Alcator C-Mod Run 1050204 Information

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Miniproposals
Miniproposal:399
Date Filed: 1/11/2005
Title:Initial Operation Using Digital Plasma Control System
First Author:Marco Ferrara
Session Leader:Steve Wolfe (shots 1-14)

Operators
Session leader(s):Steve Wolfe
Physics operator(s):Ian Hutchinson,Joseph Snipes,Ian Hutchinson
Engineering operator(s):Gary Dekow,Bill Cochran,Bill Parkin

Engineering Operator Run Comment
Power System Tests/Plasma Startup

Session Leader Plans
Entered: Feb 4 2005 10:10:10:927AM
Author: Steve Wolfe
Finish PLC Power tests not completed yesterday
Monitor dpcs inputs and outputs during PLC testing
Run one or more DPCS-controlled double-swing shots (EF4, maybe OH)
(remember to move fizzle detector to after end of swing)
Re-test/exercise Gas Valves (can do during other tests if engineers/Irby agree)

Try for plasma:
Engineering Power Systems setup as on 1031010007
Acoils set up +Dtop -Dbot -Jtop +Jbot

Gas setup:
-----------
>>> fill B-Top with 6 psi D2 Hybrid Enabled (PG4)
>>> fill B-side lower with 1 psi Ar Hybrid DISabled (PG1)
>>> fill B-side upper with 30 psi D2 Hybrid DISabled (PG2)
>>> fill (former) C-side with 30 psi D2 Hybrid Enabled (PG3)

Torvac Setup:
--------------
GV1 closed, Bypass to RGA open
Torus gate valves closed in Pulse (check with Irby for re-open time)

Physics Operators Plans
Entered: Feb 4 2005 12:16:11:080PM
Author: Joseph Snipes
Setup for power tests and perhaps first plasma attempts.

Session Leader Summaries
Entered: Feb 4 2005 07:37:17:717PM
Author: Steve Wolfe
Session Leader Summary for 1050204

Power systems test and plasma startup
MP#399 Initial Operation with DPCS (piggyback)
SL: Wolfe
PO: Hutch (Snipes filled in for first hour)
EO: Dekow, Cochran, Parkin

Power tests were completed, including EF4 double swing and A-coil
test under DPCS control.

First plasma attempt was shot#6
After a couple of duds we got a faint flash on #8.
It was then determined that the main rogowski rog_cd is broken,
open inside the machine on the upper segment. Bob swapped
in the rog_fg to DPCS_INPUT_56 in its place. This rogowski
has been flaky last year, but ohmed out ok and seems to be working
now. After some more fizzles and some tweaking by Ian, we
got 150kA disrupting at 65msec on shot 12, and
500kA dying at .14sec on shot 13. It turned out that we had
not realized the TCI feedback signal was not connected, and so
the NL_04 feedback turned the gas on hard in segment 2, which
probably was the cause of the plasma going resistive.

Overall, this phase of the DPCS operation was a success, and it
seems reasonable to leave DPCS connected for the remainder of
the campaign. Since the offsets and hand tweaks in the programming
all need to be redone because of the change in the rogowski anyway,
there is no advantage to going back to the Hybrid now. I should probably
implement an offset subtraction routine, although the legacy shot issue
remains. Note that one of the tweaks that may have helped get plasma
was changing the Seg1 RCUR offset from 5000->0->2000; Seg2 predictors
were not touched, but we haven't had a chance to see good control in
seg2 yet, either.

Other issues: the data system was limping, and required some interventions
by Tom and Josh to handle hangs. There is some kind of problem which
makes data disappear from scopes. It seems that CLOSE DATA SOURCES may
remedy this when it happens. Note that shot #1 from today was a commutation
test that had its datafiles disappear.
Big board still did not update on the last shot.
There is something wrong with the timebase on the Commutation signals.

Lots of diagnostics need to be brought online, but not a bad start.

Physics Operator Summaries
Entered: Feb 4 2005 07:06:33:480PM
Author: Ian Hutchinson
Summary

The EF4 and A-coil tests under PCS control were successfully completed.
Then full plasma attempts were used to check out the entire system.

Got 2 duds and 5 fizzles.
We got two plasmas (12, 13) with the new DPCS.
Offsets are perhaps slightly different, as expected.
However there does not seem to be any difficulty with getting startup with DPCS.

We have shown that DPCS is working well enough to get plasma, which means pretty well!

Session Leader Comments
Feb 4 2005 01:14:36:433PM1050204002Steve Wolfeshot#2: OH comm test at 10ka; OH1 failed to commutate

Next shot:They will try again, I guess.
Turn on B-top gas puff
Feb 4 2005 01:57:36:213PM1050204003Steve WolfeShot #3: Got commutation, got gas on B-top

Next shot: enable C-side (actually B-sideMain)
And do the EF4 double swing
Feb 4 2005 02:22:44:580PM1050204004Steve WolfeShot#4: EF4 double swing shot, and B-top,C-side gas puff under DPCS Control

Got EF4 just fine. Looks like the gas puff is ok too.
Feb 4 2005 02:27:04:610PM1050204005Steve Wolfeshot#5: A-coil test at 1000A under DPCS control.
Leave gas puffs on.
Feb 4 2005 02:59:51:380PM1050204005Steve Wolfeshot#5: A-coil pulse ok, considering that
we forgot about the demand offset. Got about
600A, with a drawn demand of 1000A.
Feb 4 2005 03:08:53:437PM1050204006Steve Wolfeshot#6: Go for plasma. Load 1031010007 (600kA shot)
Ian changed title of seg2 and re-drew Acoil current
Start A-coil at 0.2sec instead of 0.5sec


Feb 4 2005 03:55:17:420PM1050204006Steve Wolfeshot#6: No plasma,
Ian makes some tweaks and try again

Feb 4 2005 03:57:15:403PM1050204007Steve Wolfeshot#7: No plasma,
Br tweak was too large (finger problem)
Try -.0005 instead of -.005 and try again

Note: vacbrbz failed because of library problem on cmodws38
Josh has removed cmodws38 from submit list.
I ran the job manually.

