Alcator C-Mod Run 990217 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 1-25)

Operators
Session leader(s):Steve Wolfe
Physics operator(s):Dmitri Mossessian
Engineering operator(s):Frank Silva,Gary Dekow

Engineering Operator Run Comment
mp#206 post borinization

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:19:150PM
Author: To Be Determined
Session Leader's Summary for Wed. 990217

MP#206 Resume Operation (part 4 - post-boronization)
SL: wolfe
PO: Mossessian
EO: Silva/Dekow

We boronized the machine last friday evening (2/12/99):

. TC6 was 112 to 115 mT, TC3 was typically 3.4 mT
. approx 1900 angstroms deposition, 130 psi change in diborane bottle pressure, at approx 10 psi/hour
. r_max=96 cm

We have had approx 38 hours of ECDC in helium at 5e-5 torr over the weekend

We have had 2 hours of ECDC in D2 at 1e-4 torr just before the run

Run Plan:
--------
Goal- Assess readiness to proceed with physics campaign, based on H-mode plasmas
with up to 3MW of source power.

Plan: First, run a "Tuesday" OH test

Run 800kA, nl4=1e20 discharge, similar to 990212015. RF should try for three power
steps: 1.1MW,2.2MW, max available. Based on past experience, startup may be
problematic for the early part of the first run after boronization. We'll keep at
it until we get good shots. We will be monitoring:
H/D ratio
Prad (2pi)
Zeff (Z_ave)
Midplane & Divertor pressure
in addition to looking for heating and H-modes. If the RF is working and the
boronization went properly, we should end up with EDA H-modes, possibly even at
the low-power step (see e.g. 980220003). However, it may take a number of
discharges to get to this condition. We may also need to tweak the gaps, etc., to
help the ICRF coupling. The RF loading feedback circuit will probably not be
available; we didn't need it for plasmas of this level last year.

Success in achieving EDA h-modes is necessary before we can declare the machine
ready for physics operation. Therefore, this will be our primary objective.

If EDA is obtained at 0.8MA, we will increase the current to 1MA. If things are
really going well, we may get an early start on Spencer's MP 230 (flapping at
EDA). If things are going badly, we may need to consider a new boronization.

Results:
----------
Not terrible, considering, but we did not accomplish the primary goal.

We got off to a late start (10AM) because of an oil pump problem in the alternator.

We started with a Tuesday test, and test shots for EF3 and EF4 which had been
worked on since the last run.

We then had a long delay chasing down a Comm. bank charging problem on EF1L
(or maybe EF1U). This was eventually traced to a faulty AFOL board.

First plasma attempt (shot 9) was at about 12:40PM. It fizzled because of a
very negative Br. The next shot was successful, after a 2mT Br tweak. We then
got into a series of alternating shots and fizzles. H-modes were obtained
routinely, but there were numerous problems keeping the RF on.

All the cleanliness signs were good. H/D was in the .02 to .06 range on
the Marmar-meter, Z_ave was between 1.2 and 1.5, CII breakdown peak was around
.004mW/cm2/ster, Prad_2pi was typically less than 500kW; moreover the H-mode
threshold was around 900kW to 1MW. H-factors are a bit on the low side, around
1.5.

Argon was turned on after shot 19. There was no obvious degradation in
performance.

All the successful shots had h-modes and ran essentially full length. Good
shots to look at were #17, 19, 21 and #25. Shot 19 is nearly steady state, but
does not appear to be EDA. The pedestal width is 2mm and the Halpha is low; it
may have small type III ELMs. The oouter strike point was on the floor until
about .9sec all day until shot 25, when we moved the x-point up 1cm at
.44sec. It should probably be moved out about 1cm as well to get the strike
firmly on the outer plate.

The RF problems appeared to be much more serious today than last week. Even
the E-port antenna was unable to put out more than about 1.2MW without
faulting, and Steve indicated that the arc indications were real. Trying to
run the two antennas together was generally unsuccessful today. In my opinion,
getting the RF running more reliably at high power is the main problem now.

If we had set it up ahead of time, we would have tried between-shot ECDC (in
Helium) to fix the fizzles. This should be tried tomorrow if the alternating
sequence returns.

The midplane pressure was perhaps a little low for EDA at about .25mTorr
(around 30mTorr in the divertor). A slightly higher target density may do
better, if we can get more power in.

