| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Steve Wolfe |
| Physics operator(s): | Jim Irby |
| Engineering operator(s): | Bill Cochran |
| Engineering Operator Run Comment |
| MP# 362 ITER Shape development and MP#381 JFT2 Shape development Wolfe/ |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:02:460PM |
| Author: Steve Wolfe |
| Run Summary for Tuesday Jan 27, 2004 MP#362 ITER Shape Development SL: Wolfe PO: Irby EO: Cochran Run Plan -------- The goal of this MP is to develop a discharge in the ITER shape, kappa=1.85,delta_x=0.49, with the ITER field of 5.3T and q_95=3, which corresponds to I=1.6MA and to an I_n=I/aB=1.4. The last time we tried this experiment, 1031126, we established the shape and on shot 28 got to the target current of 1.6MA, with I_N=1.4, kappa=1.84, deltax=0.5; actual q_95 was 2.9 rather than 3, so the shape wasn't exact. N/N_Crit on this discharge was 1.05. However, we did not get this discharge to run full length, though the disruption in this case was not a VDE. Later analysis indicated that we had actually run into a locked mode, perhaps because of the 1/1 error field component. We will start from shot 1031126028 (but with power system limits raised as on 1031126029). Things that need to be tried include: 1) get rid of locked mode by varying a) density (higher, but we're pushing the flux swing as it is) b) A-coil current (probably lower, if it's really the 1/1; try both directions). 2) Tweak the fast and slow ZCUR gains to get the chopper amplitude down while still avoiding VDE's 3) If it looks like we're getting into trouble with q=3, raise Bt a little to get us up to q95~3.2. This part of the run is expected to take about half a day. In any case, we will turn over to the second MP no later than 13:30. Results: ------- We got very little progress on the MP. The run was terminated after a leak occurred following shot #10, presumably because of all the disruptions. All shots disrupted, with pulse lengths between 0.6 and 1.15sec. Some disruptions were clearly related to locked modes, and some were clearly vertical instabilities. We scanned the acoil current demand from 1500A to 3500A (from the initial setting of 2500A). Higher acoil current appeared to delay the locked mode onset, which implies that the previous interpretation of the locked mode as being due to the 1/1 sideband was incorrect. We took one step on the fast derivative gain, down from 1.2 to 1.0 on D10. This may have helped; it cetainly did not seem to hurt. However, the chopper was still bouncing off the floor. For shot #11 we had loaded the first change on the slow ZCUR (from 0.7 to 1.5 on both D and P gains, corresponding to the old settings from the Horne/Tinios high kappa run), but the leak prevented us from taking that shot. The leak was located at the B-top fill line. Some baffles around E-top need to be removed to access and repair it. |
| Physics Operator Summaries |
| Entered: Jul 7 2004 04:36:48:710PM |
| Author: Jim Irby |
| Engineering setup for Tues. 1/27/2004 MP#362 ITER Shape development (1/2 day) MP#381 JFT2-M Shape development (1/2 day) SL: Wolfe (first half) Hubbard (2nd half) PO: Irby ECDC Overnight in D2, stopping by 07:00 60C Bake (optional, check with Irby and/or Bill Burke) Run Begins at 09:00 and ends at 17:00 Power system setup for first half as on 1031126029 Power system setup for second half as on 1031212011 Gas setup: fill B-Top with 6 psi D2 Hybrid enabled (PG4) fill B-side lower with 1 psi Ar Hybrid enabled (PG1) leave B-side upper as is Hybrid DISABLED (PG2) fill C-side with 30 psi D2 Hybrid enabled (PG3) fill NINJA (lower cap) with 6psi Helium Gate valve permissives for the usual suspectsd (ECE,VUV,DNB) assuming no vacuum problems RF: NONE -------------------------------------------------------- Run