Alcator C-Mod Run 940615 Information

Miniproposals

Miniproposal: 058

Date Filed: 5/27/1994

Title: Pellet Injection Studies

First Author: Martin Greenwald

Session Leader: Unknown (shots 1-23)

Operators
Session leader(s):	Unknown
Physics operator(s):	Earl Marmar,Robert Granetz
Engineering operator(s):	Unknown

Engineering Operator Run Comment

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Physics Operator Summaries

Session Leader Comments

Physics Operator Comments

Jun 15 1994 10:13:10:450AM Earl Marmar Today's run will be pellets. Start with fiducial shot and then go to
divertor operation.

Jun 15 1994 10:13:43:640AM 940615001 Earl Marmar Fiducial. Good shot.

Jun 15 1994 10:15:13:620AM 940615002 Earl Marmar Hybrid iso-amp power supply replaced. There were .05 to .07 V offsets
on shot 1. This shot was a data system test to look at the offsets.
There were no power supplies.

Jun 15 1994 10:42:15:230AM 940615003 Earl Marmar Load shot 960610023, increase Ip demand to -700kA, increase pulsed gas
and eliminate modulated gas puffs. High voltages on Z-Meter array
changed to 500 V from 600, calibration gains changed in tree. Shearing
interferometer triggering at .5 seconds, 1 MHz, 2 channels. PF inverts
moved out to 1.5 seconds. Good shot.

Jun 15 1994 10:56:59:850AM 940615004 Earl Marmar Tweak pulsed gas. Pellet at .7 s. Good plasma. Disrupt at 1.18 seconds.

Jun 15 1994 11:05:45:320AM 940615005 Earl Marmar No pellet. Good shot. Still disrupt at 1.27.

Jun 15 1994 11:28:03:230AM 940615006 Earl Marmar Lowered argin (delete 3'rd puff). Pellet at .7. Good shot. Z position
dance at around .65 s (also on previous shot).

Jun 15 1994 11:44:48:640AM 940615007 Earl Marmar Argon also being puffed with ninja. Lowered RXL prop gain (got rid of
last step up).Disrupt at .7.

Jun 15 1994 12:10:21:730PM 940615008 Earl Marmar Ramp up gain on ZXL. Still disrupt.

Jun 15 1994 12:20:41:500PM 940615009 Earl Marmar Turn off gain on EF2L at 0.5; moved RXL gain turn on from .55 to .5.

Jun 15 1994 12:44:50:930PM 940615010 Earl Marmar Change current programming on EF2L to ramp to -3000 at .5 seconds. Good
shot.

Jun 15 1994 01:14:17:550PM 940615011 Earl Marmar Move RXL turn-on earlier. Bigger pellet. Disrupt at .83. Elongation
exceeding 1.7.

Jun 15 1994 01:39:50:930PM 940615012 Earl Marmar Zcur moved to -2 cm. Disrupt at .65

Jun 15 1994 01:47:32:080PM 940615013 Earl Marmar Disruptive, x-rays, died at .69.

Jun 15 1994 02:02:02:550PM 940615014 Earl Marmar reload shot 10.

Better shot. Lasted until 1.18 s. Pellet had a larger effect on
density than the previous shot.

Jun 15 1994 02:11:47:110PM 940615014 Robert Granetz Granetz replaces Marmar as phys. op.

This shot did NOT have a vertical control problem at 0.7 s. It disrupted
at 1.18 s. Ip=0.71 MA.

Next shot, no changes.

Jun 15 1994 02:12:18:790PM 940615014 Robert Granetz The lithium pellet injector may fire on the next shot.

Jun 15 1994 02:37:55:820PM 940615015 Robert Granetz Good pellet shot. Most humongous, longest snake I've ever seen in C-Mod!
Plasma disrupted at 1.02 s, probably due to lithium pellet injected at 1.0 s.
Pellet was size #3. Increase on density was noticeably larger than on
previous shots today. Pellet penetrated in to R=0.74 m.

Snake lasted for about 80 ms.

