Alcator C-Mod Run 931028 Information

Miniproposals

Miniproposal:

Date Filed:

Title:

First Author:

Session Leader: Tom Luke (shots 1-18)

Operators
Session leader(s):	Tom Luke
Physics operator(s):	Joseph Snipes
Engineering operator(s):	Unknown

Engineering Operator Run Comment
recover from short unscheduled vacuum break

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:09:680PM

Author: To Be Determined

From: LEADER::SNIPES
Date: 28-OCT-1993 21:29:07
Description: Run Summary 931028

The run was intended to study density limits and particle diffusion. However,
with the machine in its present condition after the opening of the Thomson
Scattering flange, plasmas were not running particularly well. The run
started late in the afternoon about 4:00 pm and ended after 9:00 pm. We
succeeded in getting plasmas immediately for two shots, then ran into
difficulties with the current rise. We succeeded in getting one long high
density shot that disrupted just before the intended injection of a Li pellet
(shot 16). There were 18 shots with 8 plasmas and according to my accounting
10 fizzles, though Ian's summary program says 7 duds and 3 fizzles.
Shot,Duration(s),Ipmax(MA) Shot,Duration(s),Ipmax
1 0.509 0.988 2 0.536 0.998
3 0.000 0.020 4 0.000 0.019
5 0.000 0.019 6 0.000 0.019
7 0.369 0.695 8 0.000 0.017
9 0.000 0.019 10 0.960 0.945
11 0.000 0.017 12 0.000 0.021
13 0.000 0.022 14 0.000 0.022
15 0.174 0.325 16 0.790 0.856
17 0.262 0.447 18 0.268 0.465

Finished summary for 931028 Total of 18 shots.
18 shots. 8 plasmas. 3 fizzles. 7 duds.
Fizzle = gt 20 lt 50kA.

Physics Operator Summaries

Session Leader Comments

Oct 28 1993 04:09:19:100PM 931028001 Tom Luke Late start on today's run. Vacuum target for Thomson scattering got
stuck in the machine overnight . Required a He backfill and bringing the
vessel up to air to free it. RF run moved to Friday and Density run
started at 4:00. We will attempt to to a scan in density and current
perfoming gas modulation for MP 030.

Oct 28 1993 04:22:12:470PM 931028001 Tom Luke Late start on today's run. Vacuum target for Thomson scattering got
stuck in the machine overnight . Required a He backfill and bringing the
vessel up to air to free it. RF run moved to Friday and Density run
started at 4:00. We will attempt to to a scan in density and current
perfoming gas modulation for MP 030.

Oct 28 1993 04:39:02:710PM 931028001 Tom Luke Repeat of last shot on 10/27. Li pellet fired at 500 ms. Amazing but
shot went. Density was very low and the plasma disrupted at 500 ms
when the pellet went in.

Oct 28 1993 05:08:23:820PM 931028002 Tom Luke Put more gas in with 3 puffs at 300,390,480 ms. Puffs are 30 ms and 40 V.
Shot ended at 500 ms with a TF fault.

Oct 28 1993 05:14:43:180PM 931028002 Tom Luke Raised prefill.. 5 puffs at 300,390,480,570,660. 20 V and 30 ms long.
fizzle

Oct 28 1993 05:31:33:880PM 931028004 Tom Luke repeat of shot 3. fizzle.

Oct 28 1993 05:40:47:460PM 931028004 Tom Luke repeat of shot 3. fizzle. Looks like there is too much RF before there
is significant plasma current.

Oct 28 1993 06:09:42:420PM 931028006 Tom Luke repeat of shot 3. RF lowered to 20 KW.fizzle.

Oct 28 1993 06:21:34:760PM 931028007 Tom Luke Got plasma. Runaway shot. Disrupted at 400 ms. Density went to 1.0e20
at disruption.

Oct 28 1993 06:39:00:360PM 931028008 Tom Luke fizzle.GAS?

Oct 28 1993 07:04:36:170PM 931028009 Tom Luke fizzle.

Oct 28 1993 07:12:39:200PM 931028010 Tom Luke Changed gas fuelling to 931025018. Shot went. lasted to 900 ms.Lowq density
4.0e19.

