Alcator C-Mod Run 930521 Information

Miniproposals

Miniproposal:

Date Filed:

Title:

First Author:

Session Leader: Martin Greenwald (shots 1-19)

Operators
Session leader(s):	Martin Greenwald
Physics operator(s):	Unknown
Engineering operator(s):	Unknown

Engineering Operator Run Comment
Work on control of plasma current and position

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Physics Operator Summaries

Session Leader Comments

May 21 1993 08:59:01:600AM Martin Greenwald Plan:

Optimize radial feedback, try to control the plasma current rise and
begin to learn how to terminate the pulse cleanly. Feedback control
plasma current using OH1 alone to start with, evolving perhaps to adding
a bit of other coils. We're currently programming the radial position as an
offset from .665 cm - it's possible that we lose the plasma radially
outward shortly after we switch the gain in. We might try steps on
the PID gain and program the plasma to be inboard by a cm or two.

Party is planned for 4:00 PM

May 21 1993 09:12:38:960AM Martin Greenwald Power Supply settings:
Supply Start Close Open Crowbar Invert
EF1L -1.6 -1.55 0.0 .05 .25
EF1U -1.6 -1.55 0.0 .05 .25
OH1 -1.45 -1.40 0.0 .04 .25
OH2L -1.6 -1.55 0.0 .05 .25
OH2U -1.6 -1.55 0.0 .05 .25
EF2L -1.0 .25
EF2U -1.0 .25
EF3 -0.1 .25
EF4 -1.6 .25
EFC -0.1 .30
TF -1.65 .10
Bus Diagnositcs integrator start: -2 sec
end +6 sec
Dig time = -1.7

May 21 1993 09:15:37:280AM 930521001 Martin Greenwald No Plasma - EF4 problem

May 21 1993 09:37:59:470AM 930521002 Martin Greenwald Intention: Repeat with EF4 fixed, add OH2's into controller for Ip (proportional
gain entered at 1/4 value of OH1) Ip waveform drawn flat at 135kA.

Result: Breakdown, 20 kA, problem with OH2 L

May 21 1993 09:54:24:470AM 930521003 Martin Greenwald Intention: 5 steps put into gain on vertical position (to reduce stress on OH2 supply)

Result: Current reached 200 kA, then disrupted at about 80 msec.

May 21 1993 10:04:22:110AM 930521004 Martin Greenwald Intention: Gas dropped by 20%, gain on Ip is now 5 steps (36 - 50 msec)
[steps on z feedback 26-40 msec]

Result: Breakdown - but minimal current

May 21 1993 10:16:23:820AM 930521005 Martin Greenwald Intention: Repeat shot 4

Result: Breakdown - but minimal current, OH2 commutation failure. + single
phasing problem recurs.

May 21 1993 10:38:57:370AM 930521006 Martin Greenwald Intention: OH2 inversion endstop changed to fix single phasing. Note commutation
failure was in OH1 on the last shot not OH2.
Otherwise repeat shot.

Result: Plasma is back, 210 kA, disrupts at 120 msec.

May 21 1993 10:59:50:620AM 930521007 Martin Greenwald Intention: Increase gain (at same times) by factor of 2.
Rcur dropped from 66.5 to 60 cm.
Gas programming altered. drop peak and increase width -
result is square wave from 20 - 150 msec.

Result: Current to 235 kA, disrupts at 75 msec, moves down and in.

May 21 1993 11:22:18:080AM 930521008 Martin Greenwald Intention: Drop gain on Z position by factor of 2 to .5

Result: Plasma reaches 270 kA but goes bad by 60 msec, disrupts at 80.

May 21 1993 11:50:11:200AM 930521009 Martin Greenwald Intention: EF3 in Ip controller at .75 (in proportion to OH1)

Result: Similar to shot 9, interaction with wall starts at about 45 msec

May 21 1993 12:16:50:570PM 930521010 Martin Greenwald Intention: Ip current control is causing plasma to move in. change predictor:
factor on ip_z and ip_rcur by factor of .25, approx.
The wavgen was overflowing.

Result: Similar shot, Ip to 270 kA

May 21 1993 12:53:09:040PM 930521012 Martin Greenwald Intention: Plasma Rcur drawn back out to 66.
Ip drawn to 200 kA\
gain on Ip controller OH2 from -1.25e-4 to -.75e-4
no gain Ip controller for EF3
Gas turned up about 30%

Result: Similar to last shot

May 21 1993 01:06:02:920PM 930521013 Martin Greenwald Intention: Ip draw to 220 kA
Ip controller EF 3 = +1.e-4, OH1 = -8.e-4

Result: Breakdown, no current

May 21 1993 01:32:10:510PM 930521014 Martin Greenwald Intention: Repeat

Result: Ip = 275 kA

May 21 1993 01:37:02:390PM 930521015 Martin Greenwald Intention: Changed Ip controller EF3 = +3.e-4

