Alcator C-Mod Run 960805 Information

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Miniproposals
Miniproposal:159a
Date Filed: 7/29/1996
Title:Restart Operation: August 1996
First Author:Steve Wolfe
Session Leader:Robert Granetz (shots 1-23)

Operators
Session leader(s):Robert Granetz
Physics operator(s):Steve Wolfe
Engineering operator(s):Frank Silva,Joe Daigle

Engineering Operator Run Comment
Re-Start C-MOD Aug. 96Granetz/Wolfe/Silva

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:15:837PM
Author: To Be Determined
Run summary for MP 159A: Re-start C-Mod tokamak

SL: R. Granetz
PO: S. Wolfe
EC: Silva/Daigle

Primary goal: Get first plasma after 5 month shutdown. Run lots of fiducial
shots.

Secondary goal: If successful, use the high number of repeatible fiducial
plasmas to test, calibrate, exercise, etc the diagnostics and
the ICRF.

-------------------------------------------------------------------------------
Summary: It was a tough day. The first half was devoted to working on EFC and
EF1 problems, and the second half was spend trying to get a full
length plasma. The best we could do were 3 short plasmas and a lot
of fizzles and duds. The machine clearly needs a good cleaning.

-------------------------------------------------------------------------------
Shot sequence plan:

Simple: lots of fiducial shots.

-------------------------------------------------------------------------------

Shot 01 -- OH1 & 2 test under PLC control (check coax resistances).
All OK

Shot 02 -- Supposed to be a plasma shot, but only the OH supplies went, and
even one or two of those crowbarred.

Shot 03 -- Another attempt at plasma, but EF2's and EFC didn't fire.
Engineering claims that everything will be enabled on the next shot.

Shot 04 -- Plasma attempt. No breakdown, too much radial field. Also no EFC.

Shot 05 -- Fizzle. No EFC. Only 20 kA. Field gradient is a little high,
but the Br is alot better. I think it just needs some repetition.

Shot 06 -- EF1 test.

Shot 07 -- Another EF1 test, this time under hybrid control.

Shot 08 -- Another EF1 test.

Shot 09 -- Another EF1 test.

Shot 10 -- Test of all PF supplies. EF1's looked good.

Shot 11 -- Plasma. Ip=0.27 MA. Died at 0.1 s because EFC didn't turn on.

Shot 12 -- Dud. EFC finally worked.

Shot 13 -- Dud. All supplies fired. Still some problems with EF1's.

Shot 14 -- Fizzle.

Shot 15 -- Plasma. Ip=0.29 MA. Died at 0.1 s. OH2U faulted then.

Shot 16 -- Dud. No changes were made between this shot and the previous one.

Shot 17 -- Fizzle.

Shot 18 -- Fizzle.

Shot 19 -- Fizzle.

Shot 20 -- Plasma. Ip=0.55 MA, duration=0.18 s (disrupted).

Shot 21 -- Fizzle.

Shot 22 -- Fizzle.

Shot 23 -- Fizzle.

End of run

Physics Operator Summaries
Entered: Jul 7 2004 04:36:56:363PM
Author: To Be Determined
Physics Operator Summary for Monday 960805
MP#159A Start up August 1996
SL: Granetz
PO: Wolfe
EO: Silva/Daigle

The goal of today's run was to get reproducible plasmas and then run a series
of shots for diagnostic alignment and calibration. This goal was NOT
accomplished. After a lot of power supply problems, we succeeded in getting a
breakdown, and a couple of current rises, but never got to programmed flattop
current. Each partially successful plasma brought off a considerable load of
dirt, with a number of subsequent fizzles. The longest plasma was shot 20,
which reached 600kA at .18 seconds.

We began the day late, as the alternator was not ready until 9:30. The
standard OH test was ok. We then had a couple of failed attempts at plasma on
which not all supplies fired. The first shot on which all the main supplies
came on was #4. The EFC was still not working, and the EF1L was showing the
same symptoms as on Friday, basically not following the hybrid demand. On shot
5 we increased the Br0 program level and got a flash. We then began a long
sequence of trying to trace and fix the EF1L problem.

