Alcator C-Mod Run 1000621 Information

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Miniproposals
Miniproposal:225
Date Filed: 1/14/1999
Title:Determination of the Mo source which dominates the core Mo levels
First Author:Bruce Lipschultz
Session Leader:Bruce Lipschultz (shots 1-20)
Miniproposal:268
Date Filed: 4/7/2000
Title:Conditioning of D-, E-, or J-Port ICRF Antenna
First Author:Gerd Schilling
Session Leader:Bruce Lipschultz (shots 1-20)

Operators
Session leader(s):Bruce Lipschultz,Bruce Lipschultz
Physics operator(s):Ron Parker
Engineering operator(s):Gary Dekow,Bill Cochran

Engineering Operator Run Comment
MP 268 ICRF Commissioning and MP 225 Impurity Screening. Wukitch/Lipsch

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:24:493PM
Author: To Be Determined
PO - Parker
EO - Cochrane
SL - Wukitch/Lipschultz

The primary goal of today's run is to evaluate the effect of changes made
in the J-Port antenna. The 2 outer straps were shorted to ground and the
inner 2 straps will be operated as a single 2-strap antenna. The idea is
that most of the parasitic loading, which the RF group thinks is leading
to the reduced power coupled to the plasma, is due to power launched
at the back of the antenna at the high voltage regions associated with the
2 outer straps.

The evaluation of the antenna performance will include a number of
steps, which must be dealt with around the fact that there is a review
of the potential changes for the J-port antenna. This review will be
ocurring in parallel with the run and so the order of occurrence may
vary from the shot plan posted.

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

Run plan:

For first plasma shot, load from 1000512016 (1 MA, 5.2 T)

Most shots will be inner wall limited.

1. Emissive probe comparison right gap 2 cm, nl_01~1.2
staircase RF power as shot (2 shots)
like 1000512016
2. Sources/core impurity comparison
staircase RF power like 1000512016 (3 shots)
3. Perform Power ramp [1-250 kW/each] for loading studies.
at ~0.5, 1.0, 1.5, 2. cm right gap (5 shots)
like shot 1000614004
4. Pabs measurement at right gap of 1.5 cm for each antenna (2 shots)
like shot 1000614013
5. Emissive probe comparison current scan
Ip=[0.6,.8,1.2] (3 shots)

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

shot 1: shot went with some difficulty in current rise. D and E fired, but not
J.
plasma
innner wall limited
D and En were flawless
J was mistuned

next shot: retune J and repeat

shot 2: Repeat of 1. Stll no J power.
plasma
innner wall limited
D and E were flawless
J was mistuned

next shot: retune J and repeat

shot 3: no changes - still no J port

plasma
innner wall limited
D and E were flawless
J was mistuned

next shot: retune J and repeat

shot 4: some amount of J-port power this time. They can now attempt to
tune it.
plasma
innner wall limited
D and E were flawless
J much better

next shot: retune J and repeat

shot 5: 0.8 MW on J. Tuning to continue.
plasma
innner wall limited
D and E were flawless
J much better

next shot: retune J and repeat

shot 6: fizzle

shot 7: SOme arcs on J, still tuning.
plasma
innner wall limited
D and E were flawless
J much better

next shot: retune J and repeat

shot 8: fizzle

shot 9: still limited power on J-port - 1 MW. Transmitter issues.
plasma - J-port is matched, but power limited
2 cm right gap

shot 10: J-port limited to 900 kW. So this shot switched over to power ramps to
get the loading resistance
plasma
2 cm right gap
250 kW ramps from all three

next shot: 1.5 cm right gap

shot 11: fizzle

shot 12: power ramps, outer gap at 1.5 cm

012 plasma
1.5 cm right gap
250 kW ramps from all three

next shot: 1.5 cm right gap

shot 13: fizzle

shot 14: power ramp, outer gap = 1. cm

shot 15: OH test

shot 16: fizzle

shot 17: ok shot. J, D and E at 1 MW each square wave 300 ms each. This is
to determine the heating efficiency of each antenna by looking at the Te
decay at shutoff. This shot was inner wall limited and 1.5 cm outer gap.
Neutrons from each seem similar which would indicate that the antenna
change to J has helped.

plasma
right gap ~1.5 cm
good shot
D,E and J - PABS calc

next shot: repeat

shot 18: fizzle

shot 19: a repeat of 17 to look at power absorption.


Summary:

We completed part of this run. J-port began slowly (had difficulty
finding a good match) but 017 suggests that as a dipole J-port heats
approximately as well as D and E according to central Te and neutrons.
Further analysis will analyze Pabs from stored magnetic energy. This
suggests that properly grounding the antenna box and shielding the
feed straps should improve the 4-strap configuration.

Physics Operator Summaries
Entered: Jul 7 2004 04:37