Alcator C-Mod Run 1050614 Information

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Miniproposals
Miniproposal:415
Date Filed: 2/24/2005
Title:Rotation and H-mode Power Threshold for LSN and USN at Different IP and ne
First Author:John Rice
Session Leader:John Rice (shots 1-30)

Operators
Session leader(s):John Rice
Physics operator(s):Joseph Snipes
Engineering operator(s):Bill Cochran,Bill Parkin

Engineering Operator Run Comment
MP#415

Session Leader Plans

Physics Operators Plans
Entered: Jun 13 2005 01:44:58:800PM
Author: Joseph Snipes
Engineering setup for Tuesday, 14 June 2005

MP #415: Rotation and H-mode Thresholds for LSN and USN at different Ip and ne

Session leader: J. Rice
Physics operator: J. Snipes

Overnight boronization with the following parameters:
. dP of 120 to 140 psi
. scan from 50 cm to 103 cm with dwell at 78.5 cm

ECDC in D2 prior to first plasma discharge

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

Power systems as on 1050427012 (0.8 MA, 5.4 T, SNL fiducial)

A-coil configuration: normal [+Dtop -Dbot -Jtop +Jbot] and enabled.

Gas Setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar Hybrid ENABLED (PG1)
leave B-side upper with whatever Hybrid disabled
fill B-main (C-side) with 30 psi D2 Hybrid enabled (PG3)
NINJA not used today

Enable the following gate valves and shutters, assuming no vacuum problems:
ECE, VUV, Z-bolo shutters

-------------------------------------------------------------------------------
ICRF Setup: All transmitters in run on at 08:30.
-------------------------------------------------------------------------------
Plan: H-mode threshold and plasma rotation.

Session Leader Summaries
Entered: Jun 15 2005 04:58:39:717PM
Author: John Rice
Session Leader Run Summary for 1050614 MP415 Rotation and H-mode Power Threshold

The first half of the run, shots 3-14, was spent on boronization and ICRF antenna conditioning.
At that time is was determined that the J-port antenna would not be of much use, and therefore
there probably wouldn't be enough power to enter H-mode with USN. It was decided to map out the
H-mode power threshold as a function of plasma current for LSN discharges with nl04 around 0.9.
For 1.0 MA plasmas, H-mode was achieved with only 240 kW of ICRF power, for 0.8 MA, with 470 kW.
H-mode was not achieved at 0.6 MA with up to 880 kW. All of these values are considerably lower
than found previously, possibly due to the recent boronization, and emphasizing the variability
of results in this area. The 0.6 MA L-mode target plasmas had a stronger counter-current rotation,
and subsequent higher H-mode power threshold, consistent with earlier speculation. No information
about one of the purposes of this run, the threshold in USN, was obtained.

Physics Operator Summaries
Entered: Jun 14 2005 05:19:07:400PM
Author: Joseph Snipes
The machine ran very well today with no issues associated with the boronization. Indeed, the startup was rather robust to small changes in EF4 current. In the end, despite some ugly looking startups, leaving EF4 at -1280 A was the optimum value. There were a few disruptions apparently caused by things falling into the plasma. There was a delay at the beginning because the power supplies were not enabled properly. There were also a lot of entries into the power room for ICRF and entries into the cell that took a long time to clear the nitrogen for breathing. Furthermore, the first half of the run was dedicated to RF tuning, so only a few shots at the end gave information on the H-mode threshold. See the SL summary for the physics details. It seems that low current really increases the threshold a great deal, more than the reduction in total input power would indicate, probably because the rotation is more in the electron direction at lower current.

Shot,Duration(s),Ipmax(MA),Result Shot,Duration(s),Ipmax,Result
| 01 0.000 0.002 Dud | 02 0.236 0.726 Plasma |
| 03 1.959 1.061 Plasma | 04 1.958 1.064 Plasma |
| 05 1.952 1.063 Plasma | 06 1.959 1.063 Plasma |
| 07 1.958 1.064 Plasma | 08 1.948 1.064 Plasma |
| 09 1.956 1.064 Plasma | 10 1.956 1.065 Plasma |
| 11 1.957 1.064 Plasma | 12 1.958 1.065 Plasma |
| 13 1.925 1.065 Plasma | 14 1.852 1.065 Plasma |
| 15 1.956 1.064 Plasma | 16 1.958 1.062 Plasma |
| 17 1.962 1.063 Plasma | 18 1.967 1.059 Plasma |
| 19 0.000 0.024 Dud | 20 1.963 1.055 Plasma |
| 21 1.962 1.054 Plasma | 22 0.597 0.815 Plasma |
| 23 1.958 0.817 Plasma | 24 1.962 0.816 Plasma |
| 25 1.962 0.816 Plasma | 26 1.962 0.811 Plasma |
| 27 1.745 0.812 Plasma | 28 1.416 0.724 Plasma |
| 29 1.429 0.729 Plasma | 30 1.469 0.729 Plasma |

Date 1050614: 30 shots. 28 plasmas. 0 fizzles. 1 dud. 1 System Error.

