| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Steve Wolfe |
| Physics operator(s): | Robert Granetz |
| Engineering operator(s): | Bill Byford,Bill Parkin,Gary Dekow |
| Engineering Operator Run Comment |
| MP #362 ITER Single-null Shape; SL: Wolfe; PO: Granetz; EO: Dekow/Byford |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:34:960PM |
| Author: Steve Wolfe |
| Session Leader Summary for Wed Nov 26, 2003 MP#362 (SN ITER shape part ) SL: wolfe PO: Granetz EO: Dekow,Byford,Parkin The goal 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. Plan ------ Engineering setup - standard except EFC Voltage Limit should be raised from 800V to 900V. C-coils should be in "standard" configuration +Dtop -Dbot -Jtop +Jbot and current programmed to 2500A (all-V screen). C-coil PLC setting should be 600V, 3000A. No RF until we get to our final shape. We will need to monitor halo current signals as we raise the current. Starting from a recent 1MA shot, 5.3T shot, e.g. 1031023019, modify the equilibrium to get higher elongation: ZCUR to 0.0 RXL to -.005 ZXL to -0.0175 RXU to -0.04 ZXU to +.030 CLEARIN from +.005 to +.008 Raise NL04 to 8e19. Confirm that shape is what we want, i.e. kappa=1.85, delta_u~delta_l~0.49, aout=.215m If this disrupts with vertical instability, then back off on CLEARIN and begin tweaking Gains on wire 2 and wire 3. Present nominal values are P2=0.7 D2=0.7 I2=4.5 P3=4.0 D3=6.0 I3=0 Back in 1995 we ran with P2 and D2 at least 1.5, and never varied it down. We need to observe the oscillation frequency, if any, to decide which gains need adjusting. Low frequency oscillations, around 20-50Hz, are associated with the OH2 response, and may indicate we need a lower wire 2 gain; a fast mode, 200-300Hz, is associated with the chopper on wire 3. If we decide we need chopper D gain above 10 then change fast ZCUR to wire 10, which has a factor of 10 higher derivative time constant. Be sure that the chopper bias is correct to avoid non-symmetric railing; this may require adjusting the chopper voltage (ALL_V) or changing the resistor value. If we can't get to the required elongation at 1MA without disruptions after about 10 shots, then proceed to 1.2MA at whatever kappa we have stably and try again there. Note change in n/n_crit as current is increased. Raise current in 100-200kA increments to 1.6MA (which should be I_n=1.4, q~3) or maximum controllable with the chopper. Watch out for locked modes as we raise current and increase A-coil current as indicated. Look at my B_21 total estimates for guidance in setting A-coil programming. The RF E transmission line is open, so we cannot pulse RF today without a lot of radiation, so we won't be able to do any coupling studies even if we finish early. Therefore, in that unlikely eventuality (note that we are ending an hour early), we will either proceed to the FIRE-shaped DN development or do some development of the JET shape in preparation for Hender's experiment MP#361. Results ----------- Despite lots of disruptions, and post-disruption fizzles, we made considerable progress toward the goal. 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, but seemed to be related to running the OH1 onto the current rail, which had been left at -27kA and actually limited at 25kA. For the last shot we increased the PLC limits on OH1 and EF3 (to -33kA and 13kA, respectively) but the disruption-induced fizzle got us. The path up to the high current had disruptions, mostly VDE's at every stage. There was only one full length shot, #18, which was at 1MA. This shot and some of those at 1.2MA had ohmic H-modes, but we lost these as we went up in current, for no clear reason. The n/ncrit of the H-mode phase was lower than the L-mode, which probably helped on shot 18. We made a number of gain tweaks on the fast ZCUR, and ended up using wire 