Alcator C-Mod Run 990224 Information

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Miniproposals
Miniproposal:214
Date Filed: 1/5/1999
Title:D and E-port RF System Commissioning
First Author:Steve Wukitch
Session Leader:Steve Wukitch (shots 1-29)

Operators
Session leader(s):Steve Wukitch
Physics operator(s):Earl Marmar
Engineering operator(s):Gary Dekow,Frank Silva

Engineering Operator Run Comment
MP 214/Marmer/Silva

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:19:553PM
Author: To Be Determined
Engineering Setup for Wednesday, 990224:

2 hours ECDC in D_2 before the run

Power supply settings should be taken from 990223021.

TF under hybrid control

Gas setup - fill B-top with 6 psi of D2 Hybrid enabled
fill B-side lower with 1 psi of Ar Hybrid enabled
pump B-side upper and leave evacuated Hybrid DISABLED
fill C-side with 30 psi of D2 Hybrid enabled
fill J-bottom with 2 psi of Kr Hybrid DISABLED
We want hydrogen and helium-4 available, for possible use in B-side upper,
so the neon bottle should be removed from the system and replaced with hydrogen.

Load from 990223021 for segment 1
990219024 for segment 2 (.8 MA, 5.4 T); leave B_T jog for ECE


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

ECE, VUV

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

Run Plan for 990224:

MP 214 ICRF Development

Start with a fiducial-like .8 MA shot, with an added B_T jog for ECE
pedestal measurements during RF.

Move plasma up 1 to 2 cm for edge Thomson evaluation.

Scan toroidal field from 5 T to 6 T to move RF resonance.

Scan outer gap.

Raise I_p to 1 MA.

Density scans are also possible.

We will be aiming for reliable simultaneous high power operation of the D and E
port systems.

ST1: 590 PS1: 422 ST2: 2390 PS2: 1043

001 plasma - multiple H-modes
faults on #2
H/D increases from 0.6-0.1 during RF
next shot: reduce power so both run cleanly

002 plasma - H-mode
screen overcurrent on #1 - retrys are too fast
#2 fault

ST1: 590 PS1: 422 ST2: 2476 PS2: 992

003 plasma - H-mode
still have faults
#2 fault seems induced by #1
004 plasma - H-modes
#2 fault seems induced by #1

next shot: retune and raise power

005 plasma - H-modes
006 plasma - H-modes
007 plasma - H-modes
008 plasma - H-modes
009 plasma - H-modes

between shot 5 minute ECDC in D

010 plasma - early disruption

next shot: turn off Ar to see if EDA remains

011 plasma -
RF still faulting
next shot; lower RF power by 2
012 plasma

Faults seem to be real events - D phase balance and E arc detector
correspond but the traces are going the correct direction.

013 plasma

Same faulting problem - Lower the power to 400 kW/xmtr

014 plasma - NO RF faulting (of course the power is a mere 800 kW)

next shot: raise power by 150 kW/xmtr
015 plasma - D failed to fire because the hi-voltage turned itself
off. FPA screen voltage and current were low - occurred without
alarm.

016 plasma simultaneous faults

017 plasma phase balance in D
018 plasma
phase balance and MIT arc detector
019 plasma
phase balance and MIT arc detector
020 plasma clean low power RF

RF operates without faults ~450 kW and begins faulting above ~500 kW.
The faults are simultaneous on D and E port where D-port had a phase
balance fault and E-port had a MIT arc detector fault.

next shot: raise power (~100kW)and separate D and E with some overlap

021 plasma
no faults during the overlap but D had a phase balance fault
and E-port had a PPPL arc detect fault.

next shot: raise power (~100kW)

022 plasma
clean RF @1.3 MW

next shot: complete overlap and raise power (~100 kW)

023 plasma
not so clean RF
0.64 D-port MIT arc detector; the remainder are phase balance
E-port's single fault is a PPPL arc detector

next shot: repeat

024 plasma
phase balance and PPPL arc detector
025 plasma
E-port is clean
D-port has phase balance and both arc detectors signalling
Next shot: raise PRF by ~100 kW

026 plasma
two faults in FMIT#2 and two on FMIT#1
next shot: raise power to 1 MW

027 plasma
faults on both but few

028 plasma
faults on both
E-port has a PPPL arc detect
D-port has phase balance and MIT arc detect

next shot: raise power by ~200 kW/xmtr

029 plasma - lousy rf


FMIT#1's power feedback performed quite well (maintained power within
~15% of requested for varying loads). Numerous faults continued
throughout the run. Vacuum conditioning was performed following the
run and it was found that the antennas were essentially unconditioned.
This was rather surprising since the previous experience suggests that the
vacuum condition could be maintained for weeks of plasma operation.
This incident suggests the vacuum condition has become suspect after a few
days. It does however offer some hope that the problems with the RF
can be solved with further vacuum conditioning.