Result: Ip = 275 kA

May 21 1993 01:41:06:540PM 930521015 Martin Greenwald Intention: Changed Ip controller EF3 = +3.e-4

Result: Ip = 275 kA

May 21 1993 01:50:52:300PM 930521016 Martin Greenwald Intention: Changed Ip controller OH1 = -1.e-3; EF3 = +3.e4

Result: Ip = 265 kA, similar to previous shots

May 21 1993 01:58:04:620PM 930521016 Martin Greenwald Intention: Changed Ip controller EF3 = -3.e4

Result: Ip = 265 kA, similar to previous shots

May 21 1993 02:07:13:080PM 930521017 Martin Greenwald Intention: Changed Ip controller OH1 - 1.24 e-3, EF3 = -1.e-3

Result: Similar to previous shots

May 21 1993 02:31:40:270PM 930521018 Martin Greenwald Intention: Draw 250 kA
in Ip controller EF3 to -1.5e-3

Result: Similar to previous shots - single phasing problem on TF

May 21 1993 03:17:39:680PM 930521019 Martin Greenwald Intention: Engineering Test for TF - end of physics run

Physics Operator Comments

Engineering Operator Comments

Shot Time Type Status Comment

1 09:07:10:180AM Plasma Bad no ef4 - turned off on control pad - operator error

2 09:31:16:190AM Plasma Ok oh2l com fail at .050

3 09:45:52:050AM Plasma Ok 200ka disrupt at .080

4 09:59:59:710AM Plasma Ok low Ip

5 10:10:22:240AM Plasma Ok 30 ka Ip - OH2L single phased at 050, oh1 com fail at 076

6 10:29:11:880AM Plasma Ok inversion end stop set to 90 on oh2l prior to shot 6

7 10:45:17:180AM Plasma Ok oh2l single phased 050 240 ka ip

8 11:11:12:780AM Plasma Ok ip 270 - oh2l single phased at 080

9 11:33:25:310AM Plasma Ok 250 ka

10 12:04:04:510PM Plasma Ok OH2 L comm fail.

11 12:26:13:170PM Plasma Ok 270ka plasma

12 12:42:03:740PM Plasma Ok 270k Plasma shot.

13 12:57:29:930PM Plasma Ok 30Kamp plasma

14 01:06:22:200PM Plasma Ok 270k Plasma shot.

15 01:23:34:530PM Plasma Ok 270 Kamp Plasma shot

16 01:45:39:630PM Plasma Ok 260Kamp Plasma shot.

17 01:58:46:640PM Plasma Ok 260 ka

18 02:18:05:720PM Plasma Ok 270 ka single phased tf at .2 == suspect loss of gates

19 03:11:55:330PM Plasma Ok 20ka tf test problem - com fail - check tf4 - end of run

