Wednesday August 22 05 57 hanson 56003-56069 discharge development Today I made some progress in creating external kink modes in scenarios where edge-q is ramped down through q=3 and where it is ramped up. Mike suggested that I adjust the start time of the VFST bank to coincide with the start time of the OHST bank. This seemed to create a more smoothly evolving discharge in the ramp-up case. I plan to continue tuning both kinds of shots and reproduce them with the Al shells in. Perhaps feedback experiments can begin next week.

Thursday August 23 05 09 hanson 56070-56120 discharge development I have completed fine-tuning my q ramp up and ramp down discharges. I am now trying to reproduce them with the Al shells fully inserted to see how the modes behave. I hope to have this done by the end of tomorrow.

Friday August 24 04 21 hanson 56122-56165 discharge development I attempted to re-create my ramp-down and ramp-up modes with the Al shells all the way in, today. The ramp-down evolution was a little easier to get right and showed more mode suppression.

Tuesday August 28 05 02 DeBono/Hanson 56166-56169 rotation Ran 10%He & 90% Deuterium for rotation diagnostic testing. Had problems with new screenroom digitizer rack initializing.

Wednesday August 29 06 17 B.DeBono/_J.Hanson 56170-56198 Velocitometer Ran shots 56170-56198 for rotation diagnostic calibration.

Thursday August 30 06 03 DeBono/Hansen 56199-56223 Rotation Diagnostic Ran shots 56199-56223 for rotation diagnostic calibration

Wednesday September 5 05 12 hanson 56224-56269 discharge development I studied the effect of the start time of the vertical field on the dynamics of my external kink modes. I made some interesting plasmas, but did not see any modes stronger than what I've made already.

Friday September 14 03 41 DeBono/Maurer 56399-56431 Velocitometer Ran Cleanup/Rotation calibration shots today with 90%Du/10%He mix.

Wednesday September 19 06 22 DeBono/Hansen/Maurer 56432-56500 Rotation Diagnostic HBTEP was run with 10%He, 90%Du for rotation diagnostic calibration: Tests were conducted with velocitometer detector mounted to view the plasma perpendicular to its flow (on the ICRH port).

Thursday September 20 06 12 hanson/shiraki 56501-56582 clean-up In the morning, I tried to re-create the modes discussed at the physics meeting last week. I was able to get very close, but I feel like there might be a little cleaning up that needs to be done yet. However, the plasmas look pretty good. In the afternoon, Daisuke got some hall probe data for edge-q ramp-up style shots.

Monday September 24 04 28 hanson 56583-56606 kalman filter I was able to get a few shots in this afternoon. Previously, the FPGA driving the top-middle control coil set was using inputs from the bottom-middle sensor coils. After discovering that the phase-shift between top-middle and bottom-middle in the sensor coil data is almost exactly 180 deg (for the m=3 mode), I added a correction to the FPGA algorithm. Data taken today confirmed that the correction works as it should. I plan now to redo my Kalman fitler phase scan, since the correction was quite drastic.

Tuesday September 25 04 57 hanson 56607-56677 kalman filter I began my Kalman filter phase scan today. Plasmas seem to be a little less reproducible; perhaps we are still cleaning up a little. I had some trouble this morning with a control coil not energizing. After swapping analog boards around and testing one on the bench, I concluded that there was simply a loose connection somewhere. Getting the analog board plugged in "just right" by trial and error seemed to fix the problem.

Wednesday September 26 02 58 hanson 56678-56724 kalman filter More Kalman filter phase scan data taken today. Plasmas looked just fine.

Thursday September 27 05 50 hanson 56746-56813 kalman filter More Kalman filter phase scan data taken today. Shot to shot reproducibility seems to be somewhat poorer than in past months; this experiment will likely continue through most of next week.

Friday September 28 02 26 hanson 56814-56834 kalman filter More Kalman filter phase scan data was taken today. We ended the run day early to get the bake turned on for the weekend. Brian and I had hoped to get some optical rotation data this afternoon, but a shortage of liquid nitrogen prevented us from being able to pump out the puff line to switch gases.

Tuesday October 2 05 37 Hanson/DeBono ?-56927 Kalman Filter/Rotation Diagnostic Shots were taken by Hanson and by DeBono Shots with 90%Du, 10% He were taken for shots 56905-56927 with the detector looking perpendicular to the direction of plasma flow. The purpose of this run was to assume the rotation velocity of the plasma was 0 (as viewed from the detector) with the data used for detector re-calibration.

Wednesday October 3 05 56 hanson 56928-56990 kalman filter More Kalman filter feedback shots taken today. Reproducibility is still somewhat poor, although there's no other evidence of the vacuum vessel being unclean. (Base pressure this morning was 1.0E-8 T.)

Thursday October 4 05 10 hanson 56992-57039 kalman filter More Kalman fitler phase scan shots taken today.

Friday October 5 05 08 hanson 57040-57093 kalman filter More feedback phase scan data taken today. I'm nearing the end of this experiment; hopefully another day or two will be all I need to finish.

Monday October 8 06 31 hanson/debono 57094- kalman filter/rotation diagnostic The morning was spent fixing a problem in the cos 1 theta Rogowski diagnostic. The L8210 used for this signal appears to have gone bad, so the signal was moved to a different L8210. In particular, the cos1 signal was moved from crate 5, slot 13, input 1 to crate 5, slot 21, input 4, and the tree was updated accordingly. In afternoon, rotation diagnostic shots 57101-57118 were taken. The detector was moved from its perpendicular viewpoint to a view looking along the torus (i.e, the detector was moved to see plasma rotation). The signals taken were relatively weak and characterized by nonexistant termination shock profiles. I will attempt to correct for this by increasing the light level output from the plasma by increasing the current and/or the pressure fill density.

Tuesday October 9 07 16 hanson 57120-57172 kalman filter More Kalman filter phase scan data taken today. Yesterday's fix for the cos1 digitizer appears to be working fine.

Wednesday October 10 06 01 hanson 57173-57228 kalman filter More Kalman filter feedback phase scan data taken today.

Thursday October 11 06 19 hanson/debono 57229-57321 kalman filter/rotation diagnostic In the morning, Hanson continued the Kalman filter feedback phase scan; in the afternoon, DeBono got some rotation data from 10% He plasmas. The phase scan is nearly finished and preliminary analysis of the m=3 Rogowski signal shows a trend that looks a lot like that of Klein's experiments, but with no excitation above 5 kHz. 3 more shots are needed to complete the dataset; these will be taken tomorrow. Rotation diagnostic was taken with the detector setup to observe plamsa rotation. The tokamak was operated with high OHST and OHEL values in order. These parameters were chosen to gain as much signal as possible from the plasma. Data showed rotation velocities within the acceptable error (+-1km/sec) and with low velocity values (0.3 km/s < velocity < 3km/sec).

Friday October 12 05 10 hanson 57322-57358 feedback A variety of things was done today. The last data points in the Kalman filter phase scan were recorded; Hall probe data was taken for feedback phasings of clear suppression and clear excitation; an open-loop, static (ie non-rotating), (m,n)=(3,1) field phase-flip FGPA algorithm was tested on the both edge-q ramp-down and ramp-up plasmas. There were problems communicating with the North rack throughout the day. Since this didn't directly impact any data taking, the issue was not fully resolved. Plan to let the crates cool off and see how things are next week.

Monday October 15 06 25 DeBono/Hanson 57360-57397 Rotation Diagnostic Today I revisited the perpendicular 0-velocity shot after obtaining a wide spread in rotation velocities for a given non-perpendicular shot last week. The detector was moved to a perpendicular view; results showed inconsistent velocities obtained by the diagnostic. More shots need to be obtained for this.

Tuesday October 16 10 23 hanson 57398-57453 mode rigidity study I'm working on doing Kalman filter feedback runs with one toroidal group of control coils muted. Rogowski coil and Hall probe data will then be analyzed as a function of the muted coil set. The scan is nearly finished; I plan to have it done with by the end of the day tomorrow.

Wednesday October 17 01 15 hanson 57454-57488 mode rigidity investigation A preliminary mode rigidity experiment was completed today. The Kalman filter feedback algorithm was used with a phasing of 60 deg (for suppression) and a single toroidal group of control coils muted. Four shots were taken for each toroidal location.

Wednesday October 17 07 39 DeBono/Hanson 57489-57559 Rotation Diagnostic Rotation Diagnostic data was taken with the detector oriented perpendicular to the plasma flow. Tokamak was run with 10%He,90%Du. Shots 57489-57559 were taken. Data seems encouraging with several excellent shots taken.

