Alcator C-Mod Run 990126 Information

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Miniproposals
Miniproposal:206
Date Filed:12/31/1998
Title:Restart Operation: January 1999
First Author:Steve Wolfe
Session Leader:Steve Wolfe (shots 1-28)

Operators
Session leader(s):Steve Wolfe
Physics operator(s):Robert Granetz
Engineering operator(s):Bill Cochran,Gary Dekow,Frank Silva

Engineering Operator Run Comment
restart operation.Wolfe/Granetz,Rowan/Silva

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:18:727PM
Author: To Be Determined
Session Leader Summary for Tues. Jan 26, 1999

MP: 206 Restart Operations 1999
SL: wolfe
PO: granetz Asst. PO: Rowan
EO: Silva,Cochran,Dekow

This run was a continuation of the attempts to clean up the machine and get
plasmas. The goals (unstated in the run plan, but in my mind) were to get to
rampdown, and get two plasmas in a row. Those goals were not met, and only
small progress was made in cleanup. We got a total of three plasmas (4,10,and
24). The current was incresed to 560kA, and the pulse length only to .175sec.
Judging from the CII signal the machine was barely cleaner than on last
Friday, despite three days of ECDC. The loop voltage got down to 4V with flat
current.

On shot 14, the segment 4 program was modified to call for Ip=600kA and
nl4=6e19 flattop values in an effort to extend the pulse. However, the only
subsequent current rise shot (24) did no better than #10 in this
respect. Nevertheless, the lower current programming is recommended for the
next attempt.

The main problem appears to still be dirt. The CII level after breakdown is
still between .02 and .03mW?cm2/ster, as it was on Friday. Recovery after
successful current rises takes many shots. It is not clear that ECDC is going
to be sufficient to improve this situation in a reasonable length of time.

On the last couple of shots (see 27,28) the F21 flux loop failed to return to
baseline, by 30 to 50mWb. This is a symptom of an intermittant contact in the
connector. Probably as a result, the Br on these shots, went from being near
zero to -.002T. This is the same flux loop that appeared to be dead during
power tests, and was resurrected for the run on 990120. The present problem is
more subtle, but may be fixable (or breakable) by re-tightening the B-Bot#1
connector, as was done before.


Physics Operator Summaries
Entered: Jul 7 2004 04:36:59:863PM
Author: To Be Determined
Physics operator summary for run 990126.

MP 206 -- Restart Operation, 1999

SL: wolfe
PO: granetz (asst: Bill Rowan)

The goals for today are to:

Continue re-establishing plasma operation, i.e. longer duration plasmas,
higher current, more reliable breakdowns.

Summary: Little progress was made in improving machine performance today.
We had only three short plasmas (shots 4, 10, 24), and Ip was about
0.5 MA for these. Judging from the RGA, all three plasma shots
released a lot of crud from the walls. The CII emission was only
marginally improved from last Friday, even though we had 3 days of
ECDC. We tried tweaking Br and Bz and pre-fill, as well as adding
up to 1 volt of loop voltage to the OH's, but none of these things
made any obvious improvement.

On the last 2 or 3 shots, flux loop #21 showed signs of
a bad electrical contact, which probably contributed to a preceived
drift in Br. We'll check it carefully again tomorrow morning.

Scorecard: 3 plasmas
21 fizzles
3 duds (2 due to power supply faults)
1 test
----------
28 total

------------------------------------------------------------------------------

Engineering Setup for Tuesday, 990126

Load from 990122028 (last shot on Friday):

Overnight ECDC in D2 (as much as possible)

TF under hybrid control

Gas setup - fill B-top with 6 psi of D2 Hybrid enabled
fill B-side lower with 1 psi of Ar NOT hybrid enabled
fill C-side* with 30 psi of D2 Hybrid enabled

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

None. (ECE will be enabled after confirming its pressure is okay.)


*used to be K-side

-------------------------------------------------------------------------------
Run Plan:
-------------------------------------------------------------------------------
PCS setup as on 990122028 to begin with. Since the TCI is working, I've set
that wire back up by copying it from segment 2 (nl=1.0e20 m-2). This weekend's
ECDC should significantly improve plasma performance. Depending on our success
rate, we may want to exercise the option of between-shot-ECDC.

