Alcator C-Mod Run 1020620 Information

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Miniproposals
Miniproposal:298a
Date Filed: 5/20/2002
Title:C-Mod Plasma Startup
First Author:Jim Irby
Session Leader:Earl Marmar (shots 1-28)
Session Leader:Steve Wolfe (shots 1-28)

Operators
Session leader(s):Earl Marmar,Steve Wolfe
Physics operator(s):Jim Irby
Engineering operator(s):Bill Parkin,Gary Dekow

Engineering Operator Run Comment
Plasma Startup/Condition, SL:Wolfe/Marmar, PO:Irby, EO:Dekow/Parkin

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Physics Operator Summaries
Entered: Jul 7 2004 04:37:14:880PM
Author: To Be Determined
Physop Summary for 1020620 Plasma Startup MP298A

SL: Marmar/Wolfe
PO: Irby
EO: Dekow/Parkin

We began with a no power cycle test to make sure the CAMAC was
okay after work on the power room UPS was completed.

Shot 02, loaded from 1020619021, was the first plasma attempt; a very nice
1.7 s long discharge with relatively low CII and H/D less than 36% at
the end of the shot. Shot 03, a repeat, was another good shot. H/D rose
to about 40% at the end of the shop. For the first time during this run
campaign we had no indication of a MARFE at the end of the shot. Both of
these shots had the lower x-point approximately .01 m higher than normal
and were therefore more "double null" than our standard shots; in theory
cleaning the upper divertor region of the plasma somewhat.

We then had a series of fizzles and duds. Tuning of gas and fields did
little good until shot 8 when we again got a very good 1.7 s plasma.

For shot 09 we raised ZCUR from -0.015 to -0.005 m. Again we got a very nice
plasma. At 1.1 s the density began to rise at about the same time we
got open flux surfaces into the upper divertor region, possibly indicating
we were cleaning off the surfaces there. Note also that this was the
first shot on which gas was required from 0.5 s to 1.1 s to maintain the
requested density of 7e19/m^2. H/D increased to 50% at the end of the
shot.

For shot 10 we raised ZCUR again from -0.005 to 0.00 m. This shot disrupted
at 0.39 s. The density rose normally until 0.36 s when the radiation
increased and the density indicated an influx of material into the plasma.

Shot 11 began a long series of mostly duds and a few fizzles. Nothing
we tried seemed to help until shot 24, when the gas was raised to a
much higher than normal level and we got a plasma lasting into rampdown.
Again the density was well controlled and the H/D was below 30% much of the
shot, rising to 40% after 1 s. This very nice shot was then followed by
two duds and a fizzle.

The run ended on shot 28 when we had a fault in the OH2L power supply.

It is not at all clear why we have had so many duds. Large tweaks in field
and gas have not made things work better. Early in the run it appeared that
the ECDC was not helping and we stopped running it between shots. This
choice may have been a mistake we will look at more closely during the
Friday run.


Score:

Test 1

Duds 12
Fizzles 6
Plasmas 6

Power supply problem 1
Data system problems 2

Total cycles 28

Session Leader Comments

Physics Operator Comments
Jun 20 2002 08:17:16:567AMJim IrbyWith Steve Wolfe's help I recomputed the predictors to take into
account the flux loop changes

Loaded 1020619021 for our first shot

Did coldstart

rtnode -- data loaded, A matrix responds
rtnode -- data loaded, M matrix responds
rtnode -- data loaded, PID matrix responds
Jun 20 2002 08:38:30:740AM1020620001Jim IrbyLoad 1020619021 for first shot

This shot will be a cycle test to make sure things are okay after work on the
power room UPS last night.

