Alcator C-Mod Run 941121 Information

Miniproposals

Miniproposal:

Date Filed:

Title:

First Author:

Session Leader: Earl Marmar (shots 1-34)

Operators
Session leader(s):	Earl Marmar
Physics operator(s):	John Goetz
Engineering operator(s):	Vinny Bertolino

Engineering Operator Run Comment
first plasmas

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Physics Operator Summaries

Entered: Jul 7 2004 04:36:52:020PM

Author: To Be Determined

Physics operator summary for 941121

EO: Bertilino
PO: Goetz/Marmar

Run 941121 was in support of Mini-Proposal #041 - Startup C-Mod in 1994.
To this end, shot 941118002 was loaded into the hybrid. This was a shot
from early in the last run that had a good field null, but no current rise.
The breakdown on this shot was early, around .005 sec. This shot has only
changes ( from 941117031 ) to the OH2's to get an earlier breakdown.

Today's goals were to try to obtain reliable current rises. Reliable
breakdowns were obtained during Run 941118. Things to try:
lower fill and increase puff
slide puff earlier in time to quench runaways
cryo-pump between shots to lower the partial pressure of water
reload shot 941118031 - the last good non-runaway shot

Engineering today: One test shot to check out the new OH stack diagnostics.
One failure (COMM FAILURE) on the OH2L supply. Otherwise a good day
for cooling - vacuum conditions - etc. Fired off 34 shots, even
though the run began at 9:30.

Mini-proposal #041 is still open as reliable current rises were not obtained
today. Forty percent of the shots had plasma, with almost all of those
reaching full rampdown. Runaways were not a problem today (190 mR total),
with most of these coming on shot 2 (75%). Loading of the walls maybe the
critical factor (over the weekend ECDC) but how the hell do you prove it?
Moving the pulse gas waveform back and forth in time seemed to help with the
early time behavior of the density. The major accomplishment of the run was
a scan in fill pressure. The scan was done primarily to try and slow down
the current rise. This scan showed that the operating space is 0.6 < P_0
<= 1.6e-5. A dud was obtained at 0.6e-5 and only fizzles at 1.8e-5. A scan
of the current in EF4 was also performed, showing that > -1065A leads to duds
for the given startup scenario being used. It seems that a new criterion has
been discovered - if the plasma current is > .04MA when the plasma bump occurs,
the plasma will survive. The current rise rate and/or Bz ramp rate needs to
be fiddled with to be able to do away with this criterion. The last shot of
the day was an attempt to do this with OH1 voltage programming, but no changes
were made to EF4 and a dud follows.

The plasmas today were inner wall limited with elongations < 1.4, although
plasmas early in the run were almost nose-limited with kappa < 1.5. These
nose-limited shots were corrected by raising the plasma current. By the end
of the run. the plasmas were 0.78MA with a nl_05 of ~1e20.

Scorecard: 34 shots = 13 plasmas + 16 fizzles + 3 duds + 1 eng dud + 1 eng test

Shot summary for Run 941121

Reload of 941118002

Changes:
Change RCUR programming to begin at .68m (was .70m)

Shot change result
____ _____ ______
1 10kA OH test
2 P_0=8.0e-6; slide PG3 waveform .005 sec earlier plasma
3 PG3 lowered after 0.4 - raise near .05sec; P_0=7e-6 plasma
4 recalculate Ip predictor plasma

A serious screwup. The predictor wasn't ROGOWSKI but CUSTOM.
When we recalculated the predictor, Custom obediently loaded all zeros
into the predictor AND WE DIDN'T NOTICE. This turned off the
gain on IP; therefore plasma current was pushed up uncontrollably.
SFH.

