Alcator C-Mod Run 1020828 Information

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Miniproposals
Miniproposal:305
Date Filed: 6/18/2002
Title:ITB - Access Conditions and Hysteresis
First Author:Martin Greenwald
Session Leader:Martin Greenwald (shots 1-31)

Operators
Session leader(s):Martin Greenwald
Physics operator(s):Dmitri Mossessian
Engineering operator(s): Unknown

Engineering Operator Run Comment
MP305 ITB Access conditions, hysteresis; SL: Greenwald; PO: Mossessian;

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:30:007PM
Author: To Be Determined
Run Plan for 1020828
mp 305 ITB Access Conditions

Session Leader - Greenwald
Phys Op - Mossessian

============================

Plan:


The purpose of the run is to investigate access conditions
or trigger for producing off-axis ICRF ITB mode.
We will also ook for hysteresis in transition and investigate
proximity to marginal stability via heat pulse propagation.

Given the difficulties in obtaining an ITB yesterday, we will
start with some preliminaries rather than just diving into the
mp plan.


First we will try to get good heating and a decent EDA at 5.3 T.
With all antennas on.

Then we will try to change the mix of powers between D,E and J
to move power off axis at 5.3 T. If this is not successful we will
lower the field - maybe in two steps to try symmetric heating at
5.0 T.

Another possibility is to increase the triangularity (upper) to get
a better EDA.

==============================

Results:

We never got to the ITB studies - most of the day was spent studying
D and E at 5.3 T. As in previous days, the heating efficiency was
not good. Decay of stored energy after an RF trip suggested that no
more than 40% of the RF power was being absorbed. This is consistent
with overall confinement/stored energy results. Analysis of
sawtooth reheat showed a drop in on-axis electron heating by about a
factor of 2 compared to the best heating results in discharges with
similar field, current, and target density. Radiated power was no
higher today than in those previous days (assuming the calibrations
can be trusted.)

The overnight ECDC seemed to help with the H/D ratio. We started
out at 2-4%. This rose during the day, reaching almost 10% by shot
25. We did some between-shot ECDC early in the run, which may have
helped a bit. Late in the run, we increased the density by a large
factor to help hold this ratio down. The RF was not able to couple
well so we didn't give this a real test.

Overall, it isn't clear whether the H/D ratio is the culprit or
whether we have some other problem.


================================

Physics Operator Summaries
Entered: Jul 7 2004 04:37:15:973PM
Author: To Be Determined
Physop summary for 1020828

MP305 ITB Access conditions, hysteresis

SL Greenwald
PO Mossessian

Start with 1020827028 - 5.3 T, 3MW D&E on-axis heating

Summary:

Multiple problems with startup, partly caused by running ECDC between shots.
On shot 25 density feedback was turned back on since earlyer attempts to change
density by changing gas puff were not very succesful. After a series of disruptions
(shots 20 and 22) we moved lower x-point out, returning to lower delta of ~.5, which seemed
to help.

31 shots
13 fizzles
1 no power shot
17 plasmas


Details:


----------------------------------------------------------------------------
1020828001 mossessian PHYSICS_OPERATOR Aug 28 2002 9:07:20:486AM
. . . . . . . . . . . . . . . . . . . .
Fizzle. Current rise is too slow .

Next shot - PG4 30 -> 25 ms
----------------------------------------------------------------------------
1020828002 mossessian PHYSICS_OPERATOR Aug 28 2002 9:22:21:373AM
. . . . . . . . . . . . . . . . . . . .
Fizzle. Current rise is too fast now.

Next shot - PG4 25 -> 27 ms
----------------------------------------------------------------------------
1020828003 mossessian PHYSICS_OPERATOR Aug 28 2002 9:40:53:520AM
. . . . . . . . . . . . . . . . . . . .
Plasma. Startup is still bad.

Next shot - IC_EF4 -1315 -> -1305, BR offset 0.0015 -> 0.002
----------------------------------------------------------------------------
1020828004 mossessian PHYSICS_OPERATOR Aug 28 2002 9:50:46:023AM
. . . . . . . . . . . . . . . . . . . .
Plasma. Startup is better, but current rise is a bit slow.

Next shot - no PCS changes
----------------------------------------------------------------------------
1020828005 mossessian PHYSICS_OPERATOR Aug 28 2002 10:08:26:806AM
. . . . . . . . . . . . . . . . . . . .
Plasma.