------------------------------------------------------------------------------

Note: overnight and overweekend ECDC in deuterium was done prior to
today's run.

Hybrid coldstart done; no errors found
($set default cmod$models:[hybrid.tcl]
$@hybinit_dispatch
$@show_bitbus_log
Use editor search to verify no occurrences of "error" nor
"not respond")
Reload 990122028 (last shot from last Friday)
Copy NL_04 from segment 2 to segment 4 and re-enable.
RF tree turned
RF feedback on RCUR is turned off (RF_LOAD_E = 0.0)

Shot 01 -- OH test (usual 10 kA Tuesday morning coax resistances test)
Resistances were "too low to measure" (J. Irby)

Next shot: try for plasma. Enable ECE gate valve.

Shot 02 -- Dud. No EF4. Checking DFOL's, etc.

Shot 03 -- Fizzle. Null was fair. CII reached 0.025 mW/cm^2/ster.
Steve W. noticed that there was a slight delay in the turnon of PG3.

Next shot: increase Br by 0.001 mT

Shot 04 -- Plasma. Ipmax=0.46 MA, duration=0.135 s. Vloop=5 volts. Lots
of junk on RGA after the shot. Br increased by 0.001 mT, as
requested.

Both before and after this shot, a LN2 valve to the top of the
TF magnet has been sticking. Cell access was granted following
this shot to work on the problem, and for several physicists as
well.

Next shot: no changes.

Shot 05 -- Fizzle. CII=0.03.

Next shot: no changes. VUV and Impurity injector gate
valves enabled.

Shot 06 -- Fizzle. CII=0.023. Null is okay.

Next shot: reduce pre-pulse puff width from 18 to 16 ms.

Shot 07 -- Dud, we think. Something went wrong with the STORE cycle, and
probably the INIT cycle as well. Many signals did not get
recorded. The shot # on the big board still says 06. Steve W.
noticed that the shot disk has filled up. According to the live
display, EF3 didn't fire.

Next shot: no changes.

There was a half-hour pause here while the shot disk was restored.

Shot 08 -- Fizzle.

Next shot: increase pre-pulse puff from 16 ms back to 18 ms.

Shot 09 -- Fizzle. CII=0.024. EF4 imbalance is getting more noticeable.
Jim Irby has just noticed that the cooling for EF4U was not set
properly. This is being remedied.

Next shot: no changes

Shot 10 -- Plasma. Ipmax=0.53 MA, disrupted at 0.17 s. Pretty bad hesitation
at 10 ms. RGA shows that a lot of stuff came off the walls on this
shot

Next shot: add about 0.4 loop volts at t=0.01 s (50 volts more on
OH1 and 10 volts more on OH2's. Also reduce pre-pulse gas puff
from 18 to 16 ms, in anticipation of more gas from walls.

Shot 11 -- Dud. All power supplies fired.

Next shot: return pre-pulse puff duration to 18 ms.

Shot 12 -- Fizzle. Null is fair.

Next shot: no changes.

Shot 13 -- Fizzle.

Next shot: increase pre-pulse puff duration from 18 to 20 ms.

Shot 14 -- Fizzle.

Next shot: keep segment 1 the same, but change segment 4 so that
the desired Ip is reduced from 0.8 to 0.6 MA, and the desired
density is reduced from nl_04=1.0 to 0.6e20 m-2. That way, in case
we get a plasma, we may be able to hold onto it longer.

Shot 15 -- Fizzle. Br is a touch high.

Next shot: reduce Br offset by 0.001 mT.

Shot 16 -- Fizzle. Maybe too little Br.

Next shot: put 0.5 mT back on Br, and reduce pre-puff to 18 ms.

Shot 17 -- Fizzle.

Next shot: make EF4 more negative by 10 amps.

Shot 18 -- Fizzle.

Next shot: reload segment 1 from shot 10 earlier today.

Shot 19 -- Fizzle. Looks like it tried to go, but bounced.

Next shot: repeat with no changes.

Shot 20 -- Fizzle, just barely and quite late. Very different from previous
shot. Flux signals look fine. Can't see a reason for the
difference. Fields look identical.

Next shot: repeat with no changes, while we scratch our heads.

