Alcator C-Mod Run 931026 Information

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Miniproposals
Miniproposal:
Date Filed:
Title:
First Author:
Session Leader:Ian Hutchinson (shots 1-17)
Session Leader:John Rice (shots 18-39)

Operators
Session leader(s):Ian Hutchinson,John Rice
Physics operator(s):Steve Wolfe
Engineering operator(s):Steve Fairfax,Vinny Bertolino

Engineering Operator Run Comment
High n Argon, Chopper/EFC St.; Hi kappa

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Physics Operator Summaries
Entered: Jul 7 2004 04:36:50:583PM
Author: To Be Determined
Physics Operator Summary for 931026
Miniproposals: 037 Chopper/EFC study
007 High n-state Ar

Session Leaders:Hutchinson (part 1)
Rice (Part 2)
Physics Op.: Wolfe
Engineering Ops: Fairfax, Bertolino

This run was divided into two parts. The first half was an attempt to increase
the elongation and find the maximum stablizable kappa. The second half was a
study of high n-state lines in He-like and H-like Argon. Neither objective was
successfully met, although some good spectroscopic data was obtained in the
second half of the run. The run was plagued with disruptions and fizzles, most
of the disruptions being self-inflicted.

We started the run by loading 931025027, with a reduction in IP PID gains
from 10. to 1. around the time of OH1 Crossover. Shot 1 fizzled, and it looked
like the EF1L wasn't getting to its current program. Gains were increased on
the IC_EF1's and the second shot ran ok. Programming was changed to ramp the
RCUR in to .66 while leaving CLEARIN alone, to squeeze the plasma. This
technique, with some changes to IC_EF2U and IC_EF4, as well as V_OH2U&L
programming, succeeded in giving marginal increases in elongation to 1.63 or
so. Several shots disrupted at the programmed "glitch" in the ZCUR feedback.
Attempts to shorten the crossover duration of OH1 by demanding higher voltage
(up to 1000V) succeeded in shortening the flat spot, but ended up being even
worse for the plasma. More work needs to be done on this problem.
Unfortunately 14-17 were fizzles, preventing us from getting data on higher
elongations by increasing the RCUR ramp to go to 0.65 and eliminating the
glitch.

For the Ar half of the run, beginning on shot 18, we took out the RCUR
ramp-in, and tried to reduce the BZ' at startup by increasing the OH1 current;
this was accomplished by raising the IC_OH1 P gain from 1 to 2, as the target
current was not being reached (shot 18). After we adjusted the EF4 current (shot
19) programming by 30A to compensate for the change in Bz (we got about 250A more
OH1 current), the fizzles became less frequent. RF-assist was tried on a few
shots, and actually seemed to blow away #21 when too much power (100kW) was
put in during startup; shot#22 had bad runaways from the beginning, and the
RF was turned off for all subsequent shots. There was only one fizzle between
shots 23 to 39. The Ar was increased to give adequate signal on the HIREX for
the excited state lines. Shot #30 seemed to be a good level, and we tried to
keep the puff at that level; unfortunately subsequient shots disrupted around
0.5 sec. Some of these had apparent Mo injections leading to the disruption,
but the others apparently died of excess Ar. The last shot, #39, had less Ar
puff and survived to nearly 1 sec.

Problems:
---------
we had a relatively high mass 28 level at the beginning of the day, and this
increased during the first half of the run. The pump on the J-port seal wasm
found to have tripped out, and was finally plugged into a different outlet,
without a GFI breaker. However, later in the run, around #34 or 35, the 28
peak started ratcheting up again, along with mass 31,32,44. This appears to be
a possible air leak. It is possible that vacuum contamination was responsible
for some of the fizzle problems.

The VAXStations on the MHD and Electron desks crashed twice, causing gaps in
the analysis output (density, FFIT, EFIT, RECON_VAC, etc.) fopr shots in the
mid-20s.

At least one meteor was observed on shot 35. It seemed to come from the upper
inside wall after the disruption that terminated the shot. Irby reported after
the run that some new pieces were on his lower window, blocking parts of the
TCI return beam. These were not observed on his TV view.

An ACK FAILURE aborted shot #32 on the transition to PULSE.

Comments/Recommendations
------------------------
Increasing the gain on OH1 to get closer to the target current (target=16600,
I got 16300) seems to be a GOOD THING; you have to increase the EF4 current to
null out Bz. Shot/fizzle ratio from 23:39 was 16/1. Too much RF during startup
is a BAD THING (Fizzle on 21 at 100kW, runaways on 22 at 25kW). The null could
still stand some improvement.


