Alcator C-Mod Run 1020925 Information

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Miniproposals
Miniproposal:301
Date Filed: 6/21/2002
Title:ITB Foot Location Movement via I
First Author:John Rice
Session Leader:John Rice (shots 1-32)

Operators
Session leader(s):John Rice
Physics operator(s):Joseph Snipes
Engineering operator(s):Gary Dekow

Engineering Operator Run Comment
MP#301 ITB foot location movement via Ip scan; SL:Rice; PO:Snipes; EO:De

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:30:693PM
Author: To Be Determined
Session Leader Run Summary for 1020925 MP301* ITB Foot, Ip Scan

There were several decent ITB discharges in this run, 6-12, which
showed a strong reduction in the toroidal rotation velocity inside of
the foot location, and modest reduction outside. However, H/D was steadily
increasing during the course of the run, and there were multiple RF trips
and H-L back transitions, so after shot 7 there were few steady ITBs.
As such, there was no time to attempt the Ip scan. It does appear that
the rotation velocity profile peaks near the resonance location, which
may help explain how the ICRF induces the ITBs.

Physics Operator Summaries
Entered: Jul 7 2004 04:37:16:270PM
Author: To Be Determined
Engineering setup for 1020924

MP#301 ITB foot location movement via Ip scan
Session leader: J. Rice
Physics Operator: J. Snipes

ECDC overnight in D2 stopping by 07:30.
Set up for possible ECDC in D2 between shots.

Power systems the same as shot 1020822010 Gas setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar Hybrid enabled (PG1)
fill B-side upper with 10 psi D2 Hybrid DISABLED (PG2) (for ECDC)
fill C-side with 30 psi D2 Hybrid enabled (PG3)
leave J-Bottom as is Hybrid DISABLED (PG5)
Enable the following gate valves, assuming no vacuum problems:
ECE, VUV, DNB

-------------------------------------------------------------------------------
RF Setup: FMIT#1 and 2 transmitters in Run On by 08:00
-------------------------------------------------------------------------------
Run Plan: Obtain standard EDA H-modes at 0.8 MA, 5.3 T, nl04 = 0.7 x 10^20 m^-2
with 2 MW ICRF from D and E. Then, use the TF waveform from shot 1020920027
ramping the TF down to 4.5 T by 1 sec to attempt to get ITB's in EDA H-mode.
Then, scan the plasma current down in steps as low as 0.6 or even 0.5 MA.

Summary: Overall, the machine ran quite well. Of 32 shots, there were 4
fizzles and 28 plasmas only one of which disrupted in flattop. Shot 1 was an
excellent standard EDA H-mode confinement shot and shot 7 was an excellent EDA
ITB shot. From there on, problems developed in maintaining D and E port power.
So, the rest of the run was devoted to attempting to tune up the ICRF. Part of
the problem could have been the high H/(H+D) ratio exceeding 10% at times. We
tried twice running ECDC in D2 between shots to reduce that ratio, but it was
not terribly effective.