Thursday October 18 05 19 Jeff_Levesque 57566-57579 Thomson Scattering Testing the Thomson scattering triggering and data acquisition. Observed scattered light in all channels of the polychromator.

Friday October 19 05 50 hanson 57581-57622 partial coverage More partial coverage Kalman filter feedback data was taken today. Feedback was performed with different toroidal sections muted, one section at a time. Additionally, vacuum shots were taken to investigate the pick-up from the feedback coils in various diagnostics. These shots were done with the TF, VF, and OH fields present as normal, and a single toroidal section of feedback coils ringing at ~5 kHz.

Tuesday October 23 05 47 Levesque 57633-57691 Thomson Scattering More tests of the Thomson scattering system. Attempted to increase scattered light collected by adjusting the collection lens. Signal levels stayed approximately the same over a small range of adjustment. Shots taken with laser firing at 3 ms and 5 ms into the plasmas. Verified that only channels 1 and 2 of the polychromator receive stray light.

Wednesday October 24 06 02 hanson 57696-57736 feedback testing After analyzing SMP data from the last phase scan and not seeing much of a trend, I decided to move the SMPs up close to the plasma and do some feedback excitation and suppression shots. I also spent a little time doing feedback with Alex's old routine to get some data for comparisons between the algorithms. Additionally, Royce plugged his photodiode array into the CPCI and saw signals due to (unfiltered) light on most of the channels.

Thursday October 25 03 03 hanson 57737-57767 feedback I finished up my run of feedback shots with the SMPs fully inserted today. Several phasings of Alex's old filter were tested in addition the Kalman filter.

Wednesday October 31 09 44 James 57697 - 87854 D-Alpha Piggy-backed Jeremy's feedback runs. I was able to get all 20 channels working properly, showing both unfiltered and d-alpha. Unfiltered light was in the .15 V range, and the d-alpha .075 V. I was able to work out the channel errors I had. It turns out that I had the channel order on the board backwards. I was able to confirm this with the filament when I was aligning the PDA and mount. The chordal signals track the plasma nicely showing more visible light in the center channels where the most plasma is intercepted and less on the edges. Conversely d-alpha signals are highest on the (outboard) edge and fairly constant in the center channels. Data analysis is the name of the game for the next few days to get ready for the poster.

Friday November 9 11 02 Jeff_Levesque TS Calibration Performed Rayleigh and Raman calibrations with nitrogen (on November 7 & 8) in order to calibrate Thomson scattering density measurements from 10/31/07.

Friday November 9 12 04 J._Andrello,_N._Rivera We pumped the chamber back down. The pressure quickly dropped to high 10^-8 Torr. The bake is on and the pressure is presently 2.4x10^-7 Torr

Thursday December 6 05 40 DeBono 58006-58065 Rotation Shots were taken at the perpendicular viewing port to test anti-aliasing amplifiers on rotation diagnostic.

Thursday December 13 03 35 hanson 58065-58094 clean-up I am attempting to reproduce the (m,n)=(3,1) kink mode used for Kalman filter feedback experiments in the summer and fall. It is quite possible to match the evolutions of the plasma current, major radius, and edge-q

Thursday December 13 03 48 hanson 58065-58094 clean-up I am attempting to reproduce the (m,n)=(3,1) kink mode used for Kalman filter feedback experiments in the summer and fall. It is quite possible to match the evolutions of the plasma current, major radius, and edge-q with previous shots, but the mode does not always appear. Possibly, impurity levels are a bit higher (after the Thompson scattering calibration), making it harder to sustain a current density gradient at the edge. The mode did seem to get stronger as the day went on. I plan to turn on the RGA tonight and continue with these shots as time allows, eventually starting phase-flip experiments when plasmas improve.

2008

Monday January 14 05 14 hanson 58235-58264 clean-up Clean-up shots were taken today, with the eventual goal of producing stable resistive wall modes for use in phase-flip experiments. The plasmas currently exhibit large disruptions before modes have a chance to grow. Loop voltages are around 8V for plasma currents in the neighborhood of 10 kA. Plan to continue running these kinds of shots all week.

Tuesday January 15 05 03 hanson 58265-58312 clean-up More clean-up shots taken today with the intention of producing a good model discharge for phase-flip experiments. Plasmas are still plagued by large disruptions in mid-shot, but these seem to be getting smaller. Plan to continue this campaign tomorrow.

Wednesday January 16 07 13 Levesque_+_Hanson 58313-58396 Clean up Clean up shots. Testing automatic recording of Thomson Scattering data. Raw data from TS oscilloscope traces is being added to the HBTEP tree. Royce was able to see a difference in D-alpha emission with changing fill pressure.

Thursday January 17 05 24 Hansen/DeBono 58415-58444 Cleanup shots Cleanup shots taken today. Plasma seems to be improving.

Friday January 18 03 47 hanson 58446-58470 clean-up More clean-up shots taken today, with the goal of developing a good model shot for phase-flip experiments. This discharge has been improving over the week, with discharge lifetimes increasing slowly, loop-voltage decreasing to < 8V, and soft x-ray signals starting to come up. We ended early today to insert the filament probe for d-alpha array spatial calibration. Plan to continue these shots next week.

Friday February 8 05 43 hanson 58610-58626 clean-up We were finally able to get back to running HBT-EP this afternoon. (There were delays due to pumping on the bias probe bellows and air-conditioner maintenance.) There is definitely some more clean-up work to be done, but the plasmas do not look that bad, all things considered. Loop voltages were reaching 8 V towards the end of some shots, for plasma currents around 12-15 kA. On the side, there was some progress made in getting the CPCI to function more consistently. A firmware upgrade to the box fixed some internal triggering problems, so the CPCI now appears to record data at the correct time for every shot. There have been some new troubles getting the time values for the data, but this is less serious.

Saturday February 9 02 02 hanson/maurer 58631-58681 clean-up More clean up shots taken today. Plasmas continue to improve, with loop voltages that drop below 8 V towards the end of the discharge. Plan to start mode development early next week.

Monday February 11 04 55 hanson 58682-58721 mode development I am now trying to develop plasmas with external kink modes in which the edqe safety factor slowly ascends from about 2.7 to above 3.0. Currently, plasmas made in this style suffer large disruptions, indicating that there is still some clean-up work to be done. Past experience has been that the disruptions will become less frequent as we clean up.

Tuesday February 12 04 36 hanson/debono 58722-58762 discharge development Continued working on creating a good q-ramp-up discharge to day. Plasmas continue to improve, but large disruptions are still observed occasionally. Some testing of the optical rotation diagnostic was done as well.

Wednesday February 13 03 41 hanson 58774-58810 discharge development Attempts to create a Shilov-style kink mode continue. The modes seem to be improving slowly, but these shots are difficult to make. Shot 58808 looked good, but it was not reproduced.

Thursday February 14 04 45 hanson 58821-58862 discharge development The q* ramp up discharges I've been working on this week are slowly improving in that they last longer and the rise through q*=3 is less dramatic. We are seeing large external modes on some shots, and lots of internal modes, too.

Friday February 15 06 11 DeBono/Hanson 58899-58949 Velocitometer Scan Shots were taken with 90% De and 10% He this afternoon. Problems involving the Ch1 connector box appear to have been repaired. A shot with a constant major radius profile @ ~94cm for ~4msec was used as the observed chord was scanned across the plasma. Bryan DeBono

Monday February 25 07 18 DeBono 59023-59063 velocitometer Shots taken on 59023-59063 with 90%De & 10% He to obtain the HeII emission profile of HBTEP plasmas. After 59063, a loud noise was heard in the basement after the start panel resets were punched. Banks were not charged. No initial sign of damage in the capacitor room.

Tuesday February 26 09 52 DeBono 59064-59094 velocitometer Ran shot numbers 59064-59094 after refilling OHEL water resistors with CuSO4 solution. No problems, no abnormal occurances.

Thursday February 28 10 53 DeBono 59096-59140 velocitometer Shots 59096-59140 were taken with 10%He, 90%De gas to finish velocitometer chord sweep of unaccelerated (i.e. no bias probe) plasmas.

Wednesday March 5 06 32 R._James 59164 - 59224 D-alpha Attempted to understand discrepancies in calibration measurements made from the filament and data taken from the plasmas. Made several variations of inboard limited and outboard limited plasmas to try and determine if I was indeed only seeing part of the plasma as the calibration measurements suggested or the entire plasma which would point to a mishap in the calibration results. Unfortunately, the results are inconclusive. As I lock down constraints (i.e. camera angle, mirror angle, and camera tangential position), things are beginning to get clearer. To do this, I have been switching back and forth between plasma shots and filament scans to investigate the outer and inner channels respectively. I did discover what seems to be either a bad diode channel or a broken connection inside the 'camera' before the amp box in the lower channels (#33) or in the input to the amplifier, it would need to be repaired before the calibration was complete as well. I will need a day or two more to systematically confirm the chord spacing and chordal view next week.

