Miniproposals

Miniproposal: 012 Date Filed: 7/15/1993 Title: Operation with EF3 coils in series First Author: Steve Wolfe Session Leader: John Rice (shots 1-37) Session Leader: Steve Wolfe (shots 1-37)

Engineering Operator Run Comment

First Plasma Run 2nd campaign; EF3 series; MP 012

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:08:053PM

Author: To Be Determined

Run Summary for 930721 -- MP #012 Session Leader/Physics Operator: wolfe Assistant: Rice Engineering Operator: Fairfax The goal of this run was to run the machine with the EF3 coils in series. Secondary goals were to determine the effect of not having these in parallel on vertical stability, and investigate use of EF2's in the vertical controller. Piggy-back tasks were MP#006 (Hirex debugging) and MP#004 (EFC Chopper ). We succeeded in operating the machine with the new EF3 configuration. To get successful current rise it was necessary to go to a higher voltage than originally desired, namely a case based on 930629010 (V_EF3 = -2400V) rather than 930629013 (V_EF3 = -2100V). Shot 13 was the first non-fizzle shot, but it was a bad runaway discharge. Shot 14, on which the Bz was adjusted to be less positive, was the first good shot, and was extremely similar to 930629010; current was nearly flat at 300kA and the pulse lasted almost to 400msec. Shot 15 was nearly identical, except we turned on the Ar puff for the HIREX debugging. Reproducibility was very bad - lots of fizzles. Shots 17 and 19 were the only successful shot with higher EF1 currents, and they were only marginaly different. We never got to the point of trying the EF2 feedback. After much screwing around, reloading shot 14 on Shot 24 recovered the shot (after 4 straight fizzles), but subsequent attempts to increase the EF1 currents (after 170msec) resulted in more fizzles. The flux plots indicate some radial field problems at 10-20msec; also the field index is somewhat more positive than usual. However, there seemed to be little correlation of fizzles and good shots with the index. The cause of the fizzles is unknown. Good shots were: 14,15,17,19,24; all but 17 & 19 had identical programming and very similar results, namely good flat 300kA pulses lasting almost 400msec. Shot 19 had a vertical disruption at 337msec. The HIREX debugging got no useful data, owing to the lack of good shots and low level of Ar observed. The EF3 chopper was fired at 400msec, after the nominal end of the pulse. All data required in preparation for using the chopper during plasma operation was obtained. Problems: --------- There was a serious N2 leak right before start of operation. The pressure jumped from 3e-7 to 3e-6 in a few seconds. The culprit was probably an inner seal on a port between G and K, based on pinching off the tube on the rough pump lines going to the inter-seal space. The N2 pressure came down very slowly, and may have contributed to our problems. The 60 cycle junk on OH1,OH2U&L was present at the beginning of the run, despite a fix made yesterday. Some shots (5-8) were spent investigating this problem by firing sets of supplies under Hybrid control. At shot 9 we asked that the Rear OH1 cabinet be taken offline, as this had been previously observed to help this problem; this seemed to help. At shot 21 the engineers decreased the integral gain on the OH2 voltage regulator boards and reported that this seemed to have helped at least one aspect of the problem. However, we did not try putting the second OH1 cabinet back online. Scorecard: ---------- Power tests 4 Duds 1 Fizzles 16 Runaway shots 1 Good Shots 5 -- Total 27