Shot 1: Copied shot 1020822010 and set nl04 = 7 x 10^19 m^-2 and kept the TF
current constant at 150 kA. Ip set to 0.8 MA. Good shot. Nice EDA.
Shot 2: Copied TF waveform from shot 1020920027. Disrupted at 0.855 s near the
bottom of the TF ramp. Prad increases around 0.8 s. Could be the tile.
Shot 3: Repeat. Fizzle!
Shot 4: Try increasing RXL by 4 mm to 0.015 during the flattop to attempt to
avoid the tile. Good shot. Disrupted late just before 1.8 s at
400 kA. Two H-modes that are more ELM-free like.
Shot 5: Raised nl04 by 10% to 7.7 x 10^19 m^-2. Good shot. Ramped down well.
Two H-modes, more EDA-like perhaps with a brief ITB.
Shot 6: Ramped down TF faster from 150 kA to 124 kA in 0.4 sec. Raised nl04
to 8.5 x 10^19 m^-2. Good EDA with ITB.
Shot 7: Repeat. Good shot. Nice EDA with ITB.
Shot 8: Repeat attempting to improve RF coupling. Good shot. EDA trips at 1 s
then recovers.
Shot 9: Repeat. Good shot. Nice long EDA with ITB.
Shot 10: Returned RXL back to 0.011 m at Yijun's request to attempt to improve
the ICRF coupling, hoping that the disruption does not also return.
Good shot. Several EDA H-modes. No disruption. RF coupling no better.
Shot 11: Repeat. Good shot. Several EDA H-modes. RF still tripping.
Shot 12: Repeat. Good shot. Multiple H-modes again.
Shot 13: Reduced RXL again to 0.004 m to increase the lower triangularity.
Good shot. Multiple H-modes.
Shot 14: Raised nl04 to 9.5 x 10^19 m^-2. Good shot. Multiple H-modes.
Shot 15: Raised nl04 to 10.5 x 10^19 m^-2. Reduced RXL by another 4 mm to 0
to increase the lower triangularity still further to attempt to
improve RF coupling. No improvement. RF still trips. Multiple H-modes
Shot 16: Reload shot 1020925007 to try to get back to decent EDA's. Fizzle!
Shot 17: Made EF4 current 7 A more negative to -1322 A at breakdown. Good shot.
Nice EDA though there appear to be some small ELMs at 0.94 s.
Shot 18: Reload shot 1020925001 back to 5.3 T flattop. Good shot. Two EDA
H-modes. Not as good as shot 1 though.
Shot 19: Reduced nl04 to 6 x 10^19 m^-2 to try to get back to the target
density of shot 1. Only a short ELM-free H-mode. Density too low.
Shot 20: Raised nl04 back to 7 x 10^19 m^-2. Good shot. Two EDA H-modes.
E tripped, but D worked well.
Shot 21: Reduced nl04 to 6.5 x 10^19 m^-3 to split the difference and try to
return to the density of shot 1. Yijun separated the D and E pulses
and 1.2 MW each was not enough to get into H-mode until late in the
shot briefly.
Shot 22: Repeat with more RF power. E port tripped. Two short H-modes late.
ECDC between shots for 15 minutes.
Shot 23: Repeat. Fizzle!
Shot 24: Repeat. Good shot. Long EDA but only D port worked.
Shot 25: Repeat. Good shot. Short ELM-free H-mode followed by a long steady
EDA. Only D port again.
Shot 26: Ramp the TF down to 4.7 T, which means ITF down to 130 kA. Good shot.
Only D port worked. Brief H-mode after 1.2 s.
Shot 27: Repeat. Good shot. Similar to shot 26.
Shot 28: Raise nl04 to 7.15 x 10^19 m^-2. Good shot. A few H-modes.
Shot 29: Repeat. Good shot. Similar to shot 28.
Shot 30: Reduce ITF to 121 kA = 4.4 T. L-mode despite 2 MW of RF.
ECDC for 10 minutes.
Shot 31: Reduced prepuff by 4 ms to 23 ms duration anticipating higher gas
after the ECDC. Fizzle!
Shot 32: Repeat. Good shot. L-mode except for a brief H-mode after 1.4 s.

