Alcator C-Mod Run 990721 Information

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Miniproposals
Miniproposal:214
Date Filed: 1/5/1999
Title:D and E-port RF System Commissioning
First Author:Steve Wukitch
Session Leader:Steve Wukitch (shots 1-20)

Operators
Session leader(s):Steve Wukitch
Physics operator(s):Dmitri Mossessian
Engineering operator(s):Frank Silva

Engineering Operator Run Comment
Start Up/RF/Granetz/Silva

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Physics Operator Summaries
Entered: Jul 7 2004 04:37:04:397PM
Author: To Be Determined
Physics operator summary for run 990721

________________________________________________________
Run Plan for 990721:

MP 214 -- RF conditioning

SL: S. Wukitch
PO: D. Mossessian

Start by loading 990716010 , an 0.8 MA, long flattop shot .
Optimise vertical position for RF balance.
_______________________________________________________
Summary:

The run was characterized by an unusual amount of duds (cause unknown) and
complete lack of fizzles. Although several plasmas were obtained, only one did not disrupt,
and another one disrupted late in the shot. Most of the plasmas disrupted early in the shot
mainly due to large impurirty injections (numerous small injections are seen on many shots too)
One shot (13) developed vertical instability because of the OH2 mulfunction. Some problems with
data cycle developed late in the day and interfered with normal shot cycle.
The general impression is that the machine is dirty and overnight ECDC
should help.
Numerous tweeks of Br, Bz and prepuff pressures carryed out during the day seem to be
irrelevant.
Shots from 06 have the right gap at 1 cm (as requested by RF). Shot 990721009 (no disruption)
could be a good shot to start the next day from.

___________________________________________________________________
Scorecard: 20 shots
8 plasmas
0 fizzles
10 duds
2 tests

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990721001 OH test.

990721002 Dud

990721003 Decreased prepuff from 23 msec to 20 msec. Decreased Br offset from 7 to 6 mT.
Dud.

990721004 Decreased Br offset to 5 mT for this shot.
Dud.

990721005 Br ofset - back to 6 mT.
Plasma.
Flattop 1e20 m^-2 , .8 MA. Disrupted at .92 sec.

990721006 Changed the right gap to 1 cm - increased Rcur to 0.6715 from .6685
Dud.

990721007 Plasma. Disrupted at 0.76 sec.

990721008 Dud.

990721009 Plasma. Touched inner wall around .356 sec producing large injection.
Small H-mode @ 0.95 sec.

990721010 Plasma. Disrupted at 1.25 sec. No H-mode this time.

990721011 Plasma. Disrupted at 0.4 sec probably due to large injection.

990721012 Plasma but disrupted very early - around 0.057 sec.

990721013 Plasma Disrupted around 0.245 sec due to OH2 problems leading
to vertical instability.

990721014 Dud.

990721015 Dud.

990721016 +0.5 mT change in Br offset.
Plasma. Disrupted at 0.5 sec - large impurity injection.

990721017 Dud. Increased gas puff in pulse_gas3.

990721018 Dud.

990721019 a) Br offset from 6.5 to 6 mT b) Moved Bz 1 mT down (15 A on EF4)
Dud

Session Leader Comments
Jul 21 1999 09:32:17:390AMSteve Wukitch

MP 214: RF conditioning


Transmitters 1 and 2 (D and E antenna) are ready to be tested into plasma.

We will be shooting #2 (E antenna) first with a few shots for tuning and optimizing plasma.
As soon as #2 is reliable, we will bring #1 (D) next using the same approach.

Optimizing and tuning both antennas will take a few more shots.

If time allows, we will bring 3 and 4 (J) along at low power, as we expect issues
with tuning and running them together.



We will start with the most recent shot, i.e. 990716010, with possibly
a small decrease in outer gap.
Jul 21 1999 09:31:33:983AM990721001Steve Wukitch
OH test shot

Jul 21 1999 11:11:36:047AM990721005Steve Wukitch
E antenna went for ~600kW.

Will adjust tuning a little bit.
Jul 21 1999 11:54:02:467AM990721007Steve Wukitch
E antenna went for ~450kW, before disruption.

Jul 21 1999 12:55:13:000PM990721009Steve Wukitch
E antenna went for ~1MW, went into H mode!