Shots 6-10 were EF1 tests with various other supplies off. See Logbook for
confusing details. Lots of ghosts were chased, none caught.

Shot 11 was still trying to diagnose the EF1L problem, but with everything
firing. We got a plasma, 250kA disrupting at .11sec or so. EF1 was still
screwed up and EFC still not working. The lack of EFC probably would have
killed the plasma anyway, but it had enough problems of its own.

On shot 12-13 EFc was fixed, but we got duds. In addition to the blown fuses
found in the 30V supply after the first shot (4), there were fried resistors on the
ON-pulse board in the chopper. The cause of these is unknown, but once the
board was replaced the chopper worked.

Shot 14, after some board swapping and increasing the margin angle on both EF1
supplies, the EF1s finally behaved. The time was 15:30. Whether it was
actually fixed, or just decided to start working on its own is debatable. This
problem may come back to haunt us. The shot produced a fizzle.

For shot 15, increased the pre-puff and got a plasma similar to 11, short and
resistive. Shot 16 was a repeat and gave a dud.

Shot 17 I eliminated the 100V point on PG3 around t=0. This shot fizzled. It
was noted that the EF4 current was not getting to flattop, and that the Bz was
somewhat too negative. It was not noted, by me at least, that getting it to
flattop would increase the negative Bz, not decrease it. Therefore, for shot
18 I increased the gain on IC_EF4 from 5 to 8, and ended up with another
fizzle with poorer vertical field. I then reduced the program value from -1180
to -1140. This one also fizzled, but the breakdown was earlier. For shot 20 I
tried increasing the vertical field by upping the OH1 current, which would
also help with the field gradient. Shot 20 was the best shot of the day, which
isn't saying much; it got almost 600kA and lasted to almost 200msec, but was
horribly resistive. The surface voltage was about 4V.

Shot 21-23 were all fizzles, apparently because of all the junk evolved on
shot 20.

Other problems, issues:
-----------------------
We had no ECDC before the run or over the weekend, because the PEI is defunct.
The plasmas we did get were extremely dirty. We need to get the ECDC back
online.

For most of the day we had OH coax resistance warnings (>1uohm). These finally
went away at 16:00, as the OH2L coax finally came down below 1uohm. Strong
cooling of the stack is the key here, apparently. By that time we were banging
away at the plasma-fizzle-fizzle-fizzle cycle, and the OH1 coax began
increasing resistance; there was another warning on the last shot at 17:01.
Hopefully these warnings will go away when we get the cooling under control.

Assessment:
------------
Supplies were not really working until around 15:30. In the last hour and a
half of the run we ran about nine shots, and were probably making progress in
cleaning up. Some ECDC would help, but even without it another few hours of
banging away tomorrow should put us in reasonable shape, if we don't have more
supply problems. We need to find out why the EFC died again today, after
having been fixed on Friday; apparently turning the supply off or on may be
doing it in.

Scorecard:
---------
PLasmas 3
Fizzles 8
Duds 6 (2 pwr supply failures)
tests 6
------ --
total 23

Session Leader Comments
Aug 4 1996 11:26:41:600AMRobert GranetzSL: R. Granetz
PO: S. Wolfe
EC: V. Bertolino

Primary goal: Get first plasma after 5 month shutdown. Run lots of fiducial
shots.

Secondary goal: If successful, use the high number of repeatible fiducial
plasmas to test, calibrate, exercise, etc the diagnostics and
the ICRF.

Aug 5 1996 09:55:57:950AM960805001Robert GranetzShot 01 -- OH1 & 2 test under PLC control (check coax resistances).
All OK

Aug 5 1996 10:08:09:560AM960805002Robert GranetzShot 02 -- Supposed to be a plasma shot, but only the OH supplies went, and
even one or two of those crowbarred.

Aug 5 1996 10:30:09:490AM960805003Robert GranetzShot 03 -- Another attempt at plasma, but EF2's and EFC didn't fire.
Engineering claims that everything will be enabled on the next shot.

Aug 5 1996 10:54:04:200AM960805004Robert GranetzShot 04 -- Plasma attempt. No breakdown, too much radial field. Also no EFC.