Tuesday March 11 03 02 James 59225 - 59251 D-Alpha Calibration complete! Channel 33, repaired, Bias probe to be installed this afternoon. Details on calibration to come as white paper.

Friday March 14 05 21 hanson 59252-59273 clean-up The bias-probe bellows was opened to the vacuum chamber yesterday night, and the first clean-up shots were taken this afternoon. In order to get an idea of what the vacuum conditions were like, I tried to reproduce my kink mode model shot from last fall's experiments: 56079. I was able to get close on a couple shots, indicating perhaps that there is not much clean-up work to do. The bake will be turned on over the weekend and clean-up efforts will continue on Monday.

Monday March 17 05 06 hanson 59281-59301 clean-up More clean-up shots taken this afternoon. Strangely, shots today did not look quite as good as on Friday. Perhaps the weekend bake re-deposited impurities onto the limiting surfaces. Also, I'm shaking out a couple bugs in the feedback system, but it is more or less working.

Tuesday March 18 03 58 hanson 59302-59353 clean-up More clean-up shots taken today. We are starting to see more mhd activity, but plasmas are not yet behaving very consistently. Also, the feedback system is now in working condition. (A D-connector in the south rack was unplugged, disconnecting half of the control coil circuits).

Wednesday March 19 07 21 James/Hanson 59354 -59429 clean-up Lots of clean-up shots today under the guise of mode development. Shiraki took more triple probe data, Hanson concentrated on Kalman filtering (59369 - 59386), while I did Shilov style RWM development (59387 - 59429). Hanson was able to recreate modes from last fall, yet it seems like the vacuum is still to dirty for RWM's. I plugged in the RGA so we can compare it to Mondays readings. More of the same tomorow.

Thursday March 20 05 27 hanson/james 59432-59493 clean-up More clean-up shots were taken today. Royce has been attempting to create a reliable q* ramp-up shot for phase-flip experiments, but this has not yet been successful. The q* ramp-down shots are looking pretty good.

Friday March 21 05 03 hanson 59494-59556 clean-up More clean-up shots taken today.

Monday March 24 05 03 hanson 59557-59583 kalman filter Experiments in adding adjustable amounts of noise to closed-loop feedback algorithms continued today.

Tuesday March 25 10 17 James 59584 - 59659 d-alpha More clean-up and RWM mode development. The loop voltage has come down to about 8.5 V from 12V last week and Shilov's shots were at about 6V so still a fair amount to do. More of the same tomorrow.

Wednesday March 26 05 14 James 59641 - 59700 Clean-up/ RWM More clean-up today. A bit of a late start after some CPCI com. issues that Jeremy and I resolved. Base pressure began to creep between shots. From 1.8 e-8 to 4.1 e-9 by the end of the day - I put on the RGA. Did a couple of phase flips, just to get familiar with the system, shot#'s:59700 (3.3 msec) and 59681 (2.5 msec).

Monday March 31 08 24 debono 59733-59790 Velocitometer Rotation Diagnostic data was taken with bias probe inserted into plasma. Bias probe voltage was varied from 0V to 275V at 25V increments. Data shows sharply reduced plasma lifetime at higher voltages, as well a tendency of the plasma to crash into the inner wall at higher bias probe voltages.

Wednesday April 2 05 58 hanson 59834-59860 kalman filter The newly reworked Kalman filter algorithm was tested on plasmas today after modeling in IDL indicated that it would behave reasonably. (The accuracy of the IDL model was checked against the actual FPGA algorithm at 10 frequency points and found to be in very good agreement.) Several phase angles and gain settings were tested today. A more formal phase scan will begin tomorrow.

Thursday April 3 06 01 hanson 59861-59921 kalman filter phase scan I scanned a good number of Kalman filter feedback phase angles today. I plan to continue this experiment into next week.

Monday April 7 07 21 R._James 59993 - 60022 RWM Development Initiated fill pressure scan today. Plan to complete tomorrow and start phase flip experiments.

Tuesday April 8 04 55 james/hanson 60023-60067 d-alpha/kalman filter Royce did some fill pressure scan experiments this morning, and I did a few more points in my phase angle scan this afternoon.

Wednesday April 9 05 59 hanson 60068-60102 kalman filter The first set of phase angles in the Kalman filter phase scan was completed today. I will probably try to do a couple more sets for averaging. The initial results are about the same as those from last fall, but with shifted regions of suppression and excitation. Now that the optimum phase angle for supressive feedback is known, I'm taking a few shots to see if the proportional gain setting can be further optimized. This should be finished by tomorrow.

Thursday April 10 07 40 James/Hanson 60103 - 60141 RWM - Feedback Hanson continued yesterdays tests following up on the phase scan completed yesterday. More pressure scans, pressure seems to cap at 5.5e-5 no matter how long the puff valve is open and bottom out at ~ 4.4e-5 to still achieve breakdown. More analysis over the weekend will help to determine if is a large enough window to appreciably alter D-alpha emissions and eventually RWM stability. It would be nice to get a factor of 10 and at least a factor of 2 difference. We will investigate the puff electronics and pressure to see if we can improve it next week.

Thursday April 10 09 46 James/Hanson 60103 - 60141 RWM - Feedback Hanson continued yesterdays tests following up on the phase scan completed yesterday. More pressure scans, pressure seems to cap at 5.5e-5 no matter how long the puff valve is open and bottom out at ~ 4.4e-5 to still achieve breakdown. More analysis over the weekend will help to determine if is a large enough window to appreciably alter D-alpha emissions and eventually RWM stability. It would be nice to get a factor of 10 and at least a factor of 2 difference. We will investigate the puff electronics and pressure to see if we can improve it next week.

Friday April 11 04 18 hanson 60142-60185 kalman filter More Kalman filter gain scan shots were taken today. I plan to analyze the results of this and the phase scan over the weekend, and we can discuss what experiments to do next on Monday.

Wednesday April 16 05 19 hanson 60191-60255 discharge development I attempted to make a stronger kink mode discharge for feedback studies. Some progress was made, but I will probably need another day or so to continue developing the shot. In other news, Royce and I added a second puff of gas during the middle of some discharges. This had a dramatic effect, temporarily damping mode activity, and causing some very large disruptions later on. We imagine that higher fill pressures could be obtained by moving this second puff to a time before the plasma breaks down, but this has not yet been tested.

Monday April 21 10 44 James 60343 - 60379 RWM / D=Alpha Investigated variations in puffed gas during shots to see how the plasma reacts. Used 3.75 ms as a base puff time and initiated a second puff of 1/8, 1/12, and 1/36 of that time at 2.5 ms. It generally takes approx. 1.5 ms after the puff is initiated to see an increase in D-alpha. Emissions were about equal to breakdown peak, half breakdown peak, and 1/5 breakdown peak respectively. The later was still about twice the emissions before and after its flow and ebb - except when there’s a disruption immediately following. As expected, 1/36 puff time seems to be the least disruptive to the plasma. The lifetime of the plasma is shorter with a major disruption usually just after the ebb of the d-alpha increase and sometimes during that ebb. Plasma current ramps always leveled off with 1/36 puff having a significant effect just like the 1/8 and 1/12 puff times. However the q seemed to behave much in the same manner as usual as long as the major radius fell off fast enough. I also attempted to increase the pressure before the shot with multiple puffs since I have had better luck with developing the mode for plasma lifetimes between 5 ms to 7 ms. With an increased puff time of 5 ms, I used 3 pre-breakdown puffs, at -95 ms, -35 ms, and -.5 ms to get a slightly higher fill pressure than with 2 puffs, up to approx. 7.6 e -5 torr from 7.0 e-5 torr seen with only 2 puffs. Later I added the 1/36 puff time at 2.5 ms as before totaling 4 puffs. See shot# 60379 use scope hbtep_da_review.jscp in my home directory Jscope – configurations under. D-alpha emissions are higher at the higher pressures yet the neutrals appear to burn out as the shot continues and the increase between breakdown and final disruption is subtle.

Tuesday April 22 05 25 hanson 60380-60409 discharge development By examining the effects of small changes to the bank settings previously used for feedback studies, I have been successful in making a mode that is both stronger and more reproducible than the old one. With the new settings, the current ramp is kept about the same, but the edge-q is kept closer to (but just below) 3. This seems to result in a robust 5 kHz mode. The mode also seems to respond to feedback: I've been able to reduce amplitudes in the sensor coils by 40-50% in a couple shots. One shot done at a positive feedback setting showed excitation of the mode. I also did a shot in which the FPGAs were not gated on until 2.5 msec (in the middle of the mode). This appeared to have a near-immediate on the mode amplitude, but more shots are needed to confirm this result. I am planning next to do a scan of the growth rate parameter in the Kalman filter model, as run time allows.

