Alcator C-Mod Run 960221 Information

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Miniproposals
Miniproposal:125a
Date Filed:11/27/1995
Title:ICRF Reversed Shear Mode
First Author:Miklos Porkolab
Session Leader:Miklos Porkolab (shots 1-39)

Operators
Session leader(s):Miklos Porkolab
Physics operator(s):Steve Wolfe
Engineering operator(s):Joe Daigle,Vinny Bertolino

Engineering Operator Run Comment
??????

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:15:303PM
Author: To Be Determined
Session Summary for 960221.
SL: Porkolab
PO: Wolfe
EO: Daigle, Bertolino

Run Plan was:
Part I. Negative central shear
------------------------------
Start from a standard fast 800kA startup, like a fiducial, but bring
RF on as early as possible. Things to try:
reduce early density
move position out earlier to match antenna (maybe use loading
feedback?)
Also vary H minority concentration to reduce orbit losses;
Try small pellet during current rise, before RF.

Monitor sawtooth onset, neutron rate. Note that automatic EFIT stored
energies will be meaningless for inverted pressure profiles, but we
may be able to get something from w_diamagnetic.

If we seem to be getting anything reproducible, try popping some Li
pellets to get a cigar measurement of Bz(R).

Part II. PEP modes
-------------------
If feasible, this part can be started during the late flattop of shots
from the first part of the run.

Set up standard 800MA plasma. Vary pellet timing relative to RF turn-on
to optimize neutron rate. Document it to death, including Sc injections
for tau_p. May want to try a pre-pellet Sc injection as well.

If the DPI is ready, try PEP modes with deuterium pellets as well.

What we have accomplished:

We had chronic power supply problems all day. We succeeded having two good
plasma shots around 8 pm ( after several early disruptions). The power
supply failures recurred near the end of the run. We did not even start on
the run-plan.



Physics Operator Summaries
Entered: Jul 7 2004 04:36:56:160PM
Author: To Be Determined
Physics operator's summary for Wed. 960221

MP# 125A ERS/PEP mode
SL: Porkolab
PO: Wolfe

This run was supposed to be in support of MP#125A, ERS/PEP mode studies. We
started the day with holdover problems from yesterday's debacle. The EF1L
supply was not fixed, and while the A-side gas driver worked on the first test
shot, the B-top driver, which had worked yesterday, was dead.

The daylight hours were spent getting things fixed. The "run" was extended
till 9PM in the expectation that things wouldn't be fixed yet. The gas system
was finally fixed: the B-top was a broken fiber; a replacement was run. The
a-side died during attempts to repair B-top, and Willy ended up changing out 5
out of six chips on the chopper board (one twice) before he got it to work.
The EF1L problem remained mysterious, but seemed to go away by itself around
7:00PM. We started trying for plasma at shot 31 at 19:10.

Shot 31 (fiducial setup from 960213011) was a dud even though all the supplies
ran. The radial field was extremely positive >2mT. This looks like the problem
Bob ran into yesterday.

Shot 32 decreased Br0 by 2mT, from .0074 to .0054, and the shot started ok,
but disrupted with a vertical problem during crossover. Shots 33-34 had minor
early gas tweaks and each lasted a littled longer, but still had vertical
problems. Shot 35 I dropped the clearin before .5sec to get rid of the
vertical problem, and it seemed to work, running full length.

The idea by this point was just to run some plasmas to reduce the amount of
conditioning needed before the 8T run tomorrow. Shots 36 was 800ka with 2.5MW;
an interesting shot for blob studies, as the H-alpha followed the D-port
power. Vinnie noted that the EF1L was exhibiting spikes during the pulse and
warned of impending doom. Sure enough, shot 37 had the PF supplies pull out
before commutation with EF1L leading the way. This looked like where the
Tuesday run ended. The engineers backed off on the gains on the EF1 supplies
to try to fix the problem. It didn't work. We gave up in disgust after shot
39, at 20:50.

General comments:
-----------------
The machine now (as of yesterday) seems to like a Br offset of .005 to .0055.

Probably because of dirt/conditioning, we had unusually bad vertical stability
problems, such that the fiducial programming wouldn't run. The CLEARIN tweak
in shot 960221035 seemed to help a lot.