5 recalculate Ip predictor - correctly this time fizzle
6 P_0=6.0e-6 plasma
7 no changes fizzle
8 no changes dud
9 P_0=8.0e-6 fizzle
10 reload 941121003; P_0=7.0e-6 fizzle
11 slide PG3 +.003; P_0=8.0e-6 fizzle
12 P_0=1.0e-5 plasma
13 slide PG3 -.003 sec fizzle
14 slide PG3 +.003 sec; P_0=1.1e-5 plasma
15 raise PG3 @ 0.5 sec; redo factor for Ip predictor fizzle
16 P_0=1.2e-5 plasma
17 load segment 1 into segment 2 and turn on at 0.4 sec;
EF1L and EF1U = 3500A @ 1.2sec fizzle
18 P_0=1.3e-5 plasma
19 IC_EF4=-1085A in segment 1 fizzle
20 P_0=1.4e-5 fizzle
21 P_0=1.5e-5; IC_EF4=-1110A in segment 1 fizzle
22 IC_EF4=-1085A in segment 1 plasma
23 IP=-750000; P_0=1.6e-5 fizzle
24 no changes plasma
25 P_0=1.8e-5 eng.dud
26 no changes fizzle
27 no changes fizzle
28 P_0=1.5e-5 fizzle
29 IC_EF4=-1075A in segment 1 plasma
30 IC_EF4=-1065A in segment 1; offset on IP in segment 2 = 30000 dud
31 IC_EF4=-1075A in segment 1; offset on IP in segment 1 = 30000 plasma
32 remove offset from Ip controller; enable B_SIDE_LOWER with
2 PSIA Ar; draw -780000 for Ip fizzle
33 no changes plasma
34 V_OH1=50V at .005 and .024 sec; P_0=1.6e-5 dud

Session Leader Comments

Nov 21 1994 09:02:39:140AM Earl Marmar Goal of today's run:

Get reliable current rise.

Plan:

1) Reduce fill pressure
2) Move pulsed gas earlier
3) Puff harder

Nov 21 1994 09:33:59:060AM 941121001 Earl Marmar OH test for instrumentation

Nov 21 1994 10:01:59:570AM 941121002 Earl Marmar Fill 8e-6; reload of 941118002 with gas tweaks.

Plasma. 0.5 MA. Lasted .7 seconds.

Nov 21 1994 10:17:17:940AM 941121003 Earl Marmar Fill 7e-6; lower late gas puff, early gas tweak.

Plasma. 0.5 MA. Lower hards, nel=6e19; nice rampdown

Nov 21 1994 10:28:13:700AM 941121004 Earl Marmar Fill 7e-6; wirehead change to correct current feedback; broke the Ip
feedback; .8 MA and then disrupt at .29 s.

Nov 21 1994 10:37:21:130AM 941121005 Earl Marmar Fill 7e-6; Fizzle.

Nov 21 1994 10:51:42:130AM 941121006 Earl Marmar Fill 6e-6; Dirty during current rise. .43 MA, disrupt at .60 s.

Nov 21 1994 11:04:25:150AM 941121007 Earl Marmar Fill 6e-6; Fizzle; spike on 2pi bolo

Nov 21 1994 11:06:32:660AM 941121008 Earl Marmar Fill 6e-6; Dud

Nov 21 1994 11:16:21:440AM 941121009 Earl Marmar Fill 8e-6; hot fizzle; 2pi bolo spike at .022 s.

Nov 21 1994 11:23:33:290AM 941121010 Earl Marmar Fill 7e-6; reload 941121003; similar to shot 9.

Nov 21 1994 11:34:08:190AM 941121011 Earl Marmar Fill 8e-6; FIzzle; big 2pi bolo spike at .02 s.

Nov 21 1994 11:46:16:810AM 941121012 Earl Marmar Fill 1e-5; Good plasma. 0.5 MA; a few hards spikes early;

Nov 21 1994 12:02:36:760PM 941121013 Earl Marmar Fill 1e-5; Fizzle

Nov 21 1994 12:21:21:460PM 941121014 Earl Marmar Fill 1.1e-5; Good shot; .5 MA

Nov 21 1994 12:27:58:270PM 941121015 Earl Marmar Fill 1.1e-5; Fizzle

Nov 21 1994 12:44:34:230PM 941121016 Earl Marmar Fill 1.2e-5; Fixed Ip feedback factor; good shot; 0.6 MA

