Alcator C-Mod Run 1030501 Information

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Miniproposals
Miniproposal:
Date Filed:
Title:
First Author:
Session Leader:Joseph Snipes (shots 1-27)
Session Leader:Steve Wukitch (shots 1-27)

Operators
Session leader(s):Joseph Snipes,Steve Wukitch
Physics operator(s):Ron Parker
Engineering operator(s): Unknown

Engineering Operator Run Comment
Continued Startup, ICRF Conditioning, TAE Mode Studies/Wukitch?Snipes/Pa

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:32:007PM
Author: To Be Determined
Run Summary for Active MHD Diagnostic Checkout 1030501

It was a difficult day to get results due to a number of machine problems
discussed in the Physop summary. In addition, because I was sharing the day
with Wukitch and our needs were somewhat incompatible, I could not get large
variations in the TAE mode frequency. The density was not well controlled
because of outgassing of the inner wall. The TF could not be varied
significantly because that would move the resonance and disturb the ICRF. The
ICRF also generated substantial noise on the pickup coil signals making it very
difficult to find a resonance, particularly since the peak in the present
matching circuit is right at 500 kHz, which is the beat frequency of the D and
E antennas, though J-port broadband noise also disturbs the signals. I also
could not vary the Active MHD driving frequency more than about 50 kHz without
a significant loss of current in the antenna. Then, I assumed the TAE
frequency was for deuterium, but because there was substantial hydrogen, the
actual TAE frequency was significantly higher. So, the driving frequency was
probably well away from resonance on all discharges except perhaps one, shot 6,
where there was an injection that raised the density abruptly and a peak in the
FFT was observed.

Physics Operator Summaries
Entered: Jul 7 2004 04:37:17:647PM
Author: To Be Determined
PHYSOP_SUMMARY_1030501

Run Plan for Thursday, May 1, 2003

PURPOSE: Continued Startup, ICRF Condiitoning, TAE Mode Studies

Session Leaders: Wukitch, Snipes

Physop: Parker

ENGINEERING SETUP

ECDC in D2 Overnight prior to run; 60 C Bake

Run Starts at 9:00 AM and Ends at 5:00 PM

Power Systems as on 1030429024

Gas setup:

Fill B-Top with 6 psi of D2 hybrid enabled (PG4)
Fill B-side lower with 1 psi Ar Hybrid enabled (PG1)
Fill B-side upper with 10 psi D2 Hybrid Disabled (PG2)
fill C-side with 30 psi D2 Hybrid enabled (PG3)

ICRF: Transmitters 1, 2, 3 and 4 in Run On by 7:00 AM.

Enable the ECE and DNB gate-valves, assuming no vacuum problems

RUN PLAN

Continued conditioning of the ICRF.

Investigation of TAE modes in Limited Discharges

We'll start with a fudicial discharge, e.g, 1030430018, then move to
a limited configuration. The field will be 5.4 T and the current 800 kA.
The nominal density will be about 0.8e^20, but there will be some
variations of n around that value.

RUN SUMMARY

Run started with 3 shots ending in early disruption. The cause was traced
to a problem with the EF2 power supply, apparently due to faulty cables or
connections. At any rate, there were serious differences between shunt and
rogowski monitors of the current. After disconnecting and reconeecting the
cables, the problem went away.

Discharges then lasted until disruptions occuring at the time of J-port
RF power turn on, which caused a problem with the EF1 supply. This problem
turned out to be due to open flanges in the RF transmission system. After
correcting, the shots began to run well (after shot 9).Finding and fixing
the problem caused a 1 hour delay.

Beginning with shot 10, the shots ran fairly reliably although with frequent
disruptions during rampdown. Runaways were generally a problem until shot 20
when the fill pressure was raised by 2 ms. However, this causes intermittent
fizzles as in shot 22.

A few klitches a long the way: camac/data system problems on shot 15-16 and
an early crowbar on shot 23.

These shots were inner wall limited from shot 8 on at the request of J.
Snipes. Some featured small (< 10%) modulation of the B field.

Scorecard: 27 shots, 23 started up properly, but of those 9 disrupted
mostly due to the power supply problems mentioned above, a few due to
high RF power. 2 shots were power tests, 1 was a power supply failure
and 1 was a fizzle.


Session Leader Comments

Physics Operator Comments
May 1 2003 09:04:15:733AM1030501001Ron ParkerFirst shot will reproduce shot 1030430018.

If OK, we'll proceed to move to limited discharges.
May 1 2003 09:16:55:000AM1030501001Ron ParkerShot disrupted at 140 ms. Run again
May 1 2003 09:32:46:450AM1030501002Ron ParkerShot again disrupted early. We will load shot 1030429006
May 1 2003 09:43:22:933AM1030501003Ron ParkerAgain, an early disruption. No change for next shot.
May 1 2003 10:07:49:750AM1030501004Ron ParkerShot 4 made it until 93 ms, then disrupted. At this point EF1 upper and lower
rogowski's report differing signals at that time and the disruption seems to begin with
z-movement. Suspect a pickup problem of RF from J port.