Oct 28 1993 07:20:14:610PM 931028010 Tom Luke Changed gas fuelling to 931025018. Shot went. lasted to 900 ms.Lowq density
4.0e19.

Oct 28 1993 07:22:27:260PM 931028011 Tom Luke Fizzle.

Oct 28 1993 07:58:44:780PM 931028013 Tom Luke fizzle.

Oct 28 1993 08:35:15:630PM 931028015 Tom Luke Very short plasma. 3.0e19 nl.

Oct 28 1993 08:52:21:500PM 931028016 Tom Luke Disrupts at 800 ms. Very high plasma 2.0e20. Plasma flattens out before
disruption. Possible density limit?

Oct 28 1993 09:03:20:190PM 931028017 Tom Luke Disrupted at 300 ms. 5.0e19 density.

Oct 28 1993 09:11:47:360PM 931028018 Tom Luke Disrupted at 300 ms. Very similar to shot 17.

Physics Operator Comments

Oct 28 1993 05:12:22:690PM 931028001 Joseph Snipes Luke's run for density limits, pellets, and maybe H modes. Start by
copying programming from 931027036.

Oct 28 1993 05:15:10:760PM 931028001 Joseph Snipes Shot 1
Reduced prefill to 1.1 x 10**-5 Torr. Plasma! After the He backfill to
remove the Thomson Scattering viewing dump, quite an accomplishment.

Oct 28 1993 05:17:34:860PM 931028002 Joseph Snipes Shot 2
Added H puff at the last minute as I realized that I had the B side upper
valve off. RF run needed H minority. Plasma!

Oct 28 1993 05:18:08:380PM 931028003 Joseph Snipes Shot 3
Raised prefill back to 1.3 x 10**-5 Torr.
Fizzle!

Oct 28 1993 05:25:52:930PM 931028004 Joseph Snipes Shot 4
Lowered prefill back to 1.1 x 10**-5 Torr.
Fizzle!

Oct 28 1993 05:40:59:500PM 931028005 Joseph Snipes Shot 5
Raised prefill to 1.4 x 10**-5 Torr. Also put in a Wolfe fix for a
discrepancy in the feedback on OH1 by doubling the PID gain before breakdown
and compensating EF4 by raising it slightly from -1050 to -1060 A.
Fizzle! Too much RF at breakdown 100 kW! on both shots 4 and 5.

Oct 28 1993 05:47:23:580PM 931028005 Joseph Snipes Shot 5
Raised prefill to 1.4 x 10**-5 Torr. Also put in a Wolfe fix for a
discrepancy in the feedback on OH1 by doubling the PID gain before breakdown
and compensating EF4 by raising it slightly from -1050 to -1060 A.
Fizzle! Too much RF at breakdown 100 kW! on both shots 4 and 5.

Oct 28 1993 06:03:16:670PM 931028006 Joseph Snipes Shot 6
Lowered prefill to 1.1 x 10**-5 Torr. Reduced Br offset in the A matrix from
-2.5 to -2.0.
Fizzle!

Oct 28 1993 06:18:56:370PM 931028007 Joseph Snipes Shot 7
Lowered initial gas programming from 80 V to 60 V on the first time point.
Raised prefill to 1.3 x 10**-5 Torr.
Plasma! Lots of runaways.

Oct 28 1993 06:30:16:580PM 931028008 Joseph Snipes Shot 8
Raised initial gas programming from 60 V to 70 V on the first time point.
Fizzle.

Oct 28 1993 07:01:00:950PM 931028009 Joseph Snipes Shot 9
Raised prefill to 1.4 x 10**-5 torr.
fizzle!

Oct 28 1993 07:16:08:660PM 931028010 Joseph Snipes Shot 10
Copied gas programming from shot 931028019.
Good shot!

Oct 28 1993 07:22:24:010PM 931028011 Joseph Snipes Shot 11
Increased gas programming to obtain higher density and added 5 gas puffs
each 30 ms wide and starting every 90 ms from 300 ms.
Fizzle!

Oct 28 1993 07:43:06:240PM 931028012 Joseph Snipes Shot 12
No change.
Fizzle!

Oct 28 1993 07:52:56:260PM 931028013 Joseph Snipes Shot 13
Increased EF4 current before breakdown from -1060 to -1090 A.
Lowered prefill to 1.3 x 10**-5 torr.
Fizzle.

