Alcator C-Mod Run 1000629 Information

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Miniproposals
Miniproposal:271
Date Filed: 5/12/2000
Title:Scaling of H-mode pedestal parameters with global plasma parameters
First Author:Dmitri Mossessian
Session Leader:Dmitri Mossessian (shots 1-24)

Operators
Session leader(s):Dmitri Mossessian
Physics operator(s):Earl Marmar
Engineering operator(s):Bill Cochran,Gary Dekow

Engineering Operator Run Comment
MP 271 Pedestal Scaling PO: Marmar SL: Mossesian EO: Dekow/Cochran

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:24:587PM
Author: To Be Determined
Run summary for 1000629 - MP271 Pedestal scalings

Plan:

The intention is to complete part 1 of the MP271 - plasma current and input
power scans at const n_e. We have two current points at nl_04=0.9e20: 0.8 MA
and 1.0 MA. We need to do 1.2 MA, 1.4 MA(or 1.3) and preferably 0.6 MA.

The plan:

1. Start with 1000616013 - 1MA, but lower nl04 target to 0.9e20 (to be
consistent with previous scans), Bt=5.3 T (~2 shots)

2. Go to 1.2 MA, same Bt, ne. Same RF waveform. Repeat with second RF levels of
1.5, 1, and 0.5 MW (~6 shots)

3. Go to 1.4 MA, repeat RF scan (~8 shots)

4. Go back to 0.6 MA, repeat RF scan (~8 shots)

5. Time permitting, set Ip=1 MA, RF=2.5MW, do density scan with nl04 varying
from 0.5e20 to 2e20 shot to shot


Summary:

We got some data, but it was not a very successful run.
We started at 1MA an obtained some good data points at various power levels,
although RF was not very reliable. The pedestal gradient was observed to
increase with input power, in agreement with previous observations.
At 1.2 MA, nl04=0.9e20 RF was unreliable, but some usable data was obtained.
The target density was increased to 1.1e20. This did not improve things much.
H-mode at 2 power levels were obtained after numerous attempts. At a first glance,
pedestal is not dramatically sharper or higher in ELM-free, but further analysis is necessary.
Not having much success with current scan, we tried to do density scan at 0.8MA.
Steady state EDA was obtained at target nl04=1.1 but attempt to go to 1.3e20 failed.


Shots that could potentially provide some data:

----------------------------------------------------------------------------
1000629003 mossessian SESSION_LEADER Jun 29 2000 10:57:17:670AM
. . . . . . . . . . . . . . . . . . . .
Good 1MA shot. 2 H-modes at 2.9MW and 1.7 MW. D_alpha looks strange
in the second H-mode.
We'll have another one at 1MA and then go to 1.2 MA
-----------------------------------------------------------------------------
1000629005 mossessian SESSION_LEADER Jun 29 2000 11:02:45:183AM
. . . . . . . . . . . . . . . . . . . .
RF has trips at 3MW, but 1.6MW portion is steady state EDA

Go to 1.2 MA
-----------------------------------------------------------------------------
1000629013 mossessian SESSION_LEADER Jun 29 2000 1:36:47:936PM
. . . . . . . . . . . . . . . . . . . .
Several EDA/ELM-free H-modes at various RF levels. RF trips a lot.
Try again with 3/1.5MW RF pulse.
-----------------------------------------------------------------------------
1000629014 mossessian SESSION_LEADER Jun 29 2000 1:38:57:530PM
. . . . . . . . . . . . . . . . . . . .
Short ELM-free (?) H-mode at 2.9MW RF, no H-mode at 1.6 and 0.9MW.
RF trips.
Try lower power in the first half of RF pulse - do 2.5/2 MW
-----------------------------------------------------------------------------
1000629016 mossessian SESSION_LEADER Jun 29 2000 2:24:31:920PM
. . . . . . . . . . . . . . . . . . . .
Two short H-modes at 2.6 MW, no L-H transition at 1.5 MW
This kind of shots does not give any good data.
Try to go to higher density nl04 -> 1.1e20
-----------------------------------------------------------------------------
1000629017 mossessian SESSION_LEADER Jun 29 2000 3:31:24:796PM
. . . . . . . . . . . . . . . . . . . .
Multiple H-modes at RF power about 1 MW