Next shot - start ECDC between shots (5 min). Drop gas from 27 to 25 ms.
----------------------------------------------------------------------------
1020828006 mossessian PHYSICS_OPERATOR Aug 28 2002 10:15:16:163AM
. . . . . . . . . . . . . . . . . . . .
Fizzle

Next shot - Drop gas from 25 to 22 ms.
----------------------------------------------------------------------------
1020828007 mossessian PHYSICS_OPERATOR Aug 28 2002 10:38:34:566AM
. . . . . . . . . . . . . . . . . . . .
Plasma.

Next shot - Br offset 0.002 -> 0.0025
----------------------------------------------------------------------------
1020828008 mossessian PHYSICS_OPERATOR Aug 28 2002 10:48:40:666AM
. . . . . . . . . . . . . . . . . . . .
NO power shot - power supply fault.
----------------------------------------------------------------------------
1020828009 mossessian PHYSICS_OPERATOR Aug 28 2002 11:25:46:400AM
. . . . . . . . . . . . . . . . . . . .
Plasma

Next shot - no change
----------------------------------------------------------------------------
1020828010 mossessian PHYSICS_OPERATOR Aug 28 2002 11:26:27:526AM
. . . . . . . . . . . . . . . . . . . .
Fizzle

Next shot - Bz IC_EF4 -1305 -> -1300, gas 22 ms -> 23 ms
----------------------------------------------------------------------------
1020828011 mossessian PHYSICS_OPERATOR Aug 28 2002 11:54:07:626AM
. . . . . . . . . . . . . . . . . . . .
Fizzle

Next shot - Bz IC_EF4 -1300 -> -1310, Br offset 0.0025 -> 0.002
----------------------------------------------------------------------------
1020828012 mossessian PHYSICS_OPERATOR Aug 28 2002 11:54:36:550AM
. . . . . . . . . . . . . . . . . . . .
Plasma.

Next shot - IC_EF4 -1310 -> -1320, Ip to 1 MA

----------------------------------------------------------------------------
1020828013 mossessian PHYSICS_OPERATOR Aug 28 2002 12:43:24:643PM
. . . . . . . . . . . . . . . . . . . .
Plasma.

Next shot - gas 22 -> 23 ms to slow down current rise.
----------------------------------------------------------------------------
1020828014 mossessian PHYSICS_OPERATOR Aug 28 2002 12:43:42:846PM
. . . . . . . . . . . . . . . . . . . .
Plasma.

Next shot - no changes
----------------------------------------------------------------------------
1020828015 mossessian PHYSICS_OPERATOR Aug 28 2002 12:45:22:506PM
. . . . . . . . . . . . . . . . . . . .
Fizzle. No ECDC before shot - problems with ECDC power supply

Next shot - gas up 24 -> 27 ms
----------------------------------------------------------------------------
1020828016 mossessian PHYSICS_OPERATOR Aug 28 2002 1:01:50:320PM
. . . . . . . . . . . . . . . . . . . .
PLasma. Startup is bad - current rises too fast

Next shot - gas up 27 -> 30 ms
----------------------------------------------------------------------------
1020828017 mossessian PHYSICS_OPERATOR Aug 28 2002 1:14:08:483PM
. . . . . . . . . . . . . . . . . . . .
Fizzle. Current stops rising at 10 ms and plasma is killed by rising Bz

Next shot - no changes
----------------------------------------------------------------------------
1020828018 mossessian PHYSICS_OPERATOR Aug 28 2002 1:22:52:436PM
. . . . . . . . . . . . . . . . . . . .
Plasma. Starting ECDC between shots again.

Next shot - gas down 30 -> 27 ms
----------------------------------------------------------------------------
1020828019 mossessian PHYSICS_OPERATOR Aug 28 2002 2:05:21:330PM
. . . . . . . . . . . . . . . . . . . .
Fizzle.

Next shot - no changes
----------------------------------------------------------------------------
1020828020 mossessian PHYSICS_OPERATOR Aug 28 2002 2:06:03:193PM
. . . . . . . . . . . . . . . . . . . .
Plasma. Disrupted at .78

Next shot - RXL up 2 cm
----------------------------------------------------------------------------
1020828021 mossessian PHYSICS_OPERATOR Aug 28 2002 2:18:04:760PM
. . . . . . . . . . . . . . . . . . . .
Fizzle.

Next shot - PG3 up to get higher density
----------------------------------------------------------------------------
1020828022 mossessian PHYSICS_OPERATOR Aug 28 2002 2:30:09:206PM
. . . . . . . . . . . . . . . . . . . .
Disruption. Bad startup

Next shot - RCUR at 1 ms down 0.697 -> 0.68. Br offset 2 -> 1.5 mT
----------------------------------------------------------------------------
1020828023 mossessian PHYSICS_OPERATOR Aug 28 2002 3:11:30:616PM
. . . . . . . . . . . . . . . . . . . .
Plasma. Density did not seemto go up much. RXL was moved 2 mm only.