Session Leader Comments
May 21 1993 08:59:01:600AM		Martin Greenwald	Plan: Optimize radial feedback, try to control the plasma current rise and begin to learn how to terminate the pulse cleanly. Feedback control plasma current using OH1 alone to start with, evolving perhaps to adding a bit of other coils. We're currently programming the radial position as an offset from .665 cm - it's possible that we lose the plasma radially outward shortly after we switch the gain in. We might try steps on the PID gain and program the plasma to be inboard by a cm or two. Party is planned for 4:00 PM
May 21 1993 09:12:38:960AM		Martin Greenwald	Power Supply settings: Supply Start Close Open Crowbar Invert EF1L -1.6 -1.55 0.0 .05 .25 EF1U -1.6 -1.55 0.0 .05 .25 OH1 -1.45 -1.40 0.0 .04 .25 OH2L -1.6 -1.55 0.0 .05 .25 OH2U -1.6 -1.55 0.0 .05 .25 EF2L -1.0 .25 EF2U -1.0 .25 EF3 -0.1 .25 EF4 -1.6 .25 EFC -0.1 .30 TF -1.65 .10 Bus Diagnositcs integrator start: -2 sec end +6 sec Dig time = -1.7
May 21 1993 09:15:37:280AM	930521001	Martin Greenwald	No Plasma - EF4 problem
May 21 1993 09:37:59:470AM	930521002	Martin Greenwald	Intention: Repeat with EF4 fixed, add OH2's into controller for Ip (proportional gain entered at 1/4 value of OH1) Ip waveform drawn flat at 135kA. Result: Breakdown, 20 kA, problem with OH2 L
May 21 1993 09:54:24:470AM	930521003	Martin Greenwald	Intention: 5 steps put into gain on vertical position (to reduce stress on OH2 supply) Result: Current reached 200 kA, then disrupted at about 80 msec.
May 21 1993 10:04:22:110AM	930521004	Martin Greenwald	Intention: Gas dropped by 20%, gain on Ip is now 5 steps (36 - 50 msec) [steps on z feedback 26-40 msec] Result: Breakdown - but minimal current
May 21 1993 10:16:23:820AM	930521005	Martin Greenwald	Intention: Repeat shot 4 Result: Breakdown - but minimal current, OH2 commutation failure. + single phasing problem recurs.
May 21 1993 10:38:57:370AM	930521006	Martin Greenwald	Intention: OH2 inversion endstop changed to fix single phasing. Note commutation failure was in OH1 on the last shot not OH2. Otherwise repeat shot. Result: Plasma is back, 210 kA, disrupts at 120 msec.
May 21 1993 10:59:50:620AM	930521007	Martin Greenwald	Intention: Increase gain (at same times) by factor of 2. Rcur dropped from 66.5 to 60 cm. Gas programming altered. drop peak and increase width - result is square wave from 20 - 150 msec. Result: Current to 235 kA, disrupts at 75 msec, moves down and in.
May 21 1993 11:22:18:080AM	930521008	Martin Greenwald	Intention: Drop gain on Z position by factor of 2 to .5 Result: Plasma reaches 270 kA but goes bad by 60 msec, disrupts at 80.
May 21 1993 11:50:11:200AM	930521009	Martin Greenwald	Intention: EF3 in Ip controller at .75 (in proportion to OH1) Result: Similar to shot 9, interaction with wall starts at about 45 msec
May 21 1993 12:16:50:570PM	930521010	Martin Greenwald	Intention: Ip current control is causing plasma to move in. change predictor: factor on ip_z and ip_rcur by factor of .25, approx. The wavgen was overflowing. Result: Similar shot, Ip to 270 kA
May 21 1993 12:53:09:040PM	930521012	Martin Greenwald	Intention: Plasma Rcur drawn back out to 66. Ip drawn to 200 kA\ gain on Ip controller OH2 from -1.25e-4 to -.75e-4 no gain Ip controller for EF3 Gas turned up about 30% Result: Similar to last shot
May 21 1993 01:06:02:920PM	930521013	Martin Greenwald	Intention: Ip draw to 220 kA Ip controller EF 3 = +1.e-4, OH1 = -8.e-4 Result: Breakdown, no current
May 21 1993 01:32:10:510PM	930521014	Martin Greenwald	Intention: Repeat Result: Ip = 275 kA
May 21 1993 01:37:02:390PM	930521015	Martin Greenwald	Intention: Changed Ip controller EF3 = +3.e-4 Result: Ip = 275 kA
May 21 1993 01:41:06:540PM	930521015	Martin Greenwald	Intention: Changed Ip controller EF3 = +3.e-4 Result: Ip = 275 kA
May 21 1993 01:50:52:300PM	930521016	Martin Greenwald	Intention: Changed Ip controller OH1 = -1.e-3; EF3 = +3.e4 Result: Ip = 265 kA, similar to previous shots
May 21 1993 01:58:04:620PM	930521016	Martin Greenwald	Intention: Changed Ip controller EF3 = -3.e4 Result: Ip = 265 kA, similar to previous shots
May 21 1993 02:07:13:080PM	930521017	Martin Greenwald	Intention: Changed Ip controller OH1 - 1.24 e-3, EF3 = -1.e-3 Result: Similar to previous shots
May 21 1993 02:31:40:270PM	930521018	Martin Greenwald	Intention: Draw 250 kA in Ip controller EF3 to -1.5e-3 Result: Similar to previous shots - single phasing problem on TF
May 21 1993 03:17:39:680PM	930521019	Martin Greenwald	Intention: Engineering Test for TF - end of physics run

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	09:07:10:180AM	Plasma	Bad	no ef4 - turned off on control pad - operator error
2	09:31:16:190AM	Plasma	Ok	oh2l com fail at .050
3	09:45:52:050AM	Plasma	Ok	200ka disrupt at .080
4	09:59:59:710AM	Plasma	Ok	low Ip
5	10:10:22:240AM	Plasma	Ok	30 ka Ip - OH2L single phased at 050, oh1 com fail at 076
6	10:29:11:880AM	Plasma	Ok	inversion end stop set to 90 on oh2l prior to shot 6
7	10:45:17:180AM	Plasma	Ok	oh2l single phased 050 240 ka ip
8	11:11:12:780AM	Plasma	Ok	ip 270 - oh2l single phased at 080
9	11:33:25:310AM	Plasma	Ok	250 ka
10	12:04:04:510PM	Plasma	Ok	OH2 L comm fail.
11	12:26:13:170PM	Plasma	Ok	270ka plasma
12	12:42:03:740PM	Plasma	Ok	270k Plasma shot.
13	12:57:29:930PM	Plasma	Ok	30Kamp plasma
14	01:06:22:200PM	Plasma	Ok	270k Plasma shot.
15	01:23:34:530PM	Plasma	Ok	270 Kamp Plasma shot
16	01:45:39:630PM	Plasma	Ok	260Kamp Plasma shot.
17	01:58:46:640PM	Plasma	Ok	260 ka
18	02:18:05:720PM	Plasma	Ok	270 ka single phased tf at .2 == suspect loss of gates
19	03:11:55:330PM	Plasma	Ok	20ka tf test problem - com fail - check tf4 - end of run