-----------------------------------------------------------------------------
1000629019 mossessian SESSION_LEADER Jun 29 2000 3:57:21:936PM
. . . . . . . . . . . . . . . . . . . .
2 ELM-free (?) H-modes at 2MW.
-----------------------------------------------------------------------------
1000629020 mossessian SESSION_LEADER Jun 29 2000 4:00:48:000PM
. . . . . . . . . . . . . . . . . . . .
Very short ELM-free at 2MW

Not having much luck with the current scan, we'll attempt to use last
4 shots for density scan at 0.8MA, 2MW
-----------------------------------------------------------------------------
1000629021 mossessian SESSION_LEADER Jun 29 2000 4:54:34:373PM
. . . . . . . . . . . . . . . . . . . .
Steady state EDA at 1.1e20 m^-2
Go to target of 1.3e20.


Physics Operator Summaries
Entered: Jul 7 2004 04:37:11:550PM
Author: To Be Determined
#43 of 47 OPS
Date: 29-JUN-2000 18:00 Expires: 13-JUL-2000 00:00
From: SPANNA::MARMAR
Subj: Physop run summary 1000629

Engineering Setup for 1000629

MP 271 Pedestal scaling.

Overnight ECDC in D2, stopping 2 hours before run.

Power system setup: Same as for 1000616009

gas setup: B-Top 6 psi D2 Hybrid Enabled
B-side lower 1 psi Argon Hybrid Enabled
B-side upper leave as is Hybrid DISABLED
C-side 30 psi D2 Hybrid Enabled
J-bottom leave as is Hybrid DISABLED

The following Gate Valves should be ENABLED, assuming no vacuum problems:

ECE, VUV

DNB gate valve should be DISABLED

RF setup:
RF programed to go from 0 to 3 MW at 0.7 sec, drop to 2 MW at 1.1 sec and turn
off at 1.5 sec.

The intention is to complete part 1 of the MP271 - plasma current and input
power scans at const n_e. We have two current points at nl_04=0.9e20: 0.8 MA
and 1.0 MA. We need to do 1.2 MA, 1.4 MA(or 1.3) and preferably 0.6 MA.

SL: Mossessian
EO: Dekow
PO: Marmar


The plan:

1. Start with 1000616013 - 1MA, but lower nl04 target to 0.9e20 (to be
consistent with previous scans), Bt=5.3 T (~2 shots)

2. Go to 1.2 MA, same Bt, ne. Same RF waveform. Repeat with second RF levels of
1.5, 1, and 0.5 MW (~6 shots)

3. Go to 1.4 MA, repeat RF scan (~8 shots)

4. Go back to 0.6 MA, repeat RF scan (~8 shots)

5. Time permitting, set Ip=1 MA, RF=2.5MW, do density scan with nl04 varying
from 0.5e20 to 2e20 shot to shot


Results:

We had plasmas at 1.0, 1.2 and 0.8 MW; the session leader reports that 5 of
them should be useable toward the mini-proposal.

Some problems with fizzles again today, although things settled down after shot 13,
with 9 out of the last 10 having successful starts-up. Shot 4 was a dud.
Palliative tweaking of fill pressure, EF4 current and B_r offset was employed.

Shot 19 had a very interesting EN mode, between 1.27 and 1.3 seconds, with 2 MW
RF; the neutron rate went to 3.7e13 per second. This was a 1.2 MA shot.

There were no significant engineering or data system problems today.

Shot summary
6 Fizzles
1 Dud
17 Plasmas
____________
24 cycles



Shot by shot:
----------------------------------------------------------------------------
coldstart; no errors; all matrices respond.


