Miniproposals

Miniproposal: Date Filed: Title: First Author: Session Leader: Martin Greenwald (shots 1-11)

Engineering Operator Run Comment

Plasma run delayed by morning power upset

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:07:947PM

Author: To Be Determined

Summary of run 930618 Physics Operator: Granetz Asst. Operator: Greenwald Eng. Operator: Fairfax The purposes of this run: ------------------------- There were up to four things that we were hoping to address in this run: a) Push the density higher. For this, we desired a long flattop plasma that was vertically stable. We chose as the starting point shot #930618003 from last week. This shot lasted 0.35 s, and had moderate, symmetric elongation, with Ip=0.3 MA. b) Argon puffing, as requested by our x-ray spectroscopists in order to measure Ti. c) Start exercising the EFC chopper supply. d) If time permits (which it didn't), try to get a breakdown without commutating OH1. Wall Conditioning/Vacuum: ------------------------- ECDC was run for about 1.5 hours prior to the run, ending at around 10:00. The base pressure before our first serious attempt at getting a plasma was 4e-7 torr. No nitrogen "burps" occurred today. Detailed Summary: ----------------- This run was plagued by problems, many of which were directly related to the previous maintenance day. Even though we only had plasmas on the last three shots of the day, we did manage to address some of the run goals. The EFC chopper supply was successfully tested into a dummy coil, first under PLC control and then hybrid control. After the run, the EFC supply will be connected to the coils in the machine, in preparation for more operation later this week. Shot 009 was a nice plasma shot, similar to shot 930618003 from last week, which was used to program the PCS. For the next (and final) two shots, the pulse gas programming was increased substantially, resulting in very noticeable marfes, and early disruptions. Interestingly enough, no increase in plasma density was measured between shot 009 and shots 010 and 011. Also on the last two shots, argon was puffed in, and x-ray lines were observed in the plasma on shot 011. Problems: --------- 1) Cryogenic cooling was not started until early on the morning of the run, and subsequently the machine was not at operating temperature until 11:00. Cooling should have started the night before. 2) There was a power failure early in the morning which inexplicably caused the UPS to fail. All power supplies and engineering camac had to be reset and the UPS had to be tested for reliability. 3) During the first plasma attempt (after several test shots of the EFC supply) the gas pre-fill system failed to work and had to be debugged, which was somewhat time consuming. Since this was done during the INIT state, the cooling was off, and after fixing the problem, the machine had to re-cool, causing another delay. 4) The TF supply repeatedly crowbarred around t=0, tripping the breakers for all of the PF supplies as well. This turned out to be due to someone shutting off one of the TF cabinet halves while performing work during the maintenance day yesterday. 5) The pulse gas signal was not coming out of the hybrid computer. This turned out to be due to a loose cable, caused by an inadvertent bump while working on the hybrid during the maintenance day yesterday. 6) EF3 was not firing. This was due to turning off the power to its trigger interface board while work was done during the maintenance day yesterday. 7) OH2L had a single phasing problem due to an SCR gate pulse which was not getting through. It is not known whether this problem was due to any activities during the maintenance day yesterday. 8) The TF bus current shunt severely overheated today, causing solder to melt and dribble down. The 3 TF crowbars may have contributed to this. The overheating was discovered almost by accident after the run had ended. If the soldered joint had actually failed, a 300 MJ explosion would have ensued, which would have put me above Ian on the destructive machine operator list. The fix for this will probably delay tomorrow's run significantly. Score-card: ----------- 3 good shots 4 fizzles (all due to problems with power supplies) 0 no-breakdowns 4 tests (EFC and hybrid test shots) -- 11 total shots Recommendations for future runs: -------------------------------- 1) Don't have Monday maintenance days. 2) Don't be session leader on Tuesdays.

Physics Operator Summaries

Session Leader Comments
Jun 22 1993 12:01:08:620PM	930622001	Robert Granetz	Test of EFC's only
Jun 22 1993 12:01:13:690PM	930622002	Robert Granetz	Test of EFC's only
Jun 22 1993 12:01:31:300PM	930622003	Robert Granetz	Test of EFC's only.
Jun 22 1993 12:02:29:050PM	930622004	Robert Granetz	First attempt at plasma shot.
Jun 22 1993 01:14:17:080PM	930622004	Robert Granetz	There has been an hour's delay due to a problem with the TF and PF breakers.
Jun 22 1993 01:25:17:160PM	930622004	Martin Greenwald	Initial Engineering Setup Supply Start Close Open CrowBar Invert mOhms EF1L -1.6 -1.55 0 .07 .35 120 EF1U -1.6 -1.55 0 .07 .35 120 OH1 -1.45 -1.4 0 .07 .35 65.2 OH2L -1.6 -1.55 0 .12 .35 12.9 OH2U -1.6 -1.55 0 .12 .35 12.9 EF2L -1.0 .35 46 EF2U -1.0 .35 46 EF3 -.05 .35 EF4 -1.6 .35 EFC .4 .6 TF -1.65 .35
Jun 22 1993 01:27:37:310PM	930622004	Robert Granetz	Aborted first attempt. No gas prefill. Try again (without changing shot #)
Jun 22 1993 02:02:37:980PM	930622004	Robert Granetz	Another delay caused by further problems with the gas pre-fill system, and then the subsequent wait for coil temperatures to recool (since the pre-fill problem was debugged while in INIT).
Jun 22 1993 02:16:30:060PM	930622004	Martin Greenwald	Intention: Repeat shot 003 from 06/18 Result: Fizzle, OH2 Lower single phasing, no EF3
Jun 22 1993 02:45:32:570PM	930622005	Martin Greenwald	Intention: Try again Result: Same problems - OH2 single phases etc.
Jun 22 1993 03:40:05:370PM	930622006	Martin Greenwald	Intention: Try again Result: Fizzle - OH2 problems solved, but TF still crowbars, all supplies shut down
Jun 22 1993 04:02:51:250PM	930622007	Martin Greenwald	Intention: Test pulsed gas no power supplies - m out not equal to v out on previous shots Result: Loose cable fixed - good pulsed gas shot
Jun 22 1993 04:20:57:470PM	930622008	Martin Greenwald	Intention: Try for plasma again Result: Fizzle, no EF3
Jun 22 1993 04:28:12:740PM	930622009	Martin Greenwald	Intention: Try for plasma again Result: Good plasma, 310 kA
Jun 22 1993 04:47:51:330PM	930622010	Martin Greenwald	Intention: More gas after 80 msec Result: Disrupted at 224 msec, but density about the same
Jun 22 1993 05:12:03:610PM	930622011	Martin Greenwald	Intention: Small change in RCur program, move in by .5 cm, lower fill to 4e-4 Argon increased a bit Result: Ip = .3 MA, Disrupted at .185 sec

Physics Operator Comments

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	11:06:42:840AM	Test	Ok	Test of EFC chopper with no TMX DC
2	11:20:39:770AM	Test	Ok	Test of EFC chooper with TMX supplies; 1 kA for .2 sec; OK
3	11:41:37:920AM	Test	Ok	Test with hybrid feedback OK
4	01:17:51:800PM	Plasma	Bad	TF power supply crowbar at -0.136 seconds;
5	02:43:41:030PM	Plasma	Bad	TF and OH2L problems
6	03:34:19:630PM	Plasma	Ok	Plasma fizzled; TF crowbar, but found that TF 8 converter was switched o
7	03:51:48:360PM	Test	Ok	testing hybrid control of pulse gas after finding no pulse gas shots 1-6
8	04:12:56:390PM	Plasma	Bad	EF3 did not pulse; interface board disabled
9	04:23:22:100PM	Plasma	Ok	Good plasma! Over 300 msec long. First truly good shot all day.
10	04:40:49:030PM	Plasma	Ok	good plasma; disrupted at 225 mSec
11	05:03:34:910PM	Plasma	Ok	Good plasma