Next shot - RXL up 1 cm, PG3 up to get higher ne
----------------------------------------------------------------------------
1020828024 mossessian PHYSICS_OPERATOR Aug 28 2002 3:24:08:716PM
. . . . . . . . . . . . . . . . . . . .
Fizzle. Very late breakdown (11 ms).

Next shot - Br offest up 0.0015 -> 0.002
----------------------------------------------------------------------------
1020828025 mossessian PHYSICS_OPERATOR Aug 28 2002 3:42:50:893PM
. . . . . . . . . . . . . . . . . . . .
Plasma

Next shot - density feedback on. nl target 1.25e20, gas up 27 -> 29 ms
----------------------------------------------------------------------------
1020828026 mossessian PHYSICS_OPERATOR Aug 28 2002 3:54:43:400PM
. . . . . . . . . . . . . . . . . . . .
Plasma.

Next shot - no change
----------------------------------------------------------------------------
1020828027 mossessian PHYSICS_OPERATOR Aug 28 2002 4:05:06:060PM
. . . . . . . . . . . . . . . . . . . .
Fizzle.

Next shot - gas down 29 -> 27 ms
----------------------------------------------------------------------------
1020828028 mossessian PHYSICS_OPERATOR Aug 28 2002 4:32:39:816PM
. . . . . . . . . . . . . . . . . . . .
Plasma.

Next shot - no change
----------------------------------------------------------------------------
1020828029 mossessian PHYSICS_OPERATOR Aug 28 2002 4:36:01:526PM
. . . . . . . . . . . . . . . . . . . .
Fizzle.

Next shot - add gas 27 -> 29 ms. RCUR @ 1ms to 0.67
----------------------------------------------------------------------------
1020828030 mossessian PHYSICS_OPERATOR Aug 28 2002 4:47:52:143PM
. . . . . . . . . . . . . . . . . . . .
Plasma.

Next shot - no change
----------------------------------------------------------------------------
1020828031 mossessian PHYSICS_OPERATOR Aug 28 2002 4:58:42:226PM
. . . . . . . . . . . . . . . . . . . .
Fizzle.
----------------------------------------------------------------------------


-

Session Leader Comments
Aug 28 2002 08:58:46:000AMMartin GreenwaldMP 305 - ITB access conditions

The purpose of the run is to investigate access conditions
or trigger for producing off-axis ICRF ITB mode.
We will also ook for hysteresis in transition and investigate
proximity to marginal stability via heat pulse propagation.

Plan:

Given the difficulties in obtaining an ITB yesterday, we will
start with some preliminaries rather than just diving into the
mp plan.

First we will try to get good heating and a decent EDA at 5.3 T.
With all antennas on.

Then we will try to change the mix of powers between D,E and J
to move power off axis at 5.3 T. If this is not successful we will
lower the field - maybe in two steps to try symmetric heating at
5.0 T.

Another possibility is to increase the triangularity (upper) to get
a better EDA.
Aug 28 2002 09:04:05:730AM1020828001Martin Greenwaldfizzle
Aug 28 2002 09:13:30:793AM1020828002Martin Greenwaldfizzle
Aug 28 2002 09:41:45:553AM1020828003Martin GreenwaldPlasma
Only about 1 MW RF
Got steady H-mode, but not much stored energy
no TCI
H/D ration 2-4% so overnight ECDC probably helped
we'll keep an eye on this and ECDC between shots if necessary

Aug 28 2002 09:55:27:657AM1020828004Martin GreenwaldPlasma
Steady H-mode
RF power up to 2.2 MW but trips on E
H/D up a bit
Aug 28 2002 10:07:42:540AM1020828005Martin GreenwaldSimilar to last shot
Trips on E and J
H/D ~ 3.5%
We're going to ECDC between shots from now
Aug 28 2002 10:16:14:273AM1020828006Martin Greenwaldfizzle
Aug 28 2002 10:31:30:083AM1020828007Martin GreenwaldPlasma
Lots of faults on E, J
Aug 28 2002 10:47:45:053AM1020828008Martin GreenwaldNo-power test
Aug 28 2002 11:04:53:150AM1020828009Martin GreenwaldPlasma
gap to 1.5 cm
no power from D so Prf only about 1MW for most of the shot
Aug 28 2002 11:16:04:020AM1020828010Martin Greenwaldfizzle
Aug 28 2002 11:34:55:433AM1020828011Martin Greenwaldfizzle