Physics Operator Summaries
Entered: Jul 7 2004 04:37:00:287PM
Author: To Be Determined
Physop run summary 990224

EO: Silva/DeKow
SL: Wukitch
PO: Marmar

MP 214 ICRF Development

Plan:

Start with a fiducial-like .8 MA shot, with an added B_T jog for ECE
pedestal measurements during RF.

A) Move plasma up 1 to 2 cm for edge Thomson evaluation.

B) Scan toroidal field from 5 T to 6 T to move RF resonance.

C) Raise I_p to 1 MA.

D) Density scans are also possible.

E) We will be aiming for reliable simultaneous high power operation of the D and E
port systems. This is the main purpose of the run.

Engineering Setup:

2 hours ECDC in D_2 before the run, ending at 8:00 am.

Power supply settings from 990223021.

TF under hybrid control

Gas setup - fill B-top with 6 psi of D2 Hybrid enabled
fill B-side lower with 1 psi of Ar Hybrid enabled
pump B-side upper and leave evacuated Hybrid DISABLED
fill C-side with 30 psi of D2 Hybrid enabled
fill J-bottom with 2 psi of Kr Hybrid DISABLED
We want hydrogen and helium-4 available, for possible use in B-side upper,
so the neon bottle should be removed from the system and replaced with
hydrogen.

Load from 990223021 for segment 1
990219024 for segment 2 (.8 MA, 5.4 T); leave B_T jog for ECE


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

ECE, VUV


Results:

The machine ran reliably today, with 29 consecutive successful startsup. All but
1 shot ran through the ramp-down. There were no changes made to the segment 1
programming during the run.

A) was achieved, and data were obtained on the edge Thomson system and the
soft x-ray array looking at the pedestal near the top of the plasma.

B) and C) were not attempted.

D) Target density was scanned from 1e20 to 1.5e20.

The bulk of the run was devoted to E). Operation above 2MW was achieved, with
trips. See the session leader's summary for details.

Some piggybacking with krypton puffing in support of the investigation of high
Z screening was also accomplished; krypton was puffed on shots 23 through 28.
Measurements were made with the divertor RGA and HIREX. Data for atomic physics
investigations of highly charged krypton were also obtained on these shots,
with both the McPherson and HIREX. The krypton appeared to prevent access to
EDA H-mode at ICRF powers up to 2 MW, with type III ELMs being the norm.

The H/D ratio is systematically higher this week than it was immediately after
boronization, approaching .08 to .1 on many shots today. ECDC for 5 minutes in
D_2 was tried prior to shot 10, which disrupted early. The current rise was
slower on shot 10 than it was on other shots. The H/D ratio was lower on shot
11 (~.07) compared to shot 9 (~.09), at the times of maximum stored energy on
each shot.

The disruption resulted from a vertical position oscillation starting around .3
seconds, which had been happening all day, as well as on the shot we loaded
from, 990219024; the plasma did not survive it on shot 10. The oscillation was
fixed by ramping RCUR out more quickly in the early part of segment 2, starting
on shot 21. ZXL ramp changes, also in the early part of segment 2, reduced the
oscillations between shots 11 and 20, but were not as effective as the RCUR
change.

The plasma was moved up, by about 1 cm relative to our normal ZCUR settings,
starting on shot 3. The details of the position ramp were changed from shot to
shot, as detailed in the logbook. The vertical position was returned to its
nominal value starting with shot 19. Minor ZXL and ZXU tweaks accompanied the
ZCUR changes. Dimitri reported seeing signals on many more of the edge Thomson
spatial channels (more than 10) for the displaced plasmas.

There were some engineering highway camac problems early in the run. They did
not recur after the relevant highway driver was toggled off/on. All other
engineering systems performed without incident.

Scorecard:

29 plasmas
0 fizzles
0 duds

29 total shot cycles

Session Leader Comments
Feb 24 1999 10:12:54:030AM990224002Steve Wukitch002 plasma - H-mode
screen overcurrent on #1
#2 fault
Feb 24 1999 10:27:51:513AM990224003Steve Wukitch003 plasma - H-mode
still have faults
Feb 24 1999 10:29:39:937AM990224004Steve Wukitch004 plasma - H-modes
#2 fault seems induced by #1

next shot: retune and raise power
Feb 24 1999 11:58:04:140AM990224010Steve Wukitchbetween shot 5 minute ECDC in D

010 plasma - early disruption
Feb 24 1999 12:29:12:310PM990224011Steve Wukitchnext shot: turn off Ar to see if EDA remains

011 plasma -
RF still faulting
Feb 24 1999 12:54:00:060PM990224012Steve Wukitch012 plasma