Next shot, two pellets...one at 0.750, second at 0.780. Also a lithium
injection at 1.0 s

Jun 15 1994 02:48:40:360PM 940615016 Robert Granetz Good shot. First pellet was size #2, no snake. Second pellet was size #3,
with a snake lasting 15 ms. Lithium injection at 1.0 second kills the
plasma.

Plasma is nearly a double null for much of the discharge.

Next shot, no lithium injection.

Jun 15 1994 02:53:42:760PM 940615016 Robert Granetz Also next shot: 2 pellets, followed by ICRF heating.

Jun 15 1994 03:20:35:830PM 940615017 Robert Granetz Good pellet shot. Plasma ended in a disruption at 1.04 s. 2 pellets, a small
one at 0.755 and a larger one at 0.785. The disruption may be caused by
too much density.

For the next shot, decrease gas puffing from 0.8 s onward.

Jun 15 1994 03:31:49:750PM 940615018 Robert Granetz 2 pellets, but plasma disrupted shortly after the second pellet. Peak
nl was about 2.5e20 m-2, or =4.2e20 m-3. The Greenwald limit is 5e20 m-3.

Jun 15 1994 03:45:13:710PM 940615019 Robert Granetz 2 pellets, but plasma disrupted shortly after the second one.

On the next shot, I will activate the kappa feedback, using only EF1U in
the controller.

Jun 15 1994 03:48:36:950PM 940615019 Robert Granetz On this shot, the post-pellet density decayed very quickly (tau_n about 5 ms).
This may have been due to the 1 MW of ICRF which turned on at 0.75 s.

Jun 15 1994 04:14:24:560PM 940615020 Robert Granetz Better. 2 pellets. Plasma didn't disrupt until 1.1 s, which is just after
rampdown begins. No snakes.

It is questionable whether the kappa feedback did anything.

Next shot, reduce programmed demand on kappa from 0.16 to 0.05. Keep gain
the same. Also, remove the second argon puff.

Jun 15 1994 04:33:32:160PM 940615021 Robert Granetz 2 pellets, very similar to previous shot. Ended in disruption at 1.03 s.

Hybrid seems to be getting the correct predictor output for kappa, but if
anything, kappa was slightly higher.

Next shot, increase gain on kappa feedback from 1 to 2.

Jun 15 1994 04:44:31:090PM 940615022 Robert Granetz 2 pellets, similar to preceding shots. Ends in disruption at 1.08 s.
No snakes.

There is little or no change in kappa.

Next shot, program kappa to reduce towards the end of the shot.

Jun 15 1994 04:58:21:290PM 940615023 Robert Granetz 2 pellets, similar to preceding shots. Ends in disruption at 1.07 s.

End of run.

Engineering Operator Comments

Shot Time Type Status Comment

1 08:48:26:670AM Plasma Ok late hybrid power supply unbalance

2 09:45:21:370AM Plasma Ok no plasma hybrid test/data aquisition test

3 10:19:41:170AM Plasma Ok at last plasma

4 10:40:25:300AM Plasma Ok >600ka disruption

5 10:57:26:110AM Plasma Ok >600ka disruption

6 11:13:12:120AM Plasma Ok plasma no fault no disrupt

7 11:33:48:190AM Plasma Ok pelletized disruption > 600ka

8 11:50:49:260AM Plasma Ok pelletized disruption, >600ka comm fault ef1l,

9 12:12:04:690PM Plasma Ok plasma

10 12:33:49:680PM Plasma Ok plasma

11 12:58:12:280PM Plasma Ok disruption>700ka no faults

12 01:16:34:770PM Plasma Ok No faults.

13 01:34:07:370PM Plasma Ok No faults.

14 01:51:59:270PM Plasma Ok NO faults

15 02:13:18:490PM Plasma Ok No faults

16 02:35:40:920PM Plasma Ok No faults.

17 02:53:45:620PM Plasma Ok No faults.

18 03:21:33:660PM Plasma Ok No faults.

19 03:37:29:270PM Plasma Ok NO faults

20 03:54:00:050PM Plasma Ok No faults.

