Alcator C-Mod Run 970523 Information

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Miniproposals
Miniproposal:170a
Date Filed: 5/13/1997
Title:Restart Operation: May 1997
First Author:Robert Granetz
Session Leader:Steve Wolfe (shots 1-25)

Operators
Session leader(s):Steve Wolfe
Physics operator(s):John Goetz
Engineering operator(s):Frank Silva

Engineering Operator Run Comment
MP170 Startup/Goetz/Silva

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Physics Operator Summaries
Entered: Jul 7 2004 04:36:57:287PM
Author: To Be Determined
Physics operator summary for 970523

EO: Silva
PO: Goetz
SL: Wolfe

Run 970523 was in support of Mini-Proposal #170 - Restart Alcator C-Mod
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:
EF3 power supply tests
start with 970521050 and try to make plasmas until the day is over

Plasmas were obtained. A string of six full length shots was obtained. Unfortunately, this
string was terminated with five straight duds. The nulls on these duds were not that bad
compared to the nulls from earlier in the day. A nearly full current disruption occured on
the shot that ended the string and may have been in some mysterious way responsible for the
end of good plasmas. The toroidal field was brought under hybrid without incident and the
flat-tops of 4.1T were obtained from shot 14 to shot 19. The behavior of puffed argon was
different today than in previous run campaigns; the puff was actually being pumped out from
the discharge. Some data were obtained from the x-point Thomson scattering system. The RF
group started some work during this run.

Engineering, computing, and diagnostics today: The trouble with the EF3 breaker was fixed
before the run. A voltage comparator power supply needed to be replaced in order
for the supply to work correctly. Two duds were engineering related; one because
the EF2's were off and the second when the TF did not come on. Some CAMAC errors
but nothing compared to the last few days.

Scorecard: 25 shots = 10 plasmas + 6 fizzles + 5 duds + 2 tests + 2 p.s. duds

Shot summary for Run 970523:

Load 970521050
coldstart hybrid - all matrices respond

Shot change result
____ _____ ______
1 EF3 supply test nothing appears at the supply; breaker out before pulse happened

2 EF3 supply test voltage comparator power supply replaced; looks o.k.

3 load 970521050 dud - no EF2's

4 try again fizzle; Br a little negative?

5 prefill puff = 30ms; BR_0 fizzle; Br not positive enough
offset = .0055

6 BR_0 offset=.0065; prepuff = fizzle; Bz not coming in fast enough
24ms

7 RCUR offset=6850;IC_EF4=-1305A; plasma; disrupts @ .235; dirty; breakdown @ .006; Bz
prefill puff = 20ms in very quickly

8 IC_EF4=-1315A; base pressure fizzle; breakdown @ .005; a little bitty plasma
high - 1.1e-6

9 no chnages plasma; breakdown @ .007; disrupts during rampdown

10 enable 40ms argon puff plasma; breakdown @ .006; disrupts during rampdown;
density rise presumably due to argon puff and sputtering

11 30ms argon puff fizzle; breakdown @ .0055; bounced twice

12 IC_EF4=-1310A plasma; disrupts during rampdown; breakdown @ .005 with
a nice current rise

13 35ms argon puff fizzle; breakdown @ .009; null looks o.k.

14 TF current = -150kA under plasma; disrupts during rampdown; breakdown @ .006
hybrid control

15 TF current from -150kA to plasma; disrupts during rampdown; breakdown @ .006;
-113kA from 0.35 to 0.65s TF ramps down to 4.1T by .8s

16 ramp TF current from .25->.5s plasma; disrupts during rampdown (a little later);
breakdown @ .006 but with a weak current rise

17 TF ramp from .25 to .45; plasma; disrupts during rampdown (a little sooner);
slowdown CLEARIN even more; breakdown @ .005 but with a hesitation; TF flattens
2nd Ar puff @ .7 for 15ms by 0.66s