When power supplies fix themselves, they don't stay fixed.

Scorecard
---------
Shots 39
Tests 30
Duds 4 (3 due to power supply faults)
Fizzles 0
Plasmas 5


Session Leader Comments
Feb 21 1996 08:52:15:370AMMiklos PorkolabRun plan:

Part I. Negative central shear
------------------------------
Start from a standard fast 800kA startup, like a fiducial, but bring
RF on as early as possible. Things to try:
reduce early density
move position out earlier to match antenna (maybe use loading
feedback?)
Also vary H minority concentration to reduce orbit losses;
Try small pellet during current rise, before RF.

Monitor sawtooth onset, neutron rate. Note that automatic EFIT stored
energies will be meaningless for inverted pressure profiles, but we
may be able to get something from w_diamagnetic.

If we seem to be getting anything reproducible, try popping some Li
pellets to get a cigar measurement of Bz(R).

Part II. PEP modes
-------------------
If feasible, this part can be started during the late flattop of shots
from the first part of the run.

Set up standard 800MA plasma. Vary pellet timing relative to RF turn-on
to optimize neutron rate. Document it to death, including Sc injections
for tau_p. May want to try a pre-pellet Sc injection as well.

If the DPI is ready, try PEP modes with deuterium pellets as well.

Feb 21 1996 08:13:32:560PM960221035Miklos PorkolabIt is 8.08 pm, run resumed with plasma finally.

Feb 21 1996 08:33:20:230PM960221036Miklos PorkolabThis was a great shot, H-mode. Still cleaning up the walls.
Big blob in H-alpha, timing corresponded to D-port RF pulse.
RF power about 2.6 MW, stored energy about 110 kJ

Feb 21 1996 08:44:24:080PM960221037Miklos PorkolabPower supply failure again, no plasma.

Feb 21 1996 08:46:08:190PM960221038Miklos PorkolabPower supply failure again.

Feb 21 1996 08:51:20:400PM960221039Miklos PorkolabPower supply failure again. Last shot, we are quitting for the night.

Physics Operator Comments
Feb 21 1996 07:02:59:160AMSteve WolfeProposed run plan for ERS/PEP run on 960221. May be modified in progress.

Part I. Negative central shear
------------------------------
Start from a standard fast 800kA startup, like a fiducial, but bring RF on as
early as possible. Things to try:
reduce early density
move position out earlier to match antenna (maybe use loading
feedback?)
Try small pellet during current rise, before RF.

Monitor sawtooth onset, neutron rate. Note that automatic EFIT stored energies
will be meaningless for inverted pressure profiles, but we may be able to get
something from w_diamagnetic.

If we seem to be getting anything reproducible, try popping some Li pellets to
get a cigar measurement of Bz(R).

Feb 21 1996 07:03:20:010AMSteve WolfePart II. PEP modes
-------------------
If feasible, this part can be started during the late flattop of shots from
the first part of the run.

Set up standard 800MA plasma. Vary pellet timing relative to RF turn-on to
optimize neutron rate. Document it to death, including Sc injections for
tau_p. May want to try a pre-pellet Sc injection as well.

If the DPI is ready, try PEP modes with deuterium pellets as well.

Feb 21 1996 07:05:17:110AMSteve WolfeEngineering Setup for Wed. 960221 (MP#125A ERS/PEP)

ECDC in He for two hours before the run.

Gas setup:
Aside - 20psi D2
Btop 5psi D2
Bside lower 4psi Ar
Bside upper He3 as is (don't touch that valve)

Tests of PF supplies and gas system as required.

Set up for a fiducial shot as on 960213011. This setup will be used for
the first part of the experimental run as well.

Feb 21 1996 07:08:51:670AMSteve WolfeThe problem with the duty-cycle circuit on the a-side gas feed may have
been fixed. A short on the connector board due to a metal nut was
remedied by replacing the nut with a nylon nut. Supply is no longer
dragged down, no pulse test done last night.

The EF1 problem is also believed to be fixed. No power testing has been
done yet.

