Alcator C-Mod Run 960814 Information

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Miniproposals
Miniproposal:148
Date Filed: 7/16/1996
Title:RF Conditioning and Testing
First Author:Yuichi Takase
Session Leader:Yuichi Takase (shots 1-36)
Miniproposal:159a
Date Filed: 7/29/1996
Title:Restart Operation: August 1996
First Author:Steve Wolfe
Session Leader:Yuichi Takase (shots 1-36)

Operators
Session leader(s):Yuichi Takase,Yuichi Takase
Physics operator(s):John Goetz
Engineering operator(s):Frank Silva,Joe Daigle

Engineering Operator Run Comment
preboron fiducials/goetz/marmer/silva/ps supply tests

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Physics Operator Summaries
Entered: Jul 7 2004 04:36:56:440PM
Author: To Be Determined
Physics operator summary for 960814

EO: Silva / Daigle
PO: Goetz
SL: Marmar

Run 960814 was in support of Mini-Proposal #159A - Restart Alcator C-Mod and
Mini-Proposal #148 - RF Conditioning. The goals for today are to try and get
C-Mod operational once again. If indeed acceptable plasmas are produced,
check-out of diagnostics and RF conditioning will be done.

Plan:
power supply tests
OH test
run an old shot with standard precharge on the ohmic stack and
with the EF4's in series
twiddle gas and fields until reproducible
continue until the day is over

The plan was not carried out. No plasmas were obtained.

Some things discovered today:
1) Scans of Br, Bz, and fill pressure were performed. The flux plots and
the reconstructed vacuum magnetic signals looked comparable to those
obtained on 960105. Thus the string of duds and fizzles remains
unexplained.
2) The B-Top piezoelectric valve is linear (P_0[Torr] = 2.9E-6 * PG4[msec])
with 5.5PSIA of deuterium.
3) Breakdown studies clearly are needed.

Engineering, computing, and diagnostics today: Many TF crowbars occurred late
in the day which are still in under investigation. The first TF crowbar
happened with the EF4's in series. A hangup was encountered when the
system disk was full.

Scorecard: 36 shots = 0 plasmas + 13 fizzles + 5 tests + 18 duds

Shot summary for Run 960814:

Load 960105009
remove 100V point at t=0 from PG3
prefill puff = 18msec
coldstart hybrid - all matrices respond

Shot change result
____ _____ ______
1 OH coax test o.k.

2 load 960105009, remove 100V dud - radial field = 2mT
pulse from PG3 at t=0

3 BR_0 offset = .006 fizzle - Bz in too early

4 prefill pulse = 15msec; dud - too little gas?? - Bz in too early??
BR_0 = .0055

5 PG4 width = 17msec; BR_0 = .005 dud - Bz in too early

6 BR_0 offset = .006; IC_EF4 = fizzle - z_meter array says light is centered
-1180A

7 PG3 starting at .02sec fizzle - camera says the light is inside

8 IC_EF4 = -1190A fizzle - weak one

9 fill pulse = 15msec fizzle - 30kA - no current channel

10 fill pulse = 13msec fizzle - very weak - no density

11 fill pulse = 15msec; BR_0=.005 fizzle - .07MA - current channel
moves in - Br very positive at .02sec

12 V_OH1 = 200V from .005 to .015s magnet resistance fault

13 try again fizzle - weak - no current channel

14 prefill = 16msec fizzle - Br too low?

15 BR_0=.0055T; V_OH1=175V dud - Br too high

16 BR_0 = .0045 fizzle - late breakdown

17 BR_0 = .0035 dud - Br too negative

18 BR_0=.0045; V_OH1=225V dud - Br too negative

19 reload 960814011 dud - ?????

20 BR_0=.0055; prefill = 17msec fizzle - breakdown @ 7msec

21 prefill = 19msec fizzle - weak - late breakdown

22 IC_EF4 = -1180A dud

23 IC_EF4=-1190A; prefill 13msec dud

24 prefill 21msec dud

25 prefill 17msec; BR_0=.005; dud
IC_EF4=-1200A

26 prefill 26msec TF crowbar before commutation

27 try again TF crowbar before commutation

28 try again TF crowbar before commutation

29 try again TF crowbar before commutation

30 try again fizzle - breakdown @ 7msec

31 prefill 18msec, PG3 on at 8msec dud - fields look o.k.

