Alcator C-Mod Run 930603 Information

Miniproposals

Miniproposal:

Date Filed:

Title:

First Author:

Session Leader: Yuichi Takase (shots 1-29)

Operators
Session leader(s):	Yuichi Takase
Physics operator(s):	Ian Hutchinson
Engineering operator(s):	Unknown

Engineering Operator Run Comment
Plasma run

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:07:663PM

Author: To Be Determined

Objective of run was to demonstrate breakdown and current ramps at
lower voltage. This was successful in that plasmas were obtained.
However they were not reproducible and the reason is not understood
(any more than it is for the higher loop voltage plasmas).

29 shots. 2 no flash, 21 fizzles, 6 plasma current over 50 kA.

Commutation resistors were 2/3 of their previous values, throughout
the run. Loop voltage peaked at around 8V. From shot 12 onward EF3 was
limited to <1500V, i.e. less than roughly half of the nominal
power-supply voltage. This is then an in-principle demonstration of the
feasibility of startup in the EF3-series configuration.

Shot 13 showed a striking early (50kA) vertical instability. It was
fixed by shot 16 via control of the OH2 relative ramp rate, which
influences the field gradient.

The transition to the new predictors for position feedback was made at
shot 21. However, these were not seriously exercised because of the
failure of current rise in so many shots.

Shots 25-29 were a scan of the initial vertical field in the new
configuration where the EF3 front-porch is controlled at a low level
by the expedient of delaying its turn on till (-0.05 s nominal). This
is recommended, since in the old configuration there was noticeable
drift on the front porch during the day.

IHH

Physics Operator Summaries

Session Leader Comments

Jun 3 1993 09:24:45:970AM Yuichi Takase Today's objective: current ramp at lower voltage.
Commutation resistors have been lowered by 1/3.
OH1 -- 65.3mOhm
OH2 -- 12.8
EF1 -- 118.2
EF2 -- 45

Loaded 930527001.
Ian made a number of small tweaks.

Jun 3 1993 09:40:59:810AM 930603001 Yuichi Takase Poor null, no light.
V_l=10V.
B_z ramping down from -50ms (-5mT at 0ms).

Jun 3 1993 09:53:58:640AM 930603002 Yuichi Takase Raised EF4 to 800A (was 740).
B_z ramp on shot 001 was from EF3 front porch (-60A).
Got a weak flash. Breakdown at 5ms.
B_z ramping too quickly.

Jun 3 1993 10:05:34:620AM 930603003 Yuichi Takase Shot 003 Another fizzle.
Delayed EF3 by 1ms.
Breaking down with a little over 5V.

Jun 3 1993 10:29:07:310AM 930603004 Yuichi Takase Shot 004
Lowered OH2 to 14500A (was 15000, trying to improve the null).
Fizzle, horizontal field problem.
OH2 and EF2 imbalanced.

Jun 3 1993 10:40:29:670AM 930603005 Yuichi Takase Shot 005
Delayed EF3 another 1ms (now ramping 1-3ms).
Fizzle (30kA, a little better), still have horizontal field problem.
OH2 and EF2 imbalanced.
Breakdown occurring at a little under 5V.
Taking credit of 1ms for the avalanche, breakdown with about 3V.

Jun 3 1993 10:55:07:980AM 930603006 Yuichi Takase Shot 006
Delayed EF3 another 1ms (now ramping 2-4ms).
Fizzle.
B_z swinging up (to 0 at 5ms) and then down.

Jun 3 1993 11:13:43:670AM 930603007 Yuichi Takase Shot 007 Fizzle
EF4 lowered to 750.
Breakdown at 6ms (1ms later).

Jun 3 1993 11:28:55:470AM 930603008 Yuichi Takase Shot 008 Fizzle 32kA
Delayed EF2 negative ramp to -12ms (was around -18ms).
Moved EF3 ramp earlier by 1ms (1-3ms).

Jun 3 1993 11:45:08:010AM 930603009 Yuichi Takase Shot 009 No flash
B_R S lowered from .005 to .002.
Lowered EF2 S demand by 100A to 1160.
B_z < -6mT, OH2 imbalance got worse.

Jun 3 1993 11:59:08:250AM 930603010 Yuichi Takase Shot 010 Got flash back.
B_R S raised to .008 (we think we went the wrong way on shot 009).
Raised EF4 to 800A (got 760).
Fixed the horizontal field problem.
B_z still too negative (<5mT).

Jun 3 1993 12:19:19:230PM 930603011 Yuichi Takase Shot 011 Better, 70kA.
Raised EF4 to 850A.
B_z ramping too quickly.

Jun 3 1993 12:42:32:020PM 930603012 Yuichi Takase Shot 012 30kA.
EF3 voltage lowered to -1500V (was -3000V).
B_z ramping too slow now.