Aug 5 1996 11:06:31:720AM960805005Robert GranetzShot 05 -- Fizzle. No EFC. Only 20 kA. Field gradient is a little high,
but the Br is alot better. I think it just needs some repetition.

Aug 5 1996 11:28:18:770AM960805006Robert GranetzShot 06 -- EF1 test.

Aug 5 1996 11:54:46:140AM960805007Robert GranetzShot 07 -- Another EF1 test, this time under hybrid control.

Aug 5 1996 12:52:37:480PM960805008Robert GranetzShot 08 -- Another EF1 test.

Aug 5 1996 12:59:08:710PM960805009Robert GranetzShot 09 -- Another EF1 test.

Aug 5 1996 01:10:01:370PM960805010Robert GranetzShot 10 -- Test of all PF supplies. EF1's looked good.

Aug 5 1996 01:26:23:320PM960805011Robert GranetzShot 11 -- Plasma. Ip=0.27 MA. Died at 0.1 s because EFC didn't turn on.

Aug 5 1996 03:02:24:550PM960805012Robert GranetzShot 12 -- Dud. EFC finally worked.

Aug 5 1996 03:20:00:190PM960805013Robert GranetzShot 13 -- Dud. All supplies fired. Still some problems with EF1's.

Aug 5 1996 03:29:30:700PM960805014Robert GranetzShot 14 -- Fizzle.

Aug 5 1996 03:43:04:950PM960805015Robert GranetzShot 15 -- Plasma. Ip=0.29 MA. Died at 0.1 s. OH2U faulted then.

Aug 5 1996 03:56:13:560PM960805016Robert GranetzShot 16 -- Dud. No changes were made between this shot and the previous one.

Aug 5 1996 04:05:45:470PM960805017Robert GranetzShot 17 -- Fizzle.

Aug 5 1996 04:16:03:860PM960805018Robert GranetzShot 18 -- Fizzle.

Aug 5 1996 04:25:26:490PM960805019Robert GranetzShot 19 -- Fizzle.

Aug 5 1996 04:38:14:850PM960805020Robert GranetzShot 20 -- Plasma. Ip=0.55 MA, duration=0.18 s (disrupted).

Aug 5 1996 04:45:31:590PM960805021Robert GranetzShot 21 -- Fizzle.

Aug 5 1996 04:50:36:710PM960805022Robert GranetzShot 22 -- Fizzle.

Aug 5 1996 04:58:51:890PM960805023Robert GranetzShot 23 -- Fizzle.

End of run

Physics Operator Comments
Aug 5 1996 08:24:56:400AMSteve WolfeRun 960805
MP 159A First plasma run of new campaign
SL: granetz
PO: wolfe
EO: Silva/Daigle

COldstart at 08:00. Load 960227003.
Engineering instructions:
-------------------------
If possible, ECDC in D2 - t possible
Engineering setup as for 960227003
EF4 coils in series.

ote: From the power tests run on Friday, it appears that EF1L is not
following the hybrid demand very well (see scope printout left by SENSEI).
Power Systems Engineers should be prepared to instrument and diagnose this
problem, if it is still there when we start trying for plasma.

Aug 5 1996 08:25:24:080AMSteve WolfeRun 960805
MP 159A First plasma run of new campaign
SL: granetz
PO: wolfe
EO: Silva/Daigle

Run Plan:
---------
The purpose of this run is to get plasmas and run a series of reproducible
shots for clean-up and diagnostic alignment and calibration.

All power supplies have been exercised, separately and together, under hybrid
control, as of last Friday. With the possible exception of an EF1L problem
noted above, all power systems appear to be ready for operation in the
standard configuration. The new pulse-width modulation gas pulse driver for
Pulse-gas#3 (K-side valve) was installed and checked out on Saturday, after a
problem with the hybrid output to this valve had been repaired. The new gas
valve driver has been set up to have approximately linear response above a
program voltage of 20V (i.e. 20% full scale). This means the valve will be
somewhat more sensitive at low input levels than the previous pulse-rate
modulator board, so some changes in gas programming will likely be necessary.
The other gas drivers are on direct drive from the hybrid waveform, as they
have always been.