Wednesday April 23 06 00 hanson 60410-60467 kalman filter I began a scan of the Kalman filter's real growth rate parameter today, using the mode developed yesterday. I'm about halfway finished with the scan; it should take another day to finish up.

Friday April 25 06 10 DeBono 60565-60586 rotation diagnostic Shots 60565-60578 taken with 90% Du 10% He, and shots 60579-60586 taken with 100% He. Bias bank appears to be working well; probe voltage holds well with bias probe driven currents well exceeding 50 amperes in plasma. Very low signal levels observed with the rotation diagnostic while using 90% Du 10% He mix, obeserved signals became usable with use of 100% He plasmas.

Tuesday April 29 06 11 hanson 60617-60640 diagnostics testing The RC filtering for the SSI sensor coils was added to the signal path this morning and tested with plasmas. The plasmas themselves were cold and did not display much MHD activity, but the filtered sensor signals were observed to have a quasi-dc component that I believe should come from the Ohmic and vertical fields. One filter was also bench tested to make sure the frequency roll-off was as expected. With regards to the SMPs, the L8100 amplifiers have a gain and a multiplier setting. Originally the these were set to G=100 and M=.5, giving an effective voltage step of dV=.0002 V in the signal. The gain cannot be set above 100, but the multiplier was turned up to 1.0, for an effective voltage step of dV=.0001 V, improving resolution by a factor of 2. In order to achieve plasma break-down, I had to use the double puffing technique to inject extra gas. I was then able to reduce the amount of gas puffed in over the afternoon, but I could not get breakdowns with normal puff times. The plasmas had loop-voltages above 12 V and showed chaotic behaviour and little MHD activity. It also seemed to take a long time to pump out after a shot. An inspection on the RGA showed levels of He/D2 at the same order of magnitude as the base pressure. I've been told that He pumps out slowly, so I've turned on the bake to see if this will accelerate things. I will consult with Jim and Dave about regening the cryos in the morning.

Wednesday April 30 06 03 hanson 60642-60705 kalman filter More Kalman filter gain scan was done today. The hope is that the modifications to the magnetic diagnostics and the new SVD analysis will reveal a clearer pattern in the scan. After this, I plan to start a phase scan at the optimal gain. (The previous phase scan was done at a rather low gain.) Plasmas looked good today. Poor plasma performance yesterday was likely due to some confusion over what gas was in the puff lines from last week; I may have been puffing in a large amount of He.

Thursday May 1 05 45 hanson 60706-60785 kalman filter The Kalman filter proportional gain scan begun yesterday was finished today, giving a fairly clear indication of what the optimal gain is for negative feedback. A phase scan was then begun at this gain and is a little over half finished. I plan to finish at least one run of the phase scan tomorrow and possibly move on to scanning the real growth rate parameter.

Friday May 2 04 22 hanson 60786-60838 kalman filter A first round of the Kalman filter phase scan was completed today.

Monday May 5 05 33 hanson 60862-60899 phase scan More Kalman filter phase scan shots were taken today. Progress was slowed by repeated CAMAC problems. We were getting NoX errors on large numbers of digitizers during the afternoon. After turning off the Jorway serial highway driver and crates for approximately half an hour, we were able to get 4 shots in before the errors came back. This makes me think the root causes of the problems was thermal -- perhaps related to our air conditioning outage in the server room.

Tuesday May 6 10 24 hanson 60905-90987 kalman fitler More Kalman filter phase-scan data taken today. There were CAMAC problems again due to the AC outage in the control room. However, CU facilities came by with a temporary unit that is now cooling the server room, and we were able to further eliminate CAMAC errors by setting the screenroom crate's u-port to bypass. The hypothesis is that the screenroom crate was overheating, triggering NoX errors in everything else downstream. In any case, the second round of the phase scan should be complete by tomorrow morning, if there are no further hardware problems.

Wednesday May 7 06 18 Hanson 60995-61063 Jeremy continued with his phase scan, and some Mach probe tests were also done.

Thursday May 8 05 54 hanson 61064-61118 kalman filter More Kalman filter phase scan data taken today. I am just a couple shots shy of being done with the 3rd round of the scan. The trends in the data are becoming clearer with more points to average over, so I think I will try to do some added noise experiments tomorrow.

Friday May 9 05 38 hanson 61119-61165 kalman filter More Kalman filter shots today. I finished the third round of the phase scan and started investigating the effects of added noise.

Monday May 12 04 32 hanson 61166-61192 kalman filter More noise scan data was taken today.

Tuesday May 13 04 32 Hanson/Shiraki 61193-61210 kalman filter/mach probe The Kalman filter algorithm was tested with external noise inputs today. The Mach probe was tested also.

Wednesday May 14 05 39 hanson 61211-61269 kalman filter More Kalman filter experiments with added noise today. Initial analysis (on just a few shots) revealed differences between the efficacy of the Kalman filter and proportional gain only filter in both exciting and suppressing the kink mode. I hope to finish getting data by tomorrow and to start writing things up on Friday.

Thursday May 15 05 50 hanson 61270-61329 kalman filter More added noise experiments today with the Kalman filter and proportional gain only filter. Discharge repeatability has been poorer these past couple days, slowing progress. I'll probably try to run most of tomorrow, and maybe will regen a cryo on Saturday.

Friday May 16 05 39 hanson 61330-61389 kalman filter More added noise experiments today. The krytron for the VFEC bank failed and we replaced it with a spare. However, this was the last spare; we have no more spare krytrons. Aside from that interruption, the runs went well.

Tuesday May 20 05 05 James 61391 - 61414 RWM Stability Did some mode development shots today. We decided to regen the other cryo so it was slow going. Was able to get a decent mode relatively quickly plus test the Hall probe channels I will be able to use at the same time as D-alpha. Phase flips will start tomorrow.

Wednesday May 21 10 06 James 61415 - 61458 RWM Stability Opened up the 2nd cryo today after a few shot and it seems to be doing well. I did a series of static phase flip experiments and a few dynamic ones at the end (61456-58),at 2.5 and 2 ms respectively (before the q*=3 surface was broken. The hall probe, triple probe D-alpha can all be run simultaneously. We should be ale to continue testing tomorrow and include gas puffs.

Thursday May 22 08 34 R._James 61459 - 61521 RWM Stability Perfected low fill pressure stable RWM and performed static phase flip tests at 2 ms, 61492 - 495. Developed a 3 puff pre-breakdown stable mode which gave an increase from 4.4e-5 to 5.9e-5 and repeated the static flips at 2 ms, 61511 - 61519. These plasmas were a little harder to reproduce from shot to shot, but I was able to get some stable RWM's to experiment with. I will do one more static phase flip experiments tomorrow with a puff early in the shot to complete the static phase flip method. If time allows I will initiate the dynamic phase flip experiments as well.

Friday May 23 03 02 R._James 61523 - 61555 RWM Stability I completed the Phase flip experiments today. If time allows I will do the resonant response test around the end of next week. Preliminary results are promising, it looks like the realignment times after the flip for a stable mode with normal fill pressures around 4.4e-5 torr are around the same time as those Shilov reported about .25 ms. I increased the fill pressure in two ways. With 3 pre-fill puffs 61510 - 519 and with 2 pre-fill and one puff early in the shot 61541-555. The realignment times for these were subsequently longer indicating a probable decrease in stability with more neutrals!

Tuesday May 27 06 21 DeBono 61556-61590 Velocitometer Scan Shots were taken with 10%He 90%Du. Measured velocities are inconsistent shot-to-shot with the bias probe inserted (but not with the probe removed), perhaps additional shots are needed to remove impurities from the surface of the bias probe.

Wednesday May 28 06 26 DeBono 61592-616-24 Velocitometer w/ Bias Probe Shots Plasmas were run from 10% He, 90% Du. The bias probe was energized to voltages of 50V, 150V, 300V to see measured affect on plasma rotation (Probes outer edge inserted to 105.5cm with the velocitometer looking at 99.53cm). The diagnostic detects increasing toroidal rotation as the bias bank is fired, and it appears that increasing bias probe voltages result in higher rotation speeds. Unfortunately, the bias bank pre-fired ~50% of the shots taken (possibly due to craytron noise).

Thursday May 29 06 08 DeBono 61625-61657 Velocitometer scan Plasmas were run with 10% He 90 % Du. Bias bank pretriggered for nearly every shot taken, upon examination it appears that this is likely due to craytron noise from the VFST and VFEL banks, and possibly also the OHST and OHEL banks.

