Alcator C-Mod Run 1040506 Information

Back to runs

Miniproposals
Miniproposal:370
Date Filed:11/15/2003
Title:Large Volume ITBs at 2.8 T with 50 Mhz ICRF
First Author:John Rice
Session Leader:John Rice (shots 1-34)

Operators
Session leader(s):John Rice
Physics operator(s):Ron Parker
Engineering operator(s): Unknown

Engineering Operator Run Comment
Purpose: MP#390 Large Volume ITB's at 2.8 T with 50 MHz

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:05:850PM
Author: John Rice
Session Leader Run Summary for 1040506 MP370 Large Volume ITBs at 2.8 T w/ 50 MHz ICRF

The J-port ICRF got off to a slow start because of the high neutral pressures following
boronization. Suitable ITB target plasmas at 3.4 T and 500 kA were quickly established.
After several conditioning shots, H-modes were obtained on shots 19 and 23 with on-axis heating
at 3.5 T. H-modes were also obtained with off-axis heating at 2.9 T on shots 24-27. Shots
28 and 34 had ITBs. From core Thomson scattering, there was no apparent foot, with the
density peaking extending all the way to the edge pedestal, as anticipated. Density profiles
from Dalsa had a foot-like bump feature near the half radius, but further analysis is needed.

Physics Operator Summaries
Entered: Jul 7 2004 04:36:50:223PM
Author: Ron Parker
;; This buffer is for notes you don't want to save, and for Lisp evaluation.
;; If you want to create a file, visit that file with C-x C-f,
;; then enter the text in that file's own buffer.


Physop Summary 1040506

The run started a little late with three shots that were cycle tests made necessary by a computer hangup.But once underway, the machine performed well, especially considering that this was a post boronization recovery run. Only the first shot fizzled, after that every plasma started up well, although one or two disrupted early on. The first plasma shot was shot 5 and that was a fidicial shot to check wall conditions, impurity levels, gas pressure etc. Then, the field was lowered to 3.4-3.5 T for a number of shots. However, the neutral pressure was too high for J-port (at 50 MHz) to run, so a number of cleaning shots were run at 5.4 T to reduce this pressure.The field was lowered back to 3.4 T on shot 17 and to 2.8 T on shot 24 and ITB studies then began.The shots looked promising as the hour became late and unfortunately the run had to end before long ITB's could be produced.

Scorecard: 3 test cycles, 1 fizzle, no duds, 7 disruptions, the rest useable shots, although the J-port ( 50MHz ) RF was not able to run at low field until midway in the run due to excessive neutral pressure.


Engineering Setup and Run Plan 1040506

Boronization overnight, after which discharge cleaning following usual post-boronization procedure

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

Purpose: MP#390 Large Volume ITB's at 2.8 T with 50 MHz

Session leader: Rice

Physop: Parker

Engineering Setup:

Power Supplies as on 1040505, A-coil configuration as in 1031121019, power supplies enabled

Gas System 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 15 psi He3 Hybrid DISABLED (PG2)
fill C-side with 30 psi D2 Hybrid enabled (PG3)


Diagnostic gate valve permissives for ECE, VUV, DNB assuming no vacuum
problems

RF: All Transmitters in RUN-ON by 08:30

Run Plan

Since this is a post boronization run, we'll start with a fidicial discharge, e.g., 1040505015

Assuming success, we'll move on to the run plan which calls for running BT ~ 3.4 T and Ip ~ 500 kA.with the ICRF will be at 50 MHz (on axis). We'll then lower the field to 2.8 T, moving the 50 MHz off axis and, assuming ITB formation, apply 80 MHz 2nd harmonic heating on axis.

We expect the ITB, if it forms, to move its foot location outwards, near r/a =0.8 based on extrapolation of previous data.Operating at low plasma current and field should also test the ITB behavior at higher beta.