plan for first half of Tuesday, 1/27/2004 MP#362 ITER shape development EO: Cochran SL: Wolfe PO: Irby Plan ----- The goal of this MP is to develop a discharge in the ITER shape, kappa=1.85,delta_x=0.49, with the ITER field of 5.3T and q_95=3, which corresponds to I=1.6MA and to an I_n=I/aB=1.4. The last time we tried this experiment, 1031126, we established the shape and on shot 28 got to the target current of 1.6MA, with I_N=1.4, kappa=1.84, deltax=0.5; actual q_95 was 2.9 rather than 3, so the shape wasn't exact. N/N_Crit on this discharge was 1.05. However, we did not get this discharge to run full length, though the disruption in this case was not a VDE. Later analysis indicated that we had actually run into a locked mode, perhaps because of the 1/1 error field component. We will start from shot 1031126028 (but with power system limits raised as on 1031126029). Startup should be from a recent shot (e.g. 1040123xxx) Things that need to be tried include: 1) get rid of locked mode by varying a) density (higher, but we're pushing the flux swing as it is) b) A-coil current (probably lower, if it's really the 1/1; try both directions). 2) Tweak the fast and slow ZCUR gains to get the chopper amplitude down while still avoiding VDE's 3) If it looks like we're getting into trouble with q=3, raise Bt a little to get us up to q95~3.2. Halo currents and stress warnings need to be monitored, as these shots had some very hard disruptions the first time around. This part of the run is expected to take about half a day. In any case, we will turn over to the second MP no later than 13:30. ------------------------------------------------------------------------------ Run Plan for 1040127 B: MP 381 Shape development for joint EDA experiments with JFT2M. Purpose: To start the process of shape development for future matching experiments with JFT2M. Goal is to match triangularity and elongation. It is possible that we will be able to start increasing the aspect ratio, though this is likely to require more shots. This will be an ohmic run, since RF is being reconfigured this week. Starting point: Load waveforms from 1031212011 (ITB delta scan). This shot had delta_u=0.3, and delta_l=0.7, not too far from where we want to go. For first shot, raise Bt to 5.0 T, and Ip to 1.0 MA. For subsequent shots we will want to: - reduce kappa to (or towards) 1.5 (from 1.67) - increase delta_l to 0.87 - reduce delta_u to 0.2 - adjust Ip to give q95=3.2 A shape sent by JFT2M will be used for shot-to-shot comparison (see saveset in /home/wolfe/efit/test/jft2m_97156_00700.sav ) If things go really well and we achieve this, go further and attempt to increase aspect ratio (ie make a very big inner gap) as per MP. ------------------------------------------------------------------------------ Summary ------- We had disruptions on all plasma shots today, several at the halo warning level (Bt*Ih > 1500 T-kA). Fizzles on shot 7, 8, and 9 were probably the result of the disruptions, though a 0.0005 mT tweak in Br0 resulted in a plasma on shot 10. Plasma was rather dirty with Zeff > 2. We would have raised the density had we time. Shot 01 was a data system test. Problems -------- Had one data system hang, but Josh recovered all the data Unfortunately, shot 10 was the last shot of the day, since we developed a leak on the b-top gas feed line between the piezo and the manual emergency valve. Machine basepressure was at 1.3e-3 Torr for a couple of hours, and up to 220e-3 Torr briefly as we installed the leakdetector. Score ----- duds fizzles 07,08,09 plasmas 02,03,04,05,06,10 tests 01 |
| Session Leader Comments | |||
| Jan 27 2004 08:33:51:390AM | 1040127001 | Steve Wolfe | Shot#1: Data system test |