001:
load from 1000616009; reduce nl_04 program to 0.9e20.

reduce feedback gain on nl_04 from 9 to 1 between 0.71 and 1.5 seconds; attempt
to keep maintenance gas on
during H-mode phase (~40 V).

fizzle

----------------------------------------------------------------------------
1000629002 marmar PHYSICS_OPERATOR Jun 29 2000 9:18:42:483AM
. . . . . . . . . . . . . . . . . . . .
reduce B_R offset by .5 mT

reduce EF4 by 10 amps, to -1270

plasma

2 H-modes
-----------------------------------------------------------------------------
1000629003 marmar PHYSICS_OPERATOR Jun 29 2000 9:46:17:450AM
. . . . . . . . . . . . . . . . . . . .
turn off density feedback between .71 and 1.5 s

disable argon

plasma

2 H-Modes
-----------------------------------------------------------------------------
1000629004 marmar PHYSICS_OPERATOR Jun 29 2000 10:04:58:403AM
. . . . . . . . . . . . . . . . . . . .
enable argon

dud
-----------------------------------------------------------------------------
1000629005 marmar PHYSICS_OPERATOR Jun 29 2000 10:20:21:873AM
. . . . . . . . . . . . . . . . . . . .
increase B_R offset .0005 T

reduce EF4 10 amp to -1280

plasma


-----------------------------------------------------------------------------
1000629006 marmar PHYSICS_OPERATOR Jun 29 2000 10:46:41:576AM
. . . . . . . . . . . . . . . . . . . .
program for 1.2 MA

add second TF twiddle for ECE profiles at second ICRF power

fizzle
-----------------------------------------------------------------------------
1000629007 marmar PHYSICS_OPERATOR Jun 29 2000 11:20:56:403AM
. . . . . . . . . . . . . . . . . . . .
reduce EF4 10 amp

reduce prepuff to 21 msec from 23

plasma

disrupt at 0.9 s
-----------------------------------------------------------------------------
1000629008 marmar PHYSICS_OPERATOR Jun 29 2000 11:21:27:793AM
. . . . . . . . . . . . . . . . . . . .
repeat

plasma

only got 1/2 of the RF power

no H-Mode
-----------------------------------------------------------------------------
1000629009 marmar PHYSICS_OPERATOR Jun 29 2000 12:07:11:466PM
. . . . . . . . . . . . . . . . . . . .
put nl_04 feedback back on during the middle of the shot

reduce programmed rate of rise for nl_04; still have target of 0.9e20

plasma

still no D-port; L-mode

-----------------------------------------------------------------------------
1000629010 marmar PHYSICS_OPERATOR Jun 29 2000 12:22:22:230PM
. . . . . . . . . . . . . . . . . . . .
raise ZCUR 5 mm

fizzle
-----------------------------------------------------------------------------
1000629011 marmar PHYSICS_OPERATOR Jun 29 2000 12:37:58:046PM
. . . . . . . . . . . . . . . . . . . .
reduce B_R offset by .3 mT to 0.0000

reduce EF4 by 10 amps to -1300

reduce prepuff by 2 ms

fizzle
-----------------------------------------------------------------------------
1000629012 marmar PHYSICS_OPERATOR Jun 29 2000 12:58:17:250PM
. . . . . . . . . . . . . . . . . . . .
add 15 amp to EF4

fizzle
-----------------------------------------------------------------------------
1000629013 marmar PHYSICS_OPERATOR Jun 29 2000 1:33:49:843PM
. . . . . . . . . . . . . . . . . . . .
subtract 10 A from EF4

increase prepuff 1 ms

plasma

many short H-Modes
-----------------------------------------------------------------------------
1000629014 marmar PHYSICS_OPERATOR Jun 29 2000 1:34:07:013PM
. . . . . . . . . . . . . . . . . . . .
no PCS changes