Data system looks okay. No problems with Rogowski offsets. Hybrid signals
okay.
Jun 20 2002 09:19:00:663AM1020620002Jim IrbyFirst plasma attemp

Very nice first plasma: 1.73 s

CII .006

Peak H/D is 36% at 1.7 s

Density was still ramping up past the 7e19/m^2 setpoint.
All gas turned off by 0.5 s, but density reached 8e19/m^2



Jun 20 2002 09:42:44:410AM1020620003Jim IrbyRepeat of shot 2

Another good plasma: 1.73 s

Amanda reports some non-thermals early peaking around 50ms. We also almost lost control around
12 ms into the shot. Took a notch out of the current.

Except for spike at 12 ms CII was still low.

No more "MARFE" at end of shot.

Density still ramping up some; 8e19/m^2


Jun 20 2002 06:25:48:403PM1020620004Jim IrbyAdded a little more gas to PG3 in segment 1, otherwise, repeat shot 3

Dud
Jun 20 2002 10:08:39:817AM1020620005Jim IrbyNo changes

Fizzle

Will run 10 minutes of ECDC for the next shot
Jun 20 2002 10:34:46:453AM1020620006Jim Irby10 minutes of ECDC, otherwise no change.

Dud

Fields look okay compared to earlier plasma shots from today and yesterday.

Prefill is high: .06 vs .05
Jun 20 2002 10:46:16:953AM1020620007Jim IrbyBZ may be a little negative: EF4 from -1350 to -1340.

DNB gatevalve closed for this shot

Dud

Fields look fine to me

Gas may be somewhat high, but similiar to shots 2 and 3 from today ??

Jun 20 2002 11:08:16:820AM1020620008Jim IrbyNo PCS changes for this shot.

DNB gatevalve enabled again.

No ECDC

Plasma: 1.73 s

Will continue the no ECDC policy for the next shot
Jun 20 2002 11:24:55:403AM1020620009Jim IrbyNo ECDC before this shot

ZCUR from -.015 to -.005 --- put more plasma at top of machine

H/D at 34% and flat after 1 s or so.

Plasma into rampdown

Density rising after 1 s ---

Density rise may be associated with formation of upper null at 1.1 s.

Will raise plamsa another 1/2 cm for next shot

H/D 50% at end of shot --- may be doing some good running at top of machine
Jun 20 2002 11:44:47:753AM1020620010Jim IrbyZCUR from -.005 to 0.000 m

No ECDC

Steve Wolfe discovered that the xtomo centroids were being dispatched to Genesa that no longer
exists. May has centroids for this shot

Plasma for .39 s.

H/D was 40% at 200 ms; had been running about 16 to 20% on previous shots

Will repeat for next next shot
Jun 20 2002 11:58:58:037AM1020620011Jim IrbyRepeat shot 10

Fizzle: Large CII signal: up to .02 from .004

Try again..
Jun 20 2002 12:30:37:603PM1020620012Jim IrbyRepeat

Dud
Jun 20 2002 12:36:04:080PM1020620014Jim IrbyRepeat

Dud ----

Fields okay

Gas ?
Jun 20 2002 01:19:38:427PM1020620015Jim IrbyReduced prepuff from 25 to 23 ms.

We pumped/purged gas manifold to make sure the D2 was clean

Fizzle --- still lots of carbon II (.015)

Not much change in prefill pressure
Jun 20 2002 01:44:12:517PM1020620016Jim IrbyReduced prefill from 23 to 21 ms

Fizzle

Bz0 too negative
We did manage to reduce the prefill a little

Time (ms): 0 5 10 25
----------------------------------------
Ip (kA): 2.3289 -10.6419 -18.4471 -18.4471
dIp/dt (kA/ms): -1.0190 -1.5901 -1.0820 0.7630
pressure (mTorr): 0.0608 0.0615 0.0594 0.0568
Bz0 (mT): -3.6911 -2.1500 -0.6136 15.2033
Br0 (mT): 0.0247 -0.1765 -0.7215 -0.8281
Jun 20 2002 02:11:03:860PM1020620017Jim IrbyChanged EF4 from -1340 to -1320 amps

10 minutes of ECDC

Dud!