Aug 28 2002 12:03:54:223PM1020828012Martin GreenwaldPlasma
Long H-mode
Many faults on E, J, but several hundred msec steady at 2.6MW
Aug 28 2002 12:19:50:520PM1020828013Martin GreenwaldPlasma
RF power steady at 2.5 MW
Ip to 1 MA
H/D up to 5%
Stored energy increase with current but only proportionally to 0.1MJ

Aug 28 2002 12:37:24:990PM1020828014Martin GreenwaldPlasma
Steady RF
Similar to shot 13
Aug 28 2002 12:39:35:090PM1020828015Martin Greenwaldfizzle
Aug 28 2002 01:05:15:027PM1020828016Martin GreenwaldPlasma - disrupts at 1.06 sec
Aug 28 2002 01:05:28:793PM1020828017Martin Greenwaldfizzle

Aug 28 2002 01:36:14:463PM1020828019Martin Greenwaldfizzle
Aug 28 2002 02:09:48:667PM1020828021Martin Greenwaldfizzle
Aug 28 2002 02:23:26:820PM1020828022Martin GreenwaldDisrupts early
Aug 28 2002 03:11:32:990PM1020828023Martin GreenwaldPlasma - many faults on RF
multiple H-modes
no TCI
Aug 28 2002 03:14:50:857PM1020828024Martin Greenwaldfizzle
Aug 28 2002 03:45:47:117PM1020828025Martin GreenwaldPlasma
multiple H-modes, multiple RF trips
density was supposed to be higher, but wasn't
(Idea is to reduce H/D ratio
Aug 28 2002 03:47:46:120PM1020828026Martin GreenwaldPlasma - higher density
no H-modes, RF needs to tune to the higher density
only got 1 MW
Aug 28 2002 04:07:47:020PM1020828027Martin Greenwaldfizzle
Aug 28 2002 04:19:39:807PM1020828028Martin GreenwaldPlasma
Single brief H-mode
not much RF power
Strange behavior from density programming
Aug 28 2002 04:28:57:293PM1020828029Martin Greenwaldfizzle
Aug 28 2002 04:58:29:680PM1020828030Martin GreenwaldPlasma
no H-mode
Aug 28 2002 04:58:44:773PM1020828031Martin Greenwaldfizzle

Physics Operator Comments
Aug 28 2002 08:50:14:387AMDmitri MossessianMP305 ITB Access conditions, hysteresis

SL Greenwald
PO Mossessian

Start with 1020827028 - 5.3 T, 3MW D&E on-axis heating

Load 1020827028.

Coldstart OK

Aug 28 2002 09:07:20:487AM1020828001Dmitri MossessianFizzle. Current rise is too slow .

Next shot - PG4 30 -> 25 ms
Aug 28 2002 09:22:21:373AM1020828002Dmitri MossessianFizzle. Current rise is too fast now.

Next shot - PG4 25 -> 27 ms
Aug 28 2002 09:40:53:520AM1020828003Dmitri MossessianPlasma. Startup is still bad.

Next shot - IC_EF4 -1315 -> -1305, BR offset 0.0015 -> 0.002
Aug 28 2002 09:50:46:023AM1020828004Dmitri MossessianPlasma. Startup is better, but current rise is a bit slow.

Next shot - no PCS changes
Aug 28 2002 10:08:26:807AM1020828005Dmitri MossessianPlasma.

Next shot - start ECDC between shots (5 min). Drop gas from 27 to 25 ms.
Aug 28 2002 10:15:16:163AM1020828006Dmitri MossessianFizzle

Next shot - Drop gas from 25 to 22 ms.
Aug 28 2002 10:38:34:567AM1020828007Dmitri MossessianPlasma.

Next shot - Br offset 0.002 -> 0.0025
Aug 28 2002 10:48:40:667AM1020828008Dmitri MossessianNO power shot - power supply fault.
Aug 28 2002 11:25:46:400AM1020828009Dmitri MossessianPlasma

Next shot - no change
Aug 28 2002 11:26:27:527AM1020828010Dmitri MossessianFizzle

Next shot - Bz IC_EF4 -1305 -> -1300, gas 22 ms -> 23 ms
Aug 28 2002 11:54:07:627AM1020828011Dmitri MossessianFizzle

Next shot - Bz IC_EF4 -1300 -> -1310, Br offset 0.0025 -> 0.002
Aug 28 2002 11:54:36:550AM1020828012Dmitri MossessianPlasma.

