Alcator C-Mod Run 960222 Information

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Miniproposals
Miniproposal:117
Date Filed: 4/18/1995
Title:3He Minority Heating at 7.9T
First Author:Yuichi Takase
Session Leader:Yuichi Takase (shots 1-27)

Operators
Session leader(s):Yuichi Takase
Physics operator(s):Joseph Snipes
Engineering operator(s):Vinny Bertolino,Frank Silva,Joe Daigle

Engineering Operator Run Comment
7.9

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:15:507PM
Author: To Be Determined
Run summary 960222

MP117 7.9T D(He3)

SL: Takase
PO: Snipes
EO: Silva/Bertolino/Daigle

Plan:
Clean-up shots at 5.3T until H-mode improves, then:
1. 8T, 1.2MA heating (try to evaluate absorption again)
2. Try PEP mode (Li/D2 pellets)

Overnight He ECDC was performed (11 hours). After EF1 tests, the problem
appeared to have gone away. We took a fiducial shot and a 1MA, 5.3T
conditioning shot. H-mode quality was good (ELM-free), with an H factor
of almost 2.5 for shot 09 (close to the best H-mode). Comparison of
fiducial shots from yesterday and today suggests that overnight He ECDC
is beneficial for eliminating the "H_alpha blob", if that is what we want
to do (ELM-free H-mode leads to impurity accumulation and eventually
degradation of confinement). The H_alpha blob does allow steady-state
H-mode operation. With well-conditioned (degassed) walls, H_alpha blob
can be controlled by gas puffing during H-mode, so this may be how we want
to operate. With gassed-up walls it is difficult to avoid H_alpha blobs.

No 8T shots.

Shots 01-05 were EF1 tests.
EF1 problem has gone away, but not really fixed.

shot
06 pla fiducial, 3 H-modes, no D-port (crowbarred before the shot)
07 dud EF1 problem is back!
08 dud same, EF1 problem
09 pla good H-mode, 2.55MW, 200kJ, H=2.5

PF breaker broke

End of plasma run.

A TF breaker (one out of four) was swapped in for the failed PF breaker.
EF1 testing will continue for the rest of the day.

Physics Operator Summaries
Entered: Jul 7 2004 04:36:56:190PM
Author: To Be Determined
Attempt to run MP 117 ICRF H-modes at 7.9 T D(He3)
Engineer in charge: Frank Silva
Physicist in charge: Joseph Snipes
Session leader: Yuichi Takase

Li pellets (PEP) modes, attempt to measure RF power absorption with the
diamagnetic stored energies compared to fast EFIT stored energies. Attempt
full performance plasmas at 1.2 MA and 7.9 T with all available RF power.

Shot 6 was a standard fiducial shot, but the McPherson gate valve did not
open because it was set wrong. Shots 7 and 8 had EF1L failures, then shot
9 was a good H-mode shot with and H factor of about 2.4 until there was a
moly injection that degraded the stored energy. Shot 9 was another EF1L
failure. After shot 960222009, the PF breaker failed. So, there were no
further plasmas today. The rest of the day will be devoted to swapping out
one of the TF breakers to replace the broken PF breaker and do power supply
testing.

Scorecard: 4 attempts, 2 plasmas, 2 EF1L failures. (5.3 T part of 7.9 T run)
8 attempts, 2 plasmas, 4 duds, 2 fizzles (3.5 T breakdown studies)
Shot Log
---------