Session Leader Comments
Jun 14 2005 09:05:06:487AM1050614001John Ricetest
Jun 14 2005 09:23:40:860AM1050614002John Ricedisrupted early
Jun 14 2005 09:44:37:390AM1050614003John Ricegood plasma at 1.0 MA, LSN
H-mode at 540 kW!
Jun 14 2005 10:03:12:500AM1050614004John Ricegood plasma at 1.0 MA, LSN
H-mode at 800 kW
Jun 14 2005 10:16:43:857AM1050614005John Ricegood plasma at 1.0 MA, LSN
H-mode
Jun 14 2005 10:47:35:777AM1050614006John Rice1.0 MA, LSN
H-mode
Jun 14 2005 11:02:31:870AM1050614007John Rice1.0 MA, LSN
H-mode
Jun 14 2005 11:19:16:277AM1050614008John Rice1.0 MA, LSN
H-mode
Jun 14 2005 11:43:35:777AM1050614009John Rice1.0 MA, LSN
H-mode
Jun 14 2005 12:04:27:887PM1050614010John Rice1.0 MA, LSN
H-mode
Jun 14 2005 12:28:02:357PM1050614011John Rice1.0 MA, LSN
H-mode
Jun 14 2005 12:48:13:590PM1050614012John Rice1.0 MA, LSN
H-mode 0.9 MW
Jun 14 2005 12:52:10:183PM1050614013John Rice1.0 MA, LSN
H-mode 0.84 MW
Jun 14 2005 01:08:15:480PM1050614014John Rice1.0 MA, LSN
H-mode 0.78 MW
Jun 14 2005 01:20:05:247PM1050614015John Rice1.0 MA, LSN
H-mode 0.93 MW
Jun 14 2005 01:47:41:730PM1050614016John Rice1.0 MA, LSN
H-mode 0.81 MW
Jun 14 2005 01:47:50:497PM1050614017John Rice1.0 MA, LSN
H-mode 0.61 MW
Jun 14 2005 02:03:42:620PM1050614018John Rice1.0 MA, LSN
H-mode 0.37 MW
Jun 14 2005 02:33:16:200PM1050614019John Ricedud
Jun 14 2005 02:55:58:103PM1050614020John Rice1.0 MA, LSN
H-mode with 250 kW ICRF
Jun 14 2005 03:00:43:120PM1050614021John Rice1.0 MA, LSN
L-mode with 180 kW ICRF
Jun 14 2005 03:16:17:997PM1050614022John Rice0.8 MA, LSN
L-mode with 0 kW ICRF
Jun 14 2005 03:33:57:857PM1050614023John Rice0.8 MA, LSN
H-mode with 860 kW ICRF
Jun 14 2005 03:47:12:887PM1050614024John Rice0.8 MA, LSN
H-mode with 790 kW ICRF
Jun 14 2005 04:00:33:747PM1050614025John Rice0.8 MA, LSN
H-mode with 610 kW ICRF
Jun 14 2005 04:13:24:293PM1050614026John Rice0.8 MA, LSN
H-mode with 480 kW ICRF
Jun 14 2005 04:31:19:170PM1050614027John Rice0.8 MA, LSN
L-mode with 400 kW ICRF
Jun 14 2005 04:42:18:967PM1050614028John Rice0.6 MA, LSN
L-mode with 500 kW ICRF
Jun 14 2005 04:56:09:887PM1050614029John Rice0.6 MA, LSN
L-mode with 600 kW ICRF
Jun 14 2005 05:09:48:810PM1050614030John Rice0.6 MA, LSN
L-mode with 870 kW ICRF

