Alcator C-Mod Run 1010711 Information

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Miniproposals
Miniproposal:
Date Filed:
Title:
First Author:
Session Leader:Jim Irby (shots 1-9)

Operators
Session leader(s):Jim Irby
Physics operator(s):Ron Parker
Engineering operator(s):Bill Byford,Bill Cochran

Engineering Operator Run Comment
Recovery from vacuum vent to Helium, determining and reducing H/D ratio,

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:26:977PM
Author: To Be Determined
Session Leader Summary for run 1010711

SS: Irby
PO: Parker
EO: Cochran, Byford

Though the run was painful from a hardware sense, some useful
things were learned today. After the bake and glow over the
last few days, we recovered H/D ratios today that have usually taken
us several days of plasma discharges and ECDC to achieve. Shot
9 for example, started out at 10% and rose to 30% during the discharge,
with about 1 MW of RF power from the D and E antennas. With a few more
discharges today, we would have been ready for boronization.

Physics Operator Summaries
Entered: Jul 7 2004 04:37:13:613PM
Author: To Be Determined



ENGINEERING SETUP FOR 1010711:

GLOW Discharge Clean in He overnight, stopping in time for ECDC in D2 from
6:00 - 8:00 AM

RUN BEGINS AT 9:00 AND ENDS AT 5:00

Power systems the same as for shot 1010614008

Gas setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar Hybrid enabled (PG1)
fill B-side upper with 6 psi He Hybrid DISABLED (PG2)
fill C-side with 30 psi D2 Hybrid enabled (PG3)
fill J-Bottom with 6 psi He Hybrid DISABLED(PG5)

Enable the following gate valves: ECE, DNB, VUV

RF STATUS:

XMTR 1 AND 2, RUN-ON STARTED AT 8:00 AM
XMTR 3 AND 4, RUN-ON STARTED AT 9:00 AM

RUN PLAN:

Recovery from vacuum vent to Helium, determining and reducing H/D ratio, and
determining RF matching coefficients for 70 MHz operation of J-Port antenna.
We'll start with an 800 kA shot @ 5.3 T and n~1.e20, and take it from there.

RUN SUMMARY:

This was a frustrating run, with hardware problems limitng the number of
successful shots to just 3. The first problem to develop was a crowbar of
the TF after the inversion. The overvoltage protect system on the TF bus was
suspected, but this did not turn out to be the problem. Neither was the time of
inversion the cause, as the crowbar still occured even after changing the
invert time. So the crowbar problem remains to be resolved.

The second problem was associated with the hybrid.This occurred on shot 6,
which was a dud. The programming voltages to the power supplies had step-like
waveforms and caused the coil currents to be far from their proper values
at the time of commutation. After a shot to test the hybrid, during which it
seemed to perform properly, a plasma shot was reloaded and it ran well.
Unfortunately, with all the delays, this was the last shot.

The summary is: 1 dud, 1 fizzle and 3 plasma shots with the remaining 4 shots
used for tests.


Session Leader Comments

Physics Operator Comments
Jul 11 2001 08:52:12:637AM1010711001Ron ParkerFirst shot will be programmed for Ip = 800 kA, Bt = 5.3 T and n = 1e20 m-3.

Startup conditions will be those for shot 1010614008.
Jul 11 2001 09:36:13:590AM1010711001Ron Parker
The first shot was a fizzle, with late breakdown.

Initial fill pressure was high, 8.5e-5 Torr and BR was 0.0 mT.
For the next shot, the pressure will be lowered by 15% and BR offset will
be decreased to -.5 mT.

ECDC will also be initiated between shots.
Jul 11 2001 10:06:59:880AM1010711002Ron ParkerShot 2 started up OK, although breakdown was a bit late.
We'll adjust the fill to be closer to .07 mT (reducing pulse width by 10 %) and
increase the BZ offset, aiming for -1 mT, rather than -2 mT.

The plasma disrupted at about 0.97 s. also, the TF crowbarred after inversion. No
devices were lost.

The next two shots will be power tests.
Jul 11 2001 10:28:13:100AM1010711003Ron ParkerShot 3 tested alternator excitation.

Shot 4 will test the TF at 50 kA.
Jul 11 2001 10:35:56:950AM1010711004Ron ParkerPower systems checked out OK. Next shot should be a plasma shot.
Jul 11 2001 11:09:19:250AM1010711005Ron ParkerShot 5 ran OK, but TF again crowbarred.

The TF bus overvoltage protect ckt will be checked, followed by shot 6, a 100 kA TF test.
Jul 11 2001 03:07:51:890PM1010711006Ron ParkerShot 6 was a TF power test at 100 kA.
Next shot will be an attempt at a plasma shot.
Jul 11 2001 04:56:57:893PM1010711007Ron ParkerShot 7 was a dud.

The problem was traced to the hybrid. Power supply voltages exhibited step-like
waveforms prior to t=0, and the currents were not appropriate for startup.

Next shot will be a test of hybrid.

Jul 11 2001 04:58:20:350PM1010711008Ron Parker
Shot 8 was a test of hybrid, which appeared normal.
Shot 9, the last shot, will be a plasma attempt
Jul 11 2001 05:01:48:700PM1010711009Ron Parker
The last shot, somewhat surprisingly, ran normally. However, the TF again crowbarred.

Engineering Operator Comments
ShotTimeTypeStatusComment
108:59:48:580AMPlasmaOkFizzle
209:31:01:837AMPlasmaBadTF Type One Fault
310:14:20:260AMTestOkAlternator Ramp Test Only
410:27:12:583AMTestOkTF 50 Kamp test only
510:40:22:563AMPlasmaBadTF Type One Fault
602:42:26:103PMTestOkTF 100Kamp Test only
703:05:54:110PMPlasmaOkAll Power Supplies Fired, but Hybid might have a problem
804:39:31:237PMTestOkHybrid Test Shot
904:51:02:477PMPlasmaBadTF Type 1 fault