Alcator C-Mod Run 1001212 Information

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Miniproposals
Miniproposal:277a
Date Filed:11/17/2000
Title:Internal Transport Barrier Studies at 4.5T with Simultaneous Central and Off-axis ICRF Heating
First Author:Paul Bonoli
Session Leader:Paul Bonoli (shots 1-13)

Operators
Session leader(s):Paul Bonoli
Physics operator(s):Bill Rowan
Engineering operator(s): Unknown

Engineering Operator Run Comment
MP #277 Internal Transport Barrier Studies at 4.5 T with Simultaneous an

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:26:023PM
Author: To Be Determined
Run Summary for MP 277A: Internal Transport Barrier Studies at 4.5T
with Simultaneous Central and Off-axis ICRF
Heating
1001212

Physics Operator: Bill Rowan
Session Leader: Paul Bonoli

____________________________________________________________________________

Run Summary

____________________________________________________________________________

The run started at about 1:00 PM, ended at 5:00 PM, and we took 13
shots. Because additional purging and pump-down of the J-port
transmission line was required, we decided to go to part (b) of the
run plan immediately and reproduce the density barrier mode at 4.5 T
with off-axis ICRF heating at 80 MHz. We then intended to take 5-6
shots so that T_i and plasma rotation profiles could be mapped out
with HIREX.

We succeeded in producing a very nice density barrier mode on Shot 010
(first plasma of the day!) with only 1 MW of ICRF heating from
D-port. On shot 010 the NROOTZ_eff increased to almost 5 X 10^20.
Halfway through the desnity increase (at 1.08 sec) the toroidal
rotation velocity from HIREX went to zero and subsequently reversed
direction. The first 9 shots were fizzles because of problems related
to post boronization conditions in the tokamak. On shots 011 - 013 we
attempted to get both D- and E-ports to operate simultaneously at the
level of 1.0 - 1.3 MW per port. However, we ran into problems with
early disruptions at 0.78 - 0.85 sec., perhaps related to impurity
production from the rf antennas. Camera views of D-port revealed "arcs
and sparks" on shots 010 and 011. However, views on shots 012-113
displayed quiescent D-antenna operation. For operation on Wednesday
(1001213) it will probably be preferable to turn up the power levels
more gradually (in steps from 0.5 MW per port, for example).

____________________________________________________________________________

Shot Summary

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

Shot Comment

001-009 Fizzle
010 H-mode & Density barrier
011 H-mode, early disruption
012 H-mode, early disruption
013 H-mode, early disruption
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Physics Operator Summaries

Session Leader Comments
Dec 12 2000 04:43:55:653PM1001212001Paul Bonoli1001212001

We will start with part (b) of the run plan - 80 MHz only to
reproduce the ITB with off-axis ICRF. Once we have re-established
the density barrier mode we will take a 5-6 shots to get T_i and
rotation profiles using the HIREX. The 70 MHz J-port x-mission line
needs further purging and pumping.

Request: 800 kA, 4.5 T, nl_04 = 1.8
D & E ports pulsed from 0.7 - 1.4 sec. @ 1 MW / port

Plasma fizzle - try again
Dec 12 2000 01:06:35:857PM1001212002Paul Bonoli1001212002


Request: 800 kA, 4.5 T, nl_04 = 1.8
D & E ports pulsed from 0.7 - 1.4 sec. @ 1 MW / port
Load segment 1 from Friday (1001208001)

Result: Another fizzle
Dec 12 2000 01:32:26:263PM1001212003Paul Bonoli1001212003


Request: 800 kA, 4.5 T, nl_04 = 1.8
D & E ports pulsed from 0.7 - 1.4 sec. @ 1 MW / port
Add more gas to prefill

Result: Another fizzle
Dec 12 2000 01:54:11:763PM1001212004Paul Bonoli1001212004


Request: 800 kA, 4.5 T, nl_04 = 1.8
D & E ports pulsed from 0.7 - 1.4 sec. @ 1 MW / port
Now also load the engineering set up from Friday
(1001208)