Scorecard:
-----------
Fizzles 10
Duds 2
Non-shots 1
Plasmas 26
--------- --
Total 39

Session Leader Comments

Physics Operator Comments
Oct 26 1993 08:21:22:800AMSteve WolfeLoad shot 931025027, a nice 800 kA shot from yesterday.
Turn off Pulse Gas 2 programming (I don't know why it was on anyway).
Reduce P gain on IP from 10 to 1.0 between .175:.250 to reduce problems
at OH1 crossover.
Change turnon of CLEARIN PID from 0.2 to 0.3

Oct 26 1993 09:04:34:060AM931026001Steve WolfeLoad shot 931025027, a nice 800 kA shot from yesterday.
Turn off Pulse Gas 2 programming (I don't know why it was on anyway).
Reduce P gain on IP from 10 to 1.0 between .175:.250 to reduce problems
at OH1 crossover.
Change turnon of CLEARIN PID from 0.2 to 0.3

Result:
Fizzle

Oct 26 1993 09:22:45:540AM931026002Steve WolfeShot 2:
Raise P gain on IC_EF1L and IC_EF1U from 2.5 to 4.0 before commutation

Result:
Plasma. OH2's reverse sign at .2 sec - I apparently hadn't gotten
the change on CLEARIN.

Oct 26 1993 09:33:40:000AM931026003Steve WolfeShot 3:
Set CLEARIN PID to come on at 0.3
Move plasma in to .66 at .35 sec

Result: Dud! Fields look as ok as they have been.

Oct 26 1993 09:49:28:460AM931026003Steve WolfeShot 4:
Raise fill to 1.6e-5

Result: Plasma disrupts at 330

Oct 26 1993 09:49:52:650AM931026004Steve WolfeShot 4:
Raise fill to 1.6e-5

Result: Plasma disrupts at 330

Oct 26 1993 09:49:56:640AM931026004Steve WolfeShot 4:
Raise fill to 1.6e-5

Result: Plasma disrupts at 330

Oct 26 1993 07:46:45:940PM931026005Steve WolfeShot 5:
Notch in ZCUR gains at 700msec
Change RCUR at .35 to 0.67, leave end of shot at .66


Result: Plasma went all the way through
Somewhat higher elongation

Oct 26 1993 10:21:44:500AM931026006Steve WolfeShot 6:
Lower ZCUR2 P-gain from 1.0 to 0.5
Raise ZCUR from -3cm to -2cm

Result: Ran till the glitch at 700msec

Oct 26 1993 10:41:32:130AM931026007Steve WolfeShot 7:
Raise voltage demand on OH1 from 150 to 300 between 185 and 250
(crosover)
Shorten the glitch to 5msec
Raise IC_ef2U from -3000a to -4000a -
Change SCALE_BIT from 3.e-3 to 2.e-3

Result: Fizzle

Oct 26 1993 11:02:09:140AM931026008Steve WolfeShot 8:
As for shot 7:
Raise voltage demand on OH1 from 150 to 300 between 185 and 250
(crosover)
Shorten the glitch to 5msec
Raise IC_ef2U from -3000a to -4000a -
Change SCALE_BIT from 3.e-3 to 2.e-3
No other changes

Result: Disrupted at 0.5sed

Oct 26 1993 11:16:16:550AM931026009Steve WolfeShot 9:
Raise ZCUR2 Integral gain from 2. to 3.
Raise Voltage on OH1 from 300 to 500 during crosover


Result: Same thing as 8 - disrupts at 0.4sec

Oct 26 1993 11:29:25:660AM931026010Steve WolfeShot 10:
Raise voltage spike on OH1 during crossover to 1000V.
shorten it to 220.
LOwer ZCUR2 P gain from 0.5 to 0.4

Result: Fizzle

Oct 26 1993 11:48:14:530AM931026011Steve WolfeShot 11:
As for shot 10:
Raise voltage spike on OH1 during crossover to 1000V.
shorten it to 220.
LOwer ZCUR2 P gain from 0.5 to 0.4
Also:
Raise IC_EF4 current freom -1000a to -2000a
Eliminate ramp in of RXL from 0.4 sec on


Result: Short- disrupts at 245msec

Oct 26 1993 12:05:40:560PM931026012Steve WolfeShot 12:
Shorten 1000v on OH1 to end at 192
Change relative OH2U to OH2L voltage at 390 by 10V

Result: fizzle

Oct 26 1993 12:23:35:750PM931026012Steve WolfeShot 13:
Change TF invert to 0.8 to save TF cooling time.
Lower OH2L voltage from 15V to 10V at 5msec to try to fix Br blip.