Shot 21 -- Fizzle, another weak one.

Next shot: raise pre-puff from 18 to 23 ms.

Shot 22 -- Fizzle, slightly stronger.

Next shot: raise pre-puff to 26 ms.

Shot 23 -- Fizzle, weaker.

Next shot: reduce pre-puff to 20 ms and make Bz more negative (-15
amps to EF4).

Shot 24 -- Plasma. Ipmax=0.48 MA, disrupted at t=0.17 s. X-ray arrays show
good, stable position until final disruption.

Next shot: increase pre-puff from 20 to 22 ms.

Shot 25 -- Fizzle.

Next shot: add another -15 amps to EF4, and increase pre-puff from
22 to 25 ms.

Shot 26 -- Fizzle, weak one. Not enough Bz

Next shot: add 15 amps back to EF4, and reduce pre-puff to 22 ms.

Shot 27 -- Fizzle. Br was -2 mT. F21 has an offset.

Next shot: raise OH voltages by 100 volts on OH1 and 20 volts on
OH2. This will be the last shot today.

Shot 28 -- Fizzle. F21 has a larger offset.

End of run

Session Leader Comments
Jan 26 1999 07:53:50:967AMSteve WolfeRun Plan and Engineering Setup for Tuesday, 990126

MP: 206 Restart Operation, 1999
SL: wolfe
PO: granetz (asst: Bill Rowan)

-------------------------------------------------------------------------------
Engineering setup:
-------------------------------------------------------------------------------
Load from 990122028 (last shot on Friday):

Overnight ECDC in D2 (as much as possible)

TF under hybrid control
Gas setup - fill B-top with 6 psi of D2 Hybrid enabled
fill B-side lower with 1 psi of Ar NOT hybrid enabled
fill "K-side"* with 30 psi of D2 Hybrid enabled

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

None. (ECE will be enabled after confirming its pressure is okay.)


* Note that this valve is physically on C-side now, but the PLC screen is
not updated yet.

-------------------------------------------------------------------------------
Run Plan:
-------------------------------------------------------------------------------
PCS setup as on 990122028 to begin with. If the TCI is working, we'll set
that wire back up. This weekend's ECDC should significantly improve plasma
performance. Depending on our success rate, we may want to exercise the option
of between-shot-ECDC.
Jan 26 1999 07:54:49:170AMSteve WolfeAt Wukitch's request, I set the RF tree to /INCLUDE (using the Cmod_manage utility)
for this run.
Jan 26 1999 09:04:46:687AM990126001Steve Wolfeshot#1: Tuesday test - ok
Jan 26 1999 09:12:55:590AM990126002Steve Wolfeshot#2: plasma attempt
dud - no ef4
Jan 26 1999 09:54:09:530AM990126003Steve Wolfeshot#3: Delay for some problems with CRYO PLC.
fizzle. negative br, CII=.026
PG3 output signal didn't turn on until .073sec, Mout is at .028sec. Looks like a PLC timing problem
Jan 26 1999 10:47:13:840AM990126004Steve Wolfeshot#4: Br increase by .001.
Another, unrelated cryo delay: the Q1 valve is stuck open.

plasma 400ka to 130msec
CII=.02 but it burns out.
Loop voltage around 5-6V.
Earl says there was H on this one.
Jan 26 1999 11:08:07:030AM990126005Steve Wolfeshot#5: repeat. base=1.9e-7
fizzle. CII=.029, Z-meter is double humped
Jan 26 1999 11:23:05:357AM990126006Steve Wolfeshot #6: repeat. base=1.4e-7
fizzle. CII=.023
Jan 26 1999 12:16:50:793PM990126007Steve Wolfeshot #7: reduce pre-puff by 2msec. base=1.3e-7
dud. No bus rogowski data
No updates coming through. Shot number did not increment on big board.
Something bad happened to the sequence.