Jun 3 1993 01:10:12:790PM 930603013 Yuichi Takase Shot 013 30kA.
EF3 moved 2ms earlier (ramping from -1 to 1ms).
Vertical instability (starts around 25ms).

Jun 3 1993 01:18:50:900PM 930603014 Yuichi Takase Shot 014 20kA.
OH2 voltage demand -30V (4-48ms). Trying to improve field gradient.
Oops, overdone it.

Jun 3 1993 01:43:48:850PM 930603015 Yuichi Takase Shot 015 20kA
OH2 voltage demand to -10V.

Jun 3 1993 02:04:13:460PM 930603016 Yuichi Takase Shot 016 200kA (first good shot of the day)
OH2 voltage demand 10V till 10ms then step to -10V.
Successful low voltage current rampup.
5V breakdown, 8V max, -1500V on EF3, dI/dt up to 5MA/s.

Jun 3 1993 02:13:14:950PM 930603017 Yuichi Takase Shot 017 Fizzled
EF3 lowered from -1060V to -500V after 48ms.
Nothing changed before 46ms.

Jun 3 1993 02:38:52:330PM 930603018 Yuichi Takase Shot 018 Good shot, 190kA
No change from 017.

Jun 3 1993 05:21:18:110PM 930603019 Yuichi Takase Shot 019 Fizzle
OH2 -65V (was -45) OH1 -300V (was -200V) @50ms, ramping down till 200ms.

Jun 3 1993 03:20:36:080PM 930603020 Yuichi Takase Shot 020 Good shot 210kA
Raised gas to 60 (10-50ms).

Jun 3 1993 03:38:31:030PM 930603021 Yuichi Takase Shot 021 Dud
Loaded new filament predictors for R_CUR and Z_CUR.
Dropped PID gain for R_CUR to 0.2 (was 1) and Z_CUR to 0.1 (was 2).
Set at limits on M(R_CUR), pushed EF3 gain down to 0.05.
Set at limits on M(Z_CUR), pushed OH2 gain down to 0.003.

Jun 3 1993 03:45:49:190PM 930603022 Yuichi Takase Shot 022 Another dud
No change.

Jun 3 1993 03:54:34:190PM 930603023 Yuichi Takase Shot 023 Third dud in a row.
OH2 20V (1-10ms), was 12V.

Jun 3 1993 04:14:51:400PM 930603024 Yuichi Takase Shot 024 Dud
EF3 delayed by 1ms (ramping 0-2ms).

Jun 3 1993 04:35:15:220PM 930603025 Yuichi Takase Shot 025 Fizzle
EF3 turn on set to -0.05s (was -0.1s).
Got rid of the EF3 front porch problem.
More positive B_z, late breakdown.

Jun 3 1993 04:43:34:240PM 930603026 Yuichi Takase Shot 026 Fizzle
Lowered EF4 to 780A (was 850).
Not enough, still late breakdown (10ms).

Jun 3 1993 04:55:10:470PM 930603027 Yuichi Takase Shot 027 A little better.
Lowered EF4 to 720A.

Jun 3 1993 05:06:41:580PM 930603028 Yuichi Takase Shot 028 Good shot, 210kA.
Lowered EF4 to 650A.

Jun 3 1993 05:22:53:490PM 930603029 Yuichi Takase Shot 029 Fizzle
EF4 580A (end of EF4 scan).

Physics Operator Comments

Engineering Operator Comments

Shot Time Type Status Comment

1 09:21:46:300AM Plasma Ok Plasma shot no faults.

2 09:42:44:580AM Plasma Ok GOOD PLASMA SHOT NO FAULTS

3 09:55:09:960AM Plasma Ok Plasma shot no faults.

4 10:07:17:000AM Plasma Ok Plasma shot commutation fault oh1 oh2u & ef1L

5 10:27:29:290AM Plasma Ok Plasma shot no faults

6 10:41:41:320AM Plasma Ok Plasma shot no faults

7 10:57:31:930AM Plasma Ok Good

8 11:15:24:370AM Plasma Ok Plasma shot no faults

9 11:32:32:310AM Plasma Ok Plasma shot NO faults.

10 11:48:03:860AM Plasma Ok Plasma shot no faults.

11 12:04:07:870PM Plasma Ok Plasma shot no faults

12 12:28:34:550PM Plasma Ok plasma shot no faults

13 12:44:31:330PM Plasma Ok Plasma shot no faults

14 01:07:04:610PM Plasma Ok Good Shot

15 01:28:03:710PM Plasma Ok Plasma shot No faults.

16 01:45:17:910PM Plasma Ok Plasma shot no faults. 190kA

17 02:03:08:120PM Plasma Ok Plasma shot no faults

18 02:17:07:210PM Plasma Ok plasma shot no faults

19 02:39:33:900PM Plasma Ok Plasma shot no faults.