Shot 1 :EF1L test. Failed like yesterday.
Shot 2 :Repeat. EF1L worked fine.
Shot 3 :Reversed polarity. Worked O.K. but had 200 V glitches.
Shot 4 :Repeat at higher voltage.
Shot 5 :Another EF1L test. Looks O.K.
Shot 6 :Start with a fiducial copied from shot 960213011 but with Br offset
changed from 7.4 mT to 5.4 mT. Good shot. H-modes from 0.76 to
1.02 sec.
Shot 7 :Copied shot 960214027 but changed Br offset to 5.4 mT. Ip = 1 MA,
Bt = 5.3 T, nl04 ramping from 8 x 10^19 m^-2 to 1 x 10^20 m^-2 from
0.65 to 0.87 sec. EF1L failed. No plasma.
Shot 8 :Repeat. EF1L failed again.
Shot 9 :Repeat. Good shot. H-modes from 0.63 to 1.1 sec. Reached nearly
200 kJ of stored energy.
Shots 10 - 19:Power supply tests
Shot 20:Copied shot 960118032. Changed TF to no hybrid control with a set
point at 100 kA, which should be about 3.5 T. Set Br offset to 5.4
mT. Ip = 580 kA, nl04 set to 5 x 10^19 m^-2. Dud.
Shot 21:Changed EF1U and L currents before t=0 from -4800 to -5000 A.
Dud. Too close to the rail on EF1U.
Shot 22:Increased pre-puff by 3 msec to 14 msec flattop. Reduced Br by
another 0.4 mT to 5.0 mT. OH2 changed from -22200 to -23200 A.
EF1U and L returned to -4800 A.
Shot 23:Set Br offset to 4 mT, increased pre-puff by 2 msec to 16 msec.
Shot 24:Increased pre-puff by 9 msec to 25 msec. Changed EF4 current from
-1150 to -1200 A. Got breakdown.
Shot 25:Increased Br offset by 0.5 mT to 4.5 mT. Reduced pre-puff by 5
msec to 20 msec. Got plasma. Disrupted at 0.55 sec. Ran limited
on the outboard limiter.
Shot 26:Reduced RCUR from 0.675 to 0.669 m during the flattop. Fizzle.
Shot 27:One more time. Disrupted at 0.185 sec. Probably needs more gas in
the current rise.

Session Leader Comments
Feb 22 1996 10:58:35:640AMYuichi TakaseMP117 7.9T D(He3)

SL: Takase
PO: Snipes
EO: Silva/Bertolino/Daigle

Plan:
Clean-up shots at 5.3T until H-mode improves
7.9T, 1.2MA heating (try to evaluate absorption again)
Try PEP mode (Li/D2 pellets)

EF1 problem has gone away for the moment, but not really fixed.

Feb 22 1996 11:00:23:800AM960222006Yuichi TakaseShot 006: plasma
fiducial
no D-port (crowbarred before the shot)

Feb 22 1996 11:15:17:180AM960222007Yuichi TakaseShot 007: dud
loaded 960214027
Ef1 problem is back!

Feb 22 1996 11:28:23:490AM960222008Yuichi TakaseShot 008: dud
same, EF1 problem

Feb 22 1996 12:52:21:310PM960222009Yuichi TakaseShot 009: plasma
good H-mode, 2.55MW, 200kJ, H=2.5

Physics Operator Comments
Feb 22 1996 11:21:19:470AMJoseph SnipesAttempt to run MP 117 ICRF H-modes at 7.9 T D(He3)
Engineer in charge: Frank Silva
Physicist in charge: Joseph Snipes
Session leader: Yuichi Takase

Li pellets (PEP) modes, attempt to measure RF power absorption with the
diamagnetic stored energies compared to fast EFIT stored energies. Attempt
full performance plasmas at 1.2 MA and 7.9 T with all available RF power.


Feb 22 1996 11:21:45:840AM960222001Joseph SnipesShot 1 :EF1L test. Failed like yesterday.


Feb 22 1996 11:22:14:290AM960222002Joseph SnipesShot 2 :Repeat. EF1L worked fine.


Feb 22 1996 11:22:30:020AM960222003Joseph SnipesShot 3 :Reversed polarity. Worked O.K. but had 200 V glitches.


Feb 22 1996 11:22:52:520AM960222004Joseph SnipesShot 4 :Repeat at higher voltage.


Feb 22 1996 11:24:18:850AM960222005Joseph SnipesShot 5 :Another EF1L test. Looks O.K.


Feb 22 1996 11:25:14:070AM960222006Joseph SnipesShot 6 :Start with a fiducial copied from shot 960213011 but with Br offset
changed from 7.4 mT to 5.4 mT. Good shot. H-modes from 0.76 to
1.02 sec.