10 and a D10 gain of 1.2 (equivalent to 12 on wire 3); this compares to the starting value of D3=6. The values used were D3=6,9,7.5 and D10=1.2. Changes to the fast P gain did not seem to have strong effects on the vertical disruptions, though they did change the amplitude and frequency of the oscillations well away from the final event. We ended up at P10=3, compared to a starting value of 4. We ran this between 2 and 8; the higher values caused larger swings of chopper current (rail to rail) but were not apparently helpful. Note that the Df="12" also caused rail to rail chopper excursions, but the plasma survived these. At shot 8 we changed the chopper pre-program voltage to zero (nominal was +100V) to try to symmetrize the current and avoid flooring. This seems to work, although it leads to a no-plasma current level centered about 2000A rather than 1500. We should probably adjust the resistor. We made no changes to the slow zcur gains, although the Tinios run had both P2 and D2 double what we run now. This is the next thing that should be tried. The D10 gain may well be too high (it is banging the rails), but it seemed to do somewhat better than D3=9 at 1.4MA. More time, though probably not a full run, will be required to complete this development. Other Issues ------------ From the start of the run, we had a new behavior with the oh1 pre-charge current. This has been running at -19.7 to -19.8kA (bus rog) forever; with no change in the PCS program today it was running about 20.1kA. This value was consistent with the observed change in Bz at breakdown. The hybrid Aout signal also indicated that it was 300A off-target and had reduced the demand to compensate, but the gain was apparently insufficient; looking at yesterday's traces, the aout values showed a good match and the demand was ~100V, consistent with the V program, as opposed to 60V today. We compensated by changing the program waveform and lived with the 300V error value, but this seems to be a real change either in the hybrid or in the supply. There seems to be a difference right from supply turn-on at -1.1sec. The 300A differnce is already present at -1sec, and the hybrid demand is already lower by that time. The effect is consistent with a small reduction in the oh1 resistor value, or with a difference on the induced voltage. The only other supplies on at that time are te EF1's and EF4. |
| Physics Operator Summaries |
| Entered: Jul 7 2004 04:37:19:863PM |
| Author: Robert Granetz |
| Physics operator summary for run 1031126 (Wednesday): MP #362 - ITER single-null shape Session leader: S. Wolfe Physics operator: R. Granetz Engineers in charge: Summary: We achieved a 1.6 MA discharge with the proper parameters (kappa=1.83, delta=0.49-0.50, I_N=1.4, q95=2.9, nl_04=0.8-1.0e20 m-2) on shot 28. This shot disrupted -- not due to vertical instability, but rather to hitting the OH1 PLC current limit. We may want to pick up from here, with the PLC limit set to -33 kA, when we use this equilibrium for future ITER studies. In order to obtain this plasma, we played around with P and D gains on the fast ZCUR, and the voltage on the EFC chopper supply. In the end, we had to move the ZCUR control over to wire_10, which has 10 times higher derivative gain capability, and set the derivative gain to 1.2 (corresponding to 12.0 if it had still been on wire_03). We had the A-coils on for the entire run, in the normal configuration with 2200 amps. We did not see any sign of a locked mode, so this bodes well for even higher plasma current. There were many high current disruptions today, with several shots having halo currents > 150 kA (up to 210 kA). We had several stress limit warnings at the 50% level on EFCU. The numerous disruptions also led to numerous fizzles, but no duds. Scorecard: 17 plasmas 11 fizzles 0 duds 0 test or no-power