plasma

1 H-mode
-----------------------------------------------------------------------------
1000629015 marmar PHYSICS_OPERATOR Jun 29 2000 2:01:41:640PM
. . . . . . . . . . . . . . . . . . . .
increase early nl_04 prog, still target of 0.9e20

plasma

disrupt at 0.5 s
-----------------------------------------------------------------------------
1000629016 marmar PHYSICS_OPERATOR Jun 29 2000 2:20:34:326PM
. . . . . . . . . . . . . . . . . . . .
slow early nl_04 rise

target still 0.9e20

plasma

2 short H-modes


-----------------------------------------------------------------------------
1000629017 marmar PHYSICS_OPERATOR Jun 29 2000 2:39:58:950PM
. . . . . . . . . . . . . . . . . . . .
go to nl_04 target of 1.1e20

plasma

1 MW RF, 6 ELM-free H-modes
-----------------------------------------------------------------------------
1000629018 marmar PHYSICS_OPERATOR Jun 29 2000 3:00:14:873PM
. . . . . . . . . . . . . . . . . . . .
fizzle


-----------------------------------------------------------------------------
1000629019 marmar PHYSICS_OPERATOR Jun 29 2000 3:24:27:263PM
. . . . . . . . . . . . . . . . . . . .
lower prepuff 1 ms

move RF start to 0.8 s

plasma

2 H-Modes at 2 MW
-----------------------------------------------------------------------------
1000629020 marmar PHYSICS_OPERATOR Jun 29 2000 3:43:47:296PM
. . . . . . . . . . . . . . . . . . . .
move ZCUR down by 5 mm

add 0.5 ms to prepuff

eliminate second TF wiggle

plasma

disrupt at 1.37 seconds
-----------------------------------------------------------------------------
1000629021 marmar PHYSICS_OPERATOR Jun 29 2000 4:19:38:043PM
. . . . . . . . . . . . . . . . . . . .
go to0.8 MA

add some derivative gain to density feedback

plasma

big marfe early

nice RF pulse
-----------------------------------------------------------------------------
1000629022 marmar PHYSICS_OPERATOR Jun 29 2000 4:23:13:296PM
. . . . . . . . . . . . . . . . . . . .
move zcur up 2.5 mm

slow the programmed density rise

nl_04 target to 1.3e20

plasma

little RF power

no big marfe

----------------------------------------------------------------------------
1000629023 marmar PHYSICS_OPERATOR Jun 29 2000 4:50:30:420PM
. . . . . . . . . . . . . . . . . . . .
no pcs changes

plasma

2+ MW RF, L-Mode, disrupt at 1.22 s
-----------------------------------------------------------------------------
1000629024 marmar PHYSICS_OPERATOR Jun 29 2000 5:06:41:233PM
. . . . . . . . . . . . . . . . . . . .
no pcs changes

plasma

no H-Mode
-

Session Leader Comments
Jun 29 2000 10:57:17:670AM1000629003Dmitri MossessianGood 1MA shot. 2 H-modes at 2.9MW and 1.7 MW. D_alpha looks strange
in the second H-mode.
We'll have another one at 1MA and then go to 1.2 MA
Jun 29 2000 11:02:45:183AM1000629005Dmitri MossessianRF has trips at 3MW, but 1.6MW portion is steady state EDA

Go to 1.2 MA
Jun 29 2000 01:36:47:937PM1000629013Dmitri MossessianSeveral EDA/ELM-free H-modes at various RF levels. RF trips a lot.
Try again with 3/1.5MW RF pulse.
Jun 29 2000 01:38:57:530PM1000629014Dmitri MossessianShort ELM-free (?) H-mode at 2.9MW RF, no H-modeat 1.6 and 0.9MW.
RF trips.
Try lower power in the first half of RF pulse - do 2.5/2 MW
Jun 29 2000 02:24:31:920PM1000629016Dmitri MossessianTwo short H-modes at 2.6 MW, no L-H transition at 1.5 MW
This kind of shots does not give any good data.
Try to go to higher density nl04 -> 1.1e20
Jun 29 2000 03:31:24:797PM1000629017Dmitri MossessianMultiple H-modes at RF power about 1 MW

