Alcator C-Mod Run 1000823 Information

Back to runs

Miniproposals
Miniproposal:268
Date Filed: 4/7/2000
Title:Conditioning of D-, E-, or J-Port ICRF Antenna
First Author:Gerd Schilling
Session Leader:Steve Wukitch (shots 1-17)
Miniproposal:276
Date Filed: 6/1/2000
Title:Transport Experiments in the Scrape-Off Layer during Ohmic L- andH-mode using Gas-Injection Plumes
First Author:Sanjay Gangadhara
Session Leader:Brian Labombard (shots 1-17)

Operators
Session leader(s):Brian Labombard,Steve Wukitch
Physics operator(s):Ron Parker
Engineering operator(s):Gary Dekow,Bill Cochran

Engineering Operator Run Comment
MP 268 ICRF Commissioning and MP 276 Trans/Burping. Wukitch/Parker/Cochr

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:24:633PM
Author: To Be Determined
Engineering setup for Tuesday, 1000823:

Overnight ECDC in D2, stopping 1-2 hours prior to the run.

Run begins at *** 10:00 *** NOTE!!! (It could be later, depending
on success of RF conditioning) and ends at 17:00.

Power system setup as on 1000621019 (5.2 T, 1 MA inner wall limited).

Set OH1, OH2U and OH2L fizzle delays at 300 ms.
Set TF fizzle delay at 400 ms.

Gas setup - fill B-top with 6 psi of D2 Hybrid enabled
fill B-side lower with 1 psi of Ar Hybrid disabled
leave B-side upper as is Hybrid DISABLED
fill C-side with 30 psi of D2 Hybrid enabled
leave J-bottom as is Hybrid DISABLED

The following gate valves should be enabled, assuming no vacuum problems:
ECE, VUV

----------------------------------------------------------------------------

Run plan for Wedensday, 1000823:

MP 268 -- ICRF Commissioning
MP276 SOL Trans/Burping (Piggyback)

Session leader: S. Wukitch
Physics operator: R. Parker


For first plasma shot, load from 1000621019 (1.0 MA, 5.2 T).

1. Power testing and conditioning for D, E and J-port antennas
2. Power ramps for D, E and J
3. Power steps
4. gap, density, I, and BT scans

While the primary purpose of the run is RF commissioning, Sanjay and Brian will
piggyback with the burping probe as described in MP276.

----------------------------------------------------------------------------

001 fizzle
002 fizzle
003 dud
004 dud
005 fizzle
006 plasma
D-port - 750 kW, one fault
E-port - 750 kW, clean
J3 - 400 kW, couple faults
J4 - max faults > 100 kW

next shot: overlap D and E-port and retune

007 plasma
injection during J-port
D-port - failed did not work overlapped
E-port - 750 kW, clean
J3 - 400 kW, couple faults
J4 - 400 kW, couple faults

next shot: raise D and E-port to 1 MW each
J-port to 1.5 MW

008 fizzle
009 plasma, early disruption
D and E ran until disruption at ~0.84 sec

next shot: try again

010 fizzle
011 plasma
D-port failed after E-port came on
E-port clean 1 MW
max faults on J3&4 after brief ramp

next shot: repeat

012 fizzle
013 early disruption ~0.54 sec
014 fizzle
015 early disruption, ~0.53 sec
016 early disruption ~1.1 sec
D-port 1 MW, but max faults after
E-port 1 MW,clean
J3&J4 ramped but then J3 failed

next shot: repeat

017 plasma early disruption
D-port 1.3 MW
E-port failed
J-port ramped before disruption

Summary:

We had a few shots where we managed to get plasma and RF. D and
E-port struggled to run simultaneously, but this might be a result of
the poor damping.

Physics Operator Summaries
Entered: Jul 7 2004 04:37:11:753PM
Author: To Be Determined
Run Plan and Engineering Setup for 1000823

MP268 ICRF Commissioning
MP276 SOL Trans/Burping (Piggyback)

Session Leader: S. Wukitch
Physics Operator: R. Parker
Engineering Operators: B. Cochran/G. Dekow

Engineering Setup:

Overnight ECDC in D2, stopping 1-2 hours before run.

Run begins at *** 10:00 *** NOTE!!! (It could be later, depending
on success of RF conditioning) and ends at 17:00.