Friday May 30 06 14 Shiraki 61658-61688 Took hall probe and triple probe data. Results to be analyzed over the weekend.

Wednesday June 4 10 46 R._James 61733 - 61779 RWM Shot development today, experiments to follow tomorrow.

Thursday June 5 01 47 DeBono 61780-61792 Bias Bank Prefiring Tests Tests were run in 100% He to test an attempted fix to the bias bank prefiring problem. The tests proved to be successful mostly: the bank did prefire for most shots taken at high voltage (>300 volts) but no pretriggering occured for shots taken at 50 or 150 volts. The fix to the problem is described below. bias bank power supply was rerouted to a plug outside the capacitor room, as earlier it was plugged into the same power outlet as the crytrons. The power supply connects to an isolation transformer, which has cheaters plugged into both its power outlets to provide power to the avionics trigger and to the power supply for the bias bank as well as potentially avoiding any ground loops. The lid to the bias bank was closed (previously it was left open) as well to minimize EM interference with the triggering circuit.

Friday June 6 04 45 debono 61793-61817 velocitometer scan Plasma were run with 90% Du 10% He. The repairs to the bias probe triggering appear to work well for voltages <=200V, however, at higher voltages the bank still suffers from pretriggering. A sweep was conducted between 50V and 250V to attempt to characterize the increase in He ion velocity with temperature. Data to be analyzed over weekend. A loud noise in the capacitor room was heard during the last shot of the day; one of the relays in the TF bank appears to have been the culprit.

Wednesday June 11 12 28 R.W._James 61819 - 61843 RWM Regend Cryo again today the air conditioner in the room with the Tokamak was repaired just after lunch so we got a late start. When I left, the temp was pegged at 20K and had been for the last 2 hours. It was slow running with the single cyro and mode development was all that I was really able to accomplish. Phase-Flip experiments in the morning. There is leaking in Mo's area from the wall above next to the reactor. The engineering students downstairs came up to let us know and they also called facilities. The water is localized to the floor just under the wall and damage looks minimal to Mo's space, but there is about 3-5 gallons of water on the floor.

Thursday June 12 02 33 James 61819 - 61968 RWM Stability I was able to get a plasma response from the Phase Flips after a lot of wrestling with the tokamak. I did phase flips at 2ms, 2.5ms, and 3ms which also corresponded to different D-alpha emissions. Plasmas were not very reproducible so it took a long time. I will attempt tocomplete this experiment on Monday after the meeting.

Thursday June 12 06 01 debono 61977-61992 Bias Probe Shot development with bias probe inserted and 10%He 90% Du plasmas. Slow going due to only one cryopump operational. DeBono

Friday June 13 06 23 debono 61993-62023 Bias Probe Shots taken in 90% Du 10% He. Shots were taken with bias probe was run at voltages from 0-200V in 25V increments. Pace was slowed considerably due to lack of a second cryopump.

Tuesday June 17 03 04 hanson 62028-62043 discharge development I've started creating a mode for experiments that will scan the Kalman filter parameters. This will be very close to the mode used in previous experiments, but some small adjustments need to be made, probably due to differences in the vacuum conditions.

Thursday June 19 05 06 hanson 62056-62110 discharge development More discharge development for Kalman filter studies today. I've had some good shots, but reproducibility has been poor. Hopefully this will improve as I continue to run.

Friday June 20 05 39 hanson 62111-62163 kalman filter growth rate studies I started an experiment today to scan the real growth rate parameter in the Kalman filter equations for negative feedback. Plan to continue and hopefully finish this scan by mid next week.

Monday June 23 04 42 hanson 62164-62192 kalman filter The scan of the Kalman filter's real growth rate parameter continued today. Unfortunately, there were problems with the in the output on several control coils: either the output was null or had a large dc offset. It appears that the analog boards may be part of the problem, but investigations are still underway.

Wednesday June 25 02 40 James 62193 - 62231 RWM stability Completed aditional stability / phase-flip experiments at 2.0, 2.5, and 3.0 ms. Shot to shot variability was better than in the past, but still not the best. these shots will give more statistical might to the results I got two weeks ago.

Thursday June 26 05 31 hanson 62232-62296 kalman filter More Kalman fitler growth rate scan today. The analog boards seemed to be working normally again. I hope to be finished with this scan tomorrow.

Friday June 27 04 52 hanson 62297-62335 kalman filter I finished the scan of the real growth rate parameter in the Kalman filter today. Plan to begin a scan of the imaginary part next week.

Monday July 7 07 00 James 62341 -62372 RWM More shot development with additional puff. More tomorrow with Phase-Flip experiments too.

Wednesday July 9 12 16 James 62441 = 62405 RWM Was able to create shots with 2nd puff during the shot. Plasma parameters seem unaffected for a few ms after the affects of the puff are seen in d-alpha. This is promising. However, our back of the envelope calculation puts the perturbation delivered by the new control coils onto the plasma at about 1/6 of the old coils. Tomorrow I will attempt to get a more stable mode so the response will have some hope of being measured.

Wednesday July 9 11 41 James 62407 - 62501 RWM Attempted to squelch the MHD noise in the magnetic probes by altering the VFS timing and subsequent mode development. This was not too successful. At times, the MHD noise was much worse that shots I took two weeks ago.

Tuesday July 15 08 35 James,_Levesque 62518 - 62539 Density/Temp Scan Used Thompson Scattering to investigate density and temperature levels before, during, and after affects of the 2nd puff are seen in d-alpha. Initial inspection shows temp and density to be fairly inversely proportional. I will compare TS data to triple probe data and hall probe data to see how the increase in neutrals changes the plasma. The triple probe had all three tips inserted and one hall probe from the array was inside the plasma.

Wednesday July 16 05 27 hanson 62537-62569 Kalman filter I started a scan of the Kalman filter's rotation rate parameter today. I'm pleased to report that I was able to reproduce my target plasma relatively quickly. Hopefully the scan will be nearing completion by the end of this week.

Thursday July 17 04 15 hanson 62570-62591 kalman filter More Kalman filter phase scan data taken today. The run was cut short by a dump relay failure on the TF bank. Work is currently underway to repair the damage.

Tuesday July 22 03 44 shiraki 62602-62604 TF Test Tested TF bank, up to the usual 6.1 kV. Normal running will resume tomorrow.

Wednesday July 23 04 47 hanson 62605-62634 kalman filter I attempted to continue my scan of the Kalman filter's rotation rate parameter today, but there was a small vacuum mishap. Sometime between yesterday and this morning, the gate valve for the horizontal turbo pump was opened. Fortunately, the mini turbo was turned on, backing the larger one. However, the RGA showed higher partial pressures of N2 and O2 after this problem was noticed. The behavior of plasmas after the incident was somewhat different from last week, but strong external kink modes were still achievable. We plan to continue running and will start regenning the cryo pump on the large pump stand tomorrow. The base pressure at the moment is down to 1.3E-8 Torr (with one cryo pump valved off).

Thursday July 24 06 34 hanson 62634-62685 discharge development I attempted to recreate external kink unstable discharges used in earlier Kalman filtering experiments. Plasma behavior seemed to change throughout the day, and I was getting close to my old shots by late afternoon. Base pressure this morning was 6.6E-9. The cyro on the large pump stand was allowed to warm up last night, and the cold head was pumped on today. Pressure in the line was about 10 mTorr at the end of the day, so the regenning will continue tomorrow.

Friday July 25 04 51 hanson 62688-62746 kalman filter A Kalman filter rotation rate parameter scan was started today. Plasmas and modes looked good. Regen of the cryo pump is still ongoing.

Monday July 28 04 23 hanson 62747-62775 kalman filter More Kalman filter rotation rate scan today. Plasma behavior was good. Regenning of the cryo at the large pump stand continued.

Tuesday July 29 05 19 hanson 62776-62818 kalman filter More Kalman filter rotation rate scan today. Regen of the cryo continued as well.

Wednesday July 30 02 15 hanson 62819-62826 kalman filter The scan of the Kalman filter's rotation rate parameter was finished up today. Regening of the cryo pump is still ongoing.

Thursday July 31 05 07 Levesque 62827-62838 SXR tomography Tested several amplifier boards in soft x-ray tomography system. Banks off, no plasma -- just amplified test signals.

Friday August 1 06 16 debono 62841-62859 Bias Probe Radial Electric Field Scan The objective of todays run was to characterize the radial electric field generated by the bias probe using the triple probe array, and to simultaneously measure rotation using the doppler shift diagnostic. Plasmas were run in 10% He 90% Du plasmas. Plasmas appeared cold (<30eV core temp as measured by thomson scattering) but good radial profiles were easily obtained. Bias probe voltages were scanned from 0-150V in 50V increments. Triple probe data seems anomalous, more to follow on this.

