Alcator C-Mod Run 990303 Information

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Miniproposals
Miniproposal:230
Date Filed: 1/15/1999
Title:Effect of Divertor Baffling on Confinement, Thresholds
First Author:Spencer Pitcher
Session Leader:Spencer Pitcher (shots 1-27)

Operators
Session leader(s):Spencer Pitcher
Physics operator(s):Dmitri Mossessian
Engineering operator(s):Frank Silva

Engineering Operator Run Comment
MP230 Divertor Baffling/Pitcher/Silva

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:19:930PM
Author: To Be Determined
Run Summary for 990303

/continued from 990302

MP 230 Effect of Divertor Baffling on Confinement, Thresholds
and the ELM-free/EDA Boundary

Session Leader: S Pitcher
Phys Op : D Mossessian

Purpose:

The purpose of this experiment was to investigate
the effect of divertor baffling on confinement,
H-mode thresholds and the ELM-free/EDA boundary.
Conditions in the pedestal/edge region were
carefully monitored.

Summary:

The machine ran somewhat better today after the boronization
last night, in comparison to yesterday.
We ran alternate shots, flapper closed and then open.
With only 1.5 MW of RF, we got multiple EDA's in a single discharge,
which made shot to shot comparisons difficult.
Nevertheless, it was clear that divertor
neutral pressure was approx a factor of 2
lower with flapper open, midplane pressure and H-alpha
were not affected, Wmhd not affected.

The following conditions were investigated:

(1) target nl04 = 1.0, 1.5 MW (eg. cf shots 7,8)

(2) target nl04 = 0.7, 1.5 MW (eg. cf shots 15,16)

(3) target nl04 = 1.5, 1.5 MW (eg. cf shots 20,21)


From shot 22, we attemped to investigate the effect
of the flapper on threshold, but RF had problems.
This was not done.

Conclusion:

It is becoming fairly clear that the flapper does
not influence midplane pressures or Halpha, or confinement,
although we are still looking for truly steady reproducible EDA's with
flapper open/closed, ie trophy shots.

Again, divertor pressures are reduced by a factor of 2 with
the flapper open.

Still not clear regarding the effect
on thresholds.....remains to be done.




Physics Operator Summaries
Entered: Jul 7 2004 04:37:00:537PM
Author: To Be Determined
Run summary for 990303

SL: S. Pitcher
PO: D. Mossessian

The run was in support of MP 230 - Effect of divertor baffling on confinement.
thresholds and ELM-free/EDA boundary.

Scorecard: 27 shots, 4 fizzles, 23 plasmas.

First shot was loaded from 990302019 - 800 kA current, 1.0e20 target density. After 5 plasmas
in a row we went in alternating plasma/fizzle mode for shots 6 - 12. For shot 13 the Br0 offset
was reduced by 0.5 mT thus producing negative Br0 at t=0 sec and after that there was no more
fizzles. On shot 6 the ZCUR was moved down 4 mm to provide for better coverage for edge TS. It
was moved down 2 more mm on shot 22. The lower x-point was pulled down 4 mm at 1.2 sec on shot
6 and 3 mm more on shot 22. From shot 4 to shot 22 two Btor bumps were programmed for ECE.

The RF broke down on shot 25 so the last 2 shots were programmed for density ramp up to 1.7e20.
Shot 26 had density ramped up to 1.5e20, but next shot was a fizzle.