Physics Operator Summaries

Session Leader Comments
Jul 21 1993 08:11:28:410AM		Steve Wolfe	Run 930721 Mini-proposal#012 - Run with EF3 in series Session leader/Phys. Op. Wolfe Assistant Phys. Op. Rice Engineering Op. Fairfax Set up based on 930629013, except EF3 voltages and controllers adjusted as follows: V_EF3 doubled after blip time. Also added a front porch of -50V from -12msec to -1ms (it was at +100V until -1ms) Controller on IP_RCUR changed from [(-3,.015),(.2,.04),(3.,0.)] to [(-3,.03),(.2,.04),(3.,0.)] Also modified the limits on V14 which will be used for Pulsegas3 in future runs.
Jul 21 1993 08:14:20:100AM		Steve Wolfe	Commutation resistors at start of RUN 930721 OH1 65.6mOhm OH2U 13.1 OH2L 12.7 EF1U 120.1 EF1L 120. EF2U 45. EF2L 45.8
Jul 21 1993 08:25:32:430AM		Steve Wolfe	Power Supply timing at start of run 930721 Start Close Open Crow Bar Invert EF1U&L -1.6 -1.55 0.00 .07 .35 OH1 -1.45 -1.40 0. .07 .35 OH2U&L -1.6 -1.55 0. .12 .35 EF2U&L -1.0 .35 EF3 -.05 .35 EF4 -1.6 .35 EFC +0.4 .9 (initially off) TF -1.65 .35
Jul 21 1993 09:04:51:680AM		Steve Wolfe	At about 8:30 a 3e-6 scale leak opened up. It seems to be all N2, no He. It came up fast and is going down very slowly. There is some evidence it is on a pumped seal, from G-K.
Jul 21 1993 09:52:16:360AM	930721001	John Rice	On the transition back to automatic mode from manual mode on the coil cooling system, a surge of LN2 caused a nitrogen leak into the torus, whose base pressure reached 2 e-6 T. (This is the corrected value of the pressure. A factor of 2.5 lower pressure was achieved by recalibrating the torus, cryo, and one turbo ion gauge. Consequently the new starting fill pressure today will be 1.6e-5.) The leak has resealed and the nitrogen has been falling steadily for an hour. The rga is still dominated by H2 due to this morning's ECDC. Vessel temp 19. No plasma. No flash. Got garbage on the OHs, EF3 maybe turning on too fast, garbage on EF2 lower.
Jul 21 1993 10:10:44:010AM	930721002	John Rice	Delayed EF3 rampup by 1 ms. Fill pressure still 1.6e-5. Lead was reversed on EF2L, now fixed. Flash. 20 kA, 40 ms. Still too negative in Bz. Still a little radial field.
Jul 21 1993 10:31:27:250AM	930721003	John Rice	Increased EF4 current by 30A to 635A from -.2 to 0. sec. Flash only.
Jul 21 1993 10:45:39:350AM	930721004	John Rice	Fill pressure 1.2e-5 T. Flash only.
Jul 21 1993 11:06:45:360AM	930721005	John Rice	OH1 test. no fuzz on OH1.
Jul 21 1993 11:23:23:650AM	930721006	John Rice	OH1 and OH2 test. no fuzz on OH1, a little on OH2U.
Jul 21 1993 11:50:19:310AM	930721007	John Rice	OH1, OH2 and EF1 test. fuzz is worse on OH1, but no EF1s.
Jul 21 1993 12:00:06:710PM	930721008	John Rice	OH2 test. no fuzz.
Jul 21 1993 12:25:06:010PM	930721009	John Rice	removing an OH1 cabinet fill pressure 1.6e-5 flash only, lower fuzz
Jul 21 1993 12:36:29:560PM	930721010	John Rice	fill pressure 1.2e-5, added post plasma gas pulse flash only
Jul 21 1993 12:48:30:960PM	930721011	John Rice	EF3 now -2400 from 0 to .026 s OH1, OH2s loaded from 930629010. base pressure now 7e-7 T flash only index too high
Jul 21 1993 01:06:35:140PM	930721012	John Rice	OH2s lowered by 10V at all points between 8 and 26 ms. t v .008 0 to -10 .010 -10 to -20 .024 -10 to -20 .026 -20 to -30 flash only. went the wrong way
Jul 21 1993 01:19:18:170PM	930721013	John Rice	OH2s raised by 20V at all points between 8 and 26 ms. t v .008 -10 to 10 .010 -20 to 0 .024 -20 to 0 .026 -30 to -10 got plasma!
Jul 21 1993 01:34:02:640PM	930721014	John Rice	ef4s lowered to 605 A between -.2 and 0 sec raised fill pressure to 1.6 e-5 T good plasma, not a bad plasma
Jul 21 1993 01:50:00:510PM	930721015	John Rice	fill pressure 1.4e-5T and argon pulse 80V from -100 to -90 ms chopper turned off good plasma
Jul 21 1993 02:05:38:070PM	930721016	John Rice	fill pressure 1.4e-5T and argon pulse 80V from -100 to -88 ms delayed post plasma pulse by 10 ms extended ef1 current waveform to linear ramp from 1500 A to 0 from 170ms to 380ms flash only ???
Jul 21 1993 02:21:23:990PM	930721017	John Rice	radial field problem with previous shot. fill pressure raised to 1.6e-5T good plasma, elongated getting some randomness in ef3
Jul 21 1993 02:43:06:380PM	930721018	John Rice	lengthened argon pulse by 2 ms, delayed post plasma pulse to 1 sec. lowered fill pressure to 1.4 e-5 changed ic_ef1u+l to a ramp from .17,1500 to .37,1000A ef3 current is now coming down and holding during the front porch from -4ms on. previously not coming down at that time. flash only. 'I tooold you'. still too much positive gradient.
Jul 21 1993 02:58:37:040PM	930721019	John Rice	1.6e-5 on fill plasma!
Jul 21 1993 03:15:03:750PM	930721020	John Rice	ef1u+l increased to 1500 A until .37 sec flash only index still too positive
Jul 21 1993 03:42:50:300PM	930721021	John Rice	increased V_OH2U+L .008s 10 to 20 V .010 0 to 10 V .024 0 to 10 V .026 -10 to 0 V flash only field's negative
Jul 21 1993 03:49:32:760PM	930721022	John Rice	argon off flash only
Jul 21 1993 04:15:12:040PM	930721023	John Rice	argon on, flash only
Jul 21 1993 04:22:26:620PM	930721024	John Rice	argon off, reload shot 14 good plasma
Jul 21 1993 04:41:14:470PM	930721025	John Rice	argon on, reload shot 20 flash only
Jul 21 1993 05:00:08:220PM	930721026	John Rice	argon on, reload shot 24 manually moved ef1s to 1500A from .17 to .35 flash only
Jul 21 1993 05:04:07:380PM	930721027	John Rice	turned off PID gain on Brad 0 to .05 sec. flash only