Oct 28 1993 08:18:05:160PM 931028014 Joseph Snipes Shot 14
Raise prefill to 1.5 x 10**-5. It seems that the F port guage reads somewhat
lower than the requested prefill pressure just before breakdown. Also, it
seemed that the change in EF4 was a bit too much, so I reduced EF4 current
from -1090 to -1070 before breakdown.

Oct 28 1993 08:24:45:070PM 931028015 Joseph Snipes Shot 15
Lower prefill to 1.3 x 10**-5.
I reduced EF4 current from -1090 to -1060 before breakdown. It seems that
the change was not made on shot 14 in EF4 though I was sure I loaded the
change into model.
Plasma!

Oct 28 1993 08:51:57:330PM 931028016 Joseph Snipes Shot 16
Good plasma! Li pellet at 0.8 s. Zeff of 0.66 before the density limit
disruption.

Oct 28 1993 09:01:59:090PM 931028017 Joseph Snipes Shot 17
Disrupted at 0.26 s.

Oct 28 1993 09:11:44:910PM 931028018 Joseph Snipes Shot 18
Disrupted at 0.27 s.

Oct 28 1993 09:26:29:150PM 931028018 Joseph Snipes Run Summary 931028

The run was intended to study density limits and particle diffusion. However,
with the machine in its present condition after the opening of the Thomson
Scattering flange, plasmas were not running particularly well. The run
started late in the afternoon about 4:00 pm and ended after 9:00 pm. We
succeeded in getting plasmas immediately for two shots, then ran into
difficulties with the current rise. We succeeded in getting one long high
density shot that disrupted just before the intended injection of a Li pellet
(shot 16). There were 18 shots with 8 plasmas and according to my accounting
10 fizzles, though Ian's summary program says 7 duds and 3 fizzles.

Engineering Operator Comments

Shot Time Type Status Comment

1 03:52:08:760PM Plasma Bad tf inverted at .24 sec instead of .8 sec

2 04:50:10:660PM Plasma Bad tf inverted prematurely

3 05:10:42:230PM Plasma Ok fizzle

4 05:22:42:840PM Plasma Ok fizzle

5 05:37:27:460PM Plasma Ok fizzle

6 05:57:57:340PM Plasma Ok fizzle

7 06:12:08:560PM Plasma Ok 690 ka

8 06:28:02:530PM Plasma Ok fizzle

9 06:44:57:550PM Plasma Ok fizzle

10 07:03:06:540PM Test Ok 940 ka

11 07:19:05:740PM Plasma Ok fizzle

12 07:33:36:260PM Plasma Ok fizzle

13 07:48:41:940PM Plasma Ok fizzle

14 08:06:47:970PM Plasma Ok fizzle

15 08:21:43:110PM Plasma Ok 320 ka

16 08:36:58:810PM Plasma Ok 850 ka

17 08:52:45:750PM Plasma Ok 425 ka

18 09:06:51:650PM Plasma Ok No faults.