Results: A fizzle
Dec 12 2000 02:10:10:687PM1001212005Paul Bonoli1001212005


Request: 800 kA, 4.5 T, nl_04 = 1.8
D & E ports pulsed from 0.7 - 1.4 sec. @ 1 MW / port
Increase gas puff from 24ms to 28 ms

Result: Another fizzle
Dec 12 2000 02:27:26:967PM1001212006Paul Bonoli1001212006


Request: 800 kA, 4.5 T, nl_04 = 1.8
D & E ports pulsed from 0.7 - 1.4 sec. @ 1 MW / port

Results: No plasma - fizzle
Dec 12 2000 03:18:39:560PM1001212007Paul Bonoli1001212007


Request: 800 kA, 4.5 T, nl_04 = 1.8
D & E ports pulsed from 0.7 - 1.4 sec. @ 1 MW / port
Turn on ECDC

Results: Fizzle - now the gas pressure is too high.
Reduce the gas puff time.
Dec 12 2000 03:19:13:577PM1001212008Paul Bonoli1001212008


Request: 800 kA, 4.5 T, nl_04 = 1.8
D & E ports pulsed from 0.7 - 1.4 sec. @ 1 MW / port
No ECDC
Reduced gas pressure

Results: Stll got a fizzle
Dec 12 2000 03:24:41:450PM1001212009Paul Bonoli1001212009


Request: 800 kA, 4.5 T, nl_04 = 1.8
D & E ports pulsed from 0.7 - 1.4 sec. @ 1 MW / port


Result: Fizzle
Dec 12 2000 04:05:09:280PM1001212010Paul Bonoli1001212010


Request: 800 kA, 4.5 T, nl_04 = 1.8
D & E ports pulsed from 0.7 - 1.4 sec. @ 1 MW / port
Turned on ECDC before shot

Result: Plasma !!!! Got an H-mode
Got a density barrier -> V_tor goes to zero at 1.08 sec.
D-port ran @ 1 MW
E-port did not run

Dec 12 2000 04:10:47:217PM1001212010Paul Bonoli1001212010


Request: 800 kA, 4.5 T, nl_04 = 1.8
D & E ports pulsed from 0.7 - 1.4 sec. @ 1 MW / port
Turned on ECDC before shot

Result: Plasma !!!! Got an H-mode
Got a density barrier -> V_tor goes to zero at 1.08 sec.
NROOTZ = 4.8 X 10^20
H/D = 0.035
D-port ran @ 1 MW
E-port did not run

Dec 12 2000 04:23:47:937PM1001212011Paul Bonoli1001212011


Request: 800 kA, 4.5 T, nl_04 = 1.8
D & E ports pulsed from 0.7 - 1.4 sec. @ 1 MW / port

Result: Disruption at 0.8 sec., but got an H-mode transition
H/D = 0.035
D-port ran
E-port ran

Dec 12 2000 04:40:43:810PM1001212012Paul Bonoli1001212012


Request: 800 kA, 4.5 T, nl_04 = 1.8
Increase D-port to 1.5 MW
Keep E-port at 1.0 MW
Lower density by 10%

Result: Got an early disruption again at 0.78 sec. - with H-mode
D-port view looked good, but E-port may be causing the plasma to disrupt.



Dec 12 2000 04:55:49:873PM1001212013Paul Bonoli1001212013


Request: 800 kA, 4.5 T, nl_04 = 1.6
Lower D-port power to 1.3 MW
Lower E-port power to 1.1 MW
This will be the last shot.

Result: Early disruption again at 0.85 sec. with an H-mode.
View on D-port again looked clean.



Physics Operator Comments
Dec 12 2000 11:19:52:827AMBill RowanEngineering setup for Tuesday 12 Dec 2000.