21 04:15:16:060PM Plasma Ok No faults

22 04:34:48:880PM Plasma Ok No faults.

23 04:52:14:100PM Plasma Ok No faults.

Physics Operator Comments
Jun 15 1994 10:13:10:450AM		Earl Marmar	Today's run will be pellets. Start with fiducial shot and then go to divertor operation.
Jun 15 1994 10:13:43:640AM	940615001	Earl Marmar	Fiducial. Good shot.
Jun 15 1994 10:15:13:620AM	940615002	Earl Marmar	Hybrid iso-amp power supply replaced. There were .05 to .07 V offsets on shot 1. This shot was a data system test to look at the offsets. There were no power supplies.
Jun 15 1994 10:42:15:230AM	940615003	Earl Marmar	Load shot 960610023, increase Ip demand to -700kA, increase pulsed gas and eliminate modulated gas puffs. High voltages on Z-Meter array changed to 500 V from 600, calibration gains changed in tree. Shearing interferometer triggering at .5 seconds, 1 MHz, 2 channels. PF inverts moved out to 1.5 seconds. Good shot.
Jun 15 1994 10:56:59:850AM	940615004	Earl Marmar	Tweak pulsed gas. Pellet at .7 s. Good plasma. Disrupt at 1.18 seconds.
Jun 15 1994 11:05:45:320AM	940615005	Earl Marmar	No pellet. Good shot. Still disrupt at 1.27.
Jun 15 1994 11:28:03:230AM	940615006	Earl Marmar	Lowered argin (delete 3'rd puff). Pellet at .7. Good shot. Z position dance at around .65 s (also on previous shot).
Jun 15 1994 11:44:48:640AM	940615007	Earl Marmar	Argon also being puffed with ninja. Lowered RXL prop gain (got rid of last step up).Disrupt at .7.
Jun 15 1994 12:10:21:730PM	940615008	Earl Marmar	Ramp up gain on ZXL. Still disrupt.
Jun 15 1994 12:20:41:500PM	940615009	Earl Marmar	Turn off gain on EF2L at 0.5; moved RXL gain turn on from .55 to .5.
Jun 15 1994 12:44:50:930PM	940615010	Earl Marmar	Change current programming on EF2L to ramp to -3000 at .5 seconds. Good shot.
Jun 15 1994 01:14:17:550PM	940615011	Earl Marmar	Move RXL turn-on earlier. Bigger pellet. Disrupt at .83. Elongation exceeding 1.7.
Jun 15 1994 01:39:50:930PM	940615012	Earl Marmar	Zcur moved to -2 cm. Disrupt at .65
Jun 15 1994 01:47:32:080PM	940615013	Earl Marmar	Disruptive, x-rays, died at .69.
Jun 15 1994 02:02:02:550PM	940615014	Earl Marmar	reload shot 10. Better shot. Lasted until 1.18 s. Pellet had a larger effect on density than the previous shot.
Jun 15 1994 02:11:47:110PM	940615014	Robert Granetz	Granetz replaces Marmar as phys. op. This shot did NOT have a vertical control problem at 0.7 s. It disrupted at 1.18 s. Ip=0.71 MA. Next shot, no changes.
Jun 15 1994 02:12:18:790PM	940615014	Robert Granetz	The lithium pellet injector may fire on the next shot.
Jun 15 1994 02:37:55:820PM	940615015	Robert Granetz	Good pellet shot. Most humongous, longest snake I've ever seen in C-Mod! Plasma disrupted at 1.02 s, probably due to lithium pellet injected at 1.0 s. Pellet was size #3. Increase on density was noticeably larger than on previous shots today. Pellet penetrated in to R=0.74 m. Snake lasted for about 80 ms. Next shot, two pellets...one at 0.750, second at 0.780. Also a lithium injection at 1.0 s
Jun 15 1994 02:48:40:360PM	940615016	Robert Granetz	Good shot. First pellet was size #2, no snake. Second pellet was size #3, with a snake lasting 15 ms. Lithium injection at 1.0 second kills the plasma. Plasma is nearly a double null for much of the discharge. Next shot, no lithium injection.
Jun 15 1994 02:53:42:760PM	940615016	Robert Granetz	Also next shot: 2 pellets, followed by ICRF heating.
Jun 15 1994 03:20:35:830PM	940615017	Robert Granetz	Good pellet shot. Plasma ended in a disruption at 1.04 s. 2 pellets, a small one at 0.755 and a larger one at 0.785. The disruption may be caused by too much density. For the next shot, decrease gas puffing from 0.8 s onward.
Jun 15 1994 03:31:49:750PM	940615018	Robert Granetz	2 pellets, but plasma disrupted shortly after the second pellet. Peak nl was about 2.5e20 m-2, or =4.2e20 m-3. The Greenwald limit is 5e20 m-3.
Jun 15 1994 03:45:13:710PM	940615019	Robert Granetz	2 pellets, but plasma disrupted shortly after the second one. On the next shot, I will activate the kappa feedback, using only EF1U in the controller.
Jun 15 1994 03:48:36:950PM	940615019	Robert Granetz	On this shot, the post-pellet density decayed very quickly (tau_n about 5 ms). This may have been due to the 1 MW of ICRF which turned on at 0.75 s.
Jun 15 1994 04:14:24:560PM	940615020	Robert Granetz	Better. 2 pellets. Plasma didn't disrupt until 1.1 s, which is just after rampdown begins. No snakes. It is questionable whether the kappa feedback did anything. Next shot, reduce programmed demand on kappa from 0.16 to 0.05. Keep gain the same. Also, remove the second argon puff.
Jun 15 1994 04:33:32:160PM	940615021	Robert Granetz	2 pellets, very similar to previous shot. Ended in disruption at 1.03 s. Hybrid seems to be getting the correct predictor output for kappa, but if anything, kappa was slightly higher. Next shot, increase gain on kappa feedback from 1 to 2.
Jun 15 1994 04:44:31:090PM	940615022	Robert Granetz	2 pellets, similar to preceding shots. Ends in disruption at 1.08 s. No snakes. There is little or no change in kappa. Next shot, program kappa to reduce towards the end of the shot.
Jun 15 1994 04:58:21:290PM	940615023	Robert Granetz	2 pellets, similar to preceding shots. Ends in disruption at 1.07 s. End of run.