Physics Operator Comments

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	09:31:35:560AM	Plasma	Ok	No plasma
2	09:56:14:860AM	Plasma	Ok	Flash. EF2LA SCR lead was reversed on shot 1. No significant plasma cu
3	10:16:37:140AM	Plasma	Ok	oh problems still evident
4	10:37:56:270AM	Plasma	Ok	oh problems still will run oh1 only
5	11:03:58:870AM	Test	Ok	OH1 Hybrid test OK
6	11:16:34:980AM	Test	Ok	OH1 and OH2 test; some slight oscillation on OH2U
7	11:30:39:160AM	Test	Ok	Same as last shot but OH2 oscillation worse
8	11:53:22:960AM	Test	Ok	OH2 Only test
9	12:12:13:350PM	Plasma	Ok	Got Flash but no current
10	12:27:08:590PM	Plasma	Ok	Fizzle
11	12:42:28:650PM	Plasma	Ok	Fizzle
12	12:56:52:970PM	Plasma	Ok	fizzle
13	01:10:10:360PM	Plasma	Ok	350 kA with 5 electrons (runaway discharge)
14	01:23:02:500PM	Plasma	Ok	nice 300 ka shot
15	01:41:36:640PM	Plasma	Ok	good 300 kA shot with Ar
16	01:56:56:920PM	Plasma	Ok	Fizzle;
17	02:10:25:240PM	Plasma	Ok	EF3 may be starting to show some problems
18	02:33:23:570PM	Plasma	Ok	Fizzle
19	02:52:28:440PM	Plasma	Ok	Plasma back
20	03:07:50:620PM	Plasma	Ok	Fizzle
21	03:21:20:370PM	Plasma	Ok	Fizzle
22	03:45:48:130PM	Plasma	Ok	Fizzle; OH2 power supplies voltage feedback gain reduced 2x; much better
23	04:07:26:320PM	Plasma	Ok	Fizzle
24	04:17:51:210PM	Plasma	Ok	Good plasma; reload of shot 014
25	04:31:10:000PM	Plasma	Ok	Fi9zzle
26	04:43:45:760PM	Plasma	Ok	fizzle
27	05:02:04:210PM	Plasma	Ok	fizzle
28	05:13:34:330PM	Test	Bad	josh testing
29	05:21:29:670PM	Test	Ok	josh again
30	05:43:38:560PM	Test	Ok	josh
31	05:47:42:190PM	Test	Ok	josh
32	05:53:12:360PM	Test	Ok	josh
33	05:58:06:780PM	Test	Bad
34	06:05:04:720PM	Test	Ok	josh
35	06:08:33:520PM	Test	Ok	josh
36	06:21:42:490PM	Test	Ok	josh
37	06:29:05:440PM	Test	Ok	josh