Monday August 4 06 33 DeBono 62861-62882 Triple Probe/ Mode Development More work was done today to characterize the radial electric field generated by the inserted bias probe. The error in the triple probe was confirmed today; the first channel and third channel of the triple probe failed to produce the same signal when inserted into the exact same position in the plasma (done by inserting/withdrawing the probe by 1cm). For some reason the signal from ch1 seems to be inverted compared to the signals obtained from channels 2 and 3, not sure why. This inconsistency problem in the triple probe does not seem to depend on the bias probe being inserted into the plasma, although inserting the bias probe did significantly alter the signal we obtained from the triple probe. On a positive note, mode development proved highly productive today. Thomson scattering shows core temperatures ~100eV (compared to ~30ev on friday) with a peak plasma current of 17kA with a very strong current ramp, plasma lifetime~7msec, and a very clean major radial profile. Rotation diagnostic signals are very clean, although perhaps some additional signal would be desirable. Plasmas were run with 10%Du 90% He.

Tuesday August 5 05 09 debono 62883-62906 Mode Development Additional mode development was done today, following experiments from yesterday. Shots developed on 8/4/2008 appear to be favorable for rotation diagnostic studies, however, the presentation of a very low edge q (1.5<q<2.5) results in high MHD activity as well as making it more difficult to potentially use Jeremy's feedback stabilization. Accordingly, efforts today were dedicated to obtaining shots of similar profile to those on 8/4/2008 but with a higher edge q and hopefully also lower MHD activity. Shots were conducted 10% He 90% Du.

Thursday August 7 05 19 hanson 62924-62970 kalman filter I wanted to get a few more points in the scan of the Kalman filter's rotation rate parameter today, because the optimal phasing for the different parameter settings is not clear from looking at the transfer functions. This work will continue tomorrow.

Saturday August 9 11 38 Hanson/Levesque 62971-63022 Kalman filter + TS Jeremy continued Kalman filter scan. Took Thomson scattering and SXR tomography data during the scan. TS data show a significant drop in central density at 3ms for shots lasting >~4ms. Temperature shows a linear rise throughout shot, though major radius is also changing. Drops in SXR emissivity around 3ms corroborate TS data.

Tuesday August 12 05 14 hanson 63023-63039 kalman filter More Kalman filter rotation rate scan data taken today. Much time was spent troubleshooting a CAMAC problem. The FO line connecting the north and basement racks had become pinched in the door of the basement rack and failed. Jeff and I removed the line and installed a new one. Various racks then had problems initializing properly. Powering off the crates, letting them cool for an hour, and restarting matterhorn fixed this problem. So things are back in working order.

Wednesday August 13 06 13 hanson 63040-63084 Kalman filter More Kalman filter rotation rate scan data taken today.

Thursday August 14 08 28 debono 63090-63117 Radial Eelctric field Work was conducted today to observe the radial electric field generated by the bias probe.

Wednesday August 20 05 46 hanson 63143-63183 discharge development I had intended to begin a scan of the Kalman filter's rotation rate parameter at the different value of the q0 parameter, but I had difficulties reproducing the modes I was seeing last week. It seems the plasmas might be heating up a little more and rotationally stabilizing the mode. I intend to continue my efforts to bring the mode back tomorrow.

Thursday August 21 09 04

Thursday August 21 05 43 hanson 63185-63232 kalman filter Some Kalman filter data taken today, for a scan of the rotation rate parameter.

Monday August 25 04 40 hanson 63282-63299 clean-up Clean up shots taken this afternoon following a weekend bake and glow discharge experiments on Friday. With some small adjustments to the banks settings, I am able to come close to reproducing shots from last week, but mode amplitudes are lower. Plasmas improved over the afternoon.

Monday August 25 05 38 Shiraki/Levesque 63233-63281 He glow discharge (Run report for Friday August 22) Ran helium glow discharge to attempt a relative calibration of probe areas in the triple probe array using a uniform density plasma. Tried to measure emission using the rotation diagnostic for a zero-rotation calibration. The resulting plasma density was too low to measure with the existing triple probe circuitry, and there was not enough emission appropriate for the rotation diagnostic due to low ion temperature and density. After the glow, took digitizers-only shots (63241-63281) as part of testing the SXR tomography system.

Tuesday August 26 05 07 hanson 63302-63348 clean-up More clean-up shots taken today. The kink mode activity continues to improve, getting closer to what was observed last week.

Wednesday August 27 06 17 hanson 63349-63372 kalman filter External kink modes improved today and some Kalman filter parameter scan data was taken. We had trouble this afternoon with the dump relay on the OH Bias bank. The relay did not fail completely, but was arcing enough that we could smell it in the control room. A couple hours were spent finding, replacing, and testing the relay.

Thursday August 28 04 50 hanson 63373-63420 kalman filter More Kalman filter rotation parameter scan data taken today.

Friday August 29 05 50 hanson 63420-63483 kalman filter More Kalman filter rotation rate parameter scan data taken today.

Tuesday September 2 04 41 hanson 63484=63510 kalman filter More Kalman filter rotation rate parameter scan data taken this afternoon.

Wednesday September 3 11 23 hanson 63511-63587 kalman filter More Kalman filter rotation rate parameter scan data taken today. This evening there were problems with low-amplitude signals on a couple of the control coils. Some inspection of the crunch amp cabinet revealed some poorly made connections in the power bus for the amps. The connections were either improperly soldered or not soldered at all, and covered with electrical tape. A dozen or so of these were fixed, but some problems with the amps remain. Debugging of the system will continue in the morning.

Thursday September 4 05 39 hanson 63589-63608 feedback system debugging Further attempts were made to get to the bottom of the feedback signal problems mentioned yesterday. Connections at the inputs to the crunch amps were examined and redone, and some testing of the analog boards was done. The problems still have not been resolved, so work on this front will continue tomorrow.

Friday September 5 04 55 hanson 63609-63641 feedback system test More debugging of the feedback system today. The crunch amps and analog boards have been eliminated as causes of the smaller signal amplitudes observed on several coils. Connections in and out of the crunch amps are now being investigated.

Monday September 8 05 13 shiraki 63645-63649 A glow was created this afternoon for calibration of the triple/mach probe, but was unsuccessful because the transimpedance amplifiers were not designed for dc currents. The bake was turned on at the end of the day.

Friday September 12 07 02 Levesque+Shiraki 63664-63704 Cleanup Cleanup shots following Monday's deuterium glow. Broken krytron in the VF electrolytic bank was replaced using one from the ICRH bank. Had problems seeing light with the Thomson scattering system, but found that the problem occurred because the TS viewport shutter was still closed from the glow (ooops).

Monday September 15 06 11 Shiraki/Levesque/Hanson 63705-63746 Cleanup Cleanup shots. Jeremy was able to get the feedback system working again by swapping analog boards.

Tuesday September 16 05 26 hanson 63747-63801 clean up More clean up shots taken today. MHD activity is approaching reasonable levels.

Wednesday September 17 05 52 hanson 63803-63836 clean up More clean up shots taken today. Hopefully, ELM noise experiments can begin tomorrow.

Thursday September 18 05 31 hanson 63837-63902 Kalman filter I attempted to take some data for Kalman filter experiments with added ELM-like noise. However, MHD activity in the plasmas was very inconsistent from shot to shot, indicating that perhaps the vacuum is not quite clean yet.

Friday September 19 07 00 DeBono/Hansen 63919-63966 Feedback & Bias Probe Shots 63919-63966 were taken with the bias probe inserted into the plasma. The objective of the experiment is to apply bias voltage in order to slow down the rotation velocity of the n=1 mode to 0hz (or as close to 0 as possible) and subsequently to apply Jeremy's feedback algorithm. Mode development was conducted today, more results next week.

Monday September 22 07 35 hanson 63967-64019 feedback Feedback algorithms were tested in vacuum with both elm-like and white-noise inputs. While the algorithm without the Kalman filter appears to be more or less transparent to both types of noise, the Kalman filter reacts to both noise varieties at frequencies near the programmed mode rotation frequency. The vacuum response of the Kalman filter was greater than I expected for both types of noise, given the results of previous experiments with plasma. Plasma-mode development continued, but there was not much time left for it this evening.

Tuesday September 23 04 45 hanson 64020-64057 kalman filter Experiments with adding ELM-like noise to feedback algorithms started today, but the run was cut short by problems firing the VF crowbar in mid afternoon. Subsequent investigation pin-pointed the trigger box for the ignitron, probably the krytron tube. Nick is still working on the circuit to eliminate other possibilities. We are now out of krytron tubes.