Session Leader Comments
Sep 25 2002 01:02:44:477PM1020925001John Ricegood EDA, 5.4T
Sep 25 2002 01:03:32:790PM1020925002John Ricedisrupted
Sep 25 2002 01:03:43:197PM1020925003John Ricephiz
Sep 25 2002 01:04:26:153PM1020925004John Riceramped TF down late, velocity profile peak seems to move out with the resonance location
Sep 25 2002 01:05:09:607PM1020925005John Ricegood EDA, no ITB
Sep 25 2002 01:07:17:423PM1020925006John Ricewith faster rampdown of TF, good ITB formation
Sep 25 2002 01:07:34:940PM1020925007John Ricewith faster rampdown of TF, good ITB formation
Sep 25 2002 01:08:03:097PM1020925008John Ricegood ITB formation, but RFR trip
Sep 25 2002 01:08:24:923PM1020925009John Ricegood ITB formation
Sep 25 2002 01:11:37:993PM1020925010John Ricegood ITB formation, RF trips
Sep 25 2002 01:16:27:300PM1020925011John Ricegood ITB formation, H-L transitions
Sep 25 2002 01:19:08:960PM1020925012John Ricegood ITB formation, RF trips
Sep 25 2002 01:19:41:540PM1020925013John RiceH-L xitions
Sep 25 2002 01:19:57:853PM1020925014John RiceH-L xitions, RF trips
Sep 25 2002 01:20:10:040PM1020925015John RiceH-L xitions, RF trips
Sep 25 2002 01:20:22:887PM1020925016John Ricephiz
Sep 25 2002 01:23:41:080PM1020925017John RiceRF trips
Sep 25 2002 01:23:57:157PM1020925018John Rice5.4 T, RF trips
Sep 25 2002 01:31:54:267PM1020925019John Rice5.4 T, ELM-free
Sep 25 2002 01:46:16:513PM1020925020John Rice5.4 T, RF trips
Sep 25 2002 01:51:56:040PM1020925020John Rice5.4 T, D and E separate
Sep 25 2002 02:32:31:570PM1020925021John Rice5.4 T, D and E separate
Sep 25 2002 02:32:51:337PM1020925022John RiceE trips
Sep 25 2002 02:33:53:980PM1020925023John Ricephiz, after long ECDC
Sep 25 2002 03:03:57:820PM1020925024John Riceno E port
Sep 25 2002 03:18:54:970PM1020925025John Riceno E port
Sep 25 2002 03:30:43:747PM1020925026John Rice4.7 T, E port trips
Sep 25 2002 04:02:36:133PM1020925027John Rice4.7 T, E port trips
Sep 25 2002 04:02:56:277PM1020925028John Rice4.7 T, RF trips, H-L
Sep 25 2002 04:13:25:763PM1020925029John Rice4.7 T, H-Ls
Sep 25 2002 04:27:42:603PM1020925030John Rice4.5 T, L-mode
Sep 25 2002 04:54:24:687PM1020925031John Ricephiz

Physics Operator Comments
Sep 25 2002 08:24:49:013AMJoseph SnipesEngineering setup for 1020924

MP#301 ITB foot location movement via Ip scan
Session leader: J. Rice
Physics Operator: J. Snipes

ECDC overnight in D2 stopping by 07:30.
Set up for possible ECDC in D2 between shots.

Power systems the same as shot 1020822010 Gas setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar Hybrid enabled (PG1)
fill B-side upper with 10 psi D2 Hybrid DISABLED (PG2) (for ECDC)
fill C-side with 30 psi D2 Hybrid enabled (PG3)
leave J-Bottom as is Hybrid DISABLED (PG5)