Aug 5 1996 08:27:39:700AMSteve WolfeRun 960805
MP 159A First plasma run of new campaign
SL: granetz
PO: wolfe
EO: Silva/Daigle
If we are successful in obtaining reasonable clean full-length plasmas, we
will spend the remainder of the run on repeat shots. A number of diagnostic
systems have expressed interest in carrying out alignment and calibration
during sucvh a sequence, including HIREX,ECE, U. Md. Spectrometer,NPA,FSP,
Impurity injector, and McPherson alignment. (Ar will be provided for HIREX
alignment only if machine cleanliness is sufficient to allow non-disruptinve
operation with Ar added). To the extent possible consistent with these
activities, we would like for some of the spectroscopic diagnostics to monitor
the cleanup of the plasmas during this sequence, which will consist of
standard fiducial parameters. If the RF wishes to begin conditioning
activities during this time, they should fire late in the pulse to avoid
complications with diagnostic activities.

Aug 5 1996 08:27:56:340AMSteve WolfeRun 960805
MP 159A First plasma run of new campaign
SL: granetz
PO: wolfe
EO: Silva/Daigle
The plan for subsequent runs will depend on the degree of success of this run,
which may have to be continued on Tuesday.

Aug 5 1996 09:52:41:550AM960805001Steve Wolfe960805001:
OH test. Currents ok.
no warnings on coax resistance.

Aug 5 1996 10:09:54:310AM960805002Steve Wolfe960805002:
Try for plasma.
PF breaker pulled. No EF1,No Ef3, No EFc, No TF.

Aug 5 1996 10:33:18:560AM960805003Steve Wolfe960805003:
The shot counter may be screwed up. JAS is investigating.

Try for plasma again.
No EF2's. Also EFC.
EF1L still overdoing it.

Aug 5 1996 10:48:38:910AM960805004Steve Wolfe960805004:

Try for plasma again.
Still no EFc. No flash
Some negative Br. EF1L is overshooting a bit.

Aug 5 1996 11:08:09:870AM960805005Steve Wolfe960805005:

Increase Br0 offset from .0055 to .007
Got a flash. Chokes and hits something at 17msec. Seems to be moving
in. Still seems to have a small negative radial field as well.
EFc still didn't work correctly.
Still getting OH coax resistance warnings.

Aug 5 1996 11:33:05:140AM960805006Steve Wolfe960805006:

Br0 from .007 to .0075.
Reduce gas pre-pulse from 14msec to 12msec.
Not loaded into model yet.

This shot will be a PLC only pulse of EF1L to try to diagnose that
problem. EFC still not right; they can't find a problem.

Some small overshoot on EF1L, but inconclusive. Next shot try hybrid
control, EF1's only.

Aug 5 1996 12:47:40:390PM960805007Steve Wolfe960805007:

Br0 from .007 to .0075.
Reduce gas pre-pulse from 14msec to 12msec.
Not loaded into model yet.
EF1's only. Hybrid control.
It seems to be ok this way.
EF1 is the first to come on; how can it know the others aren't
enabled???????

Aug 5 1996 12:52:53:370PM960805007Steve Wolfe960805007:

Br0 from .007 to .0075.
Reduce gas pre-pulse from 14msec to 12msec.
Not loaded into model yet.
EF1's only. Hybrid control.
Same as 7, but close all the breakers.
Still looks ok? So much for that idea.

Aug 5 1996 12:54:11:130PM960805008Steve Wolfe960805008:

Br0 from .007 to .0075.
Reduce gas pre-pulse from 14msec to 12msec.
Not loaded into model yet.
EF1's only. Hybrid control.
Same as 7, except all breakers in.
Still ok. So much for the breaker idea.

Aug 5 1996 12:59:19:530PM960805009Steve Wolfe960805009:

Br0 from .007 to .0075.
Reduce gas pre-pulse from 14msec to 12msec.
Not loaded into model yet.
EF1's only. Hybrid control.
Same as 8, all breakers in, cap banks charged.
Still fine. Maybe it's fixed itself.