Power system setup: Same as for 1000621019 (5.2 T, 1 MA inner wall limited)

Set OH1, OH2U and OH2L fizzle delays at 300ms
Set TF fizzle delay at 400 ms


Gas setup: B-Top 6 psi D2 Hybrid Enabled
B-side lower 1 psi Argon Hybrid DISABLED
B-side upper leave as is Hybrid DISABLED
C-side 30 psi D2 Hybrid Enabled
J-bottom leave as is Hybrid DISABLED

The following Gate Valves should be ENABLED, assuming no vacuum problems:

ECE, VUV



Run Plan:

For the first shot, we'll load from 1000621019, an inner-wall-limited, 1.0 MA,
5 T shot. This shot will be modified as necessary to accomplish the following:

1. Power testing and conditioning for D, E and J-port antennas
2. Power ramps for D, E and J
3. Power steps
4. Gap, density, I and BT scans

While the primary purpose of the run is RF commissioning, Sanjay and Brian will
piggyback with the burping probe as described in MP276.

Run Summary:

The run began at noon, because the RF Group needed extra time for conditioning.

The first shot was an EFC power supply test, which was necessary to check
repairs made to the supply after the last run. The test was successful
and the run proceeded.

The first 4 shots were without normal plasmas: 2 fizzles, and
2 duds. The problem seemed to be associated with initial fill pressure,
which was clearly too low for the duds, shots 3 and 4. Finally after raising
the fill to 0.08 mT, a normal discharge was obtained.

B. Labombard reported that the pulse gas gauge was reading too low, based on
comparison with barotron gauges. This could have explained the relatively high
apparent pressure needed to get the discharge to start properly. However, the
pulse gas width was in proportion to the pressure according to the ratio
established from previous runs. So whether there is a problem here remains
uncertain. What is true is thata somewhat higher gauge reading than normal
was necessary to get the plasma to start up.

Shots 6 and 7 ran normally, but then difficulties began as Argon was injected
starting with shot 8 which disrupted.

Then began a pattern of disruptive shots, with normal startup,
alternating with fizzles. This pattern continued through shot 15 which ran,
but disrupted. At this point it was noticed that the Ar pulse was wider than
normal (~ 50 ms vs. 25) and that the piggyback experiment was injecting
C in the form of C2D4. Either puff might have been leading to the
disruption problems. Therefore, both injections were stopped beginning with
shot 16. In fact, the discharges continued to disrupt after the puffs were
terminated, this time possibly due to RF, but the disruptions occured at
later times and there were no further fizzles in the remaining 2 shots.

Overall, not a great day for the machine: 8 shots (6 of which disrupted),
6 fizzles and 2 duds.

Session Leader Comments
Aug 23 2000 12:08:49:530PM1000823001Steve Wukitch001 chopper test

next shot: plasma - inner wall limited, BT~5.2T, Ip~1 MA
Aug 23 2000 12:13:22:170PM1000823002Steve Wukitch002 fizzle
Aug 23 2000 12:59:19:857PM1000823003Steve Wukitch003 dud
Aug 23 2000 01:13:53:310PM1000823004Steve Wukitch004 dud
Aug 23 2000 01:14:42:857PM1000823005Steve Wukitch005 fizzle
Aug 23 2000 01:22:23:983PM1000823006Steve Wukitch006 plasma
D-port - 750 kW, one fault
E-port - 750 kW, clean
J3 - 400 kW, couple faults
J4 - max faults > 100 kW

next shot: overlap D and E-port and retune
Aug 23 2000 01:44:59:577PM1000823007Steve Wukitch007 plasma
injection during J-port

next shot: raise D and E-port to 1 MW each
J-port to 1.5 MW
Aug 23 2000 03:13:19:890PM1000823009Steve Wukitch009 plasma, early disruption
D and E ran until disruption at ~0.84 sec

next shot: try again
Aug 23 2000 03:13:42:640PM1000823010Steve Wukitch010 fizzle

next shot: try again
Aug 23 2000 03:25:21:763PM1000823011Steve Wukitch011 plasma
D-port failed after E-port came on
E-port clean 1 MW
max faults on J3&4 after brief ramp

next shot: repeat
Aug 23 2000 03:35:50:340PM1000823012Steve Wukitch012 fizzle
Aug 23 2000 03:46:19:140PM1000823013Steve Wukitch013 early disruption ~0.54 sec
Aug 23 2000 04:04:50:937PM1000823014Steve Wukitch014 fizzle
Aug 23 2000 04:39:10:467PM1000823015Steve Wukitch015 early disruption ~0.54 sec
Aug 23 2000 04:45:18:950PM1000823016Steve Wukitch016 early disruption ~1.1 sec

next shot: repeat

Physics Operator Comments
Aug 23 2000 11:47:16:513AM1000823001Ron ParkerFirst shot will be an EFC power supply test.
Aug 23 2000 12:04:55:653PM1000823001Ron ParkerPower supply test was successful. Next shot is setup for plasma--shot 1000621019
is loaded.
Aug 23 2000 12:44:43:983PM1000823002Ron ParkerShot fizzled! Plasma got tired of waiting.
Aug 23 2000 12:45:11:107PM1000823002Ron Parker
The shot fizzled, probably because BZO was too negative, ~ -4 mT. For this shot,
IEF4 was decreased by 20 A, corresponding to ~ -2 mT in BZO.