Session Leader Comments
Mar 3 1999 09:10:42:983AM990303001Spencer Pitcherflapper open, t = -.2 s to t = 1.5 s
Mar 3 1999 09:11:08:217AM990303002Spencer Pitcherflapper closed
Mar 3 1999 09:22:00:310AM990303003Spencer Pitcherflapper closed
Mar 3 1999 09:32:12:950AM990303004Spencer Pitcherflapper open whole shot
Mar 3 1999 09:56:26:763AM990303005Spencer Pitcherflapper open whole shot
Mar 3 1999 10:02:43:340AM990303006Spencer Pitcherflapper closed whole shot
Mar 3 1999 10:43:15:857AM990303007Spencer Pitcherflapper closed whole shot
Mar 3 1999 10:43:35:920AM990303008Spencer Pitcherflapper open whole shot
Mar 3 1999 11:10:04:373AM990303009Spencer Pitcherflapper open whole shot
argon enabled
Mar 3 1999 11:43:53:623AM990303010Spencer Pitcherflapper open whole shot
argon enabled......gave too much....radiation too high!!
EDA not very good
Mar 3 1999 11:45:02:530AM990303011Spencer Pitcherflapper open whole shot
argon enabled......reduce by approx factor 4
Mar 3 1999 12:11:06:793PM990303012Spencer Pitcherflapper open whole shot
argon enabled......reduce by approx factor 4
Mar 3 1999 12:19:41:937PM990303013Spencer Pitcherflapper closed whole shot
argon enabled
Mar 3 1999 12:47:11:437PM990303014Spencer Pitcherflapper open whole shot
argon enabled, but dropped to 15 ms
target density dropped to nl04 0.7
Mar 3 1999 01:01:40:450PM990303015Spencer Pitcherflapper closed whole shot
argon enabled, argon 15 ms
target density nl04 = 0.7
Mar 3 1999 01:22:48:670PM990303016Spencer Pitcherflapper open whole shot
argon disabled
target density nl04 = 0.7
Mar 3 1999 01:46:06:670PM990303017Spencer Pitcherflapper closed whole shot
argon disabled
target density nl04 = 1.5
Mar 3 1999 02:03:08:780PM990303018Spencer Pitcherflapper closed whole shot
argon disabled
target density nl04 = 1.5
Mar 3 1999 02:26:20:390PM990303019Spencer Pitcherflapper open whole shot
argon disabled
target density nl04 = 1.5
Mar 3 1999 02:46:16:043PM990303020Spencer Pitcherflapper open whole shot
argon enabled: 15 ms
target density nl04 = 1.5
Mar 3 1999 03:02:09:170PM990303021Spencer Pitcherflapper closed whole shot
argon enabled...increase to : 20 ms
target density nl04 = 1.5
Mar 3 1999 03:38:03:780PM990303022Spencer PitcherThreshold study:
flapper closed whole shot
argon disabled
RF ramp from 0.5 MW at t = 0.5 s to 1.5 MW at t = 1.2 s
nl04 = 1.0

Pthresh = 0.88 MW
Mar 3 1999 04:04:54:090PM990303023Spencer PitcherThreshold study:
flapper open whole shot
argon disabled
RF ramp from 0.5 MW at t = 0.5 s to 1.5 MW at t = 1.2 s
nl04 = 1.0
RF matching changed for this shot!
Mar 3 1999 04:13:00:590PM990303024Spencer PitcherThreshold study:
flapper open whole shot
argon disabled
change >> RF ramp from 0.5 MW at t = 0.5 s to 1.5 MW at t = 1.0 s and then flat
nl04 = 1.0
RF matching put back as in shot 22

Pthresh = 1.06 MW
Mar 3 1999 04:47:45:810PM990303026Spencer PitcherRF ist kaput!
Ohmic density ramp
flapper open whole shot
argon not enabled!
Mar 3 1999 04:51:48:250PM990303027Spencer PitcherOhmic density ramp
flapper closed whole shot
argon not enabled!

Physics Operator Comments
Mar 3 1999 08:28:45:233AMDmitri MossessianLoad from 990302019 - 800 kA, 1.0e20 density.
PCS coldstart OK.
Mar 3 1999 08:56:23:513AM990303001Dmitri MossessianPlasma. No RF.
Mar 3 1999 09:15:12:500AM990303002Dmitri MossessianRF should be on this time.
No PCS changes.

PLasma. RF is on, ELM-free H-mode.
Mar 3 1999 09:32:39:780AM990303003Dmitri MossessianNo PCS changes.

PLasma - 2 EDA H-modes
Mar 3 1999 09:55:45:827AM990303004Dmitri MossessianAdded 7 kA Btor bump from 0.8 to .893 sec for ECE scan.
Plasma, h-modes.



Mar 3 1999 10:09:59:030AM990303005Dmitri MossessianNo PCS changes

Plasma
Mar 3 1999 10:19:29:310AM990303006Dmitri MossessianMoved ZXL 4 mm down at 1.22 sec.
Moved ZCUR 4 mm down from .5 to 1.3 sec

Fizzle
Mar 3 1999 10:44:08:890AM990303007Dmitri MossessianAdd another B-tor bump for ECE at 0.55 sec.
No startup changes.

Plasma, long EDA
Mar 3 1999 11:02:15:857AM990303008Dmitri MossessianNo PCS changes.

Plasma.
Mar 3 1999 11:17:12:280AM990303009Dmitri MossessianNo PCS changes. Enable Argon valve.

Fizzle. Probably did not wait long enough for base pressure to come down.
Mar 3 1999 11:40:38:187AM990303010Dmitri MossessianNo PCS changes

Plasma

Mar 3 1999 12:03:36:140PM990303011Dmitri MossessianReduced Argon puff to 20 msec (from 30 msec).