18 TF ramp from .25 to .4; 3rd plasma; disrupts earlier in rampdown
argon puff @ .5s

19 TF invert to 1.3s; 4th argon plasma; disrupts @ 1.14s; loop voltage nearly 2V
puff @ .9s

20 TF current @ -108kA; only one dud; null looks very good; must be out of gas?
argon puff

21 prefill = 25ms dud; not enough Br and too much Bz

22 IC_EF4 = -1315A; BR_0 offset dud; too much Br now;
is .0075;

23 BR_0=.007; prefill puff = 30ms dud; too much Bz?; what is wrong here?

24 IC_EF4=-1320A dud; ?????????????

25 IC_EF4=-1335A; Br offset = dud; no TF
.0075; prefill puff =22ms

Session Leader Comments
May 23 1997 12:56:21:340PMSteve WolfeIrby reports that last night's GDC was at 12mTorr, 500mA in D2 all night long.
May 23 1997 12:57:45:350PMSteve WolfeWe also did about an hour of standard ECDC before starting the "run".
May 23 1997 01:19:14:720PM970523002Steve Wolfeshot 2: EF3 test.
Supply ran ok. 2560A for .5 sec
(was set for 3000A on PLC).
May 23 1997 01:33:30:840PM970523003Steve Wolfeshot 3: try for plasma; start from shot 970521050.
dud - No EF2 supplies.
May 23 1997 01:46:17:990PM970523004Steve Wolfeshot 4: repeat, with EF2's this time we hope.
fizzle. xpoint Laser is firing.
bd at 4.7sec.
Br is negative. EF4's not quite to their final balance state.
May 23 1997 01:53:30:760PM970523005Steve Wolfeshot 5: Lower the pre-puff, increase Br offset by .5 mT
Fizzle. No laser.
bd still at about 5msec,
Br still negative.
EF4 still shows only 20A imbalance instead of usual 50.

RF is pulsing into the machine after the pulse, we see a breakdown on the TV.
May 23 1997 02:01:30:100PM970523006Steve Wolfeshot 6: lower pre-puff more and give it more Br.
fizzle. laser was firing.
bd at 4. msec
Bz is rising too late.
CII is at .015, seems very high
May 23 1997 02:13:21:060PM970523007Steve Wolfeshot 7: RCUR offset to 6850
EF4 more positive by 10 A. also lowered fill.

plasma - short and nasty.
230 msec.
bd at 5msec
CII at .008, never comes down (in 30msec)
Bz in faster. 120kA at 20msec
May 23 1997 02:21:04:460PM970523008Steve Wolfeshot 8: remove EF4 change.
base=1.3e-6

fizzle. small hot spot moves in on ECE.
got to 35kA and smashed.
May 23 1997 02:29:21:500PM970523009Steve Wolfeshot 9: no change.
base=9e-7
plasma 1.38 sec.
no laser. bd at 6.4msec; CII .01 and stays up.

Nice plasma li=1.4, n/nc=1.04, W>40kJ

May 23 1997 02:34:54:690PM970523010Steve Wolfeshot 10: Enable Argon for John Rice.
base=1.9e-6

plasma - 1.32 sec
density is higher, rises to 1.3e20.

May 23 1997 02:38:15:240PM970523010Steve Wolfeshot 10: Density rise is coincident with Argon pulse, xray rise.

May 23 1997 02:47:35:360PM970523011Steve Wolfeshot 11: Reduce Argon puff by 10msec
base=1.3e-6

fizzle. bd at 5msec,
CII got to .015, bounces twice.
May 23 1997 03:00:10:130PM970523012Steve Wolfeshot 12: EF4 more positive by 5 amps.

Nice plasma. bd at 5msec, 150kA at 30msec
Density is closer to flat, still a bit of a rise.
li=1.4, Vs=1.35, W=48kJ.
May 23 1997 03:07:27:480PM970523013Steve Wolfeshot 13: repeat.
base=1.4e-6

fizzle, late breakdown
bd at 9msec ?
May 23 1997 03:15:55:610PM970523014Steve Wolfeshot 14: Go to hybrid control on TF.
Program for 150kA, PLC set to 1500V, 165kA.
base=1.1e-6

plasma, 1.34 sec
TF current reads 152 kA.
good current rise (140kA at 30msec)
bd at 5.4msec
Still disrupting during shark fin on ramp-down.





May 23 1997 03:27:17:210PM970523015Steve Wolfeshot 15: Program TF to ramp down to 4Tesla, beginning at .35sec
base=1.7e-6

plasma - looks nice.
TF reaches 4.1T at .75 sec.
qpsib=3.4, li=1.25, beta_N=.5




May 23 1997 03:36:14:440PM970523016Steve Wolfeshot 16: Program TF to ramp down to 4Tesla, beginning at .25sec
base=1.9e-6

plasma lasts to 1.41 sec
tf reaches 4.1T at .65 sec,
Boris reports he is getting signal on the x-pt Thomson.
WMHD is dropping through the shot, loop voltage is rising.