Result: Plasma disrupts around 710ms

Oct 26 1993 12:37:38:980PM931026013Steve WolfeShot 14:
Change OH2L from 10 to 15
and OH2U from 5 to 0 at 390msec
Move RXL out to 0.01
Remove glitch in ZCUR gains and reduce PZCUR 2 from 0.4 to 0.3

Result: Fizzle

Oct 26 1993 12:55:30:480PM931026015Steve WolfeShot 15:
As for 14:
Change OH2L from 10 to 15
and OH2U from 5 to 0 at 390msec
Move RXL out to 0.01
Remove glitch in ZCUR gains and reduce PZCUR 2 from 0.4 to 0.3
Also:
Ramp RCUR in to .65
Result: Another fizzle!

Oct 26 1993 01:13:25:680PM931026016Steve WolfeShot 15:
As for 14:
Change OH2L from 10 to 15
and OH2U from 5 to 0 at 390msec
Move RXL out to 0.01
Remove glitch in ZCUR gains and reduce PZCUR 2 from 0.4 to 0.3
Also:
Ramp RCUR in to .65
Pump on J-port seal has been off for some time. Restarted before 16
Drop Fill to 1.5e-5
Result: Another fizzle!!!

Oct 26 1993 01:31:37:640PM931026016Steve WolfeShot 17:
Raise (more positive) voltage on both OH2's at 1 and 3msec by 10V each
REset pump on J-port seal again!

Result: Yet another fizzle.

Oct 26 1993 01:49:52:490PM931026018Steve WolfeShot 18:
End of kappa run, start of Rice's Ar half-run
Raise IC_OH1 P gain from 1 to 2 to try to help the Bz' problem.
Change RCUR back to .68 from .2 sec to 1.2 sec

Result:
dud. Got about 250 amps more on OH1.

Oct 26 1993 02:03:34:920PM931026019Steve WolfeShot 19:
Bz started at 0 and goes positive on 18.
Change EF4 from -1030 to -1060A
RF assist on for this shot and previous

Result: Plasma Lasts till 1.1 sec

Oct 26 1993 02:24:48:370PM931026019Steve WolfeShot 20:
Turn off A-side puff at 0.385
Move Ar pulse to 40msec (from 100 msec)
Limit the crossover spike to .18 to .19

Result: Plasma disrupts at 1.+ sec

Oct 26 1993 02:43:48:450PM931026020Steve WolfeShot 21:
Shorted crossover blip in IP PID to end at .225
Ramp A-side puff down from .385 to 1. sec
There was a big Vertical excursion from .145
Change EF2U back to 3000A
Result: Fizzle! RF pulse was 100kW at 15msec
Fields don't look terrible
Bob sees two flashes, one in a good place, and one on the outside.

Oct 26 1993 02:52:33:970PM931026022Steve WolfeShot 22:
As on 21:
Shorted crossover blip in IP PID to end at .225
Ramp A-side puff down from .385 to 1. sec
There was a big Vertical excursion from .145
Change EF2U back to 3000A
Result: Short, looks like hard x-raysright from the beginning.
Disrupts at 350msec

Oct 26 1993 03:11:01:970PM931026023Steve WolfeShot 23:
Turn off the RF

Result: Plasma lasts till 0.9sec
PF breaker pulled out at disruption
Lots of injections

Oct 26 1993 03:24:50:690PM931026024Steve WolfeShot 24:
Raise Ar puff at 60msec to 60 from 30V
Raise end of A-side gas puff (1sec) to 30V.
Raise ZCUR 2 proportional gain to 0.5

Result:
Long plasma - PF breaker pulled again.
Disrupts after 1 sec.
John says hard xrays are still bad.
The MHD and TCI ethernet leg Vaxstations all crashed before the shot

Oct 26 1993 04:00:08:220PM931026025Steve WolfeShot 26:
Change EF2U current to -2500 (from -3000) at .159 sec

Result:
Shot ran to 1sec

Oct 26 1993 04:16:40:160PM931026027Steve WolfeShot 27:
INcrease Ar puff to 80V at 60msec

Result:
Disrupts at 450msec

Oct 26 1993 04:26:17:380PM931026028Steve WolfeShot 28:
No change

Result:
This one ran to 800msec

Oct 26 1993 04:44:12:710PM931026029Steve WolfeShot 29:
Raise Ar puff at 80msec to 40 from 15V

Result:
Short again. Dies at 200msec +
Maybe too much Ar?

Oct 26 1993 05:01:05:920PM931026030Steve WolfeShot 30:
Drop Ar puff at 80msec from 40 from 25V
Lower A-side puff late

Result:
Lasts till .95sec
John likes it. We'll leave it alone

Oct 26 1993 05:15:39:780PM931026031Steve WolfeShot 31:
No changes
Result:
Disrupts at 500msec
Injection?

Oct 26 1993 05:32:00:640PM931026032Steve WolfeShot 32:
No changes
Result:
No pulse
Ack failure on state transition.