Fizzle


Mar 3 1999 12:17:28:687PM990303012Dmitri MossessianNo PCS changes.
PLasma

Mar 3 1999 12:29:26:327PM990303013Dmitri MossessianReduced Br0 offset in segment 1 to 0.0015 from 0.002.

Plasma
Mar 3 1999 12:50:22:013PM990303014Dmitri MossessianReduced Ar puff to 15 msec. Set Pulse_gas3 0 after 0.239 sec.
Density 0.7e20.

Plasma.
Mar 3 1999 01:07:50:950PM990303015Dmitri MossessianNo PCS change.

Plasma
Mar 3 1999 01:29:47:327PM990303016Dmitri MossessianAdd a little more gas in Pulse_gas3 after 0.239 sec.
Disable B_side_lower (Ar).

Plasma.
Mar 3 1999 01:54:21:483PM990303017Dmitri MossessianDensity 1.5e20.
Add more gas in Pulse_gas3 after .239 sec.

Plasma. Did not make it to the target Ne.
Increase Pulse_gas3 puff for next shot.
Mar 3 1999 02:25:14:000PM990303018Dmitri MossessianIncrease Pulse_gas3 puff.

PLasma, no RF.

Mar 3 1999 02:40:02:263PM990303019Dmitri MossessianNo PCS changes.

Plasma
Mar 3 1999 02:58:26:653PM990303020Dmitri MossessianEnable Ar 15 msec pulse.

Plasma
Mar 3 1999 03:10:53:840PM990303021Dmitri Mossessian20 msec Ar.

Plasma
Mar 3 1999 03:32:58:420PM990303022Dmitri MossessianTarget density 1.0e20 (lowered Pulse_gas3).
Ar disabled.
Moved plasma down 2 mm (ZCUR from 0.5 to 1.3 sec)
Move ZXL down 3 mm at 1.2 sec.
Removed ECE Btor bumps.

Plasma
Mar 3 1999 03:56:27:500PM990303023Dmitri MossessianNo PCS changes.

Plasma
Mar 3 1999 04:10:16:030PM990303024Dmitri MossessianNo PCS changes.

Plasma
Mar 3 1999 04:37:40:263PM990303025Dmitri MossessianNo PCS changes.

Plasma
Mar 3 1999 04:49:34:983PM990303026Dmitri MossessianDensity increasing from 0.6e20 at 0.5 sec
to 1.8e20 at 1.2 sec.

Plasma. Density went up to 1.5e20.
Ar was desabled.
Mar 3 1999 05:01:06:640PM990303027Dmitri MossessianNo PCS changes.

Fizzle.

Engineering Operator Comments
ShotTimeTypeStatusComment
108:48:01:000AMPlasmaOkno faults/plasma
209:11:17:967AMPlasmaOkno faults/plasma
309:25:51:483AMPlasmaOkno faults/plasma
409:43:11:873AMPlasmaOkno faults/plasma
509:56:54:060AMPlasmaOkno faults/plasma
610:13:47:857AMPlasmaOkNo Faults
710:37:05:780AMPlasmaOkno faults/plasma
810:55:14:937AMPlasmaOkno faults/plasma
911:12:34:357AMPlasmaOkno faults/fizzel
1011:31:16:077AMPlasmaOkno faults/plasma
1111:54:15:187AMPlasmaOkno faults/fizzel
1212:08:20:687PMPlasmaOkno faults
1312:27:46:857PMPlasmaOkno faults
1412:47:42:390PMPlasmaOkno faults/plasma
1501:06:08:983PMPlasmaOkNo Faults / Plasma
1601:26:52:780PMPlasmaOkNo Faults / Plasma
1701:47:20:373PMPlasmaOkNo Faults /Plasma
1802:09:09:903PMPlasmaOkNo Faults / Plasma
1902:30:55:107PMPlasmaOkNo Faults / Plasma
2002:49:36:513PMPlasmaOkNo Faults / Plasma
2103:08:31:500PMPlasmaOkNo Faults / Plasma
2203:28:21:170PMPlasmaOkNo Faults / Plasma
2303:49:47:327PMPlasmaOkNo Faults / Plasma
2404:03:51:500PMPlasmaOkNo Faults / Plasma
2504:16:51:077PMPlasmaOkNo Faults / Plasma
2604:42:19:937PMPlasmaOkNo Faults / Plasma
2704:59:21:500PMPlasmaOkNo Faults