Miniproposals

Miniproposal: 116a Date Filed: 4/18/1995 Title: Begin 8 Tesla plasma operation First Author: Robert Granetz Session Leader: Ian Hutchinson (shots 1-18)

Miniproposal: 117 Date Filed: 4/18/1995 Title: 3He Minority Heating at 7.9T First Author: Yuichi Takase Session Leader: Ian Hutchinson (shots 1-18)

Engineering Operator Run Comment

8 Tesla Run Granetz/Wolfe/Bertolino/Silva

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:13:820PM

Author: To Be Determined

950530: First 8T run. PO Wolfe SL Hutch (for Granetz) EO Bertolino Summary: A serious problem with TF regulation was discovered. The discovery was done safely because the pulse duration was limited by inversion. The cause of the problem was tracked down to an incorrect chip in the TF regulator circuit. The chip was replaced and thereafter things went OK. The last three shots 16-18 had He3 injected and saw heating during the up to 2MW RF pulse. However, Mo radiation was rather strong. Shot 18 was 8T, 1MA - a nice demonstration of the engineering capability improvements over recent months. Overall, a rather successful first 8T run, with good physics and engineering progress. Details: Load from Seg1 last Friday with tweaks. Seg2 950510010. 1 PS Test Tuesday morning test. 2 I2T Test 3 Pla 6.5T, 800kA, nl04=1.e20. 4 Pla 6.85T 5 Pla 7.5T Almost no regulation. We are gtetting more Bt than demand. 6 Pla 7.6T Earlier Bt initiate -1.4s. Starting to regulate. 7 Pla 7.9T No regulation. Just keeps rising till inversion. 8 Pla 7.54T TF set 208kA.TF init to -1.6. Regulation is still soft. 9 Pla 8.18T TF set at 212ka. TF regulation completely failed. Fortunately we had decided not to move init any earlier. PF breakers pulled at about 0.4s which killed the plasma slowly. Strange OH1 fault. Kappa goes to 0.8 at the end of the shot! Long pause to try to figure out what the TF power supply is doing. Found that an incorrect op amp was installed on the current set/sense of the TF control board that saturated at about 200kA. 10 PS OH1/OH2 test. OK. 11 PS 100 kA TF only test. OK. 12 Fiz 150 kA TF looks OK. 13 Pla 200 kA set regulates nicely at 192kA, 6.89T. Initiate at -1.6s. 14 Pla 210 set, 202 got. 7.2T. good regulation. 15 Pla 220 set 211 got. 7.57T. Regulates from 0.65s. 16 Pla Helium-3 added. 230 set 221 got. 7.93T. Regulates at 1s. 17 Pla 234 set 223 got. 8.01T. 1.8MW Rf some electron heating. 18 Pla 1MA attempt. 224kA. 8.06T. 1.01 MA. Increased He-3. ECE Michelson is saturated so don't trusts its Te. Moly monitor is saturated during the 2MW RF pulse.