Physics Operator Comments
Jun 14 2005 09:09:36:750AM1050614001Joseph SnipesShot 1: Loaded shot 1050610012 at Yijun's suggestion to tune up the ICRF. Charging supplies were in a disabled state. Lost the shot. Vincent Tang's
amplifiers are railing so he went in after the shot to try to fix it.
Jun 14 2005 09:20:07:440AM1050614002Joseph SnipesShot 2: Try again. Disrupted at 0.23 s.
Jun 14 2005 09:45:08:237AM1050614003Joseph SnipesShot 3: One more time. Good shot. Got H-mode with E-port only at 0.54 MW.
Jun 14 2005 09:58:54:220AM1050614004Joseph SnipesShot 4: Increased Ar puff to 60 ms duration. Good shot. Another H-mode with
D and E port but little power from J-port.
Jun 14 2005 10:15:46:663AM1050614005Joseph SnipesShot 5: Increased Ar pressure to 1.5 psi. Good shot. A few H-modes. ICRF still needs better tuning.
Jun 14 2005 10:39:39:060AM1050614006Joseph SnipesShot 6: Repeat. Good shot.
Jun 14 2005 10:52:36:700AM1050614007Joseph SnipesShot 7: NINJA D2 gas puff at 0.7 s. Good shot.
Jun 14 2005 11:14:20:480AM1050614008Joseph SnipesShot 8: NINJA D2 gas puff at 0.7 s and 1.1 s. Good shot.
Jun 14 2005 11:55:30:370AM1050614009Joseph SnipesShot 9: Repeat. Good shot.
Jun 14 2005 11:58:52:870AM1050614010Joseph SnipesShot 10: Repeat. Good shot.
Jun 14 2005 12:30:50:980PM1050614011Joseph SnipesShot 11: Repeat with active MHD off. ICRF coupling did not improve. Good plasma shot.
Jun 14 2005 12:40:53:747PM1050614012Joseph SnipesShot 12: Repeat. Good shot.
Jun 14 2005 12:53:25:967PM1050614013Joseph SnipesShot 13: Repeat. Good shot.
Jun 14 2005 01:03:32:120PM1050614014Joseph SnipesShot 14: Increased EF4 current by 15 A to -1265 A. Good shot. Startup looks worse though.
Jun 14 2005 01:18:22:747PM1050614015Joseph SnipesShot 15: Decreased EF4 current by 30 A to -1295 A. Good shot. Startup still has a hesitation in the current rise.
Jun 14 2005 01:36:17:793PM1050614016Joseph SnipesShot 16: Returned to -1280 A on EF4. Good shot. Startup still looks bad.
Jun 14 2005 01:49:33:620PM1050614017Joseph SnipesShot 17: Increased prepuff by 3 ms to 21 ms duration. Good shot. Startup still has a hesitation.
Jun 14 2005 02:01:32:777PM1050614018Joseph SnipesShot 18: Increased EF4 current to -1270 A. Good shot.
Jun 14 2005 02:32:25:027PM1050614019Joseph SnipesShot 19: Dud!
Jun 14 2005 02:44:42:607PM1050614020Joseph SnipesShot 20: Decreased EF4 current to -1290 A. Good shot.
Jun 14 2005 02:59:48:357PM1050614021Joseph SnipesShot 21: Repeat. Good shot.
Jun 14 2005 03:25:11:620PM1050614022Joseph SnipesShot 22: Decreased Ip to 0.8 MA. Disrupted at 0.595 s. Lost vertical control and disrupted upward.
Jun 14 2005 03:31:57:513PM1050614023Joseph SnipesShot 23: Repeat. Good shot. Startup now seems to be well tuned up.
Jun 14 2005 03:47:16:997PM1050614024Joseph SnipesShot 24: Raised nl04 from 8 x 10^19 m^-2 to 9 x 10^19 m^-2. Good shot.
Jun 14 2005 03:59:41:527PM1050614025Joseph SnipesShot 25: Repeat with lower RF power. Good shot.
Jun 14 2005 04:12:40:620PM1050614026Joseph SnipesShot 26: Returned EF4 current to -1280 A. Good shot.
Jun 14 2005 04:29:18:353PM1050614027Joseph SnipesShot 27: Lower RF power a bit more. Good shot remained in L-mode with 0.4 MW.
Jun 14 2005 04:41:21:637PM1050614028Joseph SnipesShot 28: Reduced Ip to 0.6 MA. Disrupted at 1.41 s. Remained in L-mode.
Jun 14 2005 04:59:20:433PM1050614029Joseph SnipesShot 29: Repeat. Disrupted at 1.42 s. Remained in L-mode with 0.6 MW.
Jun 14 2005 05:07:20:853PM1050614030Joseph SnipesShot 30: Repeat with more RF. No H-mode with 0.9 MW. Disrupted at 1.46 s.

Engineering Operator Comments
ShotTimeTypeStatusComment
109:00:22:907AMPlasmaBadThe Oh and EF1 capacitor bank PS's were disabled
209:17:38:343AMPlasmaOk
309:38:52:767AMPlasmaOk
409:53:29:407AMPlasmaOk
510:10:20:047AMPlasmaOk
610:37:15:683AMPlasmaOk
710:50:23:573AMPlasmaOk
811:13:01:293AMPlasmaOk
911:25:47:560AMPlasmaOk
1011:56:05:747AMPlasmaOk
1112:19:00:357PMPlasmaOk
1212:31:59:090PMPlasmaOk
1312:47:25:590PMPlasmaOk
1401:00:06:730PMPlasmaOk
1501:15:08:277PMPlasmaOk
1601:30:12:810PMPlasmaOk
1701:43:09:870PMPlasmaOk
1801:59:04:950PMPlasmaOk
1902:30:33:450PMPlasmaOk
2002:43:00:590PMPlasmaOk
2102:57:50:870PMPlasmaOk
2203:11:36:073PMPlasmaOkEbreaker opened after disruption
2303:28:55:043PMPlasmaOk
2403:42:37:527PMPlasmaOk
2503:55:13:027PMPlasmaOk
2604:08:56:340PMPlasmaOk
2704:25:34:730PMPlasmaOk
2804:38:11:043PMPlasmaOk
2904:51:18:637PMPlasmaOk
3005:03:43:573PMPlasmaOk