20 02:56:05:810PM Plasma Ok Plasma shot , no faults..

21 03:22:19:830PM Plasma Ok Plasma shot no faults

22 03:33:24:620PM Plasma Ok good shot.

23 03:47:36:010PM Plasma Ok Plasma shot no faults.

24 04:02:11:190PM Plasma Ok plasma shot no faults

25 04:18:05:710PM Plasma Ok Plasma shot no faults.

26 04:35:03:750PM Plasma Ok Plasma shot no faults.

27 04:45:22:440PM Plasma Ok Plasma shot no faults

28 04:57:25:070PM Plasma Ok Plasma shot no faults.

29 05:08:55:760PM Test Bad

Session Leader Comments
Jun 3 1993 09:24:45:970AM		Yuichi Takase	Today's objective: current ramp at lower voltage. Commutation resistors have been lowered by 1/3. OH1 -- 65.3mOhm OH2 -- 12.8 EF1 -- 118.2 EF2 -- 45 Loaded 930527001. Ian made a number of small tweaks.
Jun 3 1993 09:40:59:810AM	930603001	Yuichi Takase	Poor null, no light. V_l=10V. B_z ramping down from -50ms (-5mT at 0ms).
Jun 3 1993 09:53:58:640AM	930603002	Yuichi Takase	Raised EF4 to 800A (was 740). B_z ramp on shot 001 was from EF3 front porch (-60A). Got a weak flash. Breakdown at 5ms. B_z ramping too quickly.
Jun 3 1993 10:05:34:620AM	930603003	Yuichi Takase	Shot 003 Another fizzle. Delayed EF3 by 1ms. Breaking down with a little over 5V.
Jun 3 1993 10:29:07:310AM	930603004	Yuichi Takase	Shot 004 Lowered OH2 to 14500A (was 15000, trying to improve the null). Fizzle, horizontal field problem. OH2 and EF2 imbalanced.
Jun 3 1993 10:40:29:670AM	930603005	Yuichi Takase	Shot 005 Delayed EF3 another 1ms (now ramping 1-3ms). Fizzle (30kA, a little better), still have horizontal field problem. OH2 and EF2 imbalanced. Breakdown occurring at a little under 5V. Taking credit of 1ms for the avalanche, breakdown with about 3V.
Jun 3 1993 10:55:07:980AM	930603006	Yuichi Takase	Shot 006 Delayed EF3 another 1ms (now ramping 2-4ms). Fizzle. B_z swinging up (to 0 at 5ms) and then down.
Jun 3 1993 11:13:43:670AM	930603007	Yuichi Takase	Shot 007 Fizzle EF4 lowered to 750. Breakdown at 6ms (1ms later).
Jun 3 1993 11:28:55:470AM	930603008	Yuichi Takase	Shot 008 Fizzle 32kA Delayed EF2 negative ramp to -12ms (was around -18ms). Moved EF3 ramp earlier by 1ms (1-3ms).
Jun 3 1993 11:45:08:010AM	930603009	Yuichi Takase	Shot 009 No flash B_R S lowered from .005 to .002. Lowered EF2 S demand by 100A to 1160. B_z < -6mT, OH2 imbalance got worse.
Jun 3 1993 11:59:08:250AM	930603010	Yuichi Takase	Shot 010 Got flash back. B_R S raised to .008 (we think we went the wrong way on shot 009). Raised EF4 to 800A (got 760). Fixed the horizontal field problem. B_z still too negative (<5mT).
Jun 3 1993 12:19:19:230PM	930603011	Yuichi Takase	Shot 011 Better, 70kA. Raised EF4 to 850A. B_z ramping too quickly.
Jun 3 1993 12:42:32:020PM	930603012	Yuichi Takase	Shot 012 30kA. EF3 voltage lowered to -1500V (was -3000V). B_z ramping too slow now.
Jun 3 1993 01:10:12:790PM	930603013	Yuichi Takase	Shot 013 30kA. EF3 moved 2ms earlier (ramping from -1 to 1ms). Vertical instability (starts around 25ms).
Jun 3 1993 01:18:50:900PM	930603014	Yuichi Takase	Shot 014 20kA. OH2 voltage demand -30V (4-48ms). Trying to improve field gradient. Oops, overdone it.
Jun 3 1993 01:43:48:850PM	930603015	Yuichi Takase	Shot 015 20kA OH2 voltage demand to -10V.
Jun 3 1993 02:04:13:460PM	930603016	Yuichi Takase	Shot 016 200kA (first good shot of the day) OH2 voltage demand 10V till 10ms then step to -10V. Successful low voltage current rampup. 5V breakdown, 8V max, -1500V on EF3, dI/dt up to 5MA/s.
Jun 3 1993 02:13:14:950PM	930603017	Yuichi Takase	Shot 017 Fizzled EF3 lowered from -1060V to -500V after 48ms. Nothing changed before 46ms.
Jun 3 1993 02:38:52:330PM	930603018	Yuichi Takase	Shot 018 Good shot, 190kA No change from 017.
Jun 3 1993 05:21:18:110PM	930603019	Yuichi Takase	Shot 019 Fizzle OH2 -65V (was -45) OH1 -300V (was -200V) @50ms, ramping down till 200ms.
Jun 3 1993 03:20:36:080PM	930603020	Yuichi Takase	Shot 020 Good shot 210kA Raised gas to 60 (10-50ms).
Jun 3 1993 03:38:31:030PM	930603021	Yuichi Takase	Shot 021 Dud Loaded new filament predictors for R_CUR and Z_CUR. Dropped PID gain for R_CUR to 0.2 (was 1) and Z_CUR to 0.1 (was 2). Set at limits on M(R_CUR), pushed EF3 gain down to 0.05. Set at limits on M(Z_CUR), pushed OH2 gain down to 0.003.
Jun 3 1993 03:45:49:190PM	930603022	Yuichi Takase	Shot 022 Another dud No change.
Jun 3 1993 03:54:34:190PM	930603023	Yuichi Takase	Shot 023 Third dud in a row. OH2 20V (1-10ms), was 12V.
Jun 3 1993 04:14:51:400PM	930603024	Yuichi Takase	Shot 024 Dud EF3 delayed by 1ms (ramping 0-2ms).
Jun 3 1993 04:35:15:220PM	930603025	Yuichi Takase	Shot 025 Fizzle EF3 turn on set to -0.05s (was -0.1s). Got rid of the EF3 front porch problem. More positive B_z, late breakdown.
Jun 3 1993 04:43:34:240PM	930603026	Yuichi Takase	Shot 026 Fizzle Lowered EF4 to 780A (was 850). Not enough, still late breakdown (10ms).
Jun 3 1993 04:55:10:470PM	930603027	Yuichi Takase	Shot 027 A little better. Lowered EF4 to 720A.
Jun 3 1993 05:06:41:580PM	930603028	Yuichi Takase	Shot 028 Good shot, 210kA. Lowered EF4 to 650A.
Jun 3 1993 05:22:53:490PM	930603029	Yuichi Takase	Shot 029 Fizzle EF4 580A (end of EF4 scan).