Nov 21 1994 12:55:22:360PM 941121017 Earl Marmar Fill 1.2e-5; fizzle

Nov 21 1994 01:21:55:930PM 941121018 Earl Marmar Fill 1.3e-5; nice plasma; .6 MA;

Nov 21 1994 01:22:58:960PM 941121019 Earl Marmar Fill 1.3e-5; fizzle; 2pi bolo spike at .015 s

Nov 21 1994 02:04:20:180PM 941121020 Earl Marmar Fill 1.4e-5; fizzle, but nearly went; 2pi bolo spike at .019 s

Nov 21 1994 02:19:09:230PM 941121021 Earl Marmar Fill 1.5e-5; fizzle

Nov 21 1994 02:30:32:710PM 941121022 Earl Marmar Fill 1.5e-5; EF4 tweak; good shot; 0.6 MA

Nov 21 1994 02:47:06:970PM 941121023 Earl Marmar Fill 1.6e-5; tweak

Nov 21 1994 02:47:49:870PM 941121023 Earl Marmar Fill 1.6e-5; fizzle

Nov 21 1994 02:58:03:920PM 941121024 Earl Marmar Fill 1.6e-5; good plasma; 0.73 MA

Nov 21 1994 03:14:19:510PM 941121025 Earl Marmar Fill 1.8e-5; OH2 crowbar; dud.

Nov 21 1994 03:38:36:100PM 941121026 Earl Marmar Fill 1.8e-5; fizzle

Nov 21 1994 03:45:39:280PM 941121027 Earl Marmar Fill 1.8e-5; fizzle

Nov 21 1994 03:54:38:850PM 941121028 Earl Marmar Fill 1.5e-5; close, but fizzle

Nov 21 1994 04:06:16:370PM 941121029 Earl Marmar Fill 1.5e-5; EF4 tweak; plasma; .73 MA; serious hesitation at .022 s.

Nov 21 1994 04:18:13:190PM 941121030 Earl Marmar Fill 1.5e-5; further EF4 tweak; dud.

Nov 21 1994 04:32:10:010PM 941121031 Earl Marmar Fill 1.5e-5; Undo last EF4 tweak; Plasma; .55 MA

Nov 21 1994 04:50:30:040PM 941121033 Earl Marmar Fill 1.5e-5; fizzle

Nov 21 1994 04:58:42:420PM 941121033 Earl Marmar Fill 1.5e-5; plasma; bounce at .021 s; .78 MA

Nov 21 1994 05:09:01:980PM 941121034 Earl Marmar Fill 1.6e-5; tweak OH1 voltage; dud.

Physics Operator Comments

Engineering Operator Comments

Shot Time Type Status Comment

1 09:32:18:780AM Test Ok oh1, oh2u and oh2l coax instrumentation baseline

2 09:47:25:420AM Plasma Ok no faults

3 10:07:10:860AM Plasma Ok no faults

4 10:19:55:430AM Plasma Ok no faults

5 10:31:37:950AM Plasma Ok no faults

6 10:40:59:200AM Plasma Ok no faults

7 10:52:27:770AM Plasma Ok no faults

8 11:01:41:230AM Plasma Ok no faults

9 11:10:23:320AM Plasma Ok no faults

10 11:19:20:470AM Plasma Ok no faults

11 11:29:07:080AM Plasma Ok no faults

12 11:40:06:140AM Plasma Ok no faults

13 11:52:38:650AM Plasma Ok no faults

14 12:04:41:150PM Plasma Ok no faults

15 12:21:22:330PM Plasma Ok no faults

16 12:31:18:680PM Plasma Ok no faults

17 12:50:49:330PM Plasma Ok no faults

18 01:01:02:260PM Plasma Ok no faults

19 01:17:50:160PM Plasma Ok NO power supply faults.

20 01:35:25:270PM Plasma Ok No power supply faults.

21 02:08:57:420PM Plasma Ok

22 02:20:18:220PM Plasma Ok good 600ka

23 02:44:09:140PM Plasma Ok

24 02:53:06:400PM Plasma Ok 730 ka

25 03:10:05:340PM Plasma Bad OH2l faulted. comm fault

26 03:33:01:490PM Plasma Ok No faults.

