Alcator C-Mod Run 930512 Information

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Miniproposals
Miniproposal:
Date Filed:
Title:
First Author:
Session Leader:Martin Greenwald (shots 1-25)

Operators
Session leader(s):Martin Greenwald
Physics operator(s): Unknown
Engineering operator(s): Unknown

Engineering Operator Run Comment
Today will be a plasma run.

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:06:867PM
Author: To Be Determined
Run Summary 12 May 93

23 Shots, 17 with plasma flash.

Considerable fiddling around arose from getting the power supplies
fully under hybrid control and away from their internal current
limits. Now they are in this configuration.

Difficulties with OH2 and EF1 which gave unpredictable perturbations
to the horizontal field were tracked down to time delays in coming out
of internal saturation. When the external demand has exceeded the
available voltage it causes the internal gate control loop, which is
under integral control, to integrate well above the rail on the gate
control circuit. Delays of order 40 ms can occur.

TF worked very reliably at 5T.

Shot 22 was the highest plasma current, about 22 kA.

Hexapole adjustments were made by altering the OH2 demand voltage
during the ramp-down after commutation. Comparisons between 18, 21,
and 22 show use of 0, -100, +100V demand respectively.
These shots had fill pressure of 6E-5 on the gauge. This seems to be
near the lower limits at the moment. Going to 4E-5 loses breakdown.

Plan is to ECDC overnight in the hopes of getting rid of some of the
carbon. The RGA show large amount of Methane being generated after the
shots.

Physics Operator Summaries

Session Leader Comments
May 12 1993 08:23:39:110AMMartin GreenwaldStart where we ended yesterday - then to horizontal field feedback using
OH2U-OH2L.

May 12 1993 09:40:32:970AM930512001Martin GreenwaldIntention: Start where we ended yesterday - reestablish breakdown. As shot 930512027
Except swing EF4 voltage negative after +30 msec, current program drops to
0 after commutation.

Result: Alternator test instead

May 12 1993 09:56:26:880AM930512002Martin GreenwaldIntention: Start where we ended yesterday - reestablish breakdown. As shot 930512027
Except swing EF4 voltage negative after +30 msec, current program drops to
0 after commutation.

Result: OH1 bank didn't charge? Alternator problem - shot aborted

May 12 1993 10:22:38:140AM930512002Martin GreenwaldIntention: Start where we ended yesterday - reestablish breakdown. As shot 930512027
Except swing EF4 voltage negative after +30 msec, current program drops to
0 after commutation.

Result: Third try on shot 2. Unknown triggering problem on power supplies.

May 12 1993 10:27:37:710AM930512003Martin GreenwaldIntention: Same as above

Result: Unfortunately same as above

May 12 1993 10:50:29:250AM930512004Martin GreenwaldIntention: Same as above

Result: Breakdown seen at 14 msec, 10 kA of plasma current
Field at 5 T

May 12 1993 11:01:16:330AM930512005Martin GreenwaldIntention: Turned of OH2 feed back to null horizontal field
EF4 pushed into inversion after t = 0
EF1 current limit raised from 9 - 11 kA

Result: Breakdown at 5 msec, 7 kA
Horizontal field is much improved

May 12 1993 11:16:07:520AM930512006Martin GreenwaldIntention: Move EF1_U inversion 30 msec earlier to try to
improve balance.

Result: Breakdown at 6 ms, Ip = 10 kA

May 12 1993 12:04:27:040PM930512007Martin GreenwaldIntention: EF3 on 1 msec earlier and try to program post breakdown Bz
EF1_U inverts at -30 msec

Result: Breakdown at 13 msec, Ip = 7 kA

May 12 1993 12:17:26:020PM930512008Martin Greenwald - Intention: EF3 demand voltage raised 30% between 30 and 40 msec

Result: Breakdown at 8 msec

May 12 1993 12:31:51:840PM930512009Martin Greenwald - Intention: EF3 demand voltage raised again, flat from 0 - 30 msec

Result: Breakdown at 12 msec, Ip = 15kA, EF3 overdone

May 12 1993 12:50:57:200PM930512010Martin Greenwald - Intention: EF3 demand voltage dropped by about 500 V after 12 msec
Fill pressure dropped to 6 x 10^-5