Physics Operator Summaries
Entered: Jul 7 2004 04:37:00:240PM
Author: To Be Determined
Physics operator summary for 990217

EO: Silva
SL: Wolfe
PO: Mossessian

Run 990217 was in support of Mini Proposal 206 part 4 - POst Boronization
Evaluation.
An alternator problem delayed the start of the run to 10 am, then various
supply tests and problems delayed it even further and the first plasma
attempt was made only at 12:30 on shot 9.
The first four shots were OH, EF3 and EF4 tests. On shot 5 a problem
with EF1 commutation bank power supply was discovered and shots 6-8 were
test shots in attempts to locate and fix the problem.
Little tweak of Br at startup resulted in good plasma on shot 10.
A plasma/fizzle sequence then followed for 12 shots. No attempts were made to
tweak anything in PCS since plazma or fizzle production seems to
depend only on base pressure.
Bz tweaks on shots 21-24 were made to try to obtain two plasmas
in a row but resulted in four fizzles in a row.

Scorecard: 25 shots, 7 tests, 8 plasmas, 10 fizzles

Shot summary for Run 990217:

Shot:

1 OH test

2 EF3 test

3 EF4 test

4 EF4 test

5 plasma attempt, EF1 fault

6 EF1 test

7 EF1 test

8 EF1 test

9 Fizzle

10 Plasma, H modes, Br tweak

11 Fizzle

12 Plasma, H-modes

13 Fizzle

14 Plasma, H-modes, Bz tweak

15 Fizzle

16 Plasma, H-modes

17 Plasma, waited longer for base pressure to come down

18 Fizzle

19 Plasma, H-modes

20 Fizzle

21 Plasma, H-modes

22 Fizzle, ZXL and Bz tweaks

23 Fizzle, Bz tweak

24 Fizzle, Bz tweak

25 Plasma, H-modes, Bz tweak



Session Leader Comments
Feb 17 1999 07:41:22:560AMSteve WolfeMP#206 (part 4) Post-boronization evaluation

Goal- Assess readiness to proceed with physics campaign, based on H-mode plasmas
with up to 3MW of source power.

Plan: First, run a "Tuesday" OH test

Run 800kA, nl4=1e20 discharge, similar to 990212015. RF should try for three power
steps: 1.1MW,2.2MW, max available. Based on past experience, startup may be
problematic for the early part of the first run after boronization. We'll keep at
it until we get good shots. We will be monitoring:
H/D ratio
Prad (2pi)
Zeff (Z_ave)
Midplane & Divertor pressure
in addition to looking for heating and H-modes. If the RF is working and the
boronization went properly, we should end up with EDA H-modes, possibly even at
the low-power step (see e.g. 980220003). However, it may take a number of
discharges to get to this condition. We may also need to tweak the gaps, etc., to
help the ICRF coupling. The RF loading feedback circuit will probably not be
available; we didn't need it for plasmas of this level last year.

Success in achieving EDA h-modes is necessary before we can declare the machine
ready for physics operation. Therefore, this will be our primary objective.

If EDA is obtained at 0.8MA, we will increase the current to 1MA. If things are
really going well, we may get an early start on Spencer's MP 230 (flapping at
EDA). If things are going badly, we may need to consider a new boronization.
Feb 17 1999 07:42:16:030AMSteve WolfeDue to an alternator delay, today's run will start around 10AM.
Feb 17 1999 09:56:54:483AM990217001Steve WolfeShot 1- Tuesday test. looks ok.
Next shot will be either EF3 or EF4 test
Feb 17 1999 10:07:03:700AM990217002Steve WolfeShot 2: EF3 test. Engineers replaced the overvoltage circuit on Monday.
6kA looks ok.
Next test EF4.
Feb 17 1999 10:13:35:170AM990217003Steve WolfeShot 3: EF4 test. Not ok. It wasn't enabled!
Feb 17 1999 10:19:56:357AM990217004Steve WolfeShot 4: Try again. looks ok.
Next shot, try for plasma.
Feb 17 1999 10:33:08:500AM990217005Steve WolfeShot 5: First plasma attempt.
Problem in CHECK. Went back to recool.
EF1L comm bank didn't charge. Have to check the supply.

Feb 17 1999 10:44:43:420AM990217005Steve WolfeShot 5: Supply was on. Try running through a sequence to re-synch the system after
the backout; see if the bank charges. Bank still not charging.
Feb 17 1999 11:40:09:530AM990217006Steve WolfeShot 6: another test - still no charge indication.
Apparently it's a bad AFOL.
Feb 17 1999 11:55:07:450AM990217007Steve WolfeShot 7: Swapped AFOL board. Another test shot.
Still no charging indication.
Feb 17 1999 12:24:10:530PM990217008Steve WolfeShot 8: Another test. This one works.
Feb 17 1999 12:43:41:077PM990217010Steve WolfeShot 9: Set up for a full shot.
fizzle. CII=.004. Big negative Br.
bd at 6.5msec
Feb 17 1999 12:58:11:403PM990217010Steve WolfeShot 10: Tweak Br by 2mT more positive.
plasma, with H-modes. 1.64sec
bd at 5.4msec, Br still a little negatve,

First H-mode at 1MW level. H/D=.04-.06 during the RF.
Feb 17 1999 01:12:46:123PM990217011Steve WolfeShot 11: Rf trying to tune to stay on in the H-modes. No PCS changes.
fizzle. bd at 5.1msec, br still a little negative, Bz maybe a little negative.
Gas at .065mTorr (18msec).

