| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Steve Wolfe |
| Physics operator(s): | Robert Granetz |
| Engineering operator(s): | Sam Pierson,Ed Fitzgerald |
| Engineering Operator Run Comment |
| automatically entered by signon - please replace with real comment |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jun 23 2009 05:55:22:480PM |
| Author: Steve Wolfe |
Session Leader summary for Tuesday, 23-Jun-2009 MP#298A: C-Mod restart SL: wolfe PO: granetz EO: Pierson,Fitzgerald This was a long but ultimately successful day. We had one plasma attempt and got the first fizzle of the year. The search for the cause of the attenuated signal on dpcs input_009 (F10) took much longer than anticipated, and eventually the fault was traced to a bad ribbon cable to the dpcs input patch panel in the interface room. Replacing the cable fixed the feedback signals, but then several hours were spent repairing a fault in the PLC control circuitry on OH2U. We then took a couple of PLC controlled test shots on OH2U to confirm the repair, and one PLC controlled 150kA TF test to verify that an iso-amp board#5 that had been removed from the chassis before we exonerated the iso-amps. We then took one plasma attempt, 1090623009, based on the reload from 1090622015 that I set up last night. This shot succeeded in producing a strong flash, with a good early breakdown. There was very little current and the plasma seemed to move inward,if we can trust the modified RCUR predictor. This was probably mostly due to the high programmed pre-puff (29msec), which had been done to maximize the likelihood of breakdown. The MFLUX null looks horrible, but this may be largely due to the inadequacy of the synthesized bogus flux_22 and flux_24 signals on the lower inner wall. The BR_0 predictor (RECON_VAC) indicates <1mT radial field. I expect that a lower pre-puff may be sufficient to allow some plasma current tomorrow, and then we can start to tweak the field evolution. The new predictors seem to be doing well enough. |
| Physics Operator Summaries |
| Entered: Jun 23 2009 10:16:14:880PM |
| Author: Robert Granetz |
Run summary for Tuesday 2009/06/23
MP 293a: Startup and conditioning
Session leaders: S. Wolfe
Physics operator: R. Granetz
The goal for today was to try and get a plasma, or at least a breakdown,
and we succeeded at this on the very last shot. This was only the 3rd run
day since finishing the machine reassembly, and not surprisingly, the day
was marked by a number of problems, all of which were successfully
overcome.
The first problem was a hybrid input signal that had the wrong amplitude,
resulting in improper feedback control of the PF power supplies. We spent
much of the morning investigating several iso-amplifier boards and cables
that transfer signals from the magnetics to the hybrid, but the problem
turned out to be a faulty ribbon cable in the interface room. Next, we
noticed that OH2U was putting out current that was twice the PLC setting,
which is a potentially dangerous problem. This problem showed up on shots
01 and 05 today, and resulted in about a 4-hour delay while the OH2U
control board was removed, debugged, and fixed. Several test shots (06-08) were
taken to confirm that everything was working properly, so we set up for a
plasma attempt at the very end of the day. We got a good flash (shot 09),
although the null was not optimal. There was little or no plasma
current. Tomorrow we should start by reducing the prefill gas a bit.
Another positive note is that no new problems occurred with the magnetics
diagnostics. In fact, a number of long-unused additional Bp coils were
resurrected by zapping today.
Scorecard: 0 plasmas
0 duds
1 fizzle
8 power supply tests
0 no-power MDS shot cycles
--------------
Total: 9 shot cycles
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| Session Leader Comments | |||
| Jun 23 2009 05:14:08:827PM | 1090623009 | Steve Wolfe | Shot#9: try for plasma Got plasma. Breakdown anyway. Good light signals, early breakdown (4.7msec on zmeter) Looks like it goes in, too much Bz, too much gas. Mflux null looks horrible, but I think it's because of flux_22 and flux_24 bogus signals. Quit while we're ahead. |
| Physics Operator Comments | |||
| Jun 23 2009 01:30:46:413PM | 1090623001 | Robert Granetz | We will begin with a commutation test (repeat last shot from yesterday) to check that the correct isoamp board has been removed from the rack for repair. |
| Jun 23 2009 01:31:45:867PM | 1090623001 | Robert Granetz | From this test shot, we can tell that we did NOT pull the correct
card out of the hybrid iso-amp box. Willy Burke, Steve, and I will have to go into the racks with a DC voltage and a DVM and find the correct board. |
| Jun 23 2009 01:32:51:727PM | 1090623002 | Robert Granetz | Well, the isoamp board that we pulled out appears to be working just
fine. We'll do one more commutation test shot now to confirm that we've pulled the correct isoamp board. |
| Jun 23 2009 01:34:20:727PM | 1090623002 | Robert Granetz |
Shot 002: Okay, we had definitely pulled the correct isoamp board. But
the board now seems to be working fine on the bench.