32 prefill 24mc; PG3 on at -10ms; TF crowbar before commutation
EF4's in parallel

33 try again, EF3 off TF crowbar before commutation

34 try again, EF3 off TF crowbar eliminated (low voltage)

35 test again, EF3 off TF crowbar before commutation

36 test again, EF3 off TF crowbar

Session Leader Comments
Aug 14 1996 08:55:01:850AM960814002Earl MarmarPlasma attempt. Series EF4, 18 msec gas pre-pulse;
Dud
Possibly too much radial field (~2 mT at t=0)

Aug 14 1996 09:07:38:350AM960814003Earl Marmarchange B_r offset, from 7 to 6 mT
fizzle

Aug 14 1996 09:16:01:760AM960814004Earl Marmarchange B_r offset, from 6 to 5.5 mT
gas prepulse to 15 ms (from 18)
dud

Aug 14 1996 09:25:34:240AM960814005Earl Marmarchange B_r offset, from 5.5 to 5 mT
gas prepulse to 17 ms
dud

Aug 14 1996 09:42:48:640AM960814006Earl Marmarchange B_r offset, from 5 to 6 mT
gas prepulse still 17 ms
add -30 A to EF4
fizzle

Aug 14 1996 09:52:59:220AM960814007Earl Marmargas prepulse still 17 ms
delay PG3
fizzle

Aug 14 1996 10:12:43:450AM960814008Earl Marmaradd -10 A to EF4
fizzle

Aug 14 1996 10:25:31:190AM960814009Earl Marmarlower prepuff to 15 ms
fizzle

Aug 14 1996 10:33:59:320AM960814010Earl Marmarlower prepuff to 13 ms
fizzle (very weak)

Aug 14 1996 10:56:39:880AM960814011Earl Marmarraise prepuff to 15 ms
B_r offset to 5 mT from 6 mT
70 kA fizzle

Aug 14 1996 11:04:01:950AM960814012Earl Marmaradd 50 V to OH1 (to slow the B_z ramp)
power supply dud (probable magnet resistance fault)

Aug 14 1996 11:15:57:060AM960814013Earl Marmarre-try
fizzle

Aug 14 1996 11:36:27:650AM960814014Earl Marmarprepuff to 16 ms from 15 (gasheads will be gasheads)
fizzle

Aug 14 1996 11:56:01:150AM960814015Earl MarmarB_r to 5.5 from 5
undo OH1 voltage change
dud

Aug 14 1996 12:12:56:650PM960814016Earl MarmarB_r to 4.5 from 5.5
60 kA fizzle

Aug 14 1996 12:35:12:720PM960814017Earl MarmarB_r to 3.5 from 4.5
dud

Aug 14 1996 12:35:29:120PM960814018Earl MarmarB_r to 4.5 from 3.5
dud

Aug 14 1996 01:03:15:120PM960814019Earl Marmarreload shot 11
dud

Aug 14 1996 01:12:03:930PM960814020Earl Marmarpre-puff to 17 ms from 15 ms
B_r offset to 5.5 from 5 mT
fizzle

Aug 14 1996 01:25:56:830PM960814021Earl Marmarpre-puff to 19 from 17 ms
fizzle

Aug 14 1996 01:47:43:950PM960814022Earl Marmarsubtract -10 A from EF4 to -1180
dud

Aug 14 1996 01:57:54:930PM960814023Earl MarmarEF4 to -1190
pre-puff to 13 ms
dud

Aug 14 1996 02:12:42:760PM960814024Earl Marmarpre-puff to 21 ms
dud

Aug 14 1996 02:22:35:170PM960814025Earl MarmarB_r offset to 5 mT
add -10 A to EF4
pre-puff to 17 ms
dud

Physics Operator Comments
Aug 14 1996 07:57:54:310AMJohn GoetzRun 960814

In support of mini-proposal 159A - Restart Alcator C-Mod and
mini-proposal 148 - RF Conditioning

Start from an old shot (960105009) with the EF4's in series and the
standard precharge scenario

Tweak until the plasmas are reproducible

Aug 14 1996 08:31:11:660AM960814001John GoetzShot 960814001:
OH coax test

Results:
all o.k.

