| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Steve Wolfe |
| Physics operator(s): | John Goetz |
| Engineering operator(s): | Vinny Bertolino |
| Engineering Operator Run Comment |
| Continue plasma shots >100KA |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:07:273PM |
| Author: To Be Determined |
| Summary of Run 930520 Session Leader/Physics Operator: Wolfe Assistant Physics Operator: Goetz Engineering Operator: Bertolini The main goal of today's run was to establish plasma position control by feedback on the current centroid. This goal was largely achieved, although some refinement is still required. Radial position control was achieved using the EF3 coils. We used an M value of +0.2 and a PID proportional gain of 5 (10 also worked, but tended to produce some substantial oscillations). The PID gain was turned on at 40msec. Vertical position control using the EF2 supplies was unsuccessful. The EF2's were being driven too hard by the EF3's, and EF2U did not seem to be responding properly to voltage demands. Even current feedback control on the EF2U was not working well after commutation, although it was possible to keep positive current in the coils for the duration of the shot. It probably would have been useful to edit the voltage pre-programming on the EF2's based on the shots we were getting, but this was not tried. The response of the EF2 supplies, particularly the EF2U, needs to be investigated on a maintenance day. Vertical position control was achieved using the OH2 supplies. The M values used were +/-0.01 on OH2U&L, respectively. The PID gain was set to 1.0. This combination was successful in lowering the plasma by 0.5 to 1.0 cm on shots 930520031 and 032, which were the most successful shots of the day. Note that operation with a PID proportional gain 5.0 resulted in large anti-symmetric currents in the OH2's after the fizzle on shot 25. An attempt to control the plasma current using a controller consisting of OH1 only was made on shot 32. The M value was set to -5.0e-4 with a PID proportional gain of 1.0. The feedback signal indicated a response of the correct behavior, but small magnitude. The change in the plasma current evolution relative to shot 31 was negligible. The gain was raised to 5 on shot 33, but the plasma fizzled early. We found that there is an error in the magnitude of the signal produced by the Ip-referenced channels of the Wavegen (ie IP_RCUR and IP_ZCUR) of a factor of ten. This will be remedied when we decide for sure whether the appropriate fix is in hardware (a jumper controlling gain in the reference leg) or software (in the expression for WAVEGEN OUTPUT or in the HYBEXE GET_P_TO_V routine). For now, it is necessary to draw a displacement of 5cm to get a P_out corresponding to 0.5cm. Note that larger displacements may require a resetting of FACTOR (using the SCALE BIT option in PCS) to avoid overflowing the wavegen DAC's. The secondary goal of the run was to improve the robustness of the startup. This was not done. The shots alternated almost exactly between good discharges of 180kA or more and fizzles which died by 30msec with currents less than 50kA. Of the 30 attempted plasma shots, 17 were "good", with currents over 180kA and durations of at least 100msec, and 13 were fizzles. All at least broke down, and even the fizzles would have been considered good results two days ago; how our perceptions do change! The most good shots in a row was two, and the most fizzles in a row was also two. Under these circumstances, it was not practical to try to "fix" the problem. My best guess as to the cause it that the successful shots, all of which eventually disrupted, generated enough dirt to compromise the next shot. There were no obvious differences in the magnetics on the good and bad shots, although this was not studied in detail. For most of the day, a minor disruption occurred at 70msec. Efforts to remedy this by playing with the gas puff, the triangularity, and the radial position all went for naught. The last two successful shots (31 & 32) avoided this disruption, or at least delayed it by 50msec or so. The change for these shots was to lower the plasma by 5 to 10mm. I have no idea why this improved things, but it seems to have done so. After shot 31, it was noted that the hybrid predictor for Ip was reading lower than the official Ip by about 20%. Since the hybrid predictor is simply the ROG_CD rogowski, this is very strange. Investigation after the run indicates that the ROG_CD input received at the hybrid is indeed low. Suspicion falls on the iso-amp, but this was previously calibrated and checked out OK. If there is a problem with the rogowski, we need to worry about other signals as well. However, the other predictors seem to be ok. This puzzle needs to be addressed on the next maintenance day. |