MP #277A Internal Transport Barrier Studies at 4.5 T with Simultaneous
and Off-Axis ICRF Heating

Session leaders: Bonoli
Physics operator: Rowan

-------------------------------------------------------------------------------
Engineering setup:

ECDC in He from the end of boronization until about 2 hours before the run.

Power systems as on 1000607008.

Gas setup:
fill B-top with 6 psi of D2 Hybrid enabled
fill B-side lower with 1 psi of Ar Hybrid DISABLED
fill B-side upper with 35 psi of D2 Hybrid DISABLED, for ECDC
fill C-side with 30 psi of D2 Hybrid enabled
leave J-bot as is Hybrid DISABLED

Enable the following gate valves: ECE, VUV, Beast, DNB

Run starts at 09:00 and ends at 17:00.

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

RF Setup:

XMTRs 1,2, and 4 should be made ready by 8:00 (run-on).

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


Dec 12 2000 11:36:41:700AMBill RowanLoaded shot 1000607008.
Replaced NL_04 wire with NL_ZMETER from shot 1001208018

Did a cold start . Finished 12-DEC-2000 11:33:32.80

Dec 12 2000 12:55:46:280PM1001212001Bill Rowan001. Fizzle.

Next shot: Loaded segment 01 from 1001208001.
Dec 12 2000 01:13:30:607PM1001212002Bill Rowan002. Another fizzle.

Next shot. Add 2 ms to the prefill for a total of 22 ms
Dec 12 2000 01:38:41:187PM1001212003Bill Rowan003. Another fizzle.

Next shot. Loaded an engineering setup from Friday.
Increased the gas by 2 ms to 24 ms.
Dec 12 2000 01:56:05:420PM1001212004Bill Rowan004. Another fizzle.

Next shot: Increased the gas by 4 ms to 28 ms.
Dec 12 2000 02:13:16:030PM1001212005Bill Rowan005. Another fizzle.
Prefill at approx 0.07 mT Looks okay.

Next shot. Raise BZ. IC_EF4 from -1300 to -1290
Dec 12 2000 02:41:14:500PM1001212006Bill Rowan006. Another fizzle.

Try ECDC in D2 for 10 minutes before the next shot
Dec 12 2000 02:56:19:687PM1001212007Bill Rowan007. Another fizzle
Prefill is 0.09 mT

Next shot. Reduce the prefill by 4 ms to 24 ms
Dec 12 2000 03:21:08:123PM1001212008Bill Rowan008. Another fizzle
Prefill is 0.07 mT

Next shot. Reduce BZ IC_Ef4 from -1290 to -1300
Dec 12 2000 03:41:58:217PM1001212009Bill Rowan009. Another fizzle

ECDC in D2 before the next shot.
Dec 12 2000 04:01:43:403PM1001212010Bill Rowan010. Plasma. At last.

Next shot. No changes
Dec 12 2000 04:26:14:733PM1001212011Bill Rowan011. Plasma. Disruption at 0.87 s.

Next shot. Lower density by 10%
Dec 12 2000 04:38:54:107PM1001212012Bill Rowan012. Plasma. Disruption at 0.78 s

Next shot. No changes.
Dec 12 2000 04:52:23:590PM1001212013Bill Rowan013. Plasma Disruption at 0.85 s

Last shot.

Engineering Operator Comments
ShotTimeTypeStatusComment
112:44:38:733PMPlasmaOkAll Power Supplies Fired
201:01:44:077PMPlasmaOk
301:20:14:200PMPlasmaOk
401:44:50:590PMPlasmaOk
502:01:41:170PMPlasmaOk
602:18:40:047PMPlasmaOk
702:44:11:780PMPlasmaOk
803:01:29:890PMPlasmaOk
903:22:25:373PMPlasmaOk
1003:51:28:827PMPlasmaOk
1104:09:35:187PMPlasmaOk
1204:30:47:670PMPlasmaOk
1304:49:44:373PMPlasmaOk