Enable the following gate valves, assuming no vacuum problems:
ECE, VUV, DNB

-------------------------------------------------------------------------------
RF Setup: FMIT#1 and 2 transmitters in Run On by 08:00
-------------------------------------------------------------------------------
Run Plan: Obtain standard EDA H-modes at 0.8 MA, 5.3 T, nl04 = 0.7 x 10^20 m^-2
with 2 MW ICRF from D and E. Then, use the TF waveform from shot 1020920027
ramping the TF down to 4.5 T by 1 sec to attempt to get ITB's in EDA H-mode.
Then, scan the plasma current down in steps as low as 0.6 or even 0.5 MA.
Sep 25 2002 09:10:09:287AM1020925001Joseph SnipesShot 1: Copied shot 1020822010 and set nl04 = 7 x 10^19 m^-2 and kept the TF
current constant at 150 kA. Ip set to 0.8 MA. Good shot. Nice EDA.
Sep 25 2002 09:34:36:037AM1020925002Joseph SnipesShot 2: Copied TF waveform from shot 1020920027. Disrupted at 0.855 s near the
bottom of the TF ramp. Prad increases around 0.8 s. Could be the tile.
Sep 25 2002 09:39:32:123AM1020925003Joseph SnipesShot 3: Repeat. Fizzle!
Sep 25 2002 10:02:25:137AM1020925004Joseph SnipesShot 4: Try increasing RXL by 4 mm to 0.015 during the flattop to attempt to
avoid the tile. Good shot. Disrupted late just before 1.8 s at
400 kA. Two H-modes that are more ELM-free like.
Sep 25 2002 10:16:38:743AM1020925005Joseph SnipesShot 5: Raised nl04 by 10% to 7.7 x 10^19 m^-2. Good shot. Ramped down well.
Two H-modes, more EDA-like perhaps with a brief ITB.
Sep 25 2002 10:20:26:030AM1020925006Joseph SnipesShot 6: Ramped down TF faster from 150 kA to 124 kA in 0.4 sec. Raised nl04
to 8.5 x 10^19 m^-2. Good EDA with ITB.
Sep 25 2002 10:42:06:980AM1020925007Joseph SnipesShot 7: Repeat. Good shot. Nice EDA with ITB.
Sep 25 2002 10:47:42:880AM1020925008Joseph SnipesShot 8: Repeat attempting to improve RF coupling. Good shot. EDA trips at 1 s
then recovers.
Sep 25 2002 11:00:14:640AM1020925009Joseph SnipesShot 9: Repeat. Good shot. Nice long EDA with ITB.
Sep 25 2002 11:20:52:490AM1020925010Joseph SnipesShot 10: Returned RXL back to 0.011 m at Yijun's request to attempt to improve
the ICRF coupling, hoping that the disruption does not also return.
Good shot. Several EDA H-modes. No disruption. RF coupling no better.
Sep 25 2002 11:27:36:177AM1020925011Joseph SnipesShot 11: Repeat. Good shot. Several EDA H-modes. RF still tripping.
Sep 25 2002 11:39:18:073AM1020925012Joseph SnipesShot 12: Repeat. Good shot. Multiple H-modes again.
Sep 25 2002 12:02:17:120PM1020925013Joseph SnipesShot 13: Reduced RXL again to 0.004 m to increase the lower triangularity.
Good shot. Multiple H-modes.
Sep 25 2002 12:11:53:723PM1020925014Joseph SnipesShot 14: Raised nl04 to 9.5 x 10^19 m^-2. Good shot. Multiple H-modes.
Sep 25 2002 12:26:25:267PM1020925015Joseph SnipesShot 15: Raised nl04 to 10.5 x 10^19 m^-2. Reduced RXL by another 4 mm to 0
to increase the lower triangularity still further to attempt to
improve RF coupling. No improvement. RF still trips. Multiple H-modes