Jun 29 2000 03:57:21:937PM1000629019Dmitri Mossessian2 ELM-free (?) H-modes at 2MW.
Jun 29 2000 04:00:48:000PM1000629020Dmitri MossessianVery short ELM-free at 2MW

Not having much luck with the current scan, we'll attempt to use last
4 shots for density scan at 0.8MA, 2MW
Jun 29 2000 04:54:34:373PM1000629021Dmitri MossessianSteady state EDA at 1.1e20 m^-2
Go to target of 1.3e20.

Physics Operator Comments
Jun 29 2000 08:39:31:903AMEarl MarmarEngineering Setup for 1000629

MP 271 Pedestal scaling.

Overnight ECDC in D2, stopping 2 hours before run.

Power system setup: Same as for 1000616009

gas setup: B-Top 6 psi D2 Hybrid Enabled
B-side lower 1 psi Argon Hybrid Enabled
B-side upper leave as is Hybrid DISABLED
C-side 30 psi D2 Hybrid Enabled
J-bottom leave as is Hybrid DISABLED

The following Gate Valves should be ENABLED, assuming no vacuum problems:

ECE, VUV

DNB gate valve should be DISABLED

RF setup:
RF programed to go from 0 to 3 MW at 0.7 sec, drop to 2 MW at 1.1 sec and turn
off at 1.5 sec.

The intention is to complete part 1 of the MP271 - plasma current and input
power scans at const n_e. We have two current points at nl_04=0.9e20: 0.8 MA
and 1.0 MA. We need to do 1.2 MA, 1.4 MA(or 1.3) and preferably 0.6 MA.

The plan:

1. Start with 1000616013 - 1MA, but lower nl04 target to 0.9e20 (to be
consistent with previous scans), Bt=5.3 T (~2 shots)

2. Go to 1.2 MA, same Bt, ne. Same RF waveform. Repeat with second RF levels of
1.5, 1, and 0.5 MW (~6 shots)

3. Go to 1.4 MA, repeat RF scan (~8 shots)

4. Go back to 0.6 MA, repeat RF scan (~8 shots)

5. Time permitting, set Ip=1 MA, RF=2.5MW, do density scan with nl04 varying
from 0.5e20 to 2e20 shot to shot
Jun 29 2000 08:42:10:293AM1000629001Earl Marmarcoldstart; no errors; all matrices respond.

load from 1000616009; reduce nl_04 program to 0.9e20.

reduce feedback gain on nl_04 from 9 to 1 between 0.71 and 1.5 seconds; attempt to keep maintenance gas on
during H-mode phase (~40 V).


Jun 29 2000 09:04:24:980AM1000629001Earl Marmarfizzle
Jun 29 2000 09:18:42:483AM1000629002Earl Marmarreduce B_R offset by .5 mT

reduce EF4 by 10 amps, to -1270

plasma

2 H-modes
Jun 29 2000 09:46:17:450AM1000629003Earl Marmarturn off density feedback between .71 and 1.5 s

disable argon

plasma

2 H-Modes
Jun 29 2000 10:04:58:403AM1000629004Earl Marmarenable argon

dud
Jun 29 2000 10:20:21:873AM1000629005Earl Marmarincrease B_R offset .0005 T

reduce EF4 10 amp to -1280

plasma


Jun 29 2000 10:46:41:577AM1000629006Earl Marmarprogram for 1.2 MA

add second TF twiddle for ECE profiles at second ICRF power

fizzle
Jun 29 2000 11:20:56:403AM1000629007Earl Marmarreduce EF4 10 amp

reduce prepuff to 21 msec from 23

plasma

disrupt at 0.9 s
Jun 29 2000 11:21:27:793AM1000629008Earl Marmarrepeat

plasma

only got 1/2 of the RF power

no H-Mode
Jun 29 2000 12:07:11:467PM1000629009Earl Marmarput nl_04 feedback back on during the middle of the shot