Session Leader Comments
May 6 2004 09:48:08:047AM1040506004John Ricefiz
May 6 2004 10:15:41:570AM1040506005John Ricevanilla shot
May 6 2004 10:16:53:160AM1040506006John Rice500 kA, 3.6 T
good target plasma
May 6 2004 10:28:52:343AM1040506007John Rice500 kA, 3.6 T
good target plasma
May 6 2004 10:46:58:023AM1040506008John Rice500 kA, 3.6 T
good target plasma
600 kW RF, no H-mode
May 6 2004 10:57:15:020AM1040506009John Rice470 kA, 3.4 T
good target
no J power yet
May 6 2004 11:16:30:153AM1040506010John Rice470 kA, 3.4 T
good target
no J power
May 6 2004 11:32:52:977AM1040506011John Rice800 kA, 5.4 T
to lower neutral pressure
May 6 2004 11:57:16:930AM1040506012John Rice800 kA, 5.4 T
lower density to lower neutral pressure
May 6 2004 12:10:02:143PM1040506013John Rice800 kA, 5.4 T
lower density to lower neutral pressure
May 6 2004 12:22:39:420PM1040506014John Rice800 kA, 5.4 T
lower density to lower neutral pressure
H-mode
May 6 2004 12:36:54:697PM1040506015John Rice800 kA, 5.4 T
lower density to lower neutral pressure
H-mode
May 6 2004 01:03:27:983PM1040506016John Rice800 kA, 5.4 T
lower density to lower neutral pressure
H-mode
May 6 2004 01:06:26:123PM1040506017John Rice480 kA, 3.4 T
no J power
May 6 2004 01:22:00:727PM1040506018John Rice500 kA, 3.5 T
1 MW J power
May 6 2004 01:33:31:737PM1040506019John Rice470 kA, 3.4 T
1.2 MW J power
May 6 2004 01:45:17:827PM1040506020John Rice470 kA, 3.4 T
1.2 MW J power
May 6 2004 02:04:33:883PM1040506021John Rice470 kA, 3.4 T
0.8 MW J power
May 6 2004 02:12:16:723PM1040506022John Rice470 kA, 3.4 T
1.4 MW J power
no H-mode
May 6 2004 02:26:53:030PM1040506023John Rice470 kA, 3.4 T, lower density
1.4 MW J power
H-mode
May 6 2004 02:40:01:930PM1040506024John Rice470 kA, 2.9 T
1.4 MW J power, trips
H-modes
May 6 2004 02:52:55:003PM1040506025John Rice470 kA, 2.9 T
1.4 MW J power
H-mode
May 6 2004 03:05:12:970PM1040506026John Rice470 kA, 2.9 T
1.3 MW J power
H-modes
May 6 2004 03:16:46:150PM1040506027John Rice470 kA, 2.9 T
1.3 MW J power
H-modes
May 6 2004 03:39:01:753PM1040506028John Rice470 kA, 2.9 T
1.3 MW J power
H-mode
density peaking
ITB
May 6 2004 03:45:55:797PM1040506029John Rice470 kA, 2.9 T
0 MW J power
May 6 2004 04:00:15:930PM1040506030John Rice470 kA, 2.9 T
1.1 MW J power
H-mode trips
May 6 2004 04:10:28:397PM1040506031John Ricedisrupted
May 6 2004 04:29:16:187PM1040506032John Ricemultiple H-modes
May 6 2004 04:49:09:380PM1040506033John Ricemultiple H-modes
May 6 2004 05:01:36:500PM1040506034John Rice2.8 T
1.1 MW J
1.2 MW E

multiple H-modes

Physics Operator Comments
May 6 2004 09:47:42:797AM1040506002Ron ParkerFirst shot will be setup as in 1040505015 except Ip = 800 kA.

Slight (we hope) delay while Josh attends to computer hangup. First shot will be
no power cycle test.
May 6 2004 09:48:50:797AM1040506003Ron ParkerShot 3 was also a cycle test and was successful. Next will be plasma attempt
May 6 2004 02:58:58:487PM1040506003Ron ParkerShot 23 seemed to run well, no disruption. RF at ~ 1.4 MW.
Next shot, we'll try for 2.8 T
May 6 2004 09:50:58:593AM1040506004Ron ParkerFirst plasma shot fizzled. Breakdown looked reasonble, probably too dirty to
break through impurity barrier.
May 6 2004 10:00:19:433AM1040506005Ron ParkerAfter carefully retuning (actually nothing was changed), shot ran well.

Now we'll set up for 3.4 Tesla, 94.4 kA TF and 500 kA Ip.
May 6 2004 11:30:36:320AM1040506006Ron ParkerShot 6 went off as programmed with 500 kA at 3.6 T.

Next: Repeat
May 6 2004 10:34:23:750AM1040506007Ron ParkerSjot 7 went off OK. Same discharge, field was 3.6, not 3.4 T so we'll lower TF curremt
for next shot to come closer to 3.4 T on-axis. Otherwise, no changes to machine settings.
May 6 2004 11:15:05:593AM1040506008Ron ParkerShot 8 was the same as previous shot except field was 3.4 T. No changes.
May 6 2004 11:15:45:250AM1040506009Ron ParkerShot 9 was the same as previous shot. We are continuing with same shots.
May 6 2004 11:17:42:373AM1040506010Ron ParkerShot 10 went off as programmed. No RF.
May 6 2004 11:25:27:430AM1040506010Ron ParkerNeutral pressure on these shots seems to be too high for J-port. We'll
return to shot 5, 800 kA, 5.4 T to try to burn off neutral gas.
May 6 2004 11:47:22:597AM1040506011Ron ParkerShot 11 looked good, neutral pressure at G-side was ~ 0.5 mT. We'll sit here with
this shot for a while to see if the neutral pressure can be reduced.
On the next shot, the density n_eL(4) will be reduced to 0.7.
May 6 2004 12:10:30:863PM1040506012Ron ParkerShot 12 ran nicely, with somewhat lower density, the pressure at G-side
came down a bit to ~ 0.35 mT.
May 6 2004 12:14:40:033PM1040506013Ron ParkerShot 13 also ran well, but pressure at G-side came back to 0.5 mT. But density was
also up, to 1.0e20 m-2 on n_e.L(4). E-port Rf at ~ 1MW, nothing from other antennas.
May 6 2004 12:27:02:700PM1040506014Ron ParkerShots continue to behave. Shot H-mode with 1 MW. Next shot, lower density again
to 0.5 e20 m-2.
May 6 2004 12:37:32:807PM1040506015Ron ParkerAlthough the density did not drop much if at all, the G-side pressure continues to
decrease, now at 0.2 mT.
May 6 2004 12:57:50:313PM1040506016Ron ParkerOK, shot contiues to run well and neutral pressure at G side is staying around
0.2 mT. Now we will revert to shot 10, with lower density, targeting 0.5 e 20
m-2