shot cycle 1 aborted and/or screwed up by computer problems ---------- 29 total ------------------------------------------------------------------------------- Engineering setup for Wednesday, 26 Nov 2003 MP #362 - ITER single-null shape Session leader: S. Wolfe Physics operator: R. Granetz ECDC overnight in D2 at 2e-4 Torr, stopping by 07:00. Bake at 60 C overnight as well. Run begins at 09:00 and ends at 16:00. (NOTE EARLY ENDING TIME) Power systems the same as on 1031023019 (1.0 MA, 5.3 T, lower single null), EXCEPT that the PLC voltage limit for EFC should be raised from 800 to 900 V. A-coils should be hooked up as on 1031125007 (+Dtop -Dbot -Jtop +Jbot), and the power supply should be enabled. C-coil PLC limit settings should be set at 600 volts and 3 kA. 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) NO NINJA! Enable the following gate valves, assuming no vacuum problems: ECE, VUV, DNB ------------------------------------------------------------------------------- RF Setup: No RF until we get to our final shape, which will probably be late in the run ------------------------------------------------------------------------------- Run Plan: We are trying to get 1.6 MA, 5.3 T (q95=3) equilibria with the following ITER shape: - single lower null - kappa = 1.85 - lower and upper triangularities approximately 0.49 - a=0.215 m We will start at 1.0 MA and work our way up in increments. Vertical stability is likely to be an issue, and we anticipate that the run will involve some adjustment of the slow and fast ZCUR PID gains. Monitoring and stabilization of locked modes will probably be required as the plasma current is raised. Halo currents will also be monitored. ------------------------------------------------------------------------------- ECDC was done overnight, as well as a 60 C bake. Hybrid coldstart done by the engineering group; no errors found Loaded PCS segment 1 from yesterday's 1031125002 segment 1. Loaded PCS segment 2 from 1031023019, with the following changes to get higher elongation: ZCUR to 0.0 m RXL to -.005 m ZXL to -0.0175 m RXU to -0.04 m ZXU to +.030 m CLEARIN to +.008 m Also raise NL04 to 8e19. Copied segment 2 to segment 3 and set up wire 10 to be fast ZCUR with one-tenth of the gain, and turned off wire 03, and set Ref 9-12 to IP. This is for possible use if we need a stronger fast ZCUR feedback, since the derivative time constant is 10 times faster on wire 10. Also turn off argon permissive. ------------------------------------------------------------------------------- The start of the run will be delayed while a problem with the EF1 power supply is worked on. Shot 01 -- Plasma. Disrupted at t=0.55 s due to vertical instability. Kappa got above 1.8; n/ncrit got to 1.2. Next shot: reduce CLEARIN to +0.005 m, increase RXU to -0.03 m, tweak Ip rampup. Shot 02 -- Aborted. No power cycle due to hangup in init. Shot 03 -- Fizzle. Bz a little high. Next shot: add -10 amps to IC_EF4 Shot 04 -- Fizzle. Steve notes that the OH1 current is couple of hundred amps more (negative) than normal. Next shot: add +200 amps to IC_OH1 (-20000 --> -19800) Shot 05 -- Plasma. Made it into rampdown before VDE disruption. Kappa is 1.85, delta_U and _L is 0.58. EFC current is not symmetric. We may be dithering with an upper null. Next shot: add +1 cm to both RXL and RXU to reduce the triangularities. Shot 06 -- Plasma. VDE disruption at t=0.55 s. The triangularities did indeed come down close to the desired values. Next shot: start playing with EFC chopper. Change its pre-programmed voltage to +200 V (from +100 V). We're not really sure of the direction, so this is a best guess. Shot 07 -- Plasma. Disrupted at t=0.72 s, but it was not a VDE. I think it was an injection. Kappa=1.85, delta_L and _U approx 0.49, so this is the shape we want. But the EFC current is