Earlier shots have differences in EF2 between shunt and rogowski that could have
caused the early disruption.
May 1 2003 10:16:19:613AM1030501005Ron ParkerTest shot

May 1 2003 10:26:48:080AM1030501005Ron ParkerNext shot will have J-port firing into a dummy load.
Testing interference with EF1
May 1 2003 10:55:37:593AM1030501006Ron ParkerShot ran more or less normally. J-port fired into dummay load.
May 1 2003 10:57:06:223AM1030501007Ron ParkerShot 7 ran well, J-port again fired into a dummy load. Next shot
will be limited.
May 1 2003 11:21:13:697AM1030501008Ron ParkerShot disrupted at 77 msec. Marginally limited at this time.

Move CLEARIN 1 cm more inside. Leave RCUR since the right gap was 2 cm
whereas we want ~ 1cm.
May 1 2003 12:31:36:580PM1030501009Ron ParkerShot 9 ran limited for the duration of the shot. However, it disrupted during
rampdown where it transitioned to upper single null. We'll move zxu up to avoid
becoming diverted.

RF Group found open flanges during prolonged (1 hour) power room
access. Correcting this may solve the problem of RF pickup in EF supply.
May 1 2003 12:47:59:387PM1030501010Ron ParkerSuccess. Shot 10 ran until inversion (but disrupted during rampdown) with
no interference from RF.
May 1 2003 01:00:13:513PM1030501011Ron ParkerShot 11 ran as programmed, except lack of densiy control above 0.6e20.
Still disrupting during rampdown at ~ 300 kA.


May 1 2003 01:18:30:713PM1030501012Ron ParkerShot 12 ran as programmed. Still no density control at the 6-8e^20 level.

Also disrupted during rampdown at 500 kA.

Next shot: 10 % variation in B
May 1 2003 01:26:50:350PM1030501013Ron Parker
Shot ran but disrupted at 1.12 sec, near minimum in TF ramp.

Try again.
May 1 2003 01:34:33:630PM1030501014Ron ParkerShot 14 ran, but again disrupted. Is it RF or the sweep or both or neither?
next shot will be a repeat with no RF.

May 1 2003 01:51:56:733PM1030501015Ron ParkerShot 15 was a no-power shot. Data system issues.
One of the highways is down.
May 1 2003 02:25:17:410PM1030501016Ron Parker15 minute delay due to Camac problem.

Shot ran, disrupted during shut down.

New problems with data system, no magnetics.



May 1 2003 02:48:40:027PM1030501017Ron ParkerShot 17 ran well, no RF, no disruption except ~170 ka at rampdown.
Next, J-port will be on until 0.9s, field ramp 10 % down from ~ 1s to end.
May 1 2003 03:09:00:243PM1030501018Ron Parker
Shot 18 ran well. Hards are problem early.
No changes for next shot.
May 1 2003 03:11:13:607PM1030501019Ron Parker
Shot 19 ran OK, but disrupted during rampdown.
Add 2 ms of pulse gas for next shot.
May 1 2003 03:20:09:887PM1030501020Ron ParkerShot 20 ran well. J-port power up to 1.5 MW.

Field still modulated after 1 sec.
May 1 2003 03:32:43:593PM1030501021Ron ParkerShot 21 ran well. Runaways under control by raising initial fill.
Density stabilizes at ~ 8.5e^19 without gas. RF is firing all transmitters
but power is intermittent.


May 1 2003 03:45:08:363PM1030501022Ron Parker
This was a fizzle. Probably due to raising the fill to cure hards.

Try again before reducing fill.
May 1 2003 03:59:07:837PM1030501023Ron ParkerShot 23 didn't go; crowbarred at switch closure.
May 1 2003 04:32:56:700PM1030501024Ron ParkerShot 24 went without any adjustments.

Next shot: Anticipate a fizzle.
May 1 2003 04:37:41:287PM1030501025Ron ParkerNo fizzle, but a disruption, probably RF induced.
May 1 2003 04:50:28:087PM1030501026Ron ParkerShot 26 ran well, D&E produced > 2 MW. J still intermettent.
Next shot: no changes. This will be the last shot today.
May 1 2003 05:13:42:513PM1030501027Ron ParkerShot 27 ran OK, but disrupted likely due to high RF power.

Engineering Operator Comments
ShotTimeTypeStatusComment
109:03:58:653AMPlasmaOk
209:16:58:487AMPlasmaOk
309:31:54:197AMPlasmaOk
409:44:53:093AMPlasmaBadEF1 Type 1 Flt
510:15:17:237AMTestOkEF2 Rog. Test
610:30:38:450AMPlasmaOk
710:47:42:667AMPlasmaOk
811:06:16:890AMPlasmaBadEF1 type 1 flt
911:24:49:330AMPlasmaOkNo ef1 faults
1012:31:26:173PMPlasmaOk
1112:49:13:873PMPlasmaOk
1201:03:59:100PMPlasmaOk
1301:17:09:480PMPlasmaOk
1401:29:54:780PMPlasmaOk
1501:42:31:160PMPlasmaBadcamac problem no power shot
1602:18:26:540PMPlasmaOk
1702:33:04:407PMPlasmaOk
1802:47:24:210PMPlasmaOk
1903:00:25:967PMPlasmaOk
2003:13:16:783PMPlasmaOk
2103:26:12:630PMPlasmaOk
2203:38:56:150PMPlasmaOk
2303:51:42:310PMPlasmaBadOH2U&L fault early in shot
2404:11:07:840PMPlasmaOk
2504:31:28:137PMPlasmaOk
2604:44:19:873PMPlasmaOk
2704:57:21:347PMPlasmaOk