Session Leader Comments
Oct 28 1993 04:09:19:100PM	931028001	Tom Luke	Late start on today's run. Vacuum target for Thomson scattering got stuck in the machine overnight . Required a He backfill and bringing the vessel up to air to free it. RF run moved to Friday and Density run started at 4:00. We will attempt to to a scan in density and current perfoming gas modulation for MP 030.
Oct 28 1993 04:22:12:470PM	931028001	Tom Luke	Late start on today's run. Vacuum target for Thomson scattering got stuck in the machine overnight . Required a He backfill and bringing the vessel up to air to free it. RF run moved to Friday and Density run started at 4:00. We will attempt to to a scan in density and current perfoming gas modulation for MP 030.
Oct 28 1993 04:39:02:710PM	931028001	Tom Luke	Repeat of last shot on 10/27. Li pellet fired at 500 ms. Amazing but shot went. Density was very low and the plasma disrupted at 500 ms when the pellet went in.
Oct 28 1993 05:08:23:820PM	931028002	Tom Luke	Put more gas in with 3 puffs at 300,390,480 ms. Puffs are 30 ms and 40 V. Shot ended at 500 ms with a TF fault.
Oct 28 1993 05:14:43:180PM	931028002	Tom Luke	Raised prefill.. 5 puffs at 300,390,480,570,660. 20 V and 30 ms long. fizzle
Oct 28 1993 05:31:33:880PM	931028004	Tom Luke	repeat of shot 3. fizzle.
Oct 28 1993 05:40:47:460PM	931028004	Tom Luke	repeat of shot 3. fizzle. Looks like there is too much RF before there is significant plasma current.
Oct 28 1993 06:09:42:420PM	931028006	Tom Luke	repeat of shot 3. RF lowered to 20 KW.fizzle.
Oct 28 1993 06:21:34:760PM	931028007	Tom Luke	Got plasma. Runaway shot. Disrupted at 400 ms. Density went to 1.0e20 at disruption.
Oct 28 1993 06:39:00:360PM	931028008	Tom Luke	fizzle.GAS?
Oct 28 1993 07:04:36:170PM	931028009	Tom Luke	fizzle.
Oct 28 1993 07:12:39:200PM	931028010	Tom Luke	Changed gas fuelling to 931025018. Shot went. lasted to 900 ms.Lowq density 4.0e19.
Oct 28 1993 07:20:14:610PM	931028010	Tom Luke	Changed gas fuelling to 931025018. Shot went. lasted to 900 ms.Lowq density 4.0e19.
Oct 28 1993 07:22:27:260PM	931028011	Tom Luke	Fizzle.
Oct 28 1993 07:58:44:780PM	931028013	Tom Luke	fizzle.
Oct 28 1993 08:35:15:630PM	931028015	Tom Luke	Very short plasma. 3.0e19 nl.
Oct 28 1993 08:52:21:500PM	931028016	Tom Luke	Disrupts at 800 ms. Very high plasma 2.0e20. Plasma flattens out before disruption. Possible density limit?
Oct 28 1993 09:03:20:190PM	931028017	Tom Luke	Disrupted at 300 ms. 5.0e19 density.
Oct 28 1993 09:11:47:360PM	931028018	Tom Luke	Disrupted at 300 ms. Very similar to shot 17.