Aug 14 1996 08:53:00:940AM960814002John GoetzShot 960814002:
load 960105009
remove 100V point @ t=0 from PG3

Results:
dud
radial field = .002T @ 0; too much OH2U

Aug 14 1996 09:04:48:380AM960814003John GoetzShot 960814003:
BR_0 offset = .006 (was .007)

Results:
fizzle
fairly weak discharge
Bz in too early?

Aug 14 1996 09:18:06:560AM960814004John GoetzShot 960814004:
lower prefill pulse to 15msec (was 18msec)
BR_0 offset = .0055

Results:
dud
fill pressure = 4.2e-5
Br >= 1mT

Aug 14 1996 09:26:19:620AM960814005John GoetzShot 960814005:
raise prefill pulse to 17msec
BR_0 offset = .005

Results:
dud
Bz = 12mT @ 3msec (was 9mT @ 3msec on 960105009)

Aug 14 1996 09:45:32:510AM960814006John GoetzShot 960814006:
BR_0 offset = .006
IC_EF4 = -1180A (was -1150A)

Results:
fizzle
Z-meter array shows the light is centered but no current
channel formation on the GPC

Aug 14 1996 09:54:15:800AM960814007John GoetzShot 960814007:
slide PG3 to start at .020

Results:
fizzle
camera says the light remains to the inside

Aug 14 1996 10:08:23:710AM960814008John GoetzShot 960814008:
IC_EF4 = -1190A

Results:
fizzle - a weak one

Aug 14 1996 10:22:41:270AM960814009John GoetzShot 960814009:
fill pulse = 15 msec

Results:
fizzle - 30kA - no current channel formation

Aug 14 1996 10:35:07:450AM960814010John GoetzShot 960814010:
fill pulse = 13 msec

Results:
fizzle - very weak
late breakdown - almost a dud
no density - no visible light signals

Aug 14 1996 10:57:54:550AM960814011John GoetzShot 960814011:
fill pulse = 15 msec
BR_0 = .005

Results:
fizzle - .070MA
current channel formation - moves in
radial field very positive at .02sec

Aug 14 1996 11:00:19:520AM960814012John GoetzShot 960814012:
V_OH1 = 200V from .005 to .015sec

Results:
magnet resistance fault

Aug 14 1996 11:13:43:740AM960814013John GoetzShot 960814013:
V_OH1 = 200V from .005 to .015sec

Results:
fizzle - weak - no current channel

Aug 14 1996 11:41:39:380AM960814014John GoetzShot 960814014:
prefill pulse = 16msec

Results:
fizzle - breakdown @ .008
Br a little too low?

Aug 14 1996 11:55:31:700AM960814015John GoetzShot 960814015:
BR_0 = .0055
V_OH1 = 175V

Results:
dud
Br too positive according to the recon scope

Aug 14 1996 12:11:20:800PM960814016John GoetzShot 960814016:
BR_0 = .0045

Results:
fizzle - .06MA
late breakdown
Br rises to 4mT after breakdown - was 2mT on good shots

Aug 14 1996 12:24:23:310PM960814017John GoetzShot 960814017:
BR_0 = .0035

Results:
dud
radial field too negative

Aug 14 1996 12:38:07:470PM960814018John GoetzShot 960814018:
BR_0 = .0045
V_OH1 = 225V from .005 to .015

Results:
dud - Br still too negative

Aug 14 1996 01:03:02:150PM960814019John GoetzShot 960814019:
punt - reload 960814011 with no changes

Results:
dud - explain that one

Aug 14 1996 01:11:00:520PM960814020John GoetzShot 960814020:
BR_0 offset = .0055
prefill puff = 17msec