even more asymmetric, so maybe we went the wrong direction. Next shot: change chopper pre-programming to 0.0 V (from +200 V) Shot 08 -- Plasma. Disrupted very early (t=0.35 s) Next shot: no changes. Shot 09 -- Plasma. Disrupted due to VDE. Next shot: change fast ZCUR P gain to 2.0 (from 4.0) Shot 10 -- Plasma. Disrupted earlier. Next shot: tweak Ip rampup; delay CLEARIN increase until after t=0.5 s (to avoid OH1 crossover) Shot 11 -- Plasma. Disrupted at t=0.64 s. kappa=1.85, delta_L=0.50, delta_U=0.46 Next shot: increase proportional gain on fast ZCUR to 6.0 (from 2.0). Also add -3 mm to RXU. Shot 12 -- Plasma. Disrupted at t=0.64 s. The oscillations on EFC current are back. The plasma shape is exactly what we want. Next shot: reduce fast ZCUR P gain to 4.0 (from 6.0) Shot 13 -- Fizzle. Fields and fill pressure look okay. Next shot: no changes. Shot 14 -- Plasma. Disrupted at t=0.67 s, VDE. Next shot: raise fast ZCUR derivative gain to 9.0 (from 6.0) Shot 15 -- Fizzle. Next shot: no changes. Shot 16 -- Fizzle. Next shot: add +100 amps to IC_OH1 Shot 17 -- Fizzle. Fields look okay. Next shot: try a BR_0 tweak. Shot 18 -- Plasma. Full-length shot; no disruption! Elongation=1.85, upper and lower triangularities=0.50-0.51. So this is a stable shot (just barely though) with the ITER shape at Ip=1.0 MA (q95=4.7-4.8). This shot also has an ohmic H-mode (small ELMs) starting at t=1.0 s. Startup isn't the greatest. Next shot: increase Ip to 1.2 MA Shot 19 -- Plasma. Upward VDE, disrupting at t=0.84 s. Ohmic H-mode starts at t=0.75 s. Next shot: reduce fast ZCUR P gain to 2.0 (from 4.0) Shot 20 -- Fizzle. Disruption recovery? Next shot: no changes Shot 21 -- Fizzle. Next shot: additional BR_0 tweak Shot 22 -- Plasma. Downward VDE disruption. I_halo_lower=155 kA (first time over 100 kA in a long time). Shape is still very good. Next shot: raise Ip to 1.4 MA; change fast ZCUR P gain to 3.0, tweak pre-fill gas puff. Shot 23 -- Plasma. 1.4 MA Upward VDE; disrupted at t=1.25 s. I_halo_upper=135 kA. Got a 50% warning on the EFC_U coil stress. Our locked mode compensation is spot on. kappa=1.83, delta=0.49. Next shot: decrease fast ZCUR derivative gain to 7.5 (from 9.0) Shot 24 -- Fizzle. Disruption recovery? Next shot: tweak pre-fill. Shot 25 -- Fizzle. Next shot: no changes Shot 26 -- Plasma. 1.35 MA. Disrupted at t=0.62 s. This was a VDE, but it didn't move very far down before quenching. Next shot: transfer the fast ZCUR over to wire 10, which has 10 times higher derivative gain capability. Set ZCUR derivative gain to 1.2 (corresponds to 12 on the old wire 03). Also turn off wire 03 (by hitting the "zero all" button) Shot 27 -- Plasma. Disrupted at t=1.12 s. This was NOT a VDE! Looks like an injection. Good shape, with kappa=1.83, delta=0.49-0.50. EFC current is oscillating wildly between both rails. Next shot: raise Ip to 1.6 MA, and program nl_04 to go to end of flattop. Shot 28 -- Plasma. 1.60 MA. Disrupted at t=1.17. NOT a VDE! I don't think it was due to a big impurity injection. Sawteeth go away just before the disruption, but it's not clear there was a locked mode. Shape is very good: kappa=1.83, delta_L=0.50, delta_U=0.49. OH1 rails at it's PLC limit, so this may have caused the disruption. Plasma touches the inner midplane wall just before the disruption. q95=2.9 ! Next shot: raise PLC limit on the OH1 to 33 kA (actually -33 kA). Also raise PLC limit on EF3 by 1 kA. Shot 29 -- Fizzle. End of run. |
| Session Leader Comments | |||
| Nov 26 2003 09:06:56:263AM | Steve Wolfe | There will be a short delay while the engineers replace a relay in the EF1 supply | |
| Nov 26 2003 09:42:42:487AM | 1031126001 | Steve Wolfe | Shot#1: 1MA, high elongation setup. Early disruption .54sec. Vertically unstable like mad. 150Hz oscillation on zcur Next shot: back off on clearin to .005, move RXU out by 1cm, speed up current rise. |