Wednesday September 24 06 16 hanson 64060-64102 kalman filter Nick was able to substitute a circuit with a thyrotron for the one with the broken krytron this morning, and runs resumed in the afternoon. More elm-noise experimental data was taken.

Thursday September 25 04 56 hanson 64103-64158 kalman filter More elm-like noise experiments today. I have enough data to start analyzing, and I will decide tonight if I need to get more tomorrow or if I want to pick up where I left off with the rotation-rate parameter scan.

Friday September 26 2008 7:31 pm hanson/shiraki 64159-64247 More ELM-noise experiments today. Also, a radial scan of basic plasma parameters was taken with the triple probe.

Monday September 29 2008 4:46 pm hanson 64248-64269 Kalman filter More Kalman filter rotation rate parameter scan data taken today. jmh

Tuesday September 30 2008 4:59 pm hanson 64270-64320 kalman filter More Kalman filter rotation rate parameter scan data taken today. jmh

Wednesday October 1 2008 5:49 pm Hanson 64321-64358 Kalman filter More Kalman filter rotation rate parameter scan data taken by Jeremy today. -JPL

Thursday October 2 2008 8:22 pm hansen/debono 64388-64399 Feedback & Bias Probe Plasmas were run with 100% Du. Bias probe was inserted and effects on plasma rotation were measured. The effect of the edge biasing is to reverse direction on the n=1 mode, however, unfortunatly the amplitude of the observed m=2 modes are rather weak. More work to be done tommorow.

Friday October 3 2008 6:40 pm DeBono/Hansen 64400-64444 Bias Probe/Kalman Feedback More work was done today on utilizing the bias edge probe to slow down the rotation frequency of the n=1 mode. Mode development work done today, feedback studies to be done next week. DeBono

Monday October 6 2008 8:21 pm debono 64446-64494 bias edge probe Bias probe inserted from 104.1cm-106cm in 100% Du plasmas. More work was done today on using the probe to generate a shot with ~0velocity for the n=1 mode, with the goal of then conducting feedback studies. It proved difficult to obtain a desired mode unfortunatly, with the two main difficulties being 1. obtaining sufficient signal from the SSI's and 2. flattening out the n=1 mode velocity profile around 0 km/sec. DeBono

Tuesday October 7 2008 4:57 pm hanson 64495-64529 kalman filter More scan of the Kalman filter's rotation rate parameter today. (The biased probe was turned off and retracted outside the plasma.) jmh

Thursday October 9 2008 1:05 am Hanson/Levesque/Shiraki 64530-64579 Kalman filter More scanning of the Kalman filter's rotation rate parameter today. Brief testing of the mach/triple probe array and SXR tomography. One of the two power supplies (PS) in the SXR tomography amplifier box was found to be the source of an overwheming amount of noise in data from this week. Powering all amplifier boards from the other PS alone reduced the noise significantly. Problems with the PS or its connections will be investigated further tomorrow. -JPL

Thursday October 9 2008 8:32 pm debono 64602-64638 bias probe induced n=1 mode braking More work done today on the n=1 mode breaking done today. Bias bank pretriggering ended up costing about half the runday, however this cleared up evenutally allowing a few hours of productive plasmas. Will try a modification to the bias bank soon in order to try to eliminate the pretriggering.

Friday October 10 2008 2:26 pm hanson 64648-64682 kalman filter More Kalman filter rotation rate parameter scan data taken today. Scan of the plant noise covariance parameter to begin next week. jmh

Monday October 13 2008 10:13 pm DeBono 64683-64715 Bias Probe More mode development work done today with the bias probe inserted. The edge q was kept slightly below 3.0 throught the shot duration in attempt to provoke an m=3 mode from the plasma. Biorthogonal decomposition revealed this to lead to a short (~0.75 msec) and relatively weak m=3 mode followed by a much stronger (~4x) m=2 tearing mode which terminates the plasma. More work to follow tommorow. DeBono

Tuesday October 14 2008 11:10 pm debono/shiraki 64716-64791 More mode development today.

Wednesday October 15 2008 11:09 am debono 64722-64782 Bias Probe More work done today regarding mode development with the bias probe inserted into the plasma. The goal of the days run was to develop a strong RWM with the bias probe inserted in the plamsma for future feedback studies. Biorthogonal decomposition showed that the shots we developed today had an acceptable (but not incredibly strong) n=1 mode between 2-3 msec followed by a tearing mode which eventually disrupts the plasma. After developing the mode the bias probe was initialized at 2msec at a voltages ranging from 0-125 volts to spin the n=1 mode. As expected, the n=1 mode reversed direction, and did so more rapidly as the voltage on the probe was increased. Bryan DeBono

Wednesday October 15 2008 9:52 pm hanson/levesque 64792-64847 Kalman filter Jeremey continued Kalman filter studies. Observed internal m=2 mode activity in recent SXR tomography data. -JPL

Thursday October 16 2008 10:37 pm hanson/shiraki 64848-64939 More Kalman filter data taken. More shots were taken for the triple probe profile scan.

Friday October 17 2008 4:38 pm hanson 64940-64988 More Kalman filter and Triple probe data taken today.

Tuesday October 21 2008 10:26 am DeBono 65004-65044 Bias Probe & External Mode Feedback The purpose of these experiments is to spin a sufficiently large n=1 mode using the bias probe, and then to use the feedback system to reduce the size of this mode. We obtained a n=1 external mode with sufficiently usable amplitude last week and showed that the bias probe can be used to drive its rotation frequency negative. Todays experiments was to determine the repeatability of this n=1 mode created so that we can accuratly determine the effect that feedback will have on the mode. Half the runday was hampered by pathological prefiring of the bias bank, however, the problem seems to have been fixed by moving the bias' banks digital delay generator outside the cap room. 10 shots were taken with the bias probe at a set voltage (voltage dialed on the power supply, not the actual voltage of the probe in the plasma) of ~1.5V, and 10 shots with the probe at a set voltage of 75V. Care was taken to make sure that the plasma parameters of each of the shots was similar. More analysis is needed to determine the shot-to-shot deviation of the n=1 mode amplitude, however, by eye it seems to vary considerably. More work to be done tommorow. Bryan DeBono

Tuesday October 21 2008 10:04 pm hanson/shiraki 65054-65119 More Kalman filter and Triple Probe data taken. Also, quick test showed that several tomography chords are blocked by the existing stainless shells in the hall probe section.

Wednesday October 22 2008 7:56 pm debono 65145-65206 Feedback & Bias Probe Feedback experiments conducted on shots with the n=1 mode spun negative by the bias probe. Feedback shots were taken with the Kalman filter both on and off. The start panel was behaving a little erratically towards the end of the runday. Analaysis and more work to follow. Bryan DeBono

Thursday October 23 2008 5:06 pm hanson 65207-65263 kalman filter More Kalman filter scan data taken today. There was a small problem with the OHB charging resistor. It had run out of water and was arcing. It was cleaned out and refilled, and then it functioned ok. jmh

Monday October 27 2008 3:18 pm Shiraki/DeBono 65264-65337 Bias Probe / Triple Probe Tests were done with the triple probe while the bias probe was inserted into the plasma edge (104.1 - 106 cm) and energized. Bryan DeBono

Tuesday October 28 2008 6:27 pm hanson 65340-65393 Kalman filter A phase scan with an optimized Kalman filter was started today, following a quick gain scan to determine a satisfactory gain for suppressive feedback. There was some trouble with the serial highway driver. This was fixed by restarting both the serial highway driver and matterhorn. jmh

Wednesday October 29 2008 6:04 pm hanson 65394-65462 kalman filter More Kalman filter phase scan data taken today. jmh

Thursday October 30 2008 9:36 pm hanson 65463-65543 More Kalman filter data taken today.

Friday October 31 2008 6:05 pm hanson 65544-65605 kalman filter More Kalman filter phase scan data taken today. jmh.

Saturday November 1 2008 6:07 pm hanson 65606-65680 kalman filter A third round of the Kalman filter phase scan was completed today. This will probably be a sufficient amount of data for comparison with earlier results. jmh

Tuesday December 2 2008 3:54 pm shiraki 65749-6575

Tuesday December 2 2008 3:56 pm shiraki 65749-65753 Tested the OH bias bank for the first time since the pipe burst. Everything seems to be working fine.

Tuesday December 9 2008 6:28 pm DeBono 65754-65781 I worked to reproduce shilov-style shots today as an attempt to increase the length of time the bias probe is able to perturb the plasma rotation (from the current pulse time of ~1msec). Most of the runday was spent doing cleanup shots from the last glow discharge.