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	09:21:46:300AM	Plasma	Ok	Plasma shot no faults.
2	09:42:44:580AM	Plasma	Ok	GOOD PLASMA SHOT NO FAULTS
3	09:55:09:960AM	Plasma	Ok	Plasma shot no faults.
4	10:07:17:000AM	Plasma	Ok	Plasma shot commutation fault oh1 oh2u & ef1L
5	10:27:29:290AM	Plasma	Ok	Plasma shot no faults
6	10:41:41:320AM	Plasma	Ok	Plasma shot no faults
7	10:57:31:930AM	Plasma	Ok	Good
8	11:15:24:370AM	Plasma	Ok	Plasma shot no faults
9	11:32:32:310AM	Plasma	Ok	Plasma shot NO faults.
10	11:48:03:860AM	Plasma	Ok	Plasma shot no faults.
11	12:04:07:870PM	Plasma	Ok	Plasma shot no faults
12	12:28:34:550PM	Plasma	Ok	plasma shot no faults
13	12:44:31:330PM	Plasma	Ok	Plasma shot no faults
14	01:07:04:610PM	Plasma	Ok	Good Shot
15	01:28:03:710PM	Plasma	Ok	Plasma shot No faults.
16	01:45:17:910PM	Plasma	Ok	Plasma shot no faults. 190kA
17	02:03:08:120PM	Plasma	Ok	Plasma shot no faults
18	02:17:07:210PM	Plasma	Ok	plasma shot no faults
19	02:39:33:900PM	Plasma	Ok	Plasma shot no faults.
20	02:56:05:810PM	Plasma	Ok	Plasma shot , no faults..
21	03:22:19:830PM	Plasma	Ok	Plasma shot no faults
22	03:33:24:620PM	Plasma	Ok	good shot.
23	03:47:36:010PM	Plasma	Ok	Plasma shot no faults.
24	04:02:11:190PM	Plasma	Ok	plasma shot no faults
25	04:18:05:710PM	Plasma	Ok	Plasma shot no faults.
26	04:35:03:750PM	Plasma	Ok	Plasma shot no faults.
27	04:45:22:440PM	Plasma	Ok	Plasma shot no faults
28	04:57:25:070PM	Plasma	Ok	Plasma shot no faults.
29	05:08:55:760PM	Test	Bad