| Nov 26 2003 11:49:12:620AM | 1031126002 | Steve Wolfe | Shot#2: back off on clearin to .005, move RXU out by 1cm, speed up current rise. Data hang in init. No power shot. |
| Nov 26 2003 10:05:02:077AM | 1031126004 | Steve Wolfe | Shot#3: back off on clearin to .005, move RXU out by 1cm, speed up current rise. fizzle, late breakdown. Previous one was late too. OH1 current seems to be 300A high? |
| Nov 26 2003 10:16:59:410AM | 1031126004 | Steve Wolfe | Shot#4: back off on clearin to .005, move RXU out by 1cm, speed up current rise. fizzle. Still late breakdown and too much bz. |
| Nov 26 2003 10:29:56:040AM | 1031126005 | Steve Wolfe | Shot#5: still trying for the second shot: back off on clearin to .005, move RXU out by 1cm, speed up current rise. plasma to 1.5sec, chopper is flooring but not railing. n/ncrit at 1.13. Kappa = 1.86, triang=0.6, close to DN next shot: decrease upper and lower triangularity |
| Nov 26 2003 10:44:00:030AM | 1031126006 | Steve Wolfe | Shot#6: decrease upper and lower triangularity disrupt at .54, n/n_crit=1.18, elong=1.84 same 150Hz oscillation Chopper is still asymmetric. Try changing the Vout to from +100 to +200. |
| Nov 26 2003 11:06:26:827AM | 1031126007 | Steve Wolfe | Shot#7: Try changing the Vout to from +100 to +200. plasma disrupts at .72, chopper still flooring; looks worse, I think we went the wrong way on the voltage. n/nc = 1.15, eout=1.86, triang about 0.5, ssep=-.45cm Bob says this wasn't a vde. frequency is higher before it goes. Try 0 on the chopper voltage, see if that symmetrizes better. |
| Nov 26 2003 11:25:11:483AM | 1031126008 | Steve Wolfe | Shot#8: Try 0 on the chopper voltage, see if that symmetrizes better. disrupts at 0.35sec, chopper level seems higher, but the behavior is different. next shot: repeat and see how reproducible it is. |
| Nov 26 2003 12:02:02:957PM | 1031126009 | Steve Wolfe | Shot#9: repeat and see how reproducible it is. not very, disrupts at .61, ~125kHz oscillation. n/nc = 1.17 next shot: drop P3 gain from 4 to 2 |
| Nov 26 2003 12:02:17:910PM | 1031126010 | Steve Wolfe | Shot#10: drop P3 gain from 4 to 2 disrupts at .35 again; this is near oh1 crossover. Delay the clearin and increase the current rise to try to separate these effects. |
| Nov 26 2003 12:01:40:190PM | 1031126011 | Steve Wolfe | Shot#11: Delay the clearin and increase the current rise to try to separate these effects. disrupts at 0.64, n/nc=1.17. try P3 up to 6 |
| Nov 26 2003 12:15:05:290PM | 1031126012 | Steve Wolfe | Shot#12:try P3 up to 6 disrupts at .65, big efc oscillation this time, still somewhat asym toward 0. oscillation is around 125Hz again. shot 11 was slower. P3 back to 4 |
| Nov 26 2003 12:26:40:970PM | 1031126013 | Steve Wolfe | Shot#13:P3 back to 4 fizzle |
| Nov 26 2003 12:40:19:147PM | 1031126014 | Steve Wolfe | Shot#15:P3 back to 4 disrupts at 0.67sec, oscillation ~125Hz Raise D3 gain from 6 to 9 |
| Nov 26 2003 01:06:31:720PM | 1031126016 | Steve Wolfe | Shot#16: Raise D3 gain from 6 to 9 Another fizzle. |
| Nov 26 2003 01:19:55:037PM | 1031126017 | Steve Wolfe | Shot#17: Raise D3 gain from 6 to 9, another tweak of oh1current. Yet another fizzle. |
| Nov 26 2003 01:38:27:447PM | 1031126018 | Steve Wolfe | Shot#18: Raise D3 gain from 6 to 9, tweak to BR Plasma full length! And it got an H-mode Shape looks ok, somewhat increasing triangularity, kappa=1.85 oscillating at close to 200Hz, chopper has big oscillations, but doesn't rail on either side. Some early runaways. n/nc~1.1 in L-mode, 0.9 in H-mode next shot: 1.2MA |
| Nov 26 2003 01:49:15:150PM | 1031126019 | Steve Wolfe | Shot#19: 1.2MA plasma disrupts at .85 in H-mode. Drop P3 from 4 to 2, leave D3=9 |
| Nov 26 2003 01:59:03:430PM | 1031126020 | Steve Wolfe | Shot#20: Drop P3 from 4 to 2, leave D3=9 fizzle, not surprising. |