Result: Breakdown at 8 msec, Ip = 16 kA

May 12 1993 01:02:51:740PM930512011Martin Greenwald - Intention: EF3 demand voltage dropped another 500 V after 12 msec
Fill pressure dropped to 4 x 10^-5

Result: No Breakdown

May 12 1993 01:36:59:930PM930512012Martin Greenwald - Intention: Raise pressure to 6 x 10-5

Result: Breakdown back, 13 kA

May 12 1993 01:26:03:650PM930512013Martin Greenwald - Intention: Raise OH1 current limit

Result: Breakdown at 8 msec, Ip = 20 kA, OH1 under control but
Bz no good

May 12 1993 01:35:01:240PM930512014Martin Greenwald - Intention: Raise EF3 to 2500 V (Undoes previous tweaks)

Result: No breakdown

May 12 1993 01:50:54:410PM930512015Martin Greenwald - Intention: OH1 dropped from -500V to -300V
Gas to 8 x 10-5

Result: Breakdown at 11 msec, Ip = 17kA

May 12 1993 02:08:49:240PM930512016Martin Greenwald - Intention: OH1 dropped to 0V
OH2 demand to 0V after commutation


Result: Breakdown at 7 msec, Ip = 12 kA

May 12 1993 02:28:46:960PM930512017Martin Greenwald - Intention: Moved turn on of EF3 1msec earlier


Result: Breakdown at 7 msec, Ip = 13 kA

May 12 1993 03:09:45:250PM930512018Martin Greenwald - Intention: Raise EF1_ U&L commutation resistance from 201 to 253 mOhm

Result: Breakdown at 7 msec, Ip = 12 kA

May 12 1993 03:27:18:810PM930512019Martin Greenwald - Intention: Lowered pressure to 6 x 10-5

Result: No OH2, No breakdown

May 12 1993 03:46:02:100PM930512020Martin Greenwald - Intention: Lowered pressure to 6 x 10-5
Change OH2 demand to - 100V

Result: Power Supply problem - no shot

May 12 1993 04:58:27:640PM930512022Martin Greenwald - Intention: OH2 to +100V

Result: Breakdown at 9 msec, Ip = 22 kA
Instabilities seen on visible/xray arrays

May 12 1993 05:37:09:720PM930512023Martin Greenwald - Intention: Repeat

Result: Breakdown at 9 msec, Ip = 22 kA
Instabilities seen on visible/xray arrays

Physics Operator Comments

Engineering Operator Comments
ShotTimeTypeStatusComment
107:13:55:760AMTestBadOH1 cap bank did not charge
209:27:27:800AMTestBadpower supplies did not trigger
310:24:19:800AMTestBadNo trig for power supplies
410:31:08:730AMTestOkgood plasma shot.
510:49:03:810AMTestOkGood plasma shot
611:06:54:010AMTestOkplasma shot Good
711:56:58:180AMTestOkGood Plasma Shot
812:10:04:470PMTestOkgood plasma shot .
912:24:56:620PMTestOkGood Plasma Shot.
1012:40:29:390PMTestOkGood Plasma Shot.
1112:54:52:450PMTestBadNo Plasma P.S. Good
1201:06:48:550PMTestOkGood Plasma Shot Power Supplies O.K.
1301:19:24:280PMTestOkGood Plasma Shot Power Supplies O.K.
1401:33:06:710PMTestBadNo Plasma Power Supply O.K.
1501:45:41:560PMTestOkGood Plasma Shot Power Supplies O.K.
1602:04:35:530PMTestOkGood Plasma Shot Power Supplies O.K.
1702:24:22:400PMTestBadEF1L came out first Pulling thr PF Breaker.
1803:03:08:220PMTestBadWe had Plasma The PF breaker came out EF1L commmutation fail.
1903:24:58:690PMTestBadpower supply Faulted
2003:42:51:850PMTestBadPlasma good Power Supplies EF1u&L OH1& OH2 L Commutation Faults.
2104:28:44:680PMTestOkWe had Plasma But had a commutation fault on EF1u7L, OH1,OH2 L
2204:47:21:100PMPlasmaOkWe had plasma but the pf power suplies faulted.
2305:02:12:510PMPlasmaOkHad Plasma But Pf Supplies faulted.
2405:20:56:290PMTestOkJOSH - testing state machine - seems to work
2505:28:38:300PMTestOkJosh Data system test - New state machine (OK)