May 23 1997 03:51:11:710PM970523017Steve Wolfeshot 17: Speed up the ramp-down by 50 msec
plasma. lasts to 1.38 again
maybe a little burst of mild vertical oscillation at .8sec, not serious

tf reaches target at .62sec
plasma looks the same.
May 23 1997 03:59:14:990PM970523018Steve Wolfeshot 18: Speed up the ramp-down by 50 msec more
base=1.7e-6

plasma- still disrupting at 1.36 or so
tf reaches target at .60sec, that may be about as fast as we can go

May 23 1997 04:11:04:650PM970523019Steve Wolfeshot 19: Move the invert time out to 1.3 sec.
base=1.6e-6

plasma died at 1.2 sec.
Goetz thinks there is too much Argon.
May 23 1997 04:21:37:200PM970523020Steve Wolfeshot 20: Tweak the TF down to get 4.0Tesla
reduce the Argon puff.
base=2.1e-6

dud. no laser.

May 23 1997 04:31:48:060PM970523021Steve Wolfeshot 21: add some gas to the pre-puff
base=1.3e-6

alternator did not ramp up.
stayed in check 2 minutes

dud again.
Br looks a little negative.

May 23 1997 04:42:22:480PM970523022Steve Wolfeshot 22: Br tweak and EF4 by 5 amps
base=1.0e-6

3 duds in a row.
Still no laser; Boris has gone home

May 23 1997 04:55:25:610PM970523024Steve Wolfeshot 24: EF 5 amps more negative.
4 duds in a row.

May 23 1997 05:28:13:440PM970523025Steve Wolfeshot 25: 15 amps more negative on EF4
.5 mT more positive on Br.
pre-puff from 30msec to 22msec.

No TF. Why?
Unexplained failure. Hybrid command reaches supply, but no sign gates are coming on.
Nothing changed from previous shots.
There was an IGOR communication problem before the shot (end of RECOOL), but that is
probably a red herring.

Physics Operator Comments
May 23 1997 10:12:47:010AMJohn GoetzRun 970523

In support of Mini-Proposal #170 - Restart

Try and get the machine operating reliably and check out diagnostic
systems.

May 23 1997 11:36:10:410AMSteve WolfeIGT has been changed to the Ion gauge looking straight in at J-port (with a possibly obstructed
view). The readings on the two gauges were "identical", according to Irby/Toland.

We can try turning it on and off during the run if we think it is having an effect.

May 23 1997 12:01:58:270PM970523001John GoetzShot 970523001

EF3 test under PLC control - breaker pulled very early; before the
supply even turned on.

May 23 1997 12:03:46:470PM970523001Steve Wolfeshot 1: EF3 test.
breaker opened. No sign of anything within the data system window.
May 23 1997 12:18:51:030PM970523002Steve Wolfeshot 2-: Alternator will ramp up, but we won't go from CHECK->PULSE. Monitoring voltage at
EF3 supply.

Back to recool. Breaker still closed.
Opened the breaker.
Engineers investigating.
May 23 1997 12:21:30:780PM970523002John GoetzShot 970523002

EF3 test under PLC control - engineers out in the power room looking
at things; before, during, and after the shot

May 23 1997 01:16:49:860PM970523002John GoetzShot 970523002

EF3 test under PLC control - voltage comparator power supply replaced
everything looks o.k.

May 23 1997 01:33:12:750PM970523003John GoetzShot 970523003

Start from 970521050 and try to make a go of it.

Dud - no EF2's

May 23 1997 01:44:41:800PM970523004John GoetzShot 970523004:

Try again

Results:

fizzle; breakdown at 5msec; Br a little negative

May 23 1997 01:54:49:700PM970523005John GoetzShot 970523005:
prefill puff = 30ms
BR_0 offset = .0055

Results:
fizzle
breakdown aroun 4-5ms - bounces
Br not positive enough

May 23 1997 02:04:41:320PM970523006John GoetzShot 970523006:
prefill puff = 24ms
BR_0 offset = .0065

Results:
fizzle; breakdown @ 4.3ms
Bz not coming in fast enough

May 23 1997 02:13:44:610PM970523007John GoetzShot 970523007:
prefill puff = 20ms
RCUR offset = 6850
IC_EF4 = -1305A

Results:
plasma - disrupts @ .235; probably from dirt
breakdown @ .006; vertical field in very quickly

May 23 1997 02:20:29:110PM970523008John GoetzShot 970523008:
IC_EF4 = -1315A

Results:
fizzle; breakdown @ .005
a little plasma that moves in

May 23 1997 02:29:12:470PM970523009John GoetzShot 970523009:
no changes

Results:
plasma - disrupts during rampdown
EFIT says the plasma looks good
breakdown occurs @ .007

May 23 1997 02:37:24:830PM970523010John GoetzShot 970523010:
no changes

Results:
plasma; disrupts during rampdown
base pressure was 1.9e-6 at pulse
breakdown @ .006

May 23 1997 02:48:17:050PM970523011John GoetzShot 970523011:
argon puff to 30msec