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	08:48:26:670AM	Plasma	Ok	late hybrid power supply unbalance
2	09:45:21:370AM	Plasma	Ok	no plasma hybrid test/data aquisition test
3	10:19:41:170AM	Plasma	Ok	at last plasma
4	10:40:25:300AM	Plasma	Ok	>600ka disruption
5	10:57:26:110AM	Plasma	Ok	>600ka disruption
6	11:13:12:120AM	Plasma	Ok	plasma no fault no disrupt
7	11:33:48:190AM	Plasma	Ok	pelletized disruption > 600ka
8	11:50:49:260AM	Plasma	Ok	pelletized disruption, >600ka comm fault ef1l,
9	12:12:04:690PM	Plasma	Ok	plasma
10	12:33:49:680PM	Plasma	Ok	plasma
11	12:58:12:280PM	Plasma	Ok	disruption>700ka no faults
12	01:16:34:770PM	Plasma	Ok	No faults.
13	01:34:07:370PM	Plasma	Ok	No faults.
14	01:51:59:270PM	Plasma	Ok	NO faults
15	02:13:18:490PM	Plasma	Ok	No faults
16	02:35:40:920PM	Plasma	Ok	No faults.
17	02:53:45:620PM	Plasma	Ok	No faults.
18	03:21:33:660PM	Plasma	Ok	No faults.
19	03:37:29:270PM	Plasma	Ok	NO faults
20	03:54:00:050PM	Plasma	Ok	No faults.
21	04:15:16:060PM	Plasma	Ok	No faults
22	04:34:48:880PM	Plasma	Ok	No faults.
23	04:52:14:100PM	Plasma	Ok	No faults.