Very little change in Bz0


Time (ms): 0 5 10 25
----------------------------------------
Ip (kA): 2.3062 -10.6646 -15.8529 -15.8756
dIp/dt (kA/ms): -0.8913 -0.8902 -0.7630 0.1277
pressure (mTorr): 0.0622 0.0658 0.0615 0.0622
Bz0 (mT): -3.4731 -2.1449 -0.4967 14.5241
Br0 (mT): -0.0364 -0.3649 -0.8058 -1.0681
Jun 20 2002 02:31:38:180PM1020620018Jim IrbyEF4 from -1320 to -1300 amps

Dud

Bz0 moved to positive

Time (ms): 0 5 10 25
----------------------------------------
Ip (kA): -0.2880 -10.6646 -15.8529 -15.8529
dIp/dt (kA/ms): -0.8277 -0.8271 -0.6988 0.0006
pressure (mTorr): 0.0643 0.0588 0.0615 0.0636
Bz0 (mT): -0.9176 0.6642 3.0578 17.0469
Br0 (mT): -0.3828 -0.3840 -0.6755 -1.1217
Jun 20 2002 02:54:14:457PM1020620019Jim IrbyEF4 back to -1320 from -1300

Br0 offset from .0015 to .0020

Lost shot with data hang --- ran through with no power
Jun 20 2002 02:58:30:180PM1020620020Jim IrbyAnother dud

Time (ms): 0 5 10 25
----------------------------------------
Ip (kA): -0.2880 -10.6646 -15.8529 -15.8529
dIp/dt (kA/ms): -0.8277 -0.8266 -0.7630 0.0635
pressure (mTorr): 0.0629 0.0594 0.0615 0.0629
Bz0 (mT): -2.3642 -0.3645 1.0578 15.6372
Br0 (mT): 0.2488 -0.0455 -0.3447 -0.5120

Fields and gas not too bad...
Jun 20 2002 03:03:10:187PM1020620020Jim IrbyAnother dud

Time (ms): 0 5 10 25
----------------------------------------
Ip (kA): -0.2880 -10.6646 -15.8529 -15.8529
dIp/dt (kA/ms): -0.8277 -0.8266 -0.7630 0.0635
pressure (mTorr): 0.0629 0.0594 0.0615 0.0629
Bz0 (mT): -2.3642 -0.3645 1.0578 15.6372
Br0 (mT): 0.2488 -0.0455 -0.3447 -0.5120

Fields and gas not too bad...

Will reload shot 8 for the next shot
Jun 20 2002 03:26:16:540PM1020620021Jim IrbyReloaded shot 08

Fizzle

Lots of gas, Br0 1 mT low compared to shot 8, Bz0 very close to shot 8:


Time (ms): 0 5 10 25
----------------------------------------
Ip (kA): -0.2880 -10.6646 -18.4698 -21.0639
dIp/dt (kA/ms): -0.9560 -1.2081 -0.9538 0.2549
pressure (mTorr): 0.0736 0.0787 0.0736 0.0711
Bz0 (mT): -3.0966 -0.8458 0.2139 14.9358
Br0 (mT): -0.0386 -0.4507 -1.0321 -0.6905

Jun 20 2002 03:28:21:713PM1020620022Jim IrbyReduced prefill by 2 ms

Added .5 mT to Br0

Dud
Jun 20 2002 03:48:55:330PM1020620023Jim IrbyBz0 offset to .001 from .002 --- Steve noted late breakdown on shot 21 with negative Br0.