Results:
fizzle; breakdown @ .005; bounces twice

May 23 1997 03:00:15:810PM970523012John GoetzShot 970523012:
IC_EF4 = -1310A

Results:
plasma - disrupts in rampdown
breakdown @ .005 - nice current rise

May 23 1997 03:09:33:630PM970523013John GoetzShot 970523013:
35ms of argon puff

Results:
fizzle - breakdown @ .009
null looks o.k.; don't know why this one broke down late

May 23 1997 03:20:18:760PM970523014John GoetzShot 970523014:
TF current under hybrid control
drawn at -150kA

Results:
plasma; disrupts during rampdown
breakdown @ .006

May 23 1997 03:28:14:860PM970523015John GoetzShot 970523015:
TF current drawn from -150kA to -113kA from 0.35
to 0.65sec

Results:
plasma; disrupts during rampdown
Bt ramps down to 4.1T - takes .45s to achieve this
breakdown @ .006

May 23 1997 03:38:29:000PM970523016John GoetzShot 970523016:
TF current ramp starts @ .25 and ends @ .5
slowdown CLEARIN ramp during rampdown

Results:
plasma; disrupts a little bit later
TF reaches flattop @ .68s (4.2T)
breakdown @ .006; slight hesitation on current rise

May 23 1997 03:51:55:760PM970523017John GoetzShot 970523017:
TF current ramp starts @ .25 and ends @ .45
slowdown CLEARIN ramp during rampdown some more
second argon puff @ .7s for 15ms

Results:
plasma; disrupts during rampdown; back to 1.38s
TF flattens out @ 4.1T @ .66s
breakdown @ .005 with a slight hesitation

May 23 1997 04:12:36:270PM970523018John GoetzShot 970523018:
TF current ramp starts @ .25 and ends @ .4
third argon puff @ .5s for 15ms

Results:
plasma; disrupts in rampdown (earlier)

May 23 1997 04:13:39:680PM970523019John GoetzShot 970523019:
TF invert to 1.3s (for disruption problem)

Results:
plasma; disrupts in rampdown (even earlier) - 1.14sec
loop voltage about 2V (too much argon)

May 23 1997 04:23:28:870PM970523020John GoetzShot 970523020:
TF current @ -108kA
only one argon puff

Results:
dud!!!
null looks fine - not enough prefill? disruption on 19
too big?

May 23 1997 04:34:06:910PM970523021John GoetzShot 970523021:
TF current @ -108kA
prefill puff = 25ms

Results:
dud; null needs some less negative Br

May 23 1997 04:40:58:280PM970523022John GoetzShot 970523022:
TF current @ -108kA
BR_0 offset = .0075
IC_EF4 = -1315A

Results:
dud; Br too positive now

May 23 1997 04:49:48:550PM970523023John GoetzShot 970523023:
TF current @ -108kA
BR_0 offset = .007
prefill puff = 30ms

Results:
dud; all plasmas are lost
possible too much Bz too early

May 23 1997 04:56:46:780PM970523024John GoetzShot 970523024:
TF current @ -108kA
IC_EF4 = -1320A

Results:
dud; reasons are not altogether clear

May 23 1997 05:03:41:480PM970523025John GoetzShot 970523025:
TF current @ -108kA
IC_EF4 = -1335A
prefill puff = 22ms
BR_0 offset = .0075

Results:
dud; no TF - not my fault this time

Engineering Operator Comments
ShotTimeTypeStatusComment
111:55:59:100AMTestBadef3 test plc test no good
212:13:24:520PMTestOktest EF3 PLC control OK
301:31:06:830PMPlasmaBadOperator Error; EF2 in PLC control rather than hybrid
401:37:04:980PMPlasmaOkbreakdown
501:48:05:070PMPlasmaOkAll supplies ak
601:56:19:540PMPlasmaOkOK
702:06:16:570PMPlasmaOk
802:15:13:190PMPlasmaOk
902:22:06:360PMPlasmaOk
1002:30:18:120PMPlasmaOk
1102:43:18:840PMPlasmaOk
1202:52:19:560PMPlasmaOk
1303:02:51:700PMPlasmaOk
1403:10:11:490PMPlasmaOk
1503:20:02:130PMTestOk
1603:29:29:560PMTestOk
1703:41:30:070PMTestOkramping tf hybrid control
1803:52:57:390PMTestOk
1904:05:14:340PMTestOk
2004:13:53:770PMTestOk
2104:25:09:430PMTestOkno breakdown
2204:33:12:080PMTestOkno breakdown
2304:42:26:010PMTestOk
2404:49:55:260PMTestOk
2505:00:45:590PMTestBadno tf