Feb 22 1996 11:26:09:110AM960222007Joseph SnipesShot 7 :Copied shot 960214027 but changed Br offset to 5.4 mT. Ip = 1 MA,
Bt = 5.3 T, nl04 ramping from 8 x 10^19 m^-2 to 1 x 10^20 m^-2 from
0.65 to 0.87 sec. EF1L failed. No plasma.


Feb 22 1996 11:27:04:070AM960222008Joseph SnipesShot 8 :Repeat. EF1L failed again.


Feb 22 1996 12:04:48:440PM960222009Joseph SnipesShot 9 :Repeat. Good shot. H-modes from 0.63 to 1.1 sec. Reached nearly
200 kJ of stored energy.


Feb 22 1996 02:07:24:320PM960222009Joseph SnipesAfter shot 960222009, the PF breaker failed. So, there were no
further plasmas today. The rest of the day will be devoted to swapping out
one of the TF breakers to replace the broken PF breaker and do power supply
testing.


Feb 22 1996 03:53:03:050PM960222020Joseph SnipesShot 20:Copied shot 960118032. Changed TF to no hybrid control with a set
point at 100 kA, which should be about 3.5 T. Set Br offset to 5.4
mT. Ip = 580 kA, nl04 set to 5 x 10^19 m^-2. Dud.


Feb 22 1996 03:53:40:120PM960222021Joseph SnipesShot 21:Changed EF1U and L currents before t=0 from -4800 to -5000 A.
Dud.


Feb 22 1996 04:36:41:450PM960222022Joseph SnipesShot 22:Increased pre-puff by 3 msec to 14 msec flattop. Reduced Br by
another 0.4 mT to 5.0 mT. OH2 changed from -22200 to -23200 A.
EF1U and L returned to -4800 A. Dud.


Feb 22 1996 04:36:59:400PM960222023Joseph SnipesShot 23:Set Br offset to 4 mT, increased pre-puff by 2 msec to 16 msec.


Feb 22 1996 04:37:15:720PM960222024Joseph SnipesShot 24:Increased pre-puff by 9 msec to 25 msec. Changed EF4 current from
-1150 to -1200 A. Got breakdown.


Feb 22 1996 04:52:35:840PM960222025Joseph SnipesShot 25:Increased Br offset by 0.5 mT to 4.5 mT. Reduced pre-puff by 5
msec to 20 msec. Got plasma. Disrupted at 0.55 sec. Ran limited
on the outboard limiter.



Feb 22 1996 04:58:08:780PM960222026Joseph SnipesShot 26:Reduced RCUR from 0.675 to 0.669 m during the flattop.
Fizzle.

Feb 22 1996 05:19:07:370PM960222027Joseph SnipesShot 27:One more time. Disrupted at 0.185 sec. Probably needs more gas in
the current rise.


Engineering Operator Comments
ShotTimeTypeStatusComment
109:06:41:660AMTestBadef1 lower test ioc, comm fault
209:21:29:160AMTestOkno faults ef1 test
309:27:33:440AMTestOk
409:46:11:670AMTestOk
510:15:07:270AMTestOk
610:50:48:420AMPlasmaOk
711:10:19:250AMPlasmaBadef1l ioc, comm fault
811:21:53:740AMPlasmaBadef1 faults
911:49:42:450AMPlasmaOk
1012:47:42:420PMTestOk
1112:59:54:640PMTestOk
1201:18:56:280PMTestOk
1302:09:09:010PMTestOk
1402:16:46:690PMTestOk
1502:21:54:830PMTestOk
1602:26:05:800PMTestOk
1702:29:59:770PMTestOkef1 test
1802:51:43:450PMTestOk
1902:58:08:100PMTestOk
2003:36:20:180PMPlasmaOk
2103:49:56:570PMPlasmaOk
2204:06:52:900PMPlasmaOk
2304:16:31:400PMPlasmaOk
2404:26:39:870PMPlasmaOk
2504:36:15:650PMPlasmaOk
2604:51:17:050PMPlasmaOk
2705:01:38:040PMPlasmaOk