Dud


Time (ms): 0 5 10 25
----------------------------------------
Ip (kA): 2.3289 -10.6646 -15.8302 -15.8529
dIp/dt (kA/ms): -0.8265 -0.7635 -0.8277 -0.0647
pressure (mTorr): 0.0658 0.0688 0.0665 0.0673
Bz0 (mT): -3.4707 -2.0715 -0.5028 14.1243
Br0 (mT): -0.5146 -0.7331 -1.2416 -1.6503

Jun 20 2002 04:02:30:520PM1020620024Jim IrbyIncreased prefill to 30 ms: -.530 to -.500 s

Plasma to 1.77 seconds

Time (ms): 0 5 10 25
----------------------------------------
Ip (kA): -0.2880 -10.6419 -21.0185 -44.3887
dIp/dt (kA/ms): -1.1451 -1.7814 -1.7809 -2.7352
pressure (mTorr): 0.0901 0.0921 0.0942 0.0796
Bz0 (mT): -3.5637 -2.2031 -0.0338 16.1368
Br0 (mT): -0.6121 -0.4572 -0.7565 -1.8497


Jun 20 2002 04:21:38:650PM1020620025Jim IrbyZCUR from -.0015 to 0.0000 m

Dud --- amazing

Fields and gas very similar to last shot

Time (ms): 0 5 10 25
----------------------------------------
Ip (kA): -0.2652 -13.2360 -18.4244 -15.8529
dIp/dt (kA/ms): -1.3999 -1.7804 -0.6381 -0.2565
pressure (mTorr): 0.0921 0.0891 0.0942 0.0942
Bz0 (mT): -2.7444 -1.9391 -0.5802 14.2011
Br0 (mT): -0.3077 -0.5795 -0.7505 -1.1796
Jun 20 2002 04:30:10:097PM1020620026Jim IrbyRepeat

Dud

Time (ms): 0 5 10 25
----------------------------------------
Ip (kA): 2.3062 -13.2588 -18.4471 -18.4698
dIp/dt (kA/ms): -1.2716 -2.0358 -0.5087 -0.2577
pressure (mTorr): 0.0901 0.0891 0.0942 0.0881
Bz0 (mT): -3.6985 -0.6035 -0.2974 14.6424
Br0 (mT): -0.7766 -0.8904 -1.3132 -1.7558

Will change Br0 again
Jun 20 2002 04:46:50:790PM1020620027Jim IrbyBr0 from .001 to .0015 T
Increased puff again: -.535 to -.500 s

Fizzle

Time (ms): 0 5 10 25
----------------------------------------
Ip (kA): 2.3062 -13.2588 -21.0412 -21.0412
dIp/dt (kA/ms): -1.5284 -2.2890 -1.3987 0.2543
pressure (mTorr): 0.1091 0.1141 0.1066 0.0964
Bz0 (mT): -4.3531 -1.5718 -0.3720 14.8053
Br0 (mT): -0.0884 -0.8620 -0.8994 -1.1535
Jun 20 2002 04:59:32:647PM1020620028Jim IrbyEF4 from -1340 to -1320 amp

PF breaker pulled

End of run -----

Engineering Operator Comments
ShotTimeTypeStatusComment
108:31:17:940AMTestOkCycle Test
209:04:44:487AMPlasmaOk
309:23:01:170AMPlasmaOk
409:45:07:740AMPlasmaOk
510:01:53:573AMPlasmaOk
610:21:22:530AMPlasmaOk
710:36:47:567AMPlasmaOk
810:52:01:787AMPlasmaOk
911:13:27:593AMPlasmaOk
1011:33:31:083AMPlasmaOk
1111:46:48:350AMPlasmaOk
1212:03:17:727PMPlasmaOk
1412:31:13:493PMPlasmaOk
1501:11:25:307PMPlasmaOk
1601:26:56:527PMPlasmaOk
1702:05:08:620PMPlasmaOk
1802:20:48:260PMPlasmaOk
1902:36:29:390PMPlasmaOkno power shot
2002:51:29:483PMPlasmaOk
2103:08:21:300PMPlasmaOk
2203:21:52:990PMPlasmaOk
2303:35:17:567PMPlasmaOk
2403:50:27:223PMPlasmaOk
2504:09:25:933PMPlasmaOk
2604:23:47:090PMPlasmaOk
2704:39:33:313PMPlasmaOk
2804:53:04:123PMPlasmaBadEf1 breaker opend see log book