| Physics Operator Summaries |
| Session Leader Comments | |||
| May 20 1993 07:24:43:240AM | Steve Wolfe | Run Plan for 5/20/93
Primary topic: Establish current centroid position control Secondary topic:Investigate lack of reproducibility of discharge startup, and attempt to improve robustness of startup program. Addt'l topics: Control plasma current, try increasing density, vary plasma shape. Sequence: Start from setup of 930519027. | |
| May 20 1993 07:25:45:350AM | Steve Wolfe | Detail of run plan on primary topic:
Addressing control of centroids: After obtaining discharges with Ip>200kA, pulse length >75ms: 1) Program 1-2cm steps in RCUR and ZCUR positions; observe Pout and Aout with loop open 2) Close loop on RCUR using EF3 controller; increase PID prop. gain and observe result 3) Close loop gain on ZCUR using EF2's ; need to hold EF2's on longer than on 930519. Also try using OH2's. 4) Remove steps and tune position for best plasma, least interactions with RF limiter. | |
| May 20 1993 07:26:33:570AM | Steve Wolfe | Detail of run plan on secondary topic:
Addressing startup: 1) Try scanning initial Bz a) first try EF4 scan b) if indicated, try BZ control of EF4 in pre-blip 2) Vary OH2 programming and feedback 3) Vary OH1 programming 4) Delay inital gas pulse to 15:20 msec | |
| May 20 1993 07:27:23:990AM | Steve Wolfe | Detail of run plan for additional topics:
Other topics: 1) If time permits, try OH1 controller for Ip; requires removing something else from a wire; dBZ_dR is a good candidate. 2) If it doesn't seem to cause problems, try a big, short gas pulse at ~50msec; observe on TCI and Z-meter. 3) If time permits, try driving up EF1 currents (by IC f.b. control) after 50msec | |
| May 20 1993 09:00:32:350AM | 930520003 | John Goetz |
Zero power test of OH1. No apparent output on RCUR and ZCUR. Error Message communicating with node 0. Coldstart done. BCS search o.k. |
| May 20 1993 09:10:53:820AM | 930520004 | Steve Wolfe | Set up as for shot 930519027.
Start Close Open Crow Invert Resistor EF1 U&L -1.6 -1.55 0. .04 .25 .180 OH1 -1.45 -1.4 0. .04 .25 .100 OH2U&L -1.6 -1.55 0. .05 .25 .025 EF2U&L -1.0 -1.0 .25 .0455 EF3 -0.1 .25 EF4 -1.6 .25 PCS programmed as for 930519027, except 2cm step in Rcur and 1cm in ZCur Pressure = 6e-5 Good flash: 120msec long 250kA; disruption at end See clear output on RCUR and Zcur Pout values |
| May 20 1993 09:28:46:430AM | 930520004 | Steve Wolfe | Close loop on RCUR:
M=0.2 from 0.05 to 0.08 PID = 1. from .04 to .09 BZ pID off from 0.048 on Everything else the same. Good flash. SAme shot, pretty much. A hint of output on the feedback signal, pretty negligible. No noticable response on position. |
| May 20 1993 09:41:13:940AM | 930520006 | Steve Wolfe | INcrease PID to 5. Leave M at 0.2 from -3 to 3
Extend P_RCUR step to go from 50 - 80 msec Wimpy. Dies around 30msec |
| May 20 1993 10:08:30:990AM | 930520006 | Steve Wolfe | change OH2 voltages from 30V to 10V between 4 and 48msec to try to give margin
wrt DBz/DR going negative. Result: still no good. Gradient did come up ~10mT/m. |
| May 20 1993 10:09:32:160AM | 930520007 | Steve Wolfe | change OH2 voltages from 30V to 10V between 4 and 48msec to try to give margin
wrt DBz/DR going negative. Result: still no good. Gradient did come up ~10mT/m. Note: last shot comment was for this shot. Will Void it out later. |
| May 20 1993 10:29:12:450AM | 930520008 | Steve Wolfe | No changes, see if it will come back on its own.
It did. Got visible change in EF3 current (~500A) Small position change in right(?) direction. |
| May 20 1993 10:43:07:780AM | 930520009 | Steve Wolfe | Double the PID gain (10)
Also extend gas pulse to 150msec Wiggles on the position. Got > 1000 Amp jump out of the EF3. Disrupts beginning at 95msec, but it's in trouble before that. Bumps on outside limiter at 70msec. It's working, I think! |
| May 20 1993 11:07:33:420AM | 930520010 | Steve Wolfe | Try moving it inside 1cm. No other changes.