reduce programmed rate of rise for nl_04; still have target of 0.9e20

plasma

still no D-port; L-mode

Jun 29 2000 12:22:22:230PM1000629010Earl Marmarraise ZCUR 5 mm

fizzle
Jun 29 2000 12:37:58:047PM1000629011Earl Marmarreduce B_R offset by .3 mT to 0.0000

reduce EF4 by 10 amps to -1300

reduce prepuff by 2 ms

fizzle
Jun 29 2000 12:58:17:250PM1000629012Earl Marmaradd 15 amp to EF4

fizzle
Jun 29 2000 01:33:49:843PM1000629013Earl Marmarsubtract 10 A from EF4

increase prepuff 1 ms

plasma

many short H-Modes
Jun 29 2000 01:34:07:013PM1000629014Earl Marmarno PCS changes

plasma

1 H-mode
Jun 29 2000 03:03:05:437PM1000629015Earl Marmarincrease early nl_04 prog, still target of 0.9e20

plasma

disrupt at 0.5 s
Jun 29 2000 02:20:34:327PM1000629016Earl Marmarslow early nl_04 rise

target still 0.9e20

plasma

2 short H-modes


Jun 29 2000 02:39:58:950PM1000629017Earl Marmargo to nl_04 target of 1.1e20

plasma

1 MW RF, 6 ELM-free H-modes
Jun 29 2000 03:00:14:873PM1000629018Earl Marmarfizzle


Jun 29 2000 05:57:56:670PM1000629019Earl Marmarlower prepuff 1 ms

move RF start to 0.8 s

plasma

2 H-Modes at 2 MW

interesting EN mode, around 1.3 seconds, triggered by H-->L backtransition; RF stays on at 2 MW; neutron rate goes up to
3.7e13.
Jun 29 2000 03:43:47:297PM1000629020Earl Marmarmove ZCUR down by 5 mm

add 0.5 ms to prepuff

eliminate second TF wiggle

plasma

disrupt at 1.37 seconds
Jun 29 2000 04:19:38:043PM1000629021Earl Marmargo to0.8 MA

add some derivative gain to density feedback

plasma

big marfe early

nice RF pulse
Jun 29 2000 04:23:13:297PM1000629022Earl Marmarmove zcur up 2.5 mm

slow density rise

nl_04 target to 1.3e20

plasma

little RF power

no big marfe
Jun 29 2000 04:50:30:420PM1000629023Earl Marmarno pcs changes

plasma

2+ MW RF, L-Mode, disrupt at 1.22 s
Jun 29 2000 05:06:41:233PM1000629024Earl Marmarno pcs changes

plasma

no H-Mode

Engineering Operator Comments
ShotTimeTypeStatusComment
108:58:05:840AMPlasmaOk
209:13:20:280AMPlasmaOk
309:34:13:827AMPlasmaOk
409:54:38:373AMPlasmaOk
510:13:41:013AMPlasmaOk
610:34:50:437AMPlasmaOk
710:52:18:357AMPlasmaOk
811:14:10:403AMPlasmaOk
911:54:58:903AMPlasmaOk
1012:16:15:843PMPlasmaOk
1112:31:44:200PMPlasmaOk
1212:49:43:547PMPlasmaOk
1301:06:13:797PMPlasmaOk
1401:28:51:903PMPlasmaOk
1501:50:19:827PMPlasmaOk
1602:13:00:547PMPlasmaOk
1702:33:25:857PMPlasmaOk
1802:54:51:357PMPlasmaOk
1903:14:22:450PMPlasmaOk
2003:36:43:263PMPlasmaOk
2103:56:58:200PMPlasmaOk
2204:18:30:920PMPlasmaOk
2304:39:42:967PMPlasmaOk
2405:00:42:700PMPlasmaOk