Physics Operator Comments
Oct 28 1993 05:12:22:690PM	931028001	Joseph Snipes	Luke's run for density limits, pellets, and maybe H modes. Start by copying programming from 931027036.
Oct 28 1993 05:15:10:760PM	931028001	Joseph Snipes	Shot 1 Reduced prefill to 1.1 x 10**-5 Torr. Plasma! After the He backfill to remove the Thomson Scattering viewing dump, quite an accomplishment.
Oct 28 1993 05:17:34:860PM	931028002	Joseph Snipes	Shot 2 Added H puff at the last minute as I realized that I had the B side upper valve off. RF run needed H minority. Plasma!
Oct 28 1993 05:18:08:380PM	931028003	Joseph Snipes	Shot 3 Raised prefill back to 1.3 x 10**-5 Torr. Fizzle!
Oct 28 1993 05:25:52:930PM	931028004	Joseph Snipes	Shot 4 Lowered prefill back to 1.1 x 10**-5 Torr. Fizzle!
Oct 28 1993 05:40:59:500PM	931028005	Joseph Snipes	Shot 5 Raised prefill to 1.4 x 10**-5 Torr. Also put in a Wolfe fix for a discrepancy in the feedback on OH1 by doubling the PID gain before breakdown and compensating EF4 by raising it slightly from -1050 to -1060 A. Fizzle! Too much RF at breakdown 100 kW! on both shots 4 and 5.
Oct 28 1993 05:47:23:580PM	931028005	Joseph Snipes	Shot 5 Raised prefill to 1.4 x 10**-5 Torr. Also put in a Wolfe fix for a discrepancy in the feedback on OH1 by doubling the PID gain before breakdown and compensating EF4 by raising it slightly from -1050 to -1060 A. Fizzle! Too much RF at breakdown 100 kW! on both shots 4 and 5.
Oct 28 1993 06:03:16:670PM	931028006	Joseph Snipes	Shot 6 Lowered prefill to 1.1 x 10**-5 Torr. Reduced Br offset in the A matrix from -2.5 to -2.0. Fizzle!
Oct 28 1993 06:18:56:370PM	931028007	Joseph Snipes	Shot 7 Lowered initial gas programming from 80 V to 60 V on the first time point. Raised prefill to 1.3 x 10**-5 Torr. Plasma! Lots of runaways.
Oct 28 1993 06:30:16:580PM	931028008	Joseph Snipes	Shot 8 Raised initial gas programming from 60 V to 70 V on the first time point. Fizzle.
Oct 28 1993 07:01:00:950PM	931028009	Joseph Snipes	Shot 9 Raised prefill to 1.4 x 10**-5 torr. fizzle!
Oct 28 1993 07:16:08:660PM	931028010	Joseph Snipes	Shot 10 Copied gas programming from shot 931028019. Good shot!
Oct 28 1993 07:22:24:010PM	931028011	Joseph Snipes	Shot 11 Increased gas programming to obtain higher density and added 5 gas puffs each 30 ms wide and starting every 90 ms from 300 ms. Fizzle!
Oct 28 1993 07:43:06:240PM	931028012	Joseph Snipes	Shot 12 No change. Fizzle!
Oct 28 1993 07:52:56:260PM	931028013	Joseph Snipes	Shot 13 Increased EF4 current before breakdown from -1060 to -1090 A. Lowered prefill to 1.3 x 10**-5 torr. Fizzle.
Oct 28 1993 08:18:05:160PM	931028014	Joseph Snipes	Shot 14 Raise prefill to 1.5 x 10**-5. It seems that the F port guage reads somewhat lower than the requested prefill pressure just before breakdown. Also, it seemed that the change in EF4 was a bit too much, so I reduced EF4 current from -1090 to -1070 before breakdown.
Oct 28 1993 08:24:45:070PM	931028015	Joseph Snipes	Shot 15 Lower prefill to 1.3 x 10**-5. I reduced EF4 current from -1090 to -1060 before breakdown. It seems that the change was not made on shot 14 in EF4 though I was sure I loaded the change into model. Plasma!
Oct 28 1993 08:51:57:330PM	931028016	Joseph Snipes	Shot 16 Good plasma! Li pellet at 0.8 s. Zeff of 0.66 before the density limit disruption.
Oct 28 1993 09:01:59:090PM	931028017	Joseph Snipes	Shot 17 Disrupted at 0.26 s.
Oct 28 1993 09:11:44:910PM	931028018	Joseph Snipes	Shot 18 Disrupted at 0.27 s.
Oct 28 1993 09:26:29:150PM	931028018	Joseph Snipes	Run Summary 931028 The run was intended to study density limits and particle diffusion. However, with the machine in its present condition after the opening of the Thomson Scattering flange, plasmas were not running particularly well. The run started late in the afternoon about 4:00 pm and ended after 9:00 pm. We succeeded in getting plasmas immediately for two shots, then ran into difficulties with the current rise. We succeeded in getting one long high density shot that disrupted just before the intended injection of a Li pellet (shot 16). There were 18 shots with 8 plasmas and according to my accounting 10 fizzles, though Ian's summary program says 7 duds and 3 fizzles.

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	03:52:08:760PM	Plasma	Bad	tf inverted at .24 sec instead of .8 sec
2	04:50:10:660PM	Plasma	Bad	tf inverted prematurely
3	05:10:42:230PM	Plasma	Ok	fizzle
4	05:22:42:840PM	Plasma	Ok	fizzle
5	05:37:27:460PM	Plasma	Ok	fizzle
6	05:57:57:340PM	Plasma	Ok	fizzle
7	06:12:08:560PM	Plasma	Ok	690 ka
8	06:28:02:530PM	Plasma	Ok	fizzle
9	06:44:57:550PM	Plasma	Ok	fizzle
10	07:03:06:540PM	Test	Ok	940 ka
11	07:19:05:740PM	Plasma	Ok	fizzle
12	07:33:36:260PM	Plasma	Ok	fizzle
13	07:48:41:940PM	Plasma	Ok	fizzle
14	08:06:47:970PM	Plasma	Ok	fizzle
15	08:21:43:110PM	Plasma	Ok	320 ka
16	08:36:58:810PM	Plasma	Ok	850 ka
17	08:52:45:750PM	Plasma	Ok	425 ka
18	09:06:51:650PM	Plasma	Ok	No faults.