There are no free blocks on cmod$new_shots!
Tom is working on it.
Jan 26 1999 12:15:50:483PM990126008Steve Wolfeshot #8: Tom has cleared off the disk. Go again. base=1.0e-7
fizzle. late bd. 8.7msec ; CII=0.023
EF4 has a +60A imbalance, but Br doesn't look bad.
May need to put the gas back.
Jan 26 1999 12:29:16:857PM990126009Steve Wolfeshot #9: pre-puff up by 2msec (to 18ms again)
fizzle. bd at 7.7msec, still an imbalance in EF4's.
EF4U was on auto instead of manual cooling. Put back for next shot.
Jan 26 1999 12:45:23:077PM990126010Steve Wolfeshot #10: Leave EF4 programming alone until we see what the cooling can do.
plasma: 560kA, 0.17sec
bad hesitation at 10-18msec.
Jan 26 1999 12:56:57:043PM990126011Steve Wolfeshot #11: OH voltage tweaks to fix (?) hesitation.
reduce gas puff.
Prior to this shot the logbook saeemed to hang for several minutes, then updated.

dud.
Jan 26 1999 02:50:31:623PM990126011Steve Wolfeshot #11: OH voltage tweaks to fix (?) hesitation.
reduce gas puff.


Jan 26 1999 01:17:42:357PM990126012Steve Wolfeshot #12: put back the gas. base=2.5e-7
fizzle. CII=.024.
Jan 26 1999 01:32:16:750PM990126013Steve Wolfeshot #13: bang away. base=2.1e-7
fizzle. CII=0.03
Jan 26 1999 01:46:38:937PM990126014Steve Wolfeshot #14: raise the gas a bit. base=1.8e-7
fizzle. bd 6.5msec, CII=0.028

Next shot, set up for 600kA, 6e19 flattop; try to hold it a little better when (if) we get a plasma
again.

Jan 26 1999 02:03:31:123PM990126015Steve Wolfeshot #15: base=1.6e-7
fizzle. CII=.027, z-meter still lumpy
Jan 26 1999 02:15:36:357PM990126016Steve Wolfeshot #16: br 1mT more negative. GV3 open between shots. base=1.5e-7
fizzle. br looks negative.

Jan 26 1999 02:28:15:750PM990126017Steve Wolfeshot #17: put back .5mT, lower gas. base=1.3e-7
fizzle, got a little current this time.
CII=.024. bd = 7.4msec

Bob wants to do a bz tweak.
Jan 26 1999 02:45:01:263PM990126018Steve Wolfeshot #18: 10A more negative on EF4. base=1.4e-7, up to 1.9e-7 during check. Somebody's gate valve?

fizzle. Very similar to 17.
CII=.023, slight burnout on z-meter before second lump.

Jan 26 1999 03:00:59:590PM990126019Steve Wolfeshot #19: reload seg 1 from shot 10. base=1.2e-7
fizzle. br a little positive, bd=6.9msec
CII=0.02 on first peak, then a bounce
Looks like it's moving inside, which would say put back the voltage on OH1.

Leave it for one more.
Jan 26 1999 03:19:34:123PM990126020Steve Wolfeshot #20: no changes
weak fizzle. very late, weak signals on CII, Ha, nothing on z-meter.
Jan 26 1999 03:28:05:420PM990126021Steve Wolfeshot #21: repeat, in great puzzlement. base=1.0e-7
fizzle. late bd 12.8msec on z-meter, CII=0.011

raise the fill?
Jan 26 1999 03:41:47:670PM990126022Steve Wolfeshot #22: increase gas puff to 23msec. base=1.0e-7
bd at 7.0msec, CII=.02, 43ka

Better, but why?
Jan 26 1999 03:53:06:123PM990126023Steve Wolfeshot #23: increase gas again.
fizzle. worse current, br is negative, bz a little positive.


Jan 26 1999 04:13:20:293PM990126024Steve Wolfeshot #24: 15A more negative on ef4.
plasma, similar to 10, but only 470kA, gets to 0.175sec, still around 4V
bd at 5.5msec, CII=.019
Jan 26 1999 04:23:56:450PM990126025Steve Wolfeshot #25: raise the fill.
fizzle (surprise!) CII=.023, bd at 5 msec
Jan 26 1999 04:40:55:857PM990126026Steve Wolfeshot #26: another 15a on ef4, raise fill again.
weak fizzle, bd@6msec, CII=0.024, bz too negative.