Faults seem to be real events - D phase balance and E arc detector
correspond but the traces are going the correct direction.
Feb 24 1999 12:54:17:250PM990224013Steve Wukitch013 plasma

Same faulting problem - Lower the power to 400 kW/xmtr
Feb 24 1999 01:43:40:450PM990224014Steve Wukitch014 plasma - NO RF faulting (of course the power is a mere 800 kW)

next shot: raise power by 150 kW/xmtr
Feb 24 1999 01:43:59:077PM990224015Steve Wukitch015 plasma - D failed to fire because the hi-voltage turned itself
off. FPA screen voltage and current were low - occurred without
alarm.
Feb 24 1999 01:50:34:467PM990224016Steve Wukitch016 plasma simultaneous faults
Feb 24 1999 02:35:44:233PM990224017Steve Wukitch017 plasma phase balance in D
Feb 24 1999 02:35:55:590PM990224018Steve Wukitch018 plasma
phase balance and MIT arc detector
Feb 24 1999 02:36:12:200PM990224019Steve Wukitch019 plasma
phase balance and MIT arc detector
Feb 24 1999 02:36:28:390PM990224020Steve Wukitch020 plasma clean low power RF

next shot: raise power and separate D and E with overlap
Feb 24 1999 02:55:56:543PM990224021Steve Wukitch021 plasma
no faults during the overlap but D had a phase balance fault
and E-port had a PPPL arc detect fault.

next shot: raise power (~100kW)
Feb 24 1999 03:12:52:640PM990224022Steve Wukitch022 plasma
clean RF @1.3 MW

next shot: complete overlap and raise power (~100 kW)
Feb 24 1999 03:30:02:513PM990224023Steve Wukitch023 plasma
not so clean RF
0.64 D-port MIT arc detector; the remainder are phase balance
E-port's single fault is a PPPL arc detector

next shot: repeat
Feb 24 1999 03:55:23:530PM990224024Steve Wukitch024 plasma
phase balance and PPPL arc detector
Feb 24 1999 03:56:05:373PM990224025Steve Wukitch025 plasma
E-port is clean
D-port has phase balance and both arc detectors signalling

Next shot: raise PRF by ~100 kW
Feb 24 1999 04:16:05:857PM990224026Steve Wukitch026 plasma
two faults in FMIT#2 and two on FMIT#1
next shot: raise power to 1 MW
Feb 24 1999 04:39:37:420PM990224027Steve Wukitch027 plasma
faults on both but few
Feb 24 1999 04:50:38:420PM990224028Steve Wukitch028 plasma
faults on both
E-port has a PPPL arc detect
D-port has phase balance and MIT arc detect

next shot: raise power by ~200 kW/xmtr

Physics Operator Comments
Feb 24 1999 08:33:03:873AMEarl MarmarMP214 ICRF Development

Coldstart Hybrid
no errors
all matrices respond

load from
990223021 for segment 1
990219024 for segment 2

Argon pulse to 30 msec


Feb 24 1999 09:22:55:483AM990224001Earl MarmarPlasma; current rise has slight hesitation, but looks ok

1.6 MW RF; H-modes; some trips

Dithering between EDA and ELMfree
Feb 24 1999 09:48:43:263AM990224002Earl Marmarno PCS changes

plasma

2 MW RF and then tripping

1 H-Mode, semi-EDA-ish
Feb 24 1999 10:01:34:810AM990224003Earl MarmarMove plasma gradually up during shot, total excursion 1 cm

raise ZXU ~1 cm
raise ZXL gradually, also 1 cm by 1.2 s

plasma

moved up a few mm
Feb 24 1999 10:30:58:043AM990224004Earl MarmarMove ZXL up a little more

move ZCUR up a little more

plasma
Feb 24 1999 10:39:39:840AM990224005Earl Marmarno PCS changes

plasma
Feb 24 1999 10:57:18:687AM990224006Earl MarmarNo PCS changes

plasma
Feb 24 1999 11:10:22:623AM990224007Earl Marmarraise nl_04 to 1.1e20

plasma
Feb 24 1999 11:28:16:217AM990224008Earl Marmarraise nl_04 to 1.2e20

increase voltage on PG_3 in seg 1 between 70 and 100 ms

plasma
Feb 24 1999 11:44:25:090AM990224009Earl Marmarno PCS changes

plasma
Feb 24 1999 12:02:21:840PM990224010Earl MarmarECDC 4.5 minutes in D_2 before the shot

disable argon puff

disrupt early (.35 s)

plasmas have been vertically oscillating at this time all day; this time we lost it.