Feb 4 2005 04:09:05:617PM1050204008Steve Wolfeshot#8: Faint flash on Halpha, no current rise
We are somewhat concerned about the rogowski; the signal
looks different. Bz is too positive.

Tweak ef4 and go again
Feb 4 2005 04:52:56:897PM1050204008Steve WolfeShot# 9: The CD Rogowski is broken. Bob says one half of the coil is
open circuit inside the machine. He is switching to the FG rogowski
to go into hyb_input_56. This coil seems to be continuous now, but
was flakey last year.
Feb 4 2005 07:14:40:447PM1050204013Steve WolfeShot# 13: Nice current rise, dies a slow death
in early segment 2. Gets to 500kA, then gets gassed to
death (?). It turns out there was no NL_04 feedback
signal today. Should have checked the A_in's more carefully.

Physics Operator Comments
Feb 4 2005 01:04:30:190PM1050204002Joseph SnipesShot 3: Enabled B-top with a 17 ms pulse ending at -0.5 s.
Feb 4 2005 01:59:31:090PM1050204002Ian HutchinsonHutch taking over after shot 2.
Magnetics all seems to be working.
No commutation on commutation test.
Engineering to check it out.
Feb 4 2005 01:59:44:387PM1050204003Ian HutchinsonCommutation worked after applying the MSWindows fix: Turn off and turn on again.
Got gas puffs.

Using the EF4 test. Load into model.
Enable C-side.
Feb 4 2005 02:51:14:303PM1050204004Ian HutchinsonOk seemed to work.

Now add a profile to A-coil V. 1000A.
Recheck the cell for tools to make sure we don't have flying iron.
Some junk was found!
Load.
Feb 4 2005 03:00:12:690PM1050204005Ian HutchinsonA-coil current appears to work but has a 500A offset in its setting.
We asked for 1000A and got 500, and asked for a secondary flat top
but got zero. Declare success.
Feb 4 2005 03:20:10:060PM1050204006Ian HutchinsonTry for plasma.
Load from 1031010007.
Reduce A-coil to 2000 from 4000A setting.
Load complains about wire names. Touch the wires. Load again.
Turn on sparker.
Feb 4 2005 03:44:44:703PM1050204006Ian HutchinsonDud but the fields aren't too bad.

Br offset to -.0005 from +.0005
EF4 to -1320A from -1300A
Gas puff to 30ms from 20ms.
Feb 4 2005 03:55:21:653PM1050204007Ian HutchinsonDud. Made a mistake on Br. Put -.005 instead of -.0005.
mfil job errors. Wolfe ran by hand.

Correct that Br. Load
Feb 4 2005 04:41:07:527PM1050204008Ian HutchinsonFizzle.
A very faint flash. No current.
Bz still too positive.
Worry about the rogowski signal. It looks broken.

EF4 to -1340
Load. Long wait for bus instrumentation. And working on rogowski.
Feb 4 2005 05:33:45:867PM1050204009Ian HutchinsonRogowski cd was broken inside vessel. So rog_fg put into input 56 of dpcs.
See wolfe's comments.

Fizzle. Much brighter. Some sign of plasma current.

Lower EF3 voltage by 200V to 2400 at .005s.
Fill puff to 28ms.
Feb 4 2005 06:04:26:200PM1050204010Ian HutchinsonFizzle.

Set Br offset to 0 from -.0005.
Gas puff to 26ms.
Load
Feb 4 2005 06:17:07:333PM1050204011Ian HutchinsonFizzle.

Set Rcur offset to zero in segment 1. Was 5000.
Load.
Feb 4 2005 06:32:38:453PM1050204012Ian HutchinsonPlasma. 150kA lasting 70ms and dying.
Br stays low long enough to get going with a bounce.
Strange shape plasma. Probably because of the long dwell from the bounce.

Br offset to 2000 (from 0)
Feb 4 2005 06:54:39:513PM1050204013Ian HutchinsonPlasma. 500kA peaking at .1s.

Lower the gas puff during second half of seg1.
Lower nl04 gain to 0.5 from 8 in seg2.
Load.
Feb 4 2005 06:58:00:180PM1050204014Ian HutchinsonFizzle.
Feb 4 2005 07:06:45:103PM1050204014Ian HutchinsonWe are now informed that we did not have a density feedback signal all day.

My comment is no comment.

Engineering Operator Comments
ShotTimeTypeStatusComment
112:05:39:040PMTestOkOH2L Power System Test
212:37:57:463PMTestBadNo OH1 Commutation
301:47:54:140PMTestOk
402:17:15:287PMTestOkEF4 Double Swing Test
502:51:45:930PMTestOkC_Coil Test
603:21:46:400PMPlasmaOkFirst Plasma Attempt
703:42:48:550PMPlasmaOk
804:02:39:980PMPlasmaOk
905:22:50:980PMPlasmaOk
1005:45:09:067PMPlasmaOk
1106:02:47:137PMPlasmaOk
1206:16:27:897PMPlasmaOk
1306:32:51:420PMPlasmaOk
1406:55:05:640PMPlasmaOk