Bill Rowan now operating
May 6 2004 02:18:19:550PM1040506017Ron ParkerShot 17 ran well, but RF was spotty.
May 6 2004 01:23:45:007PM1040506018Ron Parker
Disruption at 0.8 s. This looks like an injection. Just try again.

May 6 2004 01:41:26:907PM1040506019Ron Parker
Disruption at 1.15 s. Disruption occurred during RF. Evidence of injection on SXR and carbon monitor.
Increase nl_04 to 0.8e+20
May 6 2004 01:49:30:717PM1040506020Ron Parker
Disruption at 0.8 s.
nl_04 = 0.8e+19 as requested.
Still looks like an injection on the SXR signal.
Will try lower RF power for a shot to look for correlation.
May 6 2004 02:03:38:133PM1040506021Ron Parker
Disruption at 0.93 s
Soft x-ray signal takes off again before the disruption.
RXL = 0.0
May 6 2004 02:15:40:207PM1040506022Ron Parker
Disruption at 0.845 s
Reduced nl_04 to 0.5e+20 at the request of the SL
Parker back as PO
May 6 2004 03:00:22:690PM1040506023Ron ParkerShot 23 ran well, without disrupting. Next shot: the TF will be set at 2.8 T


May 6 2004 02:58:31:813PM1040506024Ron ParkerShot 24 ran well at 2.8 T. But RF straddled the point at which the field leveled off at 2.8 T.

For the next shot, the machine settings will be the same but the RF will be intitiated at the
breakpoint in the TF waveform.
May 6 2004 03:01:12:890PM1040506025Ron ParkerShot 25 disrupted at 1.14 s. We'll repeat next shot.

May 6 2004 03:31:23:707PM1040506026Ron ParkerShot 26 ran well. no changes for next shot.
May 6 2004 03:32:35:003PM1040506027Ron ParkerShot 27 ran well, RF is getting better.
May 6 2004 03:34:19:940PM1040506028Ron ParkerShot 28 was great! RF stayed on and ITB seemed to develop. Now we'll try to extend it.
May 6 2004 03:52:26:560PM1040506029Ron ParkerOoops, no RF on that shot. We'll repeat.
May 6 2004 04:10:27:240PM1040506030Ron ParkerShot 30 ran OK.
May 6 2004 04:26:51:483PM1040506031Ron ParkerShot 31 disrupted early, beginning at 100 ms. No change for next shot.
May 6 2004 04:36:02:183PM1040506032Ron ParkerShot 32 made it until the programmed end ofthe shot, then disrupted. An ITB appeared
but was somewhat intermittent. TF field will be reduced to 2.8 from 2.87 on
next shot.
May 6 2004 05:00:52:423PM1040506033Ron ParkerShot 33 ran well, ITB starts to form but RF trips out and the ITB drops out.
Steve notivced that a number of control waveforms were not properly extended
in view of the loner pulse length. These have been remedied for the last shot.
May 6 2004 05:05:30:687PM1040506034Ron ParkerShot 34 ran well and made it half way through ramp down at 2 s until disrupting.

Clear ITB forms.

Engineering Operator Comments
ShotTimeTypeStatusComment
108:25:00:510AMTestOkShot Cycle Test
309:23:53:407AMTestOk
409:34:51:957AMPlasmaOk
509:48:05:377AMPlasmaOk
610:12:42:163AMPlasmaOk
710:25:41:097AMPlasmaOk
810:41:11:310AMPlasmaOk
910:53:57:820AMPlasmaOk
1011:13:43:860AMPlasmaOk
1111:29:44:947AMPlasmaOk
1211:48:05:140AMPlasmaOk
1312:07:22:647PMPlasmaOk
1412:20:21:173PMPlasmaOk
1512:33:17:963PMPlasmaOk
1612:45:42:397PMPlasmaOk
1701:02:56:360PMPlasmaOk
1801:15:47:683PMPlasmaOk
1901:28:25:270PMPlasmaOk
2001:42:22:813PMPlasmaOk
2101:55:46:103PMPlasmaOk
2202:08:19:990PMPlasmaOk
2302:23:25:263PMPlasmaOk
2402:36:08:900PMPlasmaOk
2502:48:44:177PMPlasmaOk
2603:01:14:547PMPlasmaOk
2703:13:45:090PMPlasmaOk
2803:28:11:833PMPlasmaOk
2903:42:47:313PMPlasmaOk
3003:55:20:793PMPlasmaOk
3104:08:06:630PMPlasmaOk
3204:23:37:830PMPlasmaOk
3304:44:56:163PMPlasmaOk
3404:58:37:237PMPlasmaOk