Jan 26 1999 04:57:27:937PM990126027Steve Wolfeshot #27: Drop gas, make ef4 15amps more positive.
fizzle. Br is now very negative. late bd 8.8msec. Ef4 balance looks ok though. ??

Try a big OH voltage tweak next shot (last shot of the day).
Jan 26 1999 05:12:46:920PM990126028Steve Wolfeshot #28: 100V more positive on Voh1, 20V on OH2, from .005 to .010
fizzle. Br = -.002, bd at 7.8msec., CII=0.032

F21 has a -.05Wb baseline error. It overshoots zero after the pulse.
This may be the cause of the BR error. F21 may be in trouble again (intermitant connection).

Physics Operator Comments
Jan 26 1999 09:38:00:750AM990126001Robert GranetzShot 01 -- OH test (usual 10 kA Tuesday morning coax resistances test)
Resistances were "too low to measure" (J. Irby)

Next shot: try for plasma. Enable ECE gate valve.
Jan 26 1999 09:38:38:793AM990126002Robert GranetzShot 02 -- Dud. No EF4. Checking DFOL's, etc.
Jan 26 1999 09:54:47:920AM990126003Robert GranetzShot 03 -- Fizzle. Null was fair. CII reached 0.025 mW/cm^2/ster.
Steve W. noticed that there was a slight delay in the turnon of PG3.

Next shot: increase BR by 0.001 mT
Jan 26 1999 10:48:20:653AM990126004Robert GranetzShot 04 -- Plasma. Ipmax=0.46 MA, duration=0.135 s. Vloop=5 volts. Lots
of junk on RGA after the shot. Br increased by 0.001 mT, as
requested.

Both before and after this shot, a LN2 valve to the top of the
TF magnet has been sticking. Cell access was granted following
this shot to work on the problem, and for several physicists as
well.

Next shot: no changes.
Jan 26 1999 11:07:25:810AM990126005Robert GranetzShot 05 -- Fizzle. CII=0.03.

Next shot: no changes. VUV and Impurity injector gate
valves enabled.
Jan 26 1999 11:25:22:060AM990126006Robert GranetzShot 06 -- Fizzle. CII=0.023. Null is okay.

Next shot: reduce pre-pulse puff width from 18 to 16 ms.
Jan 26 1999 12:17:05:577PM990126007Robert GranetzShot 07 -- Dud, we think. Something went wrong with the STORE cycle, and
probably the INIT cycle as well. Many signals did not get
recorded. The shot # on the big board still says 06. Steve W.
noticed that the shot disk has filled up. According to the live
display, EF3 didn't fire.

Next shot: no changes.
Jan 26 1999 12:16:12:500PM990126008Robert GranetzShot 08 -- Fizzle.

Next shot: increase pre-pulse puff from 16 ms back to 18 ms.
Jan 26 1999 12:31:17:077PM990126009Robert GranetzShot 09 -- Fizzle. CII=0.024. EF4 imbalance is getting more noticeable.
Jim Irby has just noticed that the cooling for EF4U was not set
properly. This is being remedied.

Next shot: no changes
Jan 26 1999 12:53:15:013PM990126010Robert GranetzShot 10 -- Plasma. Ipmax=0.53 MA, disrupted at 0.17 s. Pretty bad hesitation
at 10 ms. RGA shows that a lot of stuff came off the walls on this
shot

Next shot: add about 0.4 loop volts at t=0.01 s (50 volts more on
OH1 and 10 volts more on OH2's. Also reduce pre-pulse gas puff
from 18 to 16 ms, in anticipation of more gas from walls.
Jan 26 1999 01:00:44:653PM990126011Robert GranetzShot 11 -- Dud. All power supplies fired.

Next shot: return pre-pulse puff duration to 18 ms.
Jan 26 1999 01:17:13:030PM990126012Robert GranetzShot 12 -- Fizzle. Null is fair.

Next shot: no changes.
Jan 26 1999 01:33:54:187PM990126013Robert GranetzShot 13 -- Fizzle.

Next shot: increase pre-pulse puff duration from 18 to 20 ms.
Jan 26 1999 01:51:12:890PM990126014Robert GranetzShot 14 -- Fizzle.