Result: Another wimpy failure. The irreproducibility strikes again. |
| May 20 1993 11:12:52:220AM | 930520011 | Steve Wolfe | This one went OK. Seems to hold position pretty well, but can't see the
step. It may have been near 65.5 anyway. Still disrupting like crazy. |
| May 20 1993 11:31:37:670AM | 930520012 | Steve Wolfe | Extend IC_EF2 programming to hold 500 amps through end of shot
2cm inward step on rcur Changed EF2 voltage to -100V (from -250) from 50msec PID on RCUR extended to 150msec Bad shot- dies early again. |
| May 20 1993 11:38:41:450AM | 930520013 | Steve Wolfe | Extend IC_EF2 programming to hold 500 amps through end of shot
2cm inward step on rcur Changed EF2 voltage to -100V (from -250) from 50msec PID on RCUR extended to 150msec Bad shot- dies early again. |
| May 20 1993 11:40:26:460AM | 930520014 | Steve Wolfe | This one went ok . Lasts till 140msec, with disruptions.
Error on position is decreasing the whole shot. No obvious inward step. EF2's still come down too fast. Rice says this is hottest shot yet : 1.3keV Lot's of Mo. |
| May 20 1993 11:42:16:270AM | 930520014 | Steve Wolfe | Adjusted EF2 current trace.
Short one again. It's alternating! |
| May 20 1993 12:26:38:870PM | 930520015 | Steve Wolfe | EF2 U is still going to zero. It doesn't seem to be responding to
program signal. Also, the bus voltages may be interchanged?? EF2U goes to zero around 70ms. |
| May 20 1993 12:33:45:950PM | 930520016 | Steve Wolfe | Another dud!
EF2 voltages don't seem to be balanced, although it seems to regulate close to where we ask on the dud shots. |
| May 20 1993 12:34:51:090PM | 930520016 | Steve Wolfe | Had raised program current to 750 a from 500 between 50msec and 150msec
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| May 20 1993 12:53:56:250PM | 930520017 | Steve Wolfe | Had raised program current to 750 a from 500 between 50msec and 150msec
This one went (every other fucking shot!) Seems to regulate EF2's OK this time, except that they're driven by EF3, which is trying (and succeeding) to keep the RCUR position constant during the disruptions. |
| May 20 1993 12:55:00:200PM | 930520018 | Steve Wolfe | Eliminated step in RCUR position.
Ramp gas puff down from 70msec Result: It's an even numbered shot, so it's a dud. |
| May 20 1993 01:16:05:730PM | 930520019 | Steve Wolfe | Still disrupting at the same time. It may be a density limit disruption.
TCI says ~1e20, [G] limit is 1.3e20 or so, depending on size Position looks good. |
| May 20 1993 01:19:56:950PM | 930520020 | Steve Wolfe | Try for ZCUR control using EF2's.:
M= +/- 0.05 on EF2U&L PID = 1.0 at 30msec Step 1cm positive at 50:70msec shorten gas pulse (down at 50msec instead of 70msec) Result: another dud. Try it again next shot. |
| May 20 1993 01:36:15:300PM | 930520021 | Steve Wolfe | Try for ZCUR control using EF2's.:
M= +/- 0.05 on EF2U&L PID = 1.0 at 30msec Step 1cm positive at 50:70msec shorten gas pulse (down at 50msec instead of 70msec) Shot still disrupting at the same time. Density is lower: .25 fringe compared to .35 Can't see any step in Z position. |
| May 20 1993 01:41:20:840PM | 930520022 | Steve Wolfe | Try for ZCUR control using EF2's.:
M= +/- 0.05 on EF2U&L PID = 5.0 at 30msec Step 1cm positive at 50:70msec Turn off Br PID at 30msec Another dud |
| May 20 1993 02:15:21:300PM | 930520023 | Steve Wolfe | Try for ZCUR control using EF2's.:
M= +/- 0.05 on EF2U&L PID = 5.0 at 30msec Step 1cm positive at 50:70msec Turn off Br PID at 30msec Delay crowbar on EF1U&L from 40msec to 50msec- try to get rid of plasma diverting around 70msec. result: EF2U is not responding to voltage commands properly. It ended up going to zero at 70 msec The feedback on Z isn't likely to work like this! |
| May 20 1993 02:52:14:160PM | 930520024 | Steve Wolfe | Try for ZCUR control using OH2's.:
M= +/- 0.01 on OH2U&L PID = 5.0 at 30msec Step 1cm positive at 50:70msec Leave Br PID at 30msec Ran OK - no sign of the step. The wavegen output is only 40mV!! I think there is a factor of 10 missing somewhere Looking back at shot #4, we only got .25 V on RCUR. It should have been ~2.5V I think. |
| May 20 1993 03:18:15:550PM | 930520025 | Steve Wolfe | Try for ZCUR control using OH2's.:
M= +/- 0.01 on OH2U&L PID = 5.0 at 30msec Step 1cm positive at 50:70msec Leave Br PID at 30msec Gain to 5 on PID (last was at 1.0) Horne is chasing down the factor of ten. Run this shot anyway. Commutation failure in OH2L supply . We got +/- 6V of demand out of hybrid. Gain was too high, we have an offset of -.3V out of A-out. |
| May 20 1993 03:37:48:560PM | 930520026 | Steve Wolfe | Try for ZCUR control using OH2's.:
M= +/- 0.01 on OH2U&L PID = 1.0 at 30msec Step 5cm positive at 50:70msec (we think this will give 0.5cm really) Leave Br PID at 30msec Get a +/-10V output from OH2's at step, smaller than step at 30msec when the switch time occurs. No visible response on position. |
| May 20 1993 03:53:51:060PM | 930520027 | Steve Wolfe | Try for ZCUR control using OH2's.:
M= +/- 0.01 on OH2U&L PID = 2.0 from 30msec to 80msec, then back to 1.0 Step 5cm positive at 50:70msec (we think this will give 0.5cm really) Leave Br PID at 30msec Get a +/-20V output from OH2's at step, smaller than step at 30msec when the switch time occurs. Plasma disrupts during step time at 200kA. I think we did it, but not sure. A good imagination could see a few mm step on position. |
| May 20 1993 04:00:47:630PM | 930520028 | Steve Wolfe | Try for ZCUR control using OH2's.:
M= +/- 0.01 on OH2U&L PID = 2.0 from 30msec to 80msec, then back to 1.0 Step 5cm positive at 50:70msec (we think this will give 0.5cm really) Leave Br PID at 30msec Same programming as last time. Got another dud. |
| May 20 1993 04:16:39:680PM | 930520029 | Steve Wolfe | Try for ZCUR control using OH2's.:
M= +/- 0.01 on OH2U&L PID = 1.0 from 30msec to 80msec, then back to 1.0 Step 5cm positive at 50:150msec (we think this will give 0.5cm really) Leave Br PID off at 30msec Runs raggedly to 180msec. Z position is fairly stable, but no sign of any step. We still have that disruption at 68msec. |
| May 20 1993 04:32:33:640PM | 930520030 | Steve Wolfe | Try for ZCUR control using OH2's.:
M= +/- 0.01 on OH2U&L PID = 1.0 from 30msec to 80msec, then back to 1.0 Step 5cm negative at 50:150msec (we think this will give 0.5cm really) Lower RCUR gain to 5, and extend to 200msec A dud!!!$%^&* |
| May 20 1993 04:41:45:900PM | 930520031 | Steve Wolfe | Try for ZCUR control using OH2's.:
M= +/- 0.01 on OH2U&L PID = 1.0 from 30msec to 80msec, then back to 1.0 Step 5cm negative at 50:150msec (we think this will give 0.5cm really) Lower RCUR gain to 5, and extend to 200msec Set up feedback control on IP with OH1, but don't close the loop! M=-5.e-4 from 45 msec on Shot ran until ~150. No disruption until 120msec JT reports it did look low. FFIT seems to agree, by maybe 1cm. This was a good one. |
| May 20 1993 04:57:50:490PM | 930520032 | Steve Wolfe | Try for ZCUR control using OH2's.:
M= +/- 0.01 on OH2U&L PID = 1.0 from 30msec to 80msec, then back to 1.0 Step 5cm negative at 50:150msec (we think this will give 0.5cm really) Lower RCUR gain to 5, and extend to 200msec Set up feedback control on IP with OH1, M=-5.e-4 from 45 msec on PID at 1.0 from 44msec Shot ran until ~150. No disruption until 120msec looks a lot like the last one, but did get some response from OH1 to try to flattop. |
| May 20 1993 05:03:51:610PM | 930520033 | Steve Wolfe | Try for ZCUR control using OH2's.:
M= +/- 0.01 on OH2U&L PID = 1.0 from 30msec to 80msec, then back to 1.0 Step 5cm negative at 50:150msec (we think this will give 0.5cm really) Lower RCUR gain to 5, and extend to 200msec Set up feedback control on IP with OH1, M=-5.e-4 from 44 msec on PID at 5.0 from 44msec A dud! Oh well, SH can take up here tomorrow. |
| May 21 1993 08:49:16:800AM | 930520034 | Martin Greenwald | Power Supply settings:
Supply Start Close Open Crowbar Invert EF1L -1.6 -1.55 0.0 .05 .25 EF1U -1.6 -1.55 0.0 .05 .25 OH1 -1.45 -1.40 0.0 .04 .25 OH2L -1.6 -1.55 0.0 .05 .25 OH2U -1.6 -1.55 0.0 .05 .25 EF2L -1.0 .25 EF2U -1.0 .25 EF3 -0.1 .25 EF4 -1.6 .25 EFC -0.1 .30 TF -1.65 .10 Bus Diagnositcs integrator start: -2 sec end +6 sec Dig time = -1.7 |
| Physics Operator Comments |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 07:45:17:620AM | Test | Ok | testing oh1 camac enable |
| 2 | 08:08:32:300AM | Test | Ok | test of oh1 camac enable command |
| 3 | 08:46:29:760AM | Test | Ok | oh1 camac pulse test |
| 4 | 09:02:10:530AM | Test | Ok | 240KA PLASMA FIRST SHOT |
| 5 | 09:20:05:480AM | Plasma | Ok | 240KA PLASMA, |
| 6 | 09:37:39:400AM | Plasma | Ok | 70KA PLASMA POWER SUPPLIES OK |
| 7 | 09:56:39:730AM | Plasma | Ok | 20KA PLASMA, OH1 1SCR NOT CONDUCTING, OH2'S CURRENT RIPPLE |
| 8 | 10:09:58:330AM | Plasma | Ok | 260KA PLASMA, LESS RIPPLE ON THE OH2'S--300A |
| 9 | 10:29:54:680AM | Plasma | Ok | 180KA PLASMA |
| 10 | 10:45:39:450AM | Plasma | Ok | 20KA PLASMA |
| 11 | 10:55:27:920AM | Plasma | Ok | 200KA PLASMA |
| 12 | 11:14:15:350AM | Plasma | Ok | 30KA PLASMA, TF 139KA--THIS HAS BEEN DECREASING WITH EACH RUN FROM 149KA |
| 13 | 11:24:48:120AM | Plasma | Ok | 220KA PLASMA, EVERY OTHER SHOT SEEMS TO PRODUCE HIGH PLASMA CURRENTS-- P |
| 14 | 11:40:07:710AM | Plasma | Ok | 20KA |
| 15 | 11:50:39:230AM | Plasma | Ok | 200KA |
| 16 | 12:25:12:960PM | Plasma | Ok | 20KA |
| 17 | 12:35:33:650PM | Plasma | Ok | 210KA |
| 18 | 12:51:11:360PM | Plasma | Ok | 20KA |
| 19 | 01:00:48:800PM | Plasma | Ok | 190KA |
| 20 | 01:16:39:490PM | Plasma | Ok | 20KA, OH1 1SCR NOT CONDUCTING - TYPE 3 FAULT |
| 21 | 01:26:16:720PM | Plasma | Ok | 200KA PLASMA |
| 22 | 01:38:37:190PM | Plasma | Ok | 30KA PLASMA |
| 23 | 01:50:10:150PM | Plasma | Ok | 190KA PLASMA |
| 24 | 02:22:44:110PM | Plasma | Ok | 190KA PLASMA -- OH1 1SCR NOT CONDUCTING |
| 25 | 02:57:36:120PM | Plasma | Ok | 20KA PLASMA -- OH2L COMM FAULT |
| 26 | 03:24:33:010PM | Plasma | Ok | 180KA PLASMA -- OH1 ONE SCR NOT CONDUCTING |
| 27 | 03:40:11:600PM | Plasma | Ok | 210KA PLASMA CURRENT, NO FAULTS |
| 28 | 03:53:58:270PM | Plasma | Ok | 30KA |
| 29 | 04:04:40:200PM | Plasma | Ok | 200KA PLASMA |
| 30 | 04:19:55:340PM | Plasma | Ok | 50KA PLASMA |
| 31 | 04:34:02:980PM | Plasma | Ok | 210KA PLASMA |
| 32 | 04:45:57:030PM | Plasma | Ok | 210KA PLASMA |
| 33 | 04:58:30:850PM | Plasma | Ok | ALMOST 3 IN A ROW |
| 34 | 05:20:52:570PM | Test | Bad | |