Feb 24 1999 12:17:46:187PM990224011Earl MarmarPull ZXL down more gently between .1 and .4 sec, and not quite so far

plasma

still wobbling vertically around .3 s

elongation was slightly reduced before cross-over
Feb 24 1999 12:34:18:577PM990224012Earl Marmarbring ZXL up a little more before 0.4 s

argon back on

plasma

vertical oscillation at 0.3 s reduced
Feb 24 1999 12:51:01:060PM990224013Earl Marmarmove B_T jog 100 ms earlier

plasma

Feb 24 1999 01:08:23:513PM990224014Earl Marmarramp ZCUR up sooner (to reach max at 0.8 s)

plasma

got the faster vertical ramp
Feb 24 1999 01:37:37:670PM990224014Earl Marmarchange B_T sweep to come back after the excursion to 150kA until 1.2 s

Plasma
Feb 24 1999 01:37:58:857PM990224015Earl Marmarno changes

plasma
Feb 24 1999 01:38:09:857PM990224016Earl Marmarno changes

plasma
Feb 24 1999 01:52:41:640PM990224017Earl Marmarraise nl_04 to 1.3e20; add volts to PG3 programming in segment 2

plasma

got the density we asked for
Feb 24 1999 02:07:41:967PM990224018Earl Marmarnl_04 to 1.5e20


plasma; no RF
Feb 24 1999 02:35:11:043PM990224019Earl Marmareliminate vertical position shift

nl_04 to 1.1e20; reduce volts on PF3 preprog in seg 2

plasma
Feb 24 1999 02:35:25:687PM990224020Earl Marmarno PCS changes

plasma
Feb 24 1999 02:55:39:390PM990224021Earl MarmarMove RCUR out a little sooner; try to keep minor radius more constant around .3 to .4 seconds

plasma

RCUR tweak seemed to help; vertical lurching was reduced.
Feb 24 1999 03:09:50:763PM990224022Earl Marmarno PCS changes

plasma
Feb 24 1999 03:22:37:140PM990224023Earl Marmardisable argon

enable krypton, 15 msec puff starting at 0.4 seconds

plasma
Feb 24 1999 03:52:52:543PM990224024Earl Marmarincrease Kr puff length to 25 msec from 15 msec

plasma
Feb 24 1999 03:53:16:153PM990224024Earl Marmarno PCS changes

plasma
Feb 24 1999 04:06:25:793PM990224025Earl Marmarno pcs changes

plasma
Feb 24 1999 04:17:38:123PM990224026Earl Marmarno PCS changes

plasma
Feb 24 1999 04:32:16:920PM990224027Earl Marmarno PCS changes

plasma
Feb 24 1999 04:47:24:340PM990224028Earl Marmarreduce krypton puff by 5 msec (to 20 msec)

plasma
Feb 24 1999 05:08:24:373PM990224029Earl MarmarKrypton off

Argon on, 25 msec starting at 0.375

nl_04 to 1.25e20

plasma

Engineering Operator Comments
ShotTimeTypeStatusComment
109:12:37:590AMPlasmaOk0915 no faults/plasma
209:37:26:687AMPlasmaOkno faults/plasma
309:51:17:390AMPlasmaOkno faults/plasma
410:12:51:840AMPlasmaOkno faults/plasma
510:29:33:187AMPlasmaOkno faults/plasma
610:45:24:623AMPlasmaOkno faults/plasma
711:02:04:750AMPlasmaOkno faults/plasma
811:15:27:153AMPlasmaOkno faults/plasma
911:32:20:653AMPlasmaOkno faults/plasma
1011:49:12:763AMPlasmaOkno faults/plasma disruption
1112:07:40:513PMPlasmaOkno faults/plasma
1212:21:50:920PMPlasmaOkno faults/plasma
1312:42:28:140PMPlasmaOkno faults/plasma
1412:56:28:560PMPlasmaOkno faults/plasma
1501:10:36:873PMPlasmaOkno faults/plasma
1601:25:41:420PMPlasmaOkno faults/plasma
1701:41:23:390PMPlasmaOkno faults/plasma
1801:59:15:903PMPlasmaOkNo Faults / Plasma
1902:13:54:623PMPlasmaOkNo Faults / Plasma
2002:32:44:030PMPlasmaOkNo Faults
2102:45:51:437PMPlasmaOkNo Faults / Plasma
2203:02:45:217PMPlasmaOkNo Faults / Plasma
2303:17:42:840PMPlasmaOkNo Faults / Plasma
2403:31:40:077PMPlasmaOkNo Faults / Plasma
2503:48:22:983PMPlasmaOkNo Faults / Plasma
2604:07:25:293PMPlasmaOkNo Faults / Plasma
2704:21:25:640PMPlasmaOkNo Faults / Plasma
2804:40:13:513PMPlasmaOkNo Faults / Plasma
2904:54:24:653PMPlasmaOkNo Faults / Plasma