Alcator C-Mod Run 990727 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 1-13)

Operators
Session leader(s):Steve Wukitch
Physics operator(s):Earl Marmar
Engineering operator(s):Frank Silva

Engineering Operator Run Comment
MP#214/RF Conditioning/Marmer/Silva

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Physics Operator Summaries
Entered: Jul 7 2004 04:37:07:880PM
Author: To Be Determined
990727: MP214 -- RF conditioning

EO - Silva
PO - Marmar
SL - Wukitch

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Run Plan for 990727:

Start by loading 990520003 and make changes in equilibrium as necessary
to satisfy the RF group. If early disruptions continue to be a problem, try
backing off on Ip to 0.7 MA.

_________________________________________________________________________________

The run was plagued by short, disruptive shots, usually with hard x-rays. We
got one shot (8), to go through to the start of rampdown. It was a circular,
inner wall limited discharge. Jim Terry reported much higher iron levels than
normal. We stopped the run early, and began in-vessel inspections through
various windows to look for culprits. Subsequently, it was discovered that a
stainless steel capillary tube was drooping down from the top of the machine in
the vicinity of K-port.

No suitable RF target plasmas were produced.

On the positive side, the alternator cooling problem from last week was solved,
and we were not delayed between shots. The alternator was kept at speed 3.

Startup reliability was good. Shot 1 was the usual Tuesday OH coax test, and
shot 2 was a fizzle, requiring a small B_R tweak. Shots 3 through 13 all
reached at least 500 kA. There was a small segment 1 EF4 current tweak made
before shot 4.

Scorecard:

1 test
1 fizzle
11 plasmas

0 physics plasmas

13 data system cycles

Session Leader Comments
Jul 27 1999 08:38:35:560AMRejean Boivin
MP 214 RF conditioning
PO Earl Marmar
SL Steve Wukitch


Run Plan:

Bring up D and E to full available power as
of last friday.

Bring up separately 3 and 4 (J), then
move them up above 1 and 2, separately
and then try to run them together.

Variations in plasma conditions
should be minimal, we will keep an eye
on the H conc, outer gap and related factors.

Physics Operator Comments
Jul 27 1999 08:55:46:030AMEarl Marmarcoldstart

all matrices respond; no errors


Jul 27 1999 09:04:20:640AMEarl Marmar
Engineering Setup for 990727:

Power supplies as on 990520 [990520003]

Overnight ECDC in D2 prior to run. Stop at least 2 hours before start of
run.

Gas setup - fill B-top with 6 psi of D2 Hybrid enabled
fill B-side lower with 1 psi of Ar Hybrid enabled
fill B-side upper with 6 psi of H2 Hybrid DISABLED
fill C-side with 30 psi of D2 Hybrid enabled
leave J-bottom as is Hybrid DISABLED

The following gate valves should be enabled, assuming no vacuum problems:

ECE, VUV

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Run Plan for 990727: MP 214 -- RF conditioning

Start by loading 990520003 and make changes in equilibrium as necessary
to satisfy the RF group. If early disruptions continue to be a problem, try
backing off on Ip to 0.7 MA.
Jul 27 1999 09:26:35:123AM990727001Earl MarmarTuesday OH coax test

Resistance ok

Jul 27 1999 09:35:39:483AM990727002Earl MarmarLoad from 990520003

nl_04 to 1.1e20 from 1.0

add small differential gain to nl_04 feedback

reduce argon to 20 msec

B_R offset to .006

fizzle
Jul 27 1999 09:56:57:420AM990727003Earl MarmarB_R offset to .005

bouncer

some hards

disrupt at 148 ms
Jul 27 1999 10:07:08:293AM990727004Earl Marmaradd 15 A to EF4

better start

similar disruption
Jul 27 1999 10:43:28:403AM990727005Earl Marmarmore early gas; lasted slightly longer
Jul 27 1999 10:44:06:840AM990727006Earl Marmarprepuff to 22 msec

similar; disrupted slightly sooner
Jul 27 1999 10:52:31:280AM990727007Earl Marmarprepuff to 25;

similar shot; early disrupt
Jul 27 1999 11:14:44:450AM990727008Earl MarmarLoad a limited, circular shot (990520009) into segment 3

plasma; disrupt at start of rampdown
Jul 27 1999 11:24:49:840AM990727009Earl Marmarraise nl_04 to 1e20 in segment 3

disrupt at 140 ms
Jul 27 1999 11:52:22:500AM990727010Earl Marmarprepuff to 27 ms, add early gas, lower Ip early in segment 3

disrupt finally at 170
Jul 27 1999 12:06:47:327PM990727011Earl Marmarlower early gas puff; attempt to raise plasma 1 cm

disrupt at 125 ms
Jul 27 1999 02:21:24:233PM990727012Earl Marmarreload 990723003

B_R offset to .005

prepuff to 30 msec

short and brutish, with hards
Jul 27 1999 02:22:42:983PM990727013Earl Marmarreduce prepuff to 27 msec

similar short plasma

Engineering Operator Comments
ShotTimeTypeStatusComment
109:19:57:437AMTestOkOH 10KA Test OK
209:29:55:107AMPlasmaOkno faults
309:42:34:640AMPlasmaOkno faults
409:55:27:857AMPlasmaOkno faults
510:14:24:060AMPlasmaOkno faults
610:28:35:780AMPlasmaOkno faults
710:44:12:547AMPlasmaOkno faults
811:03:37:950AMPlasmaOkno faults
911:21:09:030AMPlasmaOkno faults
1011:36:12:857AMPlasmaOkno faults
1111:54:02:810AMPlasmaOkno faults
1212:40:03:950PMPlasmaOkno faults
1301:03:15:233PMPlasmaOk(null)