Wednesday December 10 2008 7:17 pm DeBono 65782-65823 Bias Probe More work done today on extending the length of time the bias probe is able to drive n=1 toroidal mode rotation.

Friday December 12 2008 5:59 pm DeBono 65824-65854 Bias Probe More work was done today on improving the length of time that the bias probe can influence the n=1 plasma mode rotation. It was found that the depth of bias probe insertion into the plasma has a significant effect on this time length. By inserting the bias probe into the plasma to the maximum permitted by the bellows setup (outer edge 104.4, inner edge 102.5 cm) it was seen that the bias probe was able to influence the n=1 mode rotation for ~ 3msec. This is an improvement over previous runs, where the bias probe was only able to influence the plasma for ~1msec. Bryan DeBono

Tuesday December 16 2008 6:02 pm debono 65862-65881 Bias Probe More bias probe work done today. A crate error occured at the end of the runday while taking a shot; this prevented the firing of the banks, which were then dumped. DeBono

Wednesday December 17 2008 6:56 pm DeBono 65883-65924 Bias Probe More bias probe work done. The CTX Uport was giving problems, but we were able to run using the Uport's bypass switch. It proved difficult to obtain repeatable shots at the beginning of the runday, but this cleared up somewhat by the afternoon. n=1 mode amplitude was lower today than in previous runs. DeBono

Thursday December 18 2008 8:39 pm shiraki 65925-65956 The Hall probe was inserted 2.5cm into the plasma. After 17 shots, the probe appears fine. This data has not yet been analyzed. Instead, the majority of the day was spent repairing the SMP's... Channels 13, 15, and 16 were repaired by swapping waveform analyzers and 8100 modules in the North rack. However, Channel 3 went out at the end of the day; the reason is still unknown

Friday December 19 2008 5:49 pm Levesque 65957-65974 Repairing SMPs Repaired SMP channels 2 and 3 by swapping amplifiers, waveform digitizers, and memory modules in the North rack. Now it appears that the only non-working SMP is channel 14.

Thursday January 8 2009 7:12 pm DeBono 65975-66020 Bias Probe More Bias Probe work done today. Probe was inserted to 102.5-104.4cm and activated to voltages between 75 volts and 200, in 25V increments, in order to characterize the effect of biased voltage on the probe. DeBono

Friday January 23 2009 5:58 pm DeBono 66049-66074 Bias Probe More work was done with the intention of creating a strong (3,1) external kink with the bias probe fully inserted into the plasma. Plasmas were created with a current rise of ~6 MA/sec by using a combination of strong OH and a very short (1.35 msec) Deuterium puff time. This plasmas proved to be quite unstable, subject to sudden minor disruptions.

Monday January 26 2009 5:42 pm DeBono 66075-66094 Bias Probe More mode development work done today.

Wednesday January 28 2009 7:13 pm DeBono 66095-66131 Bias probe Plasmas were biased at 100V and 200V with the probe fully inserted (inner edge 102.5cm, outer edge 104.4cm). More mode development work done. Bryan

Thursday January 29 2009 8:28 pm Debono 66132-66159 Bias Probe I had been advised by Daisuke and Jeff that the SMPs had been withdrawn in the bias probe shots taken 2/28/2009. Therefore more biased shots were taken today with the SMPs re-inserted for use in mode analysis. DeBono

Thursday February 5 2009 3:17 pm DeBono 66160-66190 Bias Probe CAMAC and matterhorn proved rather testy today, which slowed down the runday. Bias Probe shots taken at 250 Volts. Upon consultation with Jim we will begin regening the cryos tommorow. Minimum base pressure is ~1.0E-08, a factor of 10 higher than what was obtainable a couple of months ago.

Wednesday February 11 2009 7:04 pm DeBono 66191-66221 Bias Probe The goal of the run was to examine the current profile of the strong, bias-probe induced (3,1) external modes we have been obtaining. The Hall probe was inserted into the plasma edge (innermost channel @104.5cm). The bias probe was at (102.5,104.4cm) for all shots. Shots were taken with the bias probe @0V and @250V. DeBono

Friday February 13 2009 1:02 am DeBono 62222 New York Times One shot was taken today to prepare the tokamak for a deuterium light show for some truant NY times reporter. Upon consultation with Daisuke yesterdays run will have to be repeated due to the Hall Probe not being calibrated. The second cryo should also be regened, will try to accomplish this tommorow. More crate problems today... DeBono

Wednesday February 18 2009 12:16 am shiraki 66243-66259 Hall Probe was recalibrated. Shots were taken before and after to confirm results of calibration.

Wednesday February 18 2009 5:29 pm DeBono 66265-66273 Bias Probe / Hall Probe Shots taken with Hall probe inserted into outer edge of plasma.

Wednesday February 18 2009 5:29 pm DeBono 66265-66273 Bias Probe / Hall Probe Shots taken with Hall probe inserted into outer edge of plasma. More to follow. DeBono

Friday February 20 2009 5:57 pm DeBono 66287-66318 Bias Probe/ Hall Probe/ Mach Probe Biased edge shots taken with the hall probe and the mach probe inserted to 104.5cm (bias probe at 102.5-104.4). Their was a problem with the D gas puff towards the end of the runday, perhaps the D bottle is empty. DeBono

Monday February 23 2009 6:17 pm Levesque/DeBono 66319-66354 Puff Valve
We fixed the problem with the gas puff valve today. The problem was a loose wire. DeBono

Wednesday February 25 2009 7:52 pm shiraki 66356-66372
The puff valve circuit failed again today. The problem turned out to be a combination of a blown transistor and a loose ground. The circuit was repaired and seems to be working again.

Friday February 27 2009 2:58 pm shiraki 66373-66391
Tried to find a good shot for n=2 feedback experiments, similar to the ones from the Kalman filter experiments. Also, a problem with the analog boards was fixed, by replacing a broken op-amp dating back to December '08.

Tuesday March 3 2009 6:26 pm shiraki 66465-66538
Continued the n=2 phase scan. Results so far don't show any significant trends, so the plan now is to do more tests with the FPGA emulator.

Wednesday March 4 2009 5:08 pm DeBono 66538-66572 Bias Probe
The days run was severly hampered by crate errors from the west rack. At first I thought the error was due to a defective J222 channel, however the J222 channel tests out fine and the problem ended up resolving itself by late afternoon. DeBono

Tuesday March 10 2009 10:45 pm DeBono 66611-66638 Bias Probe
Q scan done, with 3 <= edge q <= 4. Shots were taken with both the bias probe activated to 250V and to 0V. Significant (tearing?) mode activity was observed with edge q>3, limiting plasma duration. DeBono

Wednesday March 11 2009 6:28 pm shiraki 66639-66645
Verified that the corrected n=2 feedback algorithm works properly. The Kalman filter with increased rotation rate has yet to be implemented.

Monday March 30 2009 7:04 pm shiraki 66646-66684
At the beginning of the runday, the oil on the machine was extremely low. There was one leak at the entrance to one of the TF coils, which was tightened and cleaned up... Experiments to measure the effect of mismatched sensor coil sensitivities were performed. VF only shots at the end of the day suggest there may be significant miscalibration or other source of error.

Thursday April 2 2009 5:48 pm DeBono 666688-66710 Bias Probe
More bias probe q scan work done today.

Tuesday April 7 2009 6:31 pm shiraki 66722-66762
Made plasmas with 3/1 mode activity with and without static perturbations. At first I tried to create a base case with the bias probe inserted but turned off, but was unable to see a good mode. I then took shots with the probe retracted, but the mode doesn't appear to differ in an obvious way between having or not having the static perturbation. The sample size is small though (less than 10 shots each) so more data will be added tomorrow, included biased shots.

Wednesday April 8 2009 8:01 pm shiraki 66762-66802
Took more shots with naturally rotating modes, with and without the static perturbations. While yesterday's pessimistic analysis was based mostly on the rogowski signals, analysis of the partially integrated SMP's (B-dot) looked more promising. SMP signals when the perturbation was present seemed to have more "spiky" delta function like fluctuations. At the end of the run day, I blindly sorted through all of the available data (38 shots) and correctly predicted whether the static perturbation was there or not in 26/38 cases (68%). On shots I felt fairly confident on, I was 5/6.

Friday April 10 2009 4:43 pm shiraki 66802-66814
Applied some static perturbations to biased plasmas. Not too many shots taken today, but I'll continue next week.

Monday April 13 2009 5:24 pm shiraki 66815-66829
Applied static perturbations to more biased plasmas at full amplitude (before clipping). We now have data from about 20 biased plasmas (with and without perturbations), and analysis is underway.