27 03:41:14:340PM Plasma Ok No faults.

28 03:50:13:450PM Plasma Ok No faults

29 03:59:11:650PM Plasma Ok No faults

30 04:11:15:610PM Plasma Ok No faults

31 04:24:59:070PM Plasma Ok no faults

32 04:41:00:150PM Plasma Ok No faults,

33 04:49:21:110PM Plasma Ok good shot

34 05:01:15:180PM Plasma Ok no faults

Session Leader Comments
Nov 21 1994 09:02:39:140AM		Earl Marmar	Goal of today's run: Get reliable current rise. Plan: 1) Reduce fill pressure 2) Move pulsed gas earlier 3) Puff harder
Nov 21 1994 09:33:59:060AM	941121001	Earl Marmar	OH test for instrumentation
Nov 21 1994 10:01:59:570AM	941121002	Earl Marmar	Fill 8e-6; reload of 941118002 with gas tweaks. Plasma. 0.5 MA. Lasted .7 seconds.
Nov 21 1994 10:17:17:940AM	941121003	Earl Marmar	Fill 7e-6; lower late gas puff, early gas tweak. Plasma. 0.5 MA. Lower hards, nel=6e19; nice rampdown
Nov 21 1994 10:28:13:700AM	941121004	Earl Marmar	Fill 7e-6; wirehead change to correct current feedback; broke the Ip feedback; .8 MA and then disrupt at .29 s.
Nov 21 1994 10:37:21:130AM	941121005	Earl Marmar	Fill 7e-6; Fizzle.
Nov 21 1994 10:51:42:130AM	941121006	Earl Marmar	Fill 6e-6; Dirty during current rise. .43 MA, disrupt at .60 s.
Nov 21 1994 11:04:25:150AM	941121007	Earl Marmar	Fill 6e-6; Fizzle; spike on 2pi bolo
Nov 21 1994 11:06:32:660AM	941121008	Earl Marmar	Fill 6e-6; Dud
Nov 21 1994 11:16:21:440AM	941121009	Earl Marmar	Fill 8e-6; hot fizzle; 2pi bolo spike at .022 s.
Nov 21 1994 11:23:33:290AM	941121010	Earl Marmar	Fill 7e-6; reload 941121003; similar to shot 9.
Nov 21 1994 11:34:08:190AM	941121011	Earl Marmar	Fill 8e-6; FIzzle; big 2pi bolo spike at .02 s.
Nov 21 1994 11:46:16:810AM	941121012	Earl Marmar	Fill 1e-5; Good plasma. 0.5 MA; a few hards spikes early;
Nov 21 1994 12:02:36:760PM	941121013	Earl Marmar	Fill 1e-5; Fizzle
Nov 21 1994 12:21:21:460PM	941121014	Earl Marmar	Fill 1.1e-5; Good shot; .5 MA
Nov 21 1994 12:27:58:270PM	941121015	Earl Marmar	Fill 1.1e-5; Fizzle
Nov 21 1994 12:44:34:230PM	941121016	Earl Marmar	Fill 1.2e-5; Fixed Ip feedback factor; good shot; 0.6 MA
Nov 21 1994 12:55:22:360PM	941121017	Earl Marmar	Fill 1.2e-5; fizzle
Nov 21 1994 01:21:55:930PM	941121018	Earl Marmar	Fill 1.3e-5; nice plasma; .6 MA;
Nov 21 1994 01:22:58:960PM	941121019	Earl Marmar	Fill 1.3e-5; fizzle; 2pi bolo spike at .015 s
Nov 21 1994 02:04:20:180PM	941121020	Earl Marmar	Fill 1.4e-5; fizzle, but nearly went; 2pi bolo spike at .019 s
Nov 21 1994 02:19:09:230PM	941121021	Earl Marmar	Fill 1.5e-5; fizzle
Nov 21 1994 02:30:32:710PM	941121022	Earl Marmar	Fill 1.5e-5; EF4 tweak; good shot; 0.6 MA
Nov 21 1994 02:47:06:970PM	941121023	Earl Marmar	Fill 1.6e-5; tweak
Nov 21 1994 02:47:49:870PM	941121023	Earl Marmar	Fill 1.6e-5; fizzle
Nov 21 1994 02:58:03:920PM	941121024	Earl Marmar	Fill 1.6e-5; good plasma; 0.73 MA
Nov 21 1994 03:14:19:510PM	941121025	Earl Marmar	Fill 1.8e-5; OH2 crowbar; dud.
Nov 21 1994 03:38:36:100PM	941121026	Earl Marmar	Fill 1.8e-5; fizzle
Nov 21 1994 03:45:39:280PM	941121027	Earl Marmar	Fill 1.8e-5; fizzle
Nov 21 1994 03:54:38:850PM	941121028	Earl Marmar	Fill 1.5e-5; close, but fizzle
Nov 21 1994 04:06:16:370PM	941121029	Earl Marmar	Fill 1.5e-5; EF4 tweak; plasma; .73 MA; serious hesitation at .022 s.
Nov 21 1994 04:18:13:190PM	941121030	Earl Marmar	Fill 1.5e-5; further EF4 tweak; dud.
Nov 21 1994 04:32:10:010PM	941121031	Earl Marmar	Fill 1.5e-5; Undo last EF4 tweak; Plasma; .55 MA
Nov 21 1994 04:50:30:040PM	941121033	Earl Marmar	Fill 1.5e-5; fizzle
Nov 21 1994 04:58:42:420PM	941121033	Earl Marmar	Fill 1.5e-5; plasma; bounce at .021 s; .78 MA
Nov 21 1994 05:09:01:980PM	941121034	Earl Marmar	Fill 1.6e-5; tweak OH1 voltage; dud.