Feb 21 1996 07:22:10:540AMSteve Wolfecoldstart done at 21-FEB-1996 07:18:42.33

Feb 21 1996 08:20:04:780AM960221001Steve WolfeShot 960221001 EF1 PLC test with gas enabled. EF1L at 3kA. Aside
valve works ok, but no pre-pulse from B-top

Feb 21 1996 08:26:43:200AM960221002Steve WolfeShot 960221002 Reverse side EF1 test. - faults. B-top still didn't fire
This is the line that was working yesterday, and was
used for ECDC this morining.

Feb 21 1996 08:56:27:660AM960221003Steve WolfeShot 960221003 Changed AFOL card for B-top/B-side lower
Swapped op amps for B-top & diborane (1&5)
Vinnie and company replaced a fuse in EF1L and swapped slew
rate boards forward and reverse.

EF1L looks ok. No gas at all.

Feb 21 1996 09:24:27:390AM960221004Steve WolfeShot 960221004 Go to forward EF1U test. Swapped AFOL boards back,
leave op amps as on previous shot.
Got EF1U, still no gas no gas outputs.

Feb 21 1996 09:59:37:510AM960221005Steve WolfeShot 960221005 EF1 zero command test. Tried DC gas from B-top and it
worked prior to this shot (ECDC mode).

ASked for nothing amd got it on supply. Still no gas.

Feb 21 1996 10:15:01:310AM960221006Steve WolfeShot 960221006 EF1 zero command test. Taped up leads on hybrid enable
to diborane driver board.
Still no gas.

Feb 21 1996 11:00:16:650AM960221007Steve WolfeShot 960221007 Put a 5msec pulse on PG1 (B-side lower) at -.465s
Joe Bosco reports B-top fiber is defunct.

No gas. Still chasing the power supply prob.
signal on B-side lower output!

Feb 21 1996 11:16:49:650AM960221008Steve WolfeShot 960221008 Put a 5ms pulse on B-side upper around -.2 to see if
its working. They claim to have found something broken on ef1.

Got signals from B-side upper and B-side lower. Still nothing from A-side
or B-top. Got gas from B-side upper (He3). Turn it off for next shot.
Still chasing the EF1 problem.

Feb 21 1996 11:35:25:190AM960221009Steve WolfeShot 960221009 Bill Parkin located a 150ft spool of fiber (two fibers)
already terminated. Will run this from the I-room to replace the broken
b-top fiber.

Feb 21 1996 11:59:24:200AM960221009Steve WolfeShot 960221009 Bill Parkin located a 150ft spool of fiber (two fibers)
already terminated. Will run this from the I-room to replace the broken
b-top fiber.

Feb 21 1996 12:07:11:500PM960221013Steve WolfeShot 960221013 Duty-cycle board removed, A-side in directly. H-enabled
GOt gas from a-side. Doesn't come on until 100msec, would need to widen
first pulse, but could run like yesterday.

Feb 21 1996 01:26:53:290PM960221017Steve WolfeShot 960221017 - "repaired" duty-cycle board installed in a-side
EF1 power test (1kA)

EF1 still not working. A-side gets a waveform, but only 6.3V amplitude.

Feb 21 1996 02:10:12:610PM960221018Steve WolfeShot 960221018 - "repaired" duty-cycle board installed in a-side with
voltage tweaked up. EF1 power test (1kA)

Got 8V on A-side. Willy doesn't understand. EF1 still looks bad.
GOing to try setting up EF1 for 6pulse operation.

Feb 21 1996 02:46:38:860PM960221019Steve WolfeShot 960221019 - Get rid of segment 1 waveforms for B-side upper and
B-side lower. PUt in a spare opamp board in while he checks
the gain.
Engineers are setting EF1 up to run as 6pulse supply.
Both supplies,3kA reverse direction.

EF1 crowbarred. 7.6V on A-side output.

Feb 21 1996 04:15:22:110PM960221020Steve WolfeShot 960221020 - The output follower on the duty-cycle board was in
backwards! It was presumably acting as a resistor.
EF1L in one direction only, with other crowbar disabled.

crowbar. A-side gives 10V waveform. Gas is now working. EF1L is OTL.

Feb 21 1996 06:44:57:280PM960221029Steve WolfeShot 960221029 - EF1 may be working again. If the next test goes ok,
we will try for plasma.