MFLUx doesn't look bad. It's probably just boronization.
Feb 17 1999 01:29:00:187PM990217012Steve WolfeShot 12: plasma
3 or 4 h-modes, lower RF power (max around 1.15MW)
Feb 17 1999 01:36:32:763PM990217013Steve WolfeShot 13: fizzle.
bz looks a little negative again. Its changing shot to shot.

Go 10A more positive on ICEF4 (just for luck).
Feb 17 1999 01:58:54:233PM990217014Steve WolfeShot 14: Small tweak on Bz (EF4) ; plasma
2 h-modes, low power< 1MW
Strike point ios on the floor until .9sec; leave it for now.
H/D=0.02 until .9sec, then .05
Compression ratio is arount 100.
Zave is between 1 and 1.5;
Feb 17 1999 02:04:42:700PM990217015Steve WolfeShot 15: Wait 15 minutes to let pressure come down; cooling was ready at 12min. base=1.0e-6, M32=3.8e-8
(compare 7e-7,1.9e-8 on shot 14).

fizzle. Have to wait longer?
Feb 17 1999 02:40:55:967PM990217016Steve WolfeShot 16: No changes. base=7e-7,M32=1.8e-8
plasma. RF is all chopped up, peak values >3.5MW
4 h-modes, first one about 300msec
H/D up to .06 by the end of this one.
Feb 17 1999 03:04:32:750PM990217017Steve WolfeShot 17: wait a long time after previous shot, 21 minutes, base=8.3e-7,M32=3.2e-8
plasma. D-port on, but faulting from 0.5 to 1sec, E-port on clean from 1sec to 1.2; was supposed
to be the other way around. H/D < .06 . WMHD gets to just over 100kJ (.82sec).
Feb 17 1999 03:11:10:733PM990217018Steve WolfeShot 18: This time, swap D and E in time sequence. fizzle.
should've waited a little longer.
Feb 17 1999 03:41:52:293PM990217019Steve WolfeShot 19: Go again. plasma
one nice long h-mode, power between .9 and 1.2MW, 90kJ
More or less steady state, but it looks like Elm-free.
Next shot Argon
Feb 17 1999 03:52:20:217PM990217020Steve WolfeShot 20:Same as 19, but with argon. fizzle.
Feb 17 1999 04:09:53:857PM990217021Steve WolfeShot 21:plasma
shorter H-modes. 2pi still low. some injections.

Next shot, move X-point height up earlier in shot to try to get it off the floor.
Also a small Bz tweak .
Feb 17 1999 04:19:32:467PM990217022Steve WolfeShot 22: Steve says he has to back off the E-port power because he is getting a "series arc".
fizzle. late bd.
Put Bz (EF4) back where it was.
Feb 17 1999 04:35:23:250PM990217023Steve WolfeShot 23: fizzle! bd at 6msec
Feb 17 1999 04:58:41:327PM990217024Steve WolfeShot 24: Another fizzle. Bz now looks very positive. Programming says it is the same as 21.
Feb 17 1999 05:08:27:123PM990217024Steve WolfeShot 25: Tweak ef4 more negative by 10A,
plasma. long h-mode followed by two shorties.

Physics Operator Comments
Feb 17 1999 09:43:00:700AMDmitri MossessianMiniproposal 206 (part 4): Post-boronization evaluation
Overnight ECDC in He, then D2 ECDC for two hours before the run.

Engineering setup:

Power supply setup as on 990212
TF under hybrid control

Gas setup -

B-top - 6 psi of DEUTERIUM Hybrid enabled
C-side - 30 psi of DEUTERIUM Hybrid enabled
B-side lower - 1 psi of Ar Hybrid DISABLED

Loaded from 990212015.
Coldstart OK.
Feb 17 1999 09:56:01:793AM990217001Dmitri MossessianThis is "Tuesday" OH test
Feb 17 1999 10:03:02:827AM990217002Dmitri MossessianOH test is OK, this is EF3 test.
Feb 17 1999 10:14:09:170AM990217003Dmitri MossessianThis shot was EF4 test, which did not work.
Feb 17 1999 10:19:54:903AM990217004Dmitri MossessianAnother EF4 test. Looks OK
Feb 17 1999 10:36:29:857AM990217005Dmitri MossessianTry for plasma

EF1-lower commutation capacitor did not charge. No shot.
Feb 17 1999 11:13:24:450AM990217006Dmitri MossessianEF1 test. The lower bank power supply does not work.
Feb 17 1999 11:56:20:153AM990217007Dmitri MossessianAnother EF1 test. No charging again.
Feb 17 1999 12:23:25:170PM990217008Dmitri MossessianAnother EF1 test. Seems to be OK.
Feb 17 1999 12:40:18:013PM990217009Dmitri MossessianTry getting plasma. No success. Br too low.
Feb 17 1999 12:55:34:327PM990217010Dmitri MossessianIncreased Br0 offset by 2 mT to 0.0045.