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	09:32:18:780AM	Test	Ok	oh1, oh2u and oh2l coax instrumentation baseline
2	09:47:25:420AM	Plasma	Ok	no faults
3	10:07:10:860AM	Plasma	Ok	no faults
4	10:19:55:430AM	Plasma	Ok	no faults
5	10:31:37:950AM	Plasma	Ok	no faults
6	10:40:59:200AM	Plasma	Ok	no faults
7	10:52:27:770AM	Plasma	Ok	no faults
8	11:01:41:230AM	Plasma	Ok	no faults
9	11:10:23:320AM	Plasma	Ok	no faults
10	11:19:20:470AM	Plasma	Ok	no faults
11	11:29:07:080AM	Plasma	Ok	no faults
12	11:40:06:140AM	Plasma	Ok	no faults
13	11:52:38:650AM	Plasma	Ok	no faults
14	12:04:41:150PM	Plasma	Ok	no faults
15	12:21:22:330PM	Plasma	Ok	no faults
16	12:31:18:680PM	Plasma	Ok	no faults
17	12:50:49:330PM	Plasma	Ok	no faults
18	01:01:02:260PM	Plasma	Ok	no faults
19	01:17:50:160PM	Plasma	Ok	NO power supply faults.
20	01:35:25:270PM	Plasma	Ok	No power supply faults.
21	02:08:57:420PM	Plasma	Ok
22	02:20:18:220PM	Plasma	Ok	good 600ka
23	02:44:09:140PM	Plasma	Ok
24	02:53:06:400PM	Plasma	Ok	730 ka
25	03:10:05:340PM	Plasma	Bad	OH2l faulted. comm fault
26	03:33:01:490PM	Plasma	Ok	No faults.
27	03:41:14:340PM	Plasma	Ok	No faults.
28	03:50:13:450PM	Plasma	Ok	No faults
29	03:59:11:650PM	Plasma	Ok	No faults
30	04:11:15:610PM	Plasma	Ok	No faults
31	04:24:59:070PM	Plasma	Ok	no faults
32	04:41:00:150PM	Plasma	Ok	No faults,
33	04:49:21:110PM	Plasma	Ok	good shot
34	05:01:15:180PM	Plasma	Ok	no faults