Results:
fizzle - breakdown @ ~7msec

Aug 14 1996 01:23:10:520PM960814021John GoetzShot 960814021:
prefill puff = 19msec

Results:
fizzle - weak - late breakdown

Aug 14 1996 01:44:12:870PM960814022John GoetzShot 960814022:
IC_EF4 = -1180A

Results:
dud

Aug 14 1996 01:56:49:690PM960814023John GoetzShot 960814023:
IC_EF4 = -1190A
prefill puff = 13msec

Results:
dud

Aug 14 1996 02:12:24:240PM960814024John GoetzShot 960814024:
prefill puff = 21msec

Results:
dud

Aug 14 1996 02:32:58:790PM960814025John GoetzShot 960814025:
prefill puff = 17msec
BR_0 = .005
IC_EF4 = -1200A

Results:
dud

Aug 14 1996 02:46:37:970PM960814026John GoetzShot 960814026:
prefill puff = 26msec

Results:
TF crowbar before commutation

Aug 14 1996 03:01:03:650PM960814027John GoetzShot 960814027:
prefill puff = 26msec

Results:
TF crowbar early

Aug 14 1996 03:26:11:160PM960814028John GoetzShot 960814028:
prefill puff = 26msec

Results:
TF crowbar before commutation

Aug 14 1996 03:55:16:300PM960814029John GoetzShot 960814029:
prefill puff = 26msec

Results:
TF crowbar early

Aug 14 1996 03:58:32:990PM960814030John GoetzShot 960814030:
prefill puff = 26msec
purge and refill B_TOP to 5.5PSIA of D2

Results:
fizzle - breakdown at 7msec

Aug 14 1996 04:17:15:790PM960814031John GoetzShot 960814031:
prefill puff = 18msec
move PG3 to 8msec

Results:
dud - fields look o.k.

Aug 14 1996 04:30:33:350PM960814032John GoetzShot 960814032:
prefill puff = 24msec
move PG3 to -10msec
EF4's in parallel

Results:
TF crowbar before commutation

Aug 14 1996 04:44:55:240PM960814033John GoetzShot 960814033:
prefill puff = 24msec
move PG3 to -10msec
EF4's in parallel

Results:
TF crowbar before commutation

Aug 14 1996 05:04:30:710PM960814034John GoetzShot 960814034 - 36:
engineering tests for the TF crowbar problem

Engineering Operator Comments
ShotTimeTypeStatusComment
108:29:05:660AMTestOkoh test
208:41:35:480AMTestOkno faults
308:55:12:230AMTestOkno faults
409:09:53:400AMTestOkno faults
509:20:22:800AMTestOkno faults
609:32:15:780AMTestOkno faults
709:46:35:820AMTestOk
809:59:19:780AMTestOk
910:13:50:950AMTestOkno faults
1010:28:35:700AMTestOkno faults
1110:43:24:040AMTestOk
1210:58:08:860AMPlasmaOkno 13.8 power supplies operated
1311:04:41:900AMPlasmaOk
1411:28:08:210AMPlasmaOkno faults
1511:49:10:980AMPlasmaOkno faults
1612:03:54:350PMPlasmaOkno faults
1712:18:24:580PMPlasmaOkno faults
1812:33:00:700PMPlasmaOkno faults
1912:49:07:400PMPlasmaOkno faults
2001:03:50:320PMPlasmaOkno faults
2101:18:34:510PMPlasmaOkno faults
2201:33:12:030PMPlasmaOk
2301:49:30:100PMPlasmaOk
2402:06:28:060PMPlasmaOk
2502:20:30:550PMPlasmaOkno faults
2602:35:21:510PMPlasmaBadTF Cbar
2702:58:26:270PMPlasmaBadTF C-bar
2803:12:47:860PMPlasmaBadTF c-bar
2903:30:25:740PMTestOkC-bar TF
3003:48:22:480PMTestOk
3104:05:53:110PMTestOk
3204:27:05:840PMTestBadtf xbar
3304:38:11:020PMTestOk
3404:52:41:100PMTestOk
3504:59:34:710PMTestOk
3605:07:23:750PMTestOk