| Jan 27 2004 09:17:42:200AM | 1040127002 | Steve Wolfe | Shot#2: Disrupts at 0.668sec (original was at 1.17) Looks like a vertical problem. oscillation starts at 0.6sec next shot: try dropping D10 from 1.2->1.0 |
| Jan 27 2004 09:39:04:433AM | 1040127003 | Steve Wolfe | Shot#3: try dropping D10 from 1.2->1.0 lasted to 1.025sec, might be a locked mode. It does go to a VDE though. next shot: Drop Acoil current from 2500->1500 |
| Jan 27 2004 09:52:28:127AM | 1040127004 | Steve Wolfe | Shot#4: Drop Acoil current from 2500->1500 disrupts at 0.75sec ; no VDE, goes up a little. Very clear locked mode starting at 0.669. Got Acoil current of 1000 for program of 1500. next shot: raise Acoil current to 3000. |
| Jan 27 2004 10:18:11:903AM | 1040127005 | Steve Wolfe | Shot#5: raise Acoil current to 3000. Disrupts at .758. Downward going VDE with no precursor. got 2700A on Acoil. This one went into H-mode. Lots of runaways early. next shot: raise pre-puff to try to suppress runaways |
| Jan 27 2004 10:30:10:740AM | 1040127006 | Steve Wolfe | Shot#6: raise pre-puff to try to suppress runaways plasma to .94sec, H-mode at .69 to .80 looks like a locked mode starts at .91 or .92sec not much of a vde, going up. runaways better, still around. next shot: raise acoil demand to 3500 |
| Jan 27 2004 10:37:38:030AM | 1040127007 | Steve Wolfe | Shot#7: raise acoil demand to 3500 fizzle. next shot: try again at 3500 demand to acoil |
| Jan 27 2004 10:55:48:937AM | 1040127008 | Steve Wolfe | Shot#8: try again at 3500 demand to acoil another fizzle. No data coming up. Josh is working on it. |
| Jan 27 2004 11:19:58:637AM | 1040127009 | Steve Wolfe | Shot#9: try again at 3500 demand to acoil another fizzle. Pg4 is back to where it was on shot 5. next shot: drop br0 |
| Jan 27 2004 11:35:39:500AM | 1040127010 | Steve Wolfe | Shot#10: try again at 3500 demand to acoil plasma to 1.15sec, longest yet. Vertical oscillation, down then up. runaways again. and an H-mode at .7 to .8 sec start to lose slow zcur at 1.126 n/nc=1.1, elong=1.86 next shot: raise D2 and P2 from 0.7 to 1.5 |
| Jan 27 2004 12:08:16:943PM | 1040127010 | Steve Wolfe | Shot#10: try again at 3500 demand to acoil plasma to 1.15sec, longest yet. Vertical oscillation, down then up. runaways again. and an H-mode at .7 to .8 sec start to lose slow zcur at 1.126 n/nc=1.1, elong=1.86 next shot: raise D2 and P2 from 0.7 to 1.5 Unless we have a leak. Which there is. Torus pressure is at 1mTorr Leak Checking is in progress. |
| Jan 27 2004 01:34:31:210PM | 1040127010 | Steve Wolfe | The leak has been located at B-top gas feed. Repairs in progress. Run terminated for today. |
| Physics Operator Comments | |||
| Jan 27 2004 07:46:11:457AM | Jim Irby | Run plan for first half of Tuesday, 1/27/2004 MP#362 ITER shape development EO: Cochran SL: Wolfe PO: Irby Plan ----- The goal of this MP is to develop a discharge in the ITER shape, kappa=1.85,delta_x=0.49, with the ITER field of 5.3T and q_95=3, which corresponds to I=1.6MA and to an I_n=I/aB=1.4. The last time we tried this experiment, 1031126, we established the shape and on shot 28 got to the target current of 1.6MA, with I_N=1.4, kappa=1.84, deltax=0.5; actual q_95 was 2.9 rather than 3, so the shape wasn't exact. N/N_Crit on this discharge was 1.05. However, we did not get this discharge to run full length, though the disruption in this case was not a VDE. Later analysis indicated that we had actually run into a locked mode, perhaps because of the 1/1 error field component. We will start from shot 1031126028 (but with power system limits raised as on 1031126029). Startup should be from a recent shot (e.g. 1040123xxx) Things that need to be tried include: 1) get rid of locked mode by varying a) density (higher, but we're pushing the flux swing as it is) b) A-coil current (probably lower, if it's really the 1/1; try both directions). 2) Tweak the fast and slow ZCUR gains to get the chopper amplitude down while still avoiding VDE's 3) If it looks like we're getting into trouble with q=3, raise Bt a little to get us up to q95~3.2. Halo currents and stress warnings need to be monitored, as these shots had some very hard disruptions the first time around. This part of the run is expected to take about half a day. In any case, we will turn over to the second MP no later than 13:30. ------------------------------------------------------------------------------ Run Plan for 1040127 B: MP 381 Shape development for joint EDA experiments with JFT2M. Purpose: To start the process of shape development for future matching experiments with JFT2M. Goal is to match triangularity and elongation. It is possible that we will be able to start increasing the aspect ratio, though this is likely to require more shots. This will be an ohmic run, since RF is being reconfigured this week. Starting point: Load waveforms from 1031212011 (ITB delta scan). This shot had delta_u=0.3, and delta_l=0.7, not too far from where we want to go. For first shot, raise Bt to 5.0 T, and Ip to 1.0 MA. For subsequent shots we will want to: - reduce kappa to (or towards) 1.5 (from 1.67) - increase delta_l to 0.87 - reduce delta_u to 0.2 - adjust Ip to give q95=3.2 A shape sent by JFT2M will be used for shot-to-shot comparison (see saveset in /home/wolfe/efit/test/jft2m_97156_00700.sav ) If things go really well and we achieve this, go further and attempt to increase aspect ratio (ie make a very big inner gap) as per MP. | |
| Jan 27 2004 08:43:33:600AM | 1040127001 | Jim Irby | Loaded shot 1031126028 into seg 2 --- SNL 1.6 MA Loaded shot 1040123021 into seg 1 --- 15 ms gas puff Data system cycle test: looks okay |
| Jan 27 2004 09:17:41:623AM | 1040127002 | Jim Irby | Disruption at 0.688 seconds Ip was 1.59 MA at disruption |
| Jan 27 2004 09:39:57:573AM | 1040127003 | Jim Irby | Lost RGA on shot 01 Dropped derivitative gain on fast ZCUR from 1.2 to 1.0 disruption at 1.01 s should have gotten halos warning for the last two shots |
| Jan 27 2004 09:53:01:940AM | 1040127004 | Jim Irby | reduced a-coil current from 2500 to 1500 amps disruption at 0.74 s --- not getting better |
| Jan 27 2004 10:12:29:457AM | 1040127005 | Jim Irby | A-Coil current from 1500 to 3000 A. disruption at 0.76 s |
| Jan 27 2004 10:26:21:037AM | 1040127006 | Jim Irby | pg4 to 16 ms from 15 ms to help with runaway problem disruption at 0.94 s neuts_hards down to 3e12 from 60e12 |
| Jan 27 2004 10:38:54:323AM | 1040127007 | Jim Irby | pg4 to 17 ms from 16 ms (improve runaways a little more) A-Coils from 3000 to 3500 A fizzle --- too much gas? |
| Jan 27 2004 11:02:44:883AM | 1040127008 | Jim Irby | dropped gas back to 16 ms fizzle we think --- data system problem |
| Jan 27 2004 11:19:54:310AM | 1040127009 | Jim Irby | pg4 to 15 ms Earl noted that Zeff was high on last few shots --- will try raising density soon fizzle ---- |
| Jan 27 2004 12:50:00:980PM | 1040127010 | Jim Irby | br0 from +0.0005 to 0.0000 disruption at 1.16 s got runaways back lost vacuum after/during this shot ---- went to 1.3e-3 Torr a few minutes after the shot. Had a jump to 220e-3 Torr for a couple of minutes when the leakdetector was installed. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 08:30:50:783AM | Test | Ok | SHOT CYCLE TEST |
| 2 | 09:07:22:380AM | Plasma | Ok | |
| 3 | 09:27:39:067AM | Plasma | Ok | |
| 4 | 09:43:50:007AM | Plasma | Ok | |
| 5 | 10:01:16:090AM | Plasma | Ok | |
| 6 | 10:20:50:603AM | Plasma | Ok | |
| 7 | 10:34:21:690AM | Plasma | Ok | |
| 8 | 10:47:55:113AM | Plasma | Ok | |
| 9 | 11:11:23:690AM | Plasma | Ok | |
| 10 | 11:24:36:633AM | Plasma | Ok | |