Sep 25 2002 12:34:44:580PM1020925016Joseph SnipesShot 16: Reload shot 1020925007 to try to get back to decent EDA's. Fizzle!
Sep 25 2002 12:49:52:577PM1020925017Joseph SnipesShot 17: Made EF4 current 7 A more negative to -1322 A at breakdown. Good shot.
Nice EDA though there appear to be some small ELMs at 0.94 s.
Sep 25 2002 01:04:49:107PM1020925018Joseph SnipesShot 18: Reload shot 1020925001 back to 5.3 T flattop. Good shot. Two EDA
H-modes. Not as good as shot 1 though.
Sep 25 2002 01:18:47:257PM1020925019Joseph SnipesShot 19: Reduced nl04 to 6 x 10^19 m^-2 to try to get back to the target
density of shot 1. Only a short ELM-free H-mode. Density too low.
Sep 25 2002 01:35:06:290PM1020925020Joseph SnipesShot 20: Raised nl04 back to 7 x 10^19 m^-2. Good shot. Two EDA H-modes.
E tripped, but D worked well.
Sep 25 2002 01:46:10:030PM1020925021Joseph SnipesShot 21: Reduced nl04 to 6.5 x 10^19 m^-3 to split the difference and try to
return to the density of shot 1. Yijun separated the D and E pulses
and 1.2 MW each was not enough to get into H-mode until late in the
shot briefly.
Sep 25 2002 02:02:37:060PM1020925022Joseph SnipesShot 22: Repeat with more RF power. E port tripped. Two short H-modes late.
Sep 25 2002 02:03:08:513PM1020925022Joseph SnipesShot 22: ECDC between shots for 15 minutes.
Sep 25 2002 02:34:23:857PM1020925023Joseph SnipesShot 23: Repeat. Fizzle!
Sep 25 2002 02:54:12:893PM1020925024Joseph SnipesShot 24: Repeat. Good shot. Long EDA but only D port worked.
Sep 25 2002 03:07:02:387PM1020925025Joseph SnipesShot 25: Repeat. Good shot. Short ELM-free H-mode followed by a long steady
EDA. Only D port again.
Sep 25 2002 03:21:01:413PM1020925026Joseph SnipesShot 26: Ramp the TF down to 4.7 T, which means ITF down to 130 kA. Good shot.
Only D port worked. Brief H-mode after 1.2 s.
Sep 25 2002 03:39:59:623PM1020925027Joseph SnipesShot 27: Repeat. Good shot. Similar to shot 26.
Sep 25 2002 03:57:03:640PM1020925028Joseph SnipesShot 28: Raise nl04 to 7.15 x 10^19 m^-2. Good shot. A few H-modes.
Sep 25 2002 04:13:30:547PM1020925029Joseph SnipesShot 29: Repeat. Good shot. Similar to shot 28.
Sep 25 2002 04:26:45:727PM1020925030Joseph SnipesShot 30: Reduce ITF to 121 kA = 4.4 T. L-mode despite 2 MW of RF.
Sep 25 2002 04:27:07:493PM1020925030Joseph SnipesShot 30: ECDC for 10 minutes.
Sep 25 2002 04:56:39:317PM1020925031Joseph SnipesShot 31: Reduced prepuff by 4 ms to 23 ms duration anticipating higher gas
after the ECDC. Fizzle!
Sep 25 2002 05:08:21:090PM1020925032Joseph SnipesShot 32: Repeat. Good shot. L-mode except for a brief H-mode after 1.4 s.
Sep 25 2002 05:10:45:623PM1020925032Joseph SnipesSummary: Overall, the machine ran quite well. Of 32 shots, there were 4
fizzles and 28 plasmas only one of which disrupted in flattop. Shot 1 was an
excellent standard EDA H-mode confinement shot and shot 7 was an excellent EDA
ITB shot. From there on, problems developed in maintaining D and E port power.
So, the rest of the run was devoted to attempting to tune up the ICRF. Part of
the problem could have been the high H/(H+D) ratio exceeding 10% at times. We
tried twice running ECDC in D2 between shots to reduce that ratio, but it was
not terribly effective.

Engineering Operator Comments
ShotTimeTypeStatusComment
109:04:22:433AMPlasmaOk
209:21:14:933AMPlasmaOk
309:35:05:960AMPlasmaOk
409:50:08:443AMPlasmaOk
510:04:36:830AMPlasmaOk
610:17:40:997AMPlasmaOk
710:30:52:037AMPlasmaOk
810:44:07:267AMPlasmaOk
910:57:50:963AMPlasmaOk
1011:10:43:300AMPlasmaOk
1111:24:19:683AMPlasmaOk
1211:37:51:180AMPlasmaOk
1311:52:35:647AMPlasmaOk
1412:05:31:710PMPlasmaOk
1512:18:23:063PMPlasmaOk
1612:32:15:870PMPlasmaOk
1712:46:44:633PMPlasmaOk
1801:01:41:990PMPlasmaOk
1901:15:52:347PMPlasmaOk
2001:28:52:120PMPlasmaOk
2101:41:58:177PMPlasmaOk
2201:55:55:923PMPlasmaOk
2302:32:03:100PMPlasmaOk
2402:46:51:770PMPlasmaOk
2503:01:08:343PMPlasmaOk
2603:16:41:280PMPlasmaOk
2703:36:23:927PMPlasmaOk
2803:49:15:250PMPlasmaOk
2904:03:14:527PMPlasmaOk
3004:16:46:820PMPlasmaOk
3104:51:48:213PMPlasmaOk
3205:05:34:490PMPlasmaOk