Next shot: Put the isoamp board back in the rack and take another
commutation test shot to see if the board has mysteriously
fixed itself. If the F10 signal in input 09 is still low, then
the problem is somewhere further down the line.
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| Jun 23 2009 01:35:18:070PM | 1090623003 | Robert Granetz |
Shot 03: Isoamp for input 09 (F10) is still bad. So now Steve will
start swapping stuff in the interface room
Next shot: Another commutation test
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| Jun 23 2009 01:36:00:883PM | 1090623004 | Robert Granetz | The problem was a bad ribbon cable in the interface room. Steve had several new ribbon cables made up during the long shutdown, and one of these was bad. |
| Jun 23 2009 01:36:45:947PM | 1090623005 | Robert Granetz |
Shot 05: This will be another commutation test to check the
replacement ribbon cable in the interface room.
Okay, hybrid channel 09 is working properly now.
BUT, OH2U has twice the current of OH2L. These were
under PLC control, and they should have been equal.
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| Jun 23 2009 01:38:54:870PM | 1090623005 | Robert Granetz | We're having a long break while Bill Cochran and Dave Terry check out the OH2U supply. This lack of correct output current under PLC control is a serious problem, because we rely on that to protect the OH2U coil. |
| Jun 23 2009 01:39:14:713PM | 1090623005 | Robert Granetz | After checking the OH2U control board, Bill Cochran and Dave Terry have
decided to pull the board and work on it in the shop. This means that we are stopping the run for a least a couple of hours. |
| Jun 23 2009 04:28:03:497PM | 1090623005 | Robert Granetz | Next shot: Test of OH2U only, to test the repair to its control board. 2 kA PLC test. |
| Jun 23 2009 04:35:52:670PM | 1090623006 | Robert Granetz | Shot 06 -- PLC test of OH2U only. It's supposed to be 2 kA. It worked. Next shot: 10 kA PLC test of OH2U only. |
| Jun 23 2009 04:45:42:533PM | 1090623007 | Robert Granetz | Shot 07 -- 10 kA PLC test of OH2U only. Good. Next shot: TF-only 150 kA |
| Jun 23 2009 04:54:48:537PM | 1090623008 | Robert Granetz | Shot 08 -- Test of TF only, 150 kA. Next shot: try for plasma. This will basically be a reload of shot 015 from yesterday. |
| Jun 23 2009 05:18:04:263PM | 1090623009 | Robert Granetz |
Shot 09 -- Breakdown!! Almost no current though. Null looks less than
impressive, so there may be some improvements we should think
about for the F25 correction. The pressure was rather high (0.1 mTorr).
End of run. If we were going to continue, I would lower the prefill to 20 ms.
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| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 09:17:28:770AM | Test | Bad | OH Commutation Test |
| 2 | 10:15:44:917AM | Test | Ok | OH commutation test good |
| 3 | 10:27:19:577AM | Test | Ok | OH commutation test, good |
| 4 | 10:40:37:770AM | Test | Ok | OH Cummutation test, good |
| 5 | 11:44:54:123AM | Test | Bad | OH Test |
| 6 | 04:29:38:373PM | Test | Ok | OH2U Power Supply Test 2KA PLC |
| 7 | 04:37:56:203PM | Test | Ok | OH2U Power Supply Test 10KA PLC |
| 8 | 04:50:42:990PM | Test | Ok | TF 150KA PLC Test |
| 9 | 05:04:08:453PM | Plasma | Ok | |
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