Jul 21 1999 01:02:36:530PM990721010Steve Wukitch
E antenna went for ~1.2MW

Physics Operator Comments
Jul 21 1999 09:04:04:420AMDmitri MossessianLoad PCS from 990716010.
Coldstart OK.
We are going to do EF2 and OH test first.
Jul 21 1999 09:44:50:763AM990721001Dmitri MossessianSkipped EF2 test. Doing OH test.
Jul 21 1999 10:18:56:293AM990721002Dmitri MossessianReal shot.
Dud

For the next shot decreased prepuff from 23 msec to 20 msec.
Dropped Br offset from 7 to 6 mT.
Jul 21 1999 10:30:28:093AM990721003Dmitri MossessianDud.
Jul 21 1999 10:37:40:013AM990721003Dmitri MossessianDud.
Increase prepuff to 25 msec.
Jul 21 1999 10:51:46:983AM990721004Dmitri MossessianAlso decreased Br offset to 5 mT for this shot.

Dud again.
Add 1mT to Br ofset - back to 6 mT for next shot
Jul 21 1999 11:19:01:327AM990721005Dmitri MossessianPlasma. Flattop 1e20 m^-2 , .8 MA.
Disrupted at .92 sec.
Jul 21 1999 11:22:00:513AM990721006Dmitri MossessianChanged the right gap to 1 cm - increased Rcur to 0.6715 from .6685
Jul 21 1999 11:47:56:310AM990721006Dmitri MossessianDud.
No PCS changes for next shot
Jul 21 1999 12:08:03:153PM990721007Dmitri MossessianPlasma. Disrupted at 0.76 sec.

No PCS changes for next shot.
Jul 21 1999 12:19:11:543PM990721008Dmitri MossessianDud.

Try again with no PCS changes
Jul 21 1999 12:51:18:747PM990721009Dmitri MossessianPlasma. Touches inner wall around .356 sec producing large injection.
Small H-mode @ 0.95 sec.
NO PCS changes for next shot
Jul 21 1999 01:07:45:373PM990721010Dmitri MossessianPlasma. Disrupted at 1.25 sec.
No H-mode this time.
Jul 21 1999 01:19:58:543PM990721011Dmitri MossessianPlasma. Disrupted at 0.4 sec probably due to large injection.
Jul 21 1999 01:48:16:700PM990721012Dmitri MossessianPlasma but disrupted very early - around 0.057 sec.
Jul 21 1999 02:19:35:047PM990721013Dmitri MossessianPlasma Disrupted around 0.245 sec.
Possible cause - OH2 problems leading to vertical instability.
Jul 21 1999 02:27:03:763PM990721014Dmitri MossessianDud.
Jul 21 1999 02:52:20:903PM990721015Dmitri MossessianDud.
Try positive Br shift - +0.5 mT change in offset
Jul 21 1999 03:17:53:247PM990721016Dmitri MossessianPlasma. Disrupted at 0.5 sec - large impurity injection.
Jul 21 1999 03:40:46:670PM990721017Dmitri MossessianDud.
Increased gas puff in pulse_gas3 in response to Earl's claim that
density is too low at the beginning of the shot.
Jul 21 1999 04:18:46:700PM990721018Dmitri MossessianDud.
For the next shot: a) Br offset from 6.5 to 6 mT
b) Moved Bz 1 mT down (15 A on EF4)
Jul 21 1999 05:13:09:687PM990721019Dmitri MossessianNot a real shot - data cycle only
Jul 21 1999 05:13:27:857PM990721020Dmitri MossessianPlasma attempt - Dud.

Engineering Operator Comments
ShotTimeTypeStatusComment
109:25:28:903AMTestOkOH plc test
209:53:00:093AMPlasmaOkno faults/dud
310:20:45:937AMPlasmaOkno faults
410:46:51:543AMPlasmaOkno faults
511:06:11:653AMPlasmaOkno faults
611:27:08:013AMPlasmaOkno faults
711:49:24:623AMPlasmaOkno faults
812:12:41:310PMPlasmaOkno faults
912:34:58:420PMPlasmaOkno faults/plasma
1012:53:08:263PMPlasmaOkno faults/plasma
1101:11:51:297PMPlasmaBadOH1 overvolts flt,ef4 overvolts flt
1201:30:00:090PMPlasmaOkno faults
1301:47:57:687PMPlasmaOkNo faults
1402:19:30:750PMPlasmaOkno faults
1502:43:12:750PMPlasmaOkNo faults
1603:09:52:153PMPlasmaOkno faults
1703:33:46:543PMPlasmaOkno faults
1804:06:57:640PMPlasmaOkno faults
1904:51:55:983PMTestOkNo Power Test
2005:06:43:840PMPlasmaOkNo Plasma, Supplies okay