Next shot: keep segment 1 the same, but change segment 4 so that
the desired Ip is reduced from 0.8 to 0.6 MA, and the desired
density is reduced from nl_04=1.0 to 0.6e20 m-2. That way, in case
we get a plasma, we may be able to hold onto it longer.
Jan 26 1999 02:03:31:090PM990126015Robert GranetzShot 15 -- Fizzle. Br is a touch high.

Next shot: reduce Br offset by 0.001 mT.
Jan 26 1999 02:16:55:827PM990126016Robert GranetzShot 16 -- Fizzle. Maybe too little Br.

Next shot: put 0.5 mT back on Br, and reduce pre-puff to 18 ms.
Jan 26 1999 02:29:31:780PM990126017Robert GranetzShot 17 -- Fizzle.

Next shot: make EF4 more negative by 10 amps.
Jan 26 1999 02:59:31:937PM990126019Robert GranetzShot 19 -- Fizzle. Looks like it tried to go, but bounced.

Next shot: repeat with no changes.
Jan 26 1999 03:21:16:750PM990126020Robert GranetzShot 20 -- Fizzle, just barely and quite late. Very different from previous
shot. Flux signals look fine. Can't see a reason for the
difference.

Next shot: repeat with no changes, while we scratch our heads.
Jan 26 1999 03:41:36:780PM990126022Robert GranetzShot 22 -- Fizzle, slightly stronger.

Next shot: raise pre-puff to 26 ms.
Jan 26 1999 03:52:28:420PM990126023Robert GranetzShot 23 -- Fizzle, weaker.

Next shot: reduce pre-puff to 20 ms and make Bz more negative (-15
amps to EF4).
Jan 26 1999 04:13:22:793PM990126024Robert GranetzShot 24 -- Plasma. Ipmax=0.48 MA, disrupted at t=0.17 s. X-ray arrays show
good, stable position until final disruption.

Next shot: increase pre-puff from 20 to 22 ms.
Jan 26 1999 04:29:23:750PM990126025Robert GranetzShot 25 -- Fizzle.

Next shot: add another -15 amps to EF4, and increase pre-puff from
22 to 25 ms.
Jan 26 1999 04:41:35:920PM990126026Robert GranetzShot 26 -- Fizzle, weak one. Not enough Bz

Next shot: add 15 amps back to EF4, and reduce pre-puff to 22 ms.
Jan 26 1999 04:55:46:810PM990126027Robert GranetzShot 27 -- Fizzle. Br was -2 mT. F21 has an offset.

Next shot: raise OH voltages by 100 volts on OH1 and 20 volts on
OH2. This will be the last shot today.
Jan 26 1999 05:04:40:357PM990126028Robert GranetzShot 28 -- Fizzle. F21 has a larger offset.

Engineering Operator Comments
ShotTimeTypeStatusComment
108:59:11:200AMTestOkoh coax test
209:10:29:543AMPlasmaBadno ef4
309:40:22:293AMPlasmaOkno faults
410:31:09:607AMPlasmaOkno faults, fizzel
510:54:36:140AMPlasmaOkno faults
611:18:23:153AMPlasmaOkno faults
812:06:39:467PMPlasmaOkNo faults
912:21:48:107PMPlasmaOkNo faults
1012:38:00:467PMPlasmaOkNo faults
1112:55:20:670PMPlasmaOkNo faults
1201:11:21:483PMPlasmaOkNo faults
1301:25:30:653PMPlasmaOkNo Faults
1401:41:25:857PMPlasmaOkNo Faults
1501:57:19:687PMPlasmaOkNo Faults
1602:10:28:200PMPlasmaOkNo Faults
1702:23:35:670PMPlasmaOkNo Faults
1802:38:41:687PMPlasmaOkNo Faults
1902:51:50:983PMPlasmaOkNo Faults
2003:04:38:060PMPlasmaOkNo Faults
2103:21:19:140PMPlasmaOkNo Faults
2203:34:55:857PMPlasmaOkNo faults
2303:48:22:810PMPlasmaOkNo Faults
2404:01:32:607PMPlasmaOkNo Faults
2504:15:50:327PMPlasmaOkNo Faults
2604:28:50:920PMPlasmaOkNo Faults
2704:41:59:903PMPlasmaOkNo Faults
2804:58:07:280PMPlasmaOkNo Faults