Plasma. 1.65 sec long, multiple H-modes.
Feb 17 1999 01:09:19:560PM990217011Dmitri MossessianTry again with no changes in PCS.

Fizzle
Feb 17 1999 01:17:45:437PM990217012Dmitri MossessianTry again with no changes in PCS.

Plasma, 1.65 sec long, several H-modes at approx. 1 MW RF.
Feb 17 1999 01:38:04:090PM990217013Dmitri MossessianNo changes.

Fizzle
Feb 17 1999 02:00:17:560PM990217014Dmitri MossessianIncreased Bz0.

Plasma with some H-modes.
Feb 17 1999 02:06:38:310PM990217015Dmitri MossessianNo PCS changes.
Wait for pressure to come down to 1.1e-6. Pressure right before pulse - 8.5e-7.

Fizzle
Feb 17 1999 02:24:13:670PM990217016Dmitri MossessianNo PCS changes.
Pressure right before pulse - 6.0e-7

PLasma.

Feb 17 1999 02:45:21:733PM990217017Dmitri MossessianNo PCS changes.
Wait till pressure comes down to 7.2e-7 before pulse.

Plasma.

Feb 17 1999 03:07:19:687PM990217018Dmitri MossessianNo PCS changes.
Pressure 7.9e-7 before pulse.

Fizzle

Feb 17 1999 03:26:48:890PM990217019Dmitri MossessianNo PCS changes.

Plasma.

Feb 17 1999 03:47:22:123PM990217020Dmitri MossessianNo PCS changes.
P=7.2e-7

Fizzle

Feb 17 1999 03:58:02:200PM990217021Dmitri MossessianNo PCS changes.
P=6.0e-7

Plasma

Feb 17 1999 04:17:02:043PM990217022Dmitri MossessianMoved ZXL up 1 cm at .44 sec.
IC_EF4 up 10 A at startup to bring Bz0 up a little.

Fizzle
Feb 17 1999 04:33:33:530PM990217023Dmitri MossessianIC_EF4 down 10 A at startup - return Bz0 to previous value.

Fizzle
Feb 17 1999 04:51:03:170PM990217024Dmitri MossessianMoved the beginning of the IC_EF4 rampup back to -.003 sec (moved it to 0.0 on the previous shot)

Fizzle. Bz0 is too high, although the IC_EF4 is the same as in all good shots.


Feb 17 1999 04:58:11:250PM990217025Dmitri MossessianMoved the IC_EF4 to -1270 (10 down) - as it was before shot 14.

Plasma

Engineering Operator Comments
ShotTimeTypeStatusComment
109:54:37:420AMTestOkOH1 and OH2 Tuesday Morning Test
210:03:15:263AMTestOkEF3 test
310:10:59:217AMTestOkef4 test no good not enabled
410:17:48:043AMTestOkef4 test ok
510:28:45:840AMTestBadNo shot due to commutaion power supply problem
611:06:33:920AMTestOkNo Commutation EF1
711:52:19:543AMTestOkef1lower comm test
812:19:20:733PMTestOkEF1 Commutation supplies working
912:28:48:293PMPlasmaOkfizzle no faults
1012:43:36:653PMPlasmaOkno faults/plasma
1112:59:26:890PMPlasmaOkno faults
1201:13:05:983PMPlasmaOkno faults/plasma
1301:29:50:153PMPlasmaOkNo Faults
1401:43:45:233PMPlasmaOkno faults/plasma
1502:02:49:950PMPlasmaOkNo Faults
1602:18:28:373PMPlasmaOkNo Faults
1702:43:05:920PMPlasmaOkNo Faults / Plasma
1803:05:17:780PMPlasmaOkNo Faults
1903:21:08:450PMPlasmaOkNo Faults / Plasma
2003:45:44:390PMPlasmaOkNo Faults
2103:56:41:077PMPlasmaOkNo Faults / Plasma
2204:15:38:967PMPlasmaOkNo Faults
2304:29:38:187PMTestOkNo Faults
2404:43:13:653PMTestOkNo Faults
2504:56:38:403PMTestOkNo Faults / Plasma