Physics Operator Summaries

Entered: Jul 7 2004 04:36:54:567PM

Author: To Be Determined

Physics Operator Summary for May 30, 1995 MP 116: 8Tesla Operation MP117: D He3 Heating (piggyback) SL: Hutch (substituting for Granetz) PO: Wolfe EO: Bertolino/Daigle The goals for today's run were to establish 7.9 Tesla operation, raise the plasma current to 1MA, and allow some initial tests of He3 minority heating. These goals were successfully met, thanks to some expert trouble-shooting by the engineering team. We actually got to 8.0T, 1.03MA, and observed RF heating. The startup plan was to breakdown on the ramp-up of the TF, with the TF moved as early as necessary to get into regulation before the end of the pulse. We started with a segment 1 copied from last Friday, with the IC_OH1 current increased by 100A; this was intended for a TF start at -1.2sec. I intended to increase the OH1 current further as the TF start was brought earlier, but it turned out not to be necessary. The earliest TF start used was -1.7sec, or about 30kA more on the TF at t=0 than the initial setting. Breakdowns were very robust and current rises were fast (>100kA @30msec) all day, with the exception of one fizzle when we went back down to 5.3Tesla. The fill started at 2.0e-5 and changed to 2.2e-5 at shot #9. Segment 2 was based on 950510010, an 800kA, 6.5Tesla shot with x-point control. This was slightly modified to remove some funny gas programming. Shots #1 and 2 were test shots. The plan was to start from a TF current setting of 188kA, and increase the setting by 10kA/shot until we got to 7.9Tesla (221kA). However, we found that there was a strong non-linearity in the what-you-ask-for vs what-you-get curve, corresponding to a large effective marginal gain at high currents. Shot TF start PLC Setpoint TF Rogowski ----- ------------ ----------- ___________ 3 -1.2 188 180 4 -1.2 198 190 5 -1.2 208 208 (no flattop) 6 -1.4 208 210 7 -1.4 214 220 (no flattop) 8 -1.6 208 209 9 -1.6 212 226 (no flattop) At this point, it was clear something was wrong. If the TF invert had not been set at +1.1 there is no telling how high the current would have gone on shots 7 and 9. After much checking, the engineers determined that an op-amp in the TF current regulation circuit was loading down, and could not drive over 5.2 volts for any input, where 5V corresponded to 200kA. The op-amp was a 444, while the schematic specified a 324, which could drive smaller loads. This op amp was replaced by the correct (specified) one, which was able to drive up to 10V into the actual load. Note that another non-linearity was also found by Gwinn: a plot of the sum of the individual cabinet currents, as digitized in CAMAC, vs the TF rogowski also showed a discrepancy increasing at high currents. The cause of this non-linearity was not located, and it is still present. It is not clear why this does not seem to affect the ask-for vs get curve, but it does not seem to, as shown below. Shot TF start PLC Setpoint TF Rogowski ----- ------------ ----------- ___________ 11 -0.7 100 94 12 -1.2 156 150 13 -1.6 200 192 14 -1.6 210 201.6 15 -1.6 220 211 16 -1.6 230 220.6 (7.9Tesla) 17 -1.6 234 224 (8.0T, no flattop) 18 -1.7 234 224 (8.0T, short flattop) He3 was pulsed from the B-side upper plenum on #16-18. RF power was over 1.5MW on 17-18, and significant electron heating was observed on the polychromator signal on these shots. Shot 18 was at 1MA, and had about twice the He3 as 16&17. On all shots but the last two, the fizzle detector on the TF had a 1000msec delay, which effectively would have kept it from shortening the TF pulse. On #16 & 17 this was reduced to 100msec. In any case it didn't matter because there were no fizzles except for shot 12 at the nominal 5.3Tesla field. One of the RF antenna current probes was found to be dead, which prevented the phase-balance arc detector from working correctly. This signal, which was a redundant measurement, was disconnected during the long stoppage between shots 9 and 10. Thereafter both antennas worked normally. In addition to the TF current over-shoot, shot 9 had a mysterious OH1 failure with the supply going into a forced invert shortly after crossover. The plasma ramped down, reaching a low elongation of 0.8. No fuses were found to be blown, and the problem did not recur. Shot 10 was an OH only test. Cooling times at the high TF currents are very long. The last shots required over 20 minutes to get the TF arms cold (the usual top arms were lagging). Scanner measurements indicated that up to 80% of the resistance was in the central column after the high current pulses. The TF bus was observed with the IR camera, and the heating was not found to be severe. Fuses were checked between shots on all high current pulses. Scorecard: --------- Tests: 4 Duds: 0 Fizzles: 1 Plasmas: 13 -------- -- Total 18