Oct 26 1993 05:40:24:480PM931026032Steve WolfeShot 32:
No changes
Result:
No pulse
Ack failure on state transition.

Oct 26 1993 05:44:46:000PM931026033Steve WolfeShot 33:
No changes
Result:
Fizzle

Oct 26 1993 05:52:52:690PM931026033Steve WolfeShot 34:
No changes, try again.

Result:
Still disrupts around 500msec

Oct 26 1993 06:11:07:790PM931026035Steve WolfeShot 35:
No changes, try again.

Result:
Another half-second disruption. I saw something falling through after
the shot on the TV.
It seems to come from the upper inside.

Oct 26 1993 06:20:26:420PM931026036Steve WolfeShot 36:
No changes, maybe the falling object was part of the problem.

Result:
Another short (.5sec) shot

Oct 26 1993 06:41:09:890PM931026037Steve WolfeShot 37:
Reduce current to 700kA
Note: mass28 on the RGA has been rising for the last three shots.
J-port seal pump is ok.

Result:Didn't help, disrupts at about .3 sec.

Oct 26 1993 06:51:32:870PM931026037Steve WolfeShot 38:
Raise current to 800kA, slightly rising current

Result:

Oct 26 1993 06:52:08:620PM931026038Steve WolfeShot 38:
Raise current to 800kA, slightly rising current

Result:Another .45 sec disruption.

Oct 26 1993 07:07:24:670PM931026038Steve WolfeShot 39:
Reduce Ar puff

Result: Lasted to 0.95
It was too much Ar!

Oct 26 1993 07:07:49:780PM931026039Steve WolfeShot 39:
Reduce Ar puff

Result: Lasted to 0.95
It was too much Ar!

Engineering Operator Comments
ShotTimeTypeStatusComment
108:54:34:130AMPlasmaOkFizzle; EF1L did not make precharge; not sure if hybrid gain or PS
209:11:38:150AMPlasmaOkGood 800 kA shot with interesting dip during OH1 dead time
309:27:52:350AMPlasmaOkDud. Gas fill raised for next shot
409:44:22:480AMPlasmaOk800 ka disruption at 0.4 sec
510:00:14:740AMPlasmaOkgood 800 kA shot
610:17:43:260AMPlasmaOk800 kA disruption at .7 sec
710:39:16:570AMPlasmaOkFizzle
810:53:31:400AMPlasmaOk800 ka disruption at 0.5 sec
911:10:59:970AMPlasmaOk800 kA disruption at 0.43 sec
1011:27:13:610AMPlasmaOkFizzle
1111:42:36:920AMPlasmaOk700 kA disruption at .24 sec
1212:03:00:060PMPlasmaOkFizzle
1312:19:14:670PMPlasmaOk800 kA disruption at 0.7 sec
1412:35:27:620PMPlasmaOkFizzle
1512:52:34:040PMPlasmaOkFizzle; Irby and Rice go in cell to purge J-port seal.
1601:11:03:820PMPlasmaOkFizzle; pump on J port tripped again
1701:29:16:530PMPlasmaOkFizzle; J-port pump stayed on. RF assist next shot
1801:43:33:790PMPlasmaOkRF-assisted dud
1901:59:47:210PMPlasmaOkPlasma shot no faults.
2002:14:59:570PMPlasmaOkPlasma shot O.K.
2102:33:04:410PMPlasmaOkPlasma shot No faults.
2202:47:10:190PMPlasmaOkPlasma shot No faults.
2303:03:26:950PMPlasmaOk800 kA disruption at 0.9 seconds; EF1L comm failure at 0.97 seconds
2403:19:08:880PMPlasmaOkNice 850 kA shot, disrupted at .987 sec 700 kA, EF1L comm fail 1.05 sec
2503:33:19:370PMPlasmaOkEarly disruption at 600 kA
2603:53:14:910PMPlasmaOkgood, disrupted at .987 sec; EF1L survived
2704:06:28:510PMPlasmaOkDisrupted at 0.5 sec
2804:21:38:050PMPlasmaOkno faults
2904:38:16:030PMPlasmaOkno faults
3004:55:01:550PMPlasmaOkno faults
3105:10:24:990PMPlasmaOkno faults
3205:26:28:200PMPlasmaBadack failure -- no indication from state PC which system failed.
3305:38:10:970PMPlasmaOkno faults
3405:50:23:740PMPlasmaOkno faults
3506:04:38:150PMPlasmaOkno faults
3606:17:59:790PMPlasmaOkno faults
3706:34:21:590PMPlasmaOkno faults
3806:48:47:700PMPlasmaOkno faults
3907:04:51:120PMPlasmaOkno faults