Miniproposals

Miniproposal: Date Filed: Title: First Author: Session Leader: Robert Granetz (shots 1-2) Session Leader: Steve Wolfe (shots 3-5)

Engineering Operator Run Comment

continuation of startup after repair of flux loop connectors

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:09:790PM

Author: To Be Determined

Run Summary for 940512 (a BAD day!) MP 041 - Restart CMOD SL: Granetz/wolfe PO: Snipes EO: Gwinn Prior to the run, the connector containing the three bad flux loop signals F22,F23, and F25 was repaired. It was believed that the airside connector was faulty and responsible for two of the observed bad signals; F23 was confirmed to be open circuit inside the machine. The run did not start until after noon because we had expected the connector repair not to be done overnight. The first shot revealed that all three of the bad loops were still bad, exhibiting the usual symptom of not returning to zero after the supplies shut off. There was also a problem on the TF supply, which did not regulate at current. Shot 2 was a TF only test, to try to get data for B-field subtraction on Snipes' new Bp coils. TF still did not regulate, and reached only 4.1Tesla. While the engineers worked on the TF, we opened up the cell and checked the repaired connector. Everything appeared to be consistnt with results from the previous night: No evidence of perturbations by jiggling the connector, and when the connector was removed F23 was still open in the machine. Jiggling the pins on the feedthrough gave no indications either. We prepared a test to see if the connection to the iso-amps could be the real problem, by disconnecting all the ribbon cables going to the iso-amps. Shot #3 was a full commutation test with TF, but with PF supplies set to invert at 20msec, since all hybrid feedback based on magnetics would have zero inputs. The problem with the flux loops F22,F23, and F23 was still there, exonerating the iso-amps. After shot 3, the computers went down, apparently from the heat, as the airconditionong had failed for the second day running. This effectively terminated the run, which was abandoned at around 16:30. An attempt was made after some of the computers were revived to do a test of the remaining electronics alone, by connecting a 0.5 VDC to a spare male connector on the pins corresponding to the three bad loops and plugging the 20 pin female cable into that, and running the data system. This test failed, apparently because the way the reset works requires that there be no signal at the time the gate opens; we got a saturated 5V signal on the three channels. We left the system with the hybrid and iso-amps reconnected, and a loop of wire connected to the three inputs. We will start tomorrow by seeing if the electronics give reasonable signals when we fire a test shot under these circumstances; if this works, it will almost certainly indicate that the problem is all on the vacuum side. If that is the case, we will then try to determine whether we can run the machine sensibly using only the remaining 17 full flux loops, 26 Bp coils, and the 2 partial loops. The problem is that 3 of the bad flux loop signals are in the same vicinity, near the lower x-point. If we cannot control and/or diagnose the divertor without these loops, it will be necessary to warm up and break vacuum to attempt to repair at least some of the bad loop signals.

Physics Operator Summaries

Session Leader Comments
May 12 1994 12:40:20:590PM	940512001	Robert Granetz	Continuation of MP #041 (Startup), after repairing F22 and F25. First shot will be a re-load of shot 10 from yesterday.
May 12 1994 12:55:12:330PM	940512001	Robert Granetz	Dud. All the flux loops that were broken yesterday are still broken. Damn! There was also a problem with the TF. Next shot, TF only test shot.
May 12 1994 04:04:00:510PM	940512003	Robert Granetz	Shot 940512003: ---------------- Granetz is long gone. Wolfe now in the SL chair. Before this shot the connector was wiggled, then removed and the pins wiggled to see if the inner connector could be perturbed by external wiggling. No such effect was observed. F23 is still open circuit, although (incorrect) signal is observed on the F23 camac during a pulse. Magnetics Iso-amp inputs disconnected, ie no magnetics input to the hybrid. This will be a full-up shot, including commutation, except that supplies will invert at 0.03 sec. The idea is to test whether the iso-amps and/or the hybrid are responsible for the error in the flux loop signal. This is also a test of the TF problem (not reaching or holding current). We are now also having computer problems. Result: -------- F22, F23, F25, are still bad. The iso-amps appear to be exonerated. Just for the amusement value, F17 now seems to be working.

Physics Operator Comments
May 12 1994 12:56:42:010PM	940512002	Joseph Snipes	Shot 2 TF only test shot to check droop problem with TF on shot 1. Also provides TF pick-up data for the new RF limiter coils.
May 12 1994 02:49:46:420PM	940512002	Joseph Snipes	Problems with the TF and the flux loops F22, F23, and F25. Delay to try to solve these problems. Meanwhile, the Session Leader has changed to Steve Wolfe.
May 12 1994 03:32:26:280PM	940512003	Joseph Snipes	Shot 3 Test shot with all fields. Inversion set to 0.03 sec on all power supplies. Checking flux loops and ramp up of TF.
May 12 1994 03:38:21:790PM	940512003	Joseph Snipes	Shot 3 Computer problems with initialization of all CAMAC. Unable to initialize the shot.
May 12 1994 03:58:10:860PM	940512003	Joseph Snipes	Shot 3 Flux loops still bad. So, the hybrid was not responsible.
May 12 1994 04:44:50:480PM	940512003	Joseph Snipes	End of run since the computers are still down, perhaps due to high temperature in the control room (about 85 F).

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	12:37:56:050PM	Plasma	Bad	tf did not regulate properly- only went to 126ka
2	12:56:14:620PM	Test	Bad	tf test problem with regulation
3	03:29:51:920PM	Test	Ok	TF fixed itself
4	06:47:52:160PM	Test	Bad
5	06:54:53:030PM	Test	Ok