Also, fill pressure was reduced by about 10% to ~ .06 mTorr
Aug 23 2000 12:45:43:920PM1000823003Ron Parker
Shot 3 did not break down. For next shot, EF4 current will be increased by 15 A to -1285
and 0.5 mT will be added to BRO.
Aug 23 2000 12:53:50:093PM1000823004Ron Parker
This shot also did not break down. R. Granetz points out that the sparker appeared
not to be operating properly. Pressure will be raised by ~ 10% to .07 mT for
next shot.
Aug 23 2000 01:08:29:450PM1000823005Ron ParkerShot broke down, but fizzled. Pressure will be increased to ~ .08 mT. Also, BRO will be
reduced by .25 mT for next shot.
Aug 23 2000 01:31:49:233PM1000823006Ron ParkerFinally a normal shot! Shot ran as programmed.

Brian Labombard reports that the pulsed gas pressure gauge is reading incorrectly. This
could explain why p=0.08 mT was required to get a normal shot and why there was no
breakdown at "normal" pressures of ~ 0.06 mT.

Next shot will be a repeat of shot 6.
Aug 23 2000 01:58:01:717PM1000823007Ron Parker
Shot ran well, as programmed. No change for next shot except Ar will be injected
at ~ 350 ms. Any further problems with breakdown, fizzles, power supplies ,etc., should be
blamed on Ar injection.
Aug 23 2000 02:36:35:560PM1000823008Ron ParkerShot 8 was a fizzle, possibly the walls are becoming loaded and the pressure is
now too high. For shot 9, the fill pressure will be reduced to ~ 0.07 mT.
Aug 23 2000 02:44:19:950PM1000823009Ron ParkerShot 9 did not fizzle, but did disrupt due to unidentified injection around 0.81 s.

Shot 10 will be a repeat, hopefully without the injection.
Aug 23 2000 03:09:21:890PM1000823010Ron ParkerThis shot fizzled, not unusual after a disruption.

Initial fields and pressure are the same as for previous shot.
Aug 23 2000 03:18:40:577PM1000823011Ron ParkerShot ran, but again disrupted, this time at about 1.45 s.

No changes for next shot, which will probably fizzle after this disruption.
Aug 23 2000 03:46:04:390PM1000823012Ron ParkerShot 12 was a fizzle, expected after the disruption in shot 11.

No change for next shot.
Aug 23 2000 03:47:47:403PM1000823013Ron ParkerShot 13 started up, but disrupted at 0.6 s.

Next shot will probably fizzle.
Aug 23 2000 04:39:07:530PM1000823014Ron Parker
Shot 14 did fizzle as expected. After a disruption, there seems to be an impurity problem
during the current rise that prevents the current from rising rapidly enough.

The subsequent fizzle seems to clean the walls well enough to permit the current rise to rise
at the required rate on the next shot. This has been the pattern for most of the day.
Aug 23 2000 04:37:18:577PM1000823015Ron ParkerShot 15 disrupted, therefore the next shot will likely fizzle.

Speculation is that either the Ar puff or the C2D4 puff could be causing the disruption
problems. This will be checked by turning both puffs off for the remainder of the run, which
unfortunately will have only 2-3 more shots..

Aug 23 2000 04:47:06:030PM1000823016Ron ParkerShot 16 ran (surprisingly, since the previous shot disrupted), but did disrupt at about 1.1 s.


Aug 23 2000 05:01:53:170PM1000823017Ron Parker
The last shot ran, but again disrupted at ~ 1.1 s. This disruption might be associated
with the J port antenna.

Interestingly, there were no more fizzles after the Ar and C2D4 puffs were suppressed.

Nevertheless, the plasmas continued to disrupt.

Engineering Operator Comments
ShotTimeTypeStatusComment
111:49:57:873AMTestOkEFC Chopper Test Only
212:07:07:903PMPlasmaOk
312:24:27:437PMPlasmaOk
412:42:00:810PMPlasmaOk
512:57:45:077PMPlasmaOk
601:13:19:903PMPlasmaOk
701:38:10:060PMPlasmaOk
801:59:58:297PMPlasmaOk
902:32:27:750PMPlasmaOk
1002:50:18:293PMPlasmaOk
1103:09:37:780PMPlasmaOk
1203:24:31:607PMPlasmaOk
1303:42:50:030PMPlasmaOk
1404:03:20:280PMPlasmaOk
1504:21:26:810PMPlasmaOk
1604:38:02:733PMPlasmaOk
1704:51:23:420PMPlasmaOk