Feb 21 1996 07:03:48:780PM960221030Steve WolfeShot 960221030 - EF1L test. ok

Feb 21 1996 07:13:48:110PM960221031Steve WolfeShot 960221031 - Try for plasma - fiducial shot.
dud! All supplies seem to be there. Br is very positive.

Feb 21 1996 07:30:52:650PM960221032Steve WolfeShot 960221032 - Br offset fro .0074 to .0054.
Plasma- early disruption. PF breaker pulled.
Vertical problem during crossover. N/nc gets to 1.23.

Feb 21 1996 07:40:18:590PM960221033Steve WolfeShot 960221033 - Add early gas (PG3 in seg 1).05 to .1 sec
Same thing. this one ran to 370msec, past crossover. Still some current
rise disruptions. This one may have been a Mo injection.

Feb 21 1996 07:53:27:480PM960221034Steve WolfeShot 960221034 - Increase prepuff to 14msec
Another disruption. 420msec
Its still real close to vertical instability. No injection this time.

Feb 21 1996 08:04:19:480PM960221035Steve WolfeShot 960221035 - Decrease early clearin to reduce elongation (it is
no longer a fiducial.

Plasma all the way through. Got h-mode. looks good. Still some vertical
problems in first half sec. Lots of injections.

Feb 21 1996 08:19:02:130PM960221036Steve WolfeShot 960221036 - More RF. No equilibrium changes.
Plasma - looks good. 2.5MW 110kJ. Big h-alpha blob. Prad 2pi < 500kW

Feb 21 1996 08:26:50:630PM960221037Steve WolfeShot 960221037 - repeat.
Vinnie and Joe point out that EF1L has some spikes and skips on
the voltage.

Dud. PF breaker pulled out early. EF1L. Back to the future!

Feb 21 1996 08:28:53:150PM960221037Steve WolfeShot 960221037 - repeat.
Vinnie and Joe point out that EF1L has some spikes and skips on
the voltage on the last shot.

Dud. PF breaker pulled out early. EF1L. Back to the future!

Feb 21 1996 08:41:01:000PM960221038Steve WolfeShot 960221038 - repeat.
Engineers lowered the gain on both EF1U & L by 20%.

MagRes fault. No 13.8kV supplies.

Feb 21 1996 08:49:58:450PM960221039Steve WolfeShot 960221039 - repeat.
Engineers lowered the gain on both EF1U & L by 20%.

PF's pulled out again. EF1L.

Engineering Operator Comments
ShotTimeTypeStatusComment
108:09:51:550AMTestOk
208:17:43:540AMTestBadef1l fault
308:50:37:950AMTestOk
409:20:17:610AMTestOk
509:41:44:930AMTestOk
610:01:11:730AMTestOk
710:20:48:870AMTestOk
811:09:44:600AMTestOk
911:30:07:640AMTestOk
1011:35:48:810AMTestOk
1111:45:36:710AMTestOk
1211:51:05:030AMTestOk
1312:01:41:800PMTestOk
1412:15:15:030PMTestOk
1512:31:51:400PMTestOk
1601:01:27:740PMTestOk
1701:19:19:680PMTestBadef1l fault
1801:59:54:950PMTestOk
1902:28:18:690PMTestBadef1 bad
2004:08:47:020PMTestOk
2104:24:28:080PMTestOk
2205:28:57:960PMTestOk
2305:36:08:030PMTestOk
2405:45:17:650PMTestOk
2506:02:14:250PMTestOk
2606:13:34:790PMTestOk
2706:25:02:860PMTestOk
2806:32:26:150PMTestOk
2906:40:10:780PMTestOk
3006:48:09:740PMTestOk
3107:06:17:070PMPlasmaOk
3207:17:08:770PMPlasmaOk
3307:33:30:370PMPlasmaOk
3407:43:27:780PMPlasmaOk
3507:55:44:120PMPlasmaOk
3608:11:23:890PMPlasmaOk
3708:24:23:770PMPlasmaBadef1l fault
3808:38:15:910PMPlasmaOk
3908:46:31:110PMPlasmaBadef1l fault