Next shot - IC_EF4 -1310 -> -1320, Ip to 1 MA

Aug 28 2002 12:43:24:643PM1020828013Dmitri MossessianPlasma.

Next shot - gas 22 -> 23 ms to slow down current rise.
Aug 28 2002 12:43:42:847PM1020828014Dmitri MossessianPlasma.

Next shot - no changes
Aug 28 2002 12:45:22:507PM1020828015Dmitri MossessianFizzle. No ECDC before shot - problems with ECDC power supply

Next shot - gas up 24 -> 27 ms
Aug 28 2002 01:01:50:320PM1020828016Dmitri MossessianPLasma. Startup is bad - current rises too fast

Next shot - gas up 27 -> 30 ms
Aug 28 2002 01:14:08:483PM1020828017Dmitri MossessianFizzle. Current stops rising at 10 ms and plasma is killed by rising Bz

Next shot - no changes
Aug 28 2002 01:22:52:437PM1020828018Dmitri MossessianPlasma. Starting ECDC between shots again.

Next shot - gas down 30 -> 27 ms
Aug 28 2002 02:05:21:330PM1020828019Dmitri MossessianFizzle.

Next shot - no changes
Aug 28 2002 02:06:03:193PM1020828020Dmitri MossessianPlasma. Disrupted at .78

Next shot - RXL up 2 cm
Aug 28 2002 02:18:04:760PM1020828021Dmitri MossessianFizzle.

Next shot - PG3 up to get higher density
Aug 28 2002 02:30:09:207PM1020828022Dmitri MossessianDisruption. Bad startup

Next shot - RCUR at 1 ms down 0.697 -> 0.68. Br offset 2 -> 1.5 mT
Aug 28 2002 03:11:30:617PM1020828023Dmitri MossessianPlasma. Density did not seemto go up much. RXL was moved 2 mm only.

Next shot - RXL up 1 cm, PG3 up to get higher ne
Aug 28 2002 03:24:08:717PM1020828024Dmitri MossessianFizzle. Very late breakdown (11 ms).

Next shot - Br offest up 0.0015 -> 0.002
Aug 28 2002 03:42:50:893PM1020828025Dmitri MossessianPlasma

Next shot - density feedback on. nl target 1.25e20, gas up 27 -> 29 ms
Aug 28 2002 03:54:43:400PM1020828026Dmitri MossessianPlasma.

Next shot - no change
Aug 28 2002 04:05:06:060PM1020828027Dmitri MossessianFizzle.

Next shot - gas down 29 -> 27 ms
Aug 28 2002 04:32:39:817PM1020828028Dmitri MossessianPlasma.

Next shot - no change
Aug 28 2002 04:36:01:527PM1020828029Dmitri MossessianFizzle.

Next shot - add gas 27 -> 29 ms. RCUR @ 1ms to 0.67
Aug 28 2002 04:47:52:143PM1020828030Dmitri MossessianPlasma.

Next shot - no change
Aug 28 2002 04:58:42:227PM1020828031Dmitri MossessianFizzle.

Engineering Operator Comments
ShotTimeTypeStatusComment
108:59:19:470AMPlasmaOk
209:11:55:463AMPlasmaOk
309:24:45:707AMPlasmaOk
409:42:53:070AMPlasmaOk
509:55:40:187AMPlasmaOk
610:11:54:110AMPlasmaOk
710:27:03:903AMPlasmaOk
810:44:40:187AMPlasmaBadEF1L Commutation Bank didn't indicate a charge
910:57:36:290AMPlasmaOk
1011:14:38:613AMPlasmaOk
1111:33:19:273AMPlasmaOk
1211:48:34:973AMPlasmaOk
1312:04:22:943PMPlasmaOk
1412:21:32:977PMPlasmaOk
1512:37:26:570PMPlasmaOk
1612:50:20:267PMPlasmaOk
1701:03:48:900PMPlasmaOk
1801:17:50:303PMPlasmaOk
1901:34:53:943PMPlasmaOk
2001:51:46:103PMPlasmaOk
2102:08:19:417PMPlasmaOk
2202:21:10:720PMPlasmaOk
2302:55:52:007PMPlasmaOk
2403:13:27:570PMPlasmaOk
2503:26:35:033PMPlasmaOk
2603:44:18:037PMPlasmaOk
2703:57:24:953PMPlasmaOk
2804:10:25:417PMPlasmaOk
2904:26:30:413PMPlasmaOk
3004:43:00:370PMPlasmaOk
3104:56:20:787PMPlasmaOk