Session Leader Comments

Physics Operator Comments
May 30 1995 07:25:21:310AM		Steve Wolfe	MP116 8T Operation MP 117 D-He3 heating (piggyback) SL : Granetz (in absentia) PO: Wolfe EO: Bertolino Engineering setup: Same as on 950510010, except: TF start at -1.2sec TF invert at +1.1sec TF current set to 188ka (PLC setting) TF fizzle detector disabled. ECDC in D2 for at least 2hours prior to run. A-side plenum to 19psi of D2. B-side lower plenum 4psi Ar Run plan: Following the completion of engineering tests, we will begin trying for plasma at 6.5 Tesla, starting with a shot similar to 950510010, except that breakdown will be at a higher field. This will probably require some field tweaking. We will then proceed to increase the TF current in 10kA increments until we get to 220kA (nominal). The start time will be moved earlier, to about -1.5 sec to get the 7.9Tesla flattop to begin around 0.5sec. Once a shot is established at 800kA we will try increasing the current to 1MA. RF will piggyback D-He3 heating scenario once we get to 7.9T. Try adjusting He3 concentration to optimize heating.
May 30 1995 07:36:41:950AM		Steve Wolfe	MP116 8T Operation MP 117 D-He3 heating (piggyback) Loaded prepared shot (pcs$wolfe: 950530901) at 07:18 Segment 2 similar to 950510010; segment 1 from 950526 with OH1 current set 100A more negative. Coldstart successful
May 30 1995 08:46:45:350AM	950530001	Steve Wolfe	Shot 950530001 Tuesday Oh test. ok.
May 30 1995 09:05:38:660AM	950530001	Steve Wolfe	Shot 950530002 I^2t test (no power) to determine if it pulls the breakers successfully TF pulled, then after 3 sec the PF pulled. It seems to work.
May 30 1995 09:05:44:830AM	950530002	Steve Wolfe	Shot 950530002 I^2t test (no power) to determine if it pulls the breakers successfully TF pulled, then after 3 sec the PF pulled. It seems to work.
May 30 1995 09:22:13:020AM	950530003	Steve Wolfe	Shot 950530003 Try for plasma. Fill=2.0e-5 TF at 188kA, TFstart at -1.2sec Plasma. Ramped all the way down. TF reaches flattop at .2sec, around 180kA. Early current rise is a little slow, 70kA@30msec. Radial field a bit positive, but leave it for now.
May 30 1995 09:41:26:530AM	950530004	Steve Wolfe	Shot 950530004 Raise TF current to 198kA, same timing RF will fire at low power. Plasma - disrupts at 1.38sec, 300kA. TF flattop at 0.5sec at 190msec Better early current rise, 100ka at .03sec RF got ~0.5MW, only one xmitter
May 30 1995 10:18:42:560AM	950530005	Steve Wolfe	Shot 950530005 Raise TF current to 208kA, same timing RF will fire at low power. Enable Ar pulse 25msec at 0.3sec Plasma - disrupts at 1.33sec TF dis not reach flattop, but did get to 208 at 1.1sec! The PLC reading seems to be non-linear in this range. No, there is a problem with the reading (and feedback?) in the supply.
May 30 1995 10:32:13:720AM	950530006	Steve Wolfe	Shot 950530006 TF start time to -1.4sec, no change in demand current. See if it actually flattops Plasma - ramps down ok TF flattops around 210kA at around 0.8sec Breakdown looks good, despite the fact I didn't tweak fields
May 30 1995 11:13:52:890AM	950530007	Steve Wolfe	Shot 950530007 Raise TF set point to 214kA (was 208). No change in timing. RF is having a problem with D-port phase detector. Plasma- ramped down ok. TF got to 220kA, never regulated.
May 30 1995 11:31:42:470AM	950530008	Steve Wolfe	Shot 950530008 Drop TF set to 208, TFstart at -1.6sec Plasma - Got around 209kA, in "flattop" from around 0.6sec It's not regulating all that well, even on this one; still rises by 1-2ka.
May 30 1995 11:55:21:780AM	950530009	Steve Wolfe	Shot 950530009 Drop TF set to 212, TFstart at -1.6sec Raise fill to 2.2e-5 Note: TF cooling took about 22minutes after shot 8 Plasma - PF breaker pulled out early OH1 had a problem at crossover. TF current reached 226kA, did not regulate. We will wait until the engineers figure out what's going on!
May 30 1995 02:36:35:540PM	950530010	Steve Wolfe	Shot 950530010 OH test. should look like another Tuesday AM test: Looks fine
May 30 1995 02:47:20:360PM	950530011	Steve Wolfe	Shot 950530011 TF only test> set point at 100kA Flattop at 94kA.
May 30 1995 03:01:05:580PM	950530012	Steve Wolfe	Shot 950530012 Try for plasma, set 156kA, -1.0sec (go back to a normal 5.3T shot) Fizzle. TF looks fine at 150kA. Late bd; not surprising
May 30 1995 03:21:39:830PM	950530013	Steve Wolfe	Shot 950530013 Set TF=200kA, start=-1.6 Plasma - ramps down fine. TF gets to 192kA, flattop looks reasonable.
May 30 1995 03:43:34:680PM	950530014	Steve Wolfe	Shot 950530014 Set TF=210kA, start=-1.6 Note: #13 is still showing the non-linearity in the sum of the cabinet currents. This makes sense because those weren't changed. It may still be a problem however. Plasma - ramps down ok. TF = 201.6kA.
May 30 1995 04:08:12:270PM	950530015	Steve Wolfe	Shot 950530015 Set TF=220kA, start=-1.6 Plasma TF at 211kA, flat from 0.65 sec
May 30 1995 04:33:44:400PM	950530016	Steve Wolfe	Shot 950530016 Set TF=230kA, start=-1.6 Enable He3 pulse: open at 0.6sec for 15msec, then 20V till eof Plasma - ramped down ok. Got RF about 1MW TF = 220.6kA, from 880msec
May 30 1995 04:54:41:370PM	950530017	Steve Wolfe	Shot 950530017 Set TF=234kA, start=-1.6 (Try for 8T+, per IHH) Decide not to go to 1MA. Enable TF fizzle detector at +100msec Plasma- TF got to 224KA, no flattop Got 1.7MW of RF, some electron heating
May 30 1995 05:26:19:740PM	950530018	Steve Wolfe	Shot 950530018 Set TF=234kA, start=-1.7 (Try for 8T+, per IHH) go to 1MA. INcrease He3 level to 40V Enable TF fizzle detector at +100msec Plasma - ramps down. TF reaches 224.5kA Over 2MW of RF Looks like pretty good heating on the ECE poly. The Michaelson is saturated Moly monitor also saturates. Prad_core=2MW

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	08:22:29:240AM	Test	Ok	coax test
2	09:03:59:260AM	Test	Ok	I2t test ok
3	09:15:07:920AM	Plasma	Ok
4	09:34:03:230AM	Plasma	Ok
5	09:50:00:870AM	Plasma	Ok
6	10:22:13:320AM	Plasma	Ok
7	10:48:58:900AM	Plasma	Ok
8	11:16:56:440AM	Plasma	Ok
9	11:42:26:010AM	Plasma	Bad	oh1 type 1
10	02:33:07:710PM	Test	Ok	coax test
11	02:45:12:210PM	Test	Ok	tf only
12	02:56:34:080PM	Plasma	Ok
13	03:17:03:460PM	Plasma	Ok
14	03:34:17:280PM	Plasma	Ok
15	03:57:17:140PM	Plasma	Ok
16	04:25:30:530PM	Plasma	Ok
17	04:47:06:750PM	Plasma	Ok
18	05:12:14:670PM	Plasma	Ok