| Nov 26 2003 02:11:40:573PM | 1031126021 | Steve Wolfe | Shot#21: Drop P3 from 4 to 2, leave D3=9 another fizzle. |
| Nov 26 2003 02:30:46:620PM | 1031126022 | Steve Wolfe | Shot#22: Drop P3 from 4 to 2, leave D3=9 disrupt at 0.87sec next shot: P3 from 2 to 3, current to 1.4 |
| Nov 26 2003 02:46:06:277PM | 1031126023 | Steve Wolfe | Shot#23: P3 from 2 to 3, current to 1.4 plasma to 1.24 sec drop D3 gain from 9 to 7.5 |
| Nov 26 2003 02:54:46:260PM | 1031126024 | Steve Wolfe | Shot#24: drop D3 gain from 9 to 7.5 fizzle. |
| Nov 26 2003 03:06:25:570PM | 1031126025 | Steve Wolfe | Shot#25: drop D3 gain from 9 to 7.5 And another fizzle. |
| Nov 26 2003 03:27:11:587PM | 1031126026 | Steve Wolfe | Shot#26: drop D3 gain from 9 to 7.5 disrupts at .635 next shot: Change to wire 10 and set D10 to 1.2 (==12 on wire 3) |
| Nov 26 2003 03:42:25:917PM | 1031126028 | Steve Wolfe | Shot#27: Change to wire 10 and set D10 to 1.2 (==12 on wire 3) plasma to 1.1 but not a VDE. Injection at 1.104. next shot: up in current to 1.6MA |
| Nov 26 2003 03:54:58:900PM | 1031126028 | Steve Wolfe | Shot#28: up in current to 1.6MA plasma to 1.17sec, not a VDE hits the oh1 current rail next shot: raise current rails on oh1, ef3 |
| Nov 26 2003 03:58:51:197PM | 1031126029 | Steve Wolfe | Shot#29: raise current rails on oh1, ef3 fizzle. Out of time. Happy Thanksgiving! |
| Physics Operator Comments | |||
| Nov 25 2003 02:25:46:503PM | Robert Granetz | Engineering setup for Wednesday, 26 Nov 2003 MP #362 - ITER single-null shape Session leader: S. Wolfe Physics operator: R. Granetz ECDC overnight in D2 at 2e-4 Torr, stopping by 07:00. Bake at 60 C overnight as well. Run begins at 09:00 and ends at 16:00. (NOTE EARLY ENDING TIME) Power systems the same as on 1031023019 (1.0 MA, 5.3 T, lower single null), EXCEPT that the PLC voltage limit for EFC should be raised from 800 to 900 V. A-coils should be hooked up as on 1031125007 (+Dtop -Dbot -Jtop +Jbot), and the power supply should be enabled. C-coil PLC limit settings should be set at 600 volts and 3 kA. 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) NO NINJA! Enable the following gate valves, assuming no vacuum problems: ECE, VUV, DNB ------------------------------------------------------------------------------- RF Setup: No RF until we get to our final shape, which will probably be late in the run ------------------------------------------------------------------------------- Run Plan: We are trying to get 1.6 MA, 5.3 T (q95=3) equilibria with the following ITER shape: - single lower null - kappa = 1.85 - lower and upper triangularities approximately 0.49 - a=0.215 m We will start at 1.0 MA and work our way up in increments. Vertical stability is likely to be an issue, and we anticipate that the run will involve some adjustment of the slow and fast ZCUR PID gains. Monitoring and stabilization of locked modes will probably be required as the plasma current is raised. Halo currents will also be monitored. | |
| Nov 26 2003 08:44:09:310AM | Robert Granetz | ECDC was done overnight, as well as a 60 C bake. Hybrid coldstart done by the engineering group; no errors found Loaded PCS segment 1 from yesterday's 1031125002 segment 1. Loaded PCS segment 2 from 1031023019, with the following changes to get higher elongation: ZCUR to 0.0 m RXL to -.005 m ZXL to -0.0175 m RXU to -0.04 m ZXU to +.030 m CLEARIN to +.008 m Also raise NL04 to 8e19. Copied segment 2 to segment 3 and set up wire 10 to be fast ZCUR with one-tenth of the gain, and turned off wire 03, and set Ref 9-12 to IP. This is for possible use if we need a stronger fast ZCUR feedback, since the derivative time constant is 10 times faster on wire 10. Also turn off argon permissive. | |
| Nov 26 2003 09:03:37:717AM | Robert Granetz | The start of the run will be delayed while a problem with the EF1 power supply is worked on. | |
| Nov 26 2003 09:38:02:987AM | 1031126001 | Robert Granetz | Shot 01 -- Plasma. Disrupted at t=0.55 s due to vertical instability. Kappa got above 1.8; n/ncrit got to 1.2. Next shot: reduce CLEARIN to +0.005 m, increase RXU to -0.03 m, tweak Ip rampup. |
| Nov 26 2003 09:57:51:160AM | 1031126002 | Robert Granetz | Shot 02 -- Aborted. No power cycle due to hangup in init. |
| Nov 26 2003 09:58:02:990AM | 1031126003 | Robert Granetz | Shot 03 -- Fizzle. Bz a little high. Next shot: add -10 amps to IC_EF4 |
| Nov 26 2003 10:12:58:367AM | 1031126004 | Robert Granetz | Shot 04 -- Fizzle. Steve notes that the OH1 current is couple of hundred amps more (negative) than normal. Next shot: add +200 amps to IC_OH1 (-20000 --> -19800) |
| Nov 26 2003 10:34:11:447AM | 1031126005 | Robert Granetz | Shot 05 -- Plasma. Made it into rampdown before VDE disruption. Kappa is 1.85, delta_U and _L is 0.58. EFC current is not symmetric. We may be dithering with an upper null. Next shot: add +1 cm to both RXL and RXU to reduce the triangularities. |
| Nov 26 2003 10:45:58:343AM | 1031126006 | Robert Granetz | Shot 06 -- Plasma. VDE disruption at t=0.55 s. The triangularities did indeed come down close to the desired values. Next shot: start playing with EFC chopper. Change its pre-programmed voltage to +200 V (from +100 V). We're not really sure of the direction, so this is a best guess. |
| Nov 26 2003 11:08:49:450AM | 1031126007 | Robert Granetz | Shot 07 -- Plasma. Disrupted at t=0.72 s, but it was not a VDE. I think it was an injection. Kappa=1.85, delta_L and _U approx 0.49, so this is the shape we want. But the EFC current is even more asymmetric, so maybe we went the wrong direction. Next shot: change chopper pre-programming to 0.0 V (from +200 V) |
| Nov 26 2003 11:36:01:680AM | 1031126008 | Robert Granetz | Shot 08 -- Plasma. Disrupted very early (t=0.35 s) Next shot: no changes. |
| Nov 26 2003 11:35:40:523AM | 1031126009 | Robert Granetz | Shot 09 -- Plasma. Disrupted due to VDE. Next shot: change fast ZCUR P gain to 2.0 (from 4.0) |
| Nov 26 2003 12:03:09:407PM | 1031126010 | Robert Granetz | Shot 10 -- Plasma. Disrupted earlier. Next shot: tweak Ip rampup; delay CLEARIN increase until after t=0.5 s (to avoid OH1 crossover) |
| Nov 26 2003 12:02:33:237PM | 1031126011 | Robert Granetz | Shot 11 -- Plasma. Disrupted at t=0.64 s. kappa=1.85, delta_L=0.50, delta_U=0.46 Next shot: increase proportional gain on fast ZCUR to 6.0 (from 2.0). Also add -3 mm to RXU. |
| Nov 26 2003 12:27:40:547PM | 1031126012 | Robert Granetz | Shot 12 -- Plasma. Disrupted at t=0.64 s. The oscillations on EFC current are back. The plasma shape is exactly what we want. Next shot: reduce fast ZCUR P gain to 4.0 (from 6.0) |
| Nov 26 2003 12:27:50:247PM | 1031126013 | Robert Granetz | Shot 13 -- Fizzle. Fields and fill pressure look okay. Next shot: no changes. |
| Nov 26 2003 12:46:00:813PM | 1031126014 | Robert Granetz | Shot 14 -- Plasma. Disrupted at t=0.67 s, VDE. Next shot: raise fast ZCUR derivative gain to 9.0 (from 6.0) |
| Nov 26 2003 12:58:14:223PM | 1031126015 | Robert Granetz | Shot 15 -- Fizzle. Next shot: no changes. |
| Nov 26 2003 01:07:39:733PM | 1031126016 | Robert Granetz | Shot 16 -- Fizzle. Next shot: add +100 amps to IC_OH1 |
| Nov 26 2003 01:21:09:427PM | 1031126017 | Robert Granetz | Shot 17 -- Fizzle. Fields look okay. Next shot: try a BR_0 tweak. |
| Nov 26 2003 01:38:48:650PM | 1031126018 | Robert Granetz | Shot 18 -- Plasma. Full-length shot; no disruption! Elongation=1.85, upper and lower triangularities=0.50-0.51. So this is a stable shot (just barely though) with the ITER shape at Ip=1.0 MA (q95=4.7-4.8). This shot also has an ohmic H-mode (small ELMs) starting at t=1.0 s. Startup isn't the greatest. Next shot: increase Ip to 1.2 MA |
| Nov 26 2003 01:50:42:010PM | 1031126019 | Robert Granetz | Shot 19 -- Plasma. Upward VDE, disrupting at t=0.84 s. Ohmic H-mode starts at t=0.75 s. Next shot: reduce fast ZCUR P gain to 2.0 (from 4.0) |
| Nov 26 2003 01:59:51:137PM | 1031126020 | Robert Granetz | Shot 20 -- Fizzle. Disruption recovery? Next shot: no changes |
| Nov 26 2003 02:16:19:823PM | 1031126021 | Robert Granetz | Shot 21 -- Fizzle. Next shot: additional BR_0 tweak |
| Nov 26 2003 02:36:22:807PM | 1031126022 | Robert Granetz | Shot 22 -- Plasma. Downward VDE; disrupted at t=0.87 s. I_halo_lower=155 kA (first time over 100 kA in a long time). Shape is still very good. Next shot: raise Ip to 1.4 MA; change fast ZCUR P gain to 3.0, tweak pre-fill gas puff. |
| Nov 26 2003 02:59:40:820PM | 1031126023 | Robert Granetz | Shot 23 -- Plasma. 1.4 MA Upward VDE; disrupted at t=1.25 s. I_halo_upper=135 kA. Got a 50% warning on the EFC_U coil stress. Our locked mode compensation is spot on. kappa=1.83, delta=0.49. Next shot: decrease fast ZCUR derivative gain to 7.5 (from 9.0) |
| Nov 26 2003 02:57:36:743PM | 1031126024 | Robert Granetz | Shot 24 -- Fizzle. Disruption recovery? Next shot: tweak pre-fill. |
| Nov 26 2003 03:10:02:493PM | 1031126025 | Robert Granetz | Shot 25 -- Fizzle. Next shot: no changes |
| Nov 26 2003 03:28:38:667PM | 1031126026 | Robert Granetz | Shot 26 -- Plasma. 1.35 MA. Disrupted at t=0.62 s. This was a VDE, but it didn't move very far down before quenching. Next shot: transfer the fast ZCUR over to wire 10, which has 10 times higher derivative gain capability. Set ZCUR derivative gain to 1.2 (corresponds to 12 on the old wire 03). Also turn off wire 03 (by hitting the "zero all" button) |
| Nov 26 2003 03:42:11:103PM | 1031126027 | Robert Granetz | Shot 27 -- Plasma. Disrupted at t=1.12 s. This was NOT a VDE! Looks like an injection. Good shape, with kappa=1.83, delta=0.49-0.50. EFC current is oscillating wildly between both rails. Next shot: raise Ip to 1.6 MA, and program nl_04 to go to end of flattop. |
| Nov 26 2003 04:01:10:527PM | 1031126028 | Robert Granetz | Shot 28 -- Plasma. 1.60 MA. Disrupted at t=1.17. NOT a VDE! I don't think it was due to a big impurity injection. Sawteeth go away just before the disruption, but it's not clear there was a locked mode. Shape is very good: kappa=1.83, delta_L=0.50, delta_U=0.49. OH1 rails at it's PLC limit, so this may have caused the disruption. Plasma touches the inner midplane wall just before the disruption. q95=2.9 ! Next shot: raise PLC limit on the OH1 to 33 kA (actually -33 kA). Also raise PLC limit on EF3 by 1 kA. |
| Nov 26 2003 04:17:24:273PM | 1031126029 | Robert Granetz | Shot 29 -- Fizzle. End of run. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 09:23:53:013AM | Plasma | Ok | |
| 3 | 09:51:46:320AM | Plasma | Ok | |
| 4 | 10:04:24:810AM | Plasma | Ok | |
| 5 | 10:17:05:520AM | Plasma | Ok | |
| 6 | 10:35:03:600AM | Plasma | Ok | |
| 7 | 10:57:25:757AM | Plasma | Ok | |
| 8 | 11:12:06:760AM | Plasma | Ok | |
| 9 | 11:25:39:703AM | Plasma | Ok | |
| 10 | 11:40:15:957AM | Plasma | Ok | |
| 11 | 11:54:06:273AM | Plasma | Ok | |
| 12 | 12:08:39:687PM | Plasma | Ok | |
| 13 | 12:23:29:127PM | Plasma | Ok | |
| 14 | 12:36:20:117PM | Plasma | Ok | |
| 15 | 12:49:36:153PM | Plasma | Ok | |
| 16 | 01:02:41:270PM | Plasma | Ok | |
| 17 | 01:15:21:603PM | Plasma | Ok | |
| 18 | 01:27:58:980PM | Plasma | Ok | |
| 19 | 01:41:19:057PM | Plasma | Ok | |
| 20 | 01:55:53:040PM | Plasma | Ok | |
| 21 | 02:09:01:027PM | Plasma | Ok | |
| 22 | 02:21:40:963PM | Plasma | Ok | |
| 23 | 02:34:55:493PM | Plasma | Ok | |
| 24 | 02:48:36:773PM | Plasma | Ok | |
| 25 | 03:01:31:383PM | Plasma | Ok | |
| 26 | 03:14:12:120PM | Plasma | Ok | |
| 27 | 03:29:18:790PM | Plasma | Ok | |
| 28 | 03:42:04:853PM | Plasma | Ok | |
| 29 | 03:56:42:277PM | Plasma | Ok | |