Aug 5 1996 01:08:51:880PM960805010Steve Wolfe960805010:

Br0 from .007 to .0075.
Reduce gas pre-pulse from 14msec to 12msec.
Not loaded into model yet.
All PF's.No TF. Hybrid control.
all breakers in, cap banks charged.
Still starts off ok. There is a deviation at -.6sec

Aug 5 1996 01:26:49:550PM960805011Steve Wolfe960805011:

Br0 from .007 to .0075.
Reduce gas pre-pulse from 14msec to 12msec.
Not loaded into model yet.
All PF's.and TF. Hybrid control.
all breakers in, cap banks charged.
Basically, a full shot. This time they have instrumented some points in
the EF1L supply.

Plasma - 250kA, disrupts after .1sec. We need the EFc.
The EF1 still didn't do its thing at -1.2, but the problem around
-.5sec is still there.

Aug 5 1996 03:02:21:630PM960805012Steve Wolfe960805012:

PUt BR0 and gas backj the way they were in scratch; never loaded it.
There is a hot chip on the control board in EF1L supply.
Daigle is dealing. Andy and Sam are looking into EFC

Set up again. The boards from EF1U and EF1L may have been swapped.
EFC may have been fixed.

No flash. EFC is workiong again.

Aug 5 1996 03:29:15:360PM960805013Steve Wolfe960805013:

INcrease margin angle on both EF1's. Swapped boards?
Still no flash. Where'd it go?

Aug 5 1996 03:57:16:950PM960805015Steve Wolfe960805015:

INcrease prepulse from 14msec to 16msec
PLasma-
PF crowbar.
Has a vertical problem. EFIT is not working. Don't know why.

Aug 5 1996 04:12:14:540PM960805017Steve Wolfe960805017:
Get rid of early high voltage point on PG3.
flash, no rise. late breakdown.
EF4 only got to 1114 A this time.

Aug 5 1996 04:19:35:660PM960805018Steve Wolfe960805018:
INcrease gain on IC_EF4 from 5 to 8.

fizzle. EF4 at 1150 this time. Still a late breakdown
Clearly too negative Bz this time.

Aug 5 1996 04:40:02:930PM960805020Steve Wolfe960805020:
Increase IC_OH1 from -16600 to -16700
plasma - 600kA. .18sec.

Aug 5 1996 04:45:02:560PM960805021Steve Wolfe960805021:
Repeat.
fizzle. b.d. around 10msec.

Aug 5 1996 04:52:13:610PM960805022Steve Wolfe960805022:
Repeat.
fizzle - bd at 6msec

Aug 5 1996 04:59:07:670PM960805023Steve Wolfe960805023:
Repeat.
fizzle. That's all for today.

Engineering Operator Comments
ShotTimeTypeStatusComment
109:43:07:950AMTestOkCoax Test
210:04:33:510AMTestBad
310:25:57:150AMPlasmaBadNO EF2 or EFC
410:33:42:630AMPlasmaBadno efc chopper
510:52:55:330AMPlasmaBadefc chopper not working
611:24:50:030AMPlasmaOkef1 plc test ok
711:36:06:050AMPlasmaOkef1 u-l hybrid test
812:49:21:020PMPlasmaOkef1 ul hybrid test all breakers closed
912:55:20:920PMPlasmaOkef1 test ok
1001:02:14:670PMPlasmaOkpf test ok
1101:21:04:420PMPlasmaBadEFc Did not go on ef1 not following command.
1202:55:50:680PMPlasmaOkefc and ef1 no breakdown
1303:14:04:300PMPlasmaOkef1 u problem
1403:27:27:890PMPlasmaOkOK
1503:38:34:750PMPlasmaOkSelf powered Fired OH2 U
1603:54:14:630PMPlasmaOk
1704:03:59:900PMPlasmaOkflash
1804:14:25:470PMPlasmaOk
1904:23:39:230PMPlasmaOk
2004:32:16:530PMPlasmaOk
2104:40:56:030PMPlasmaOk
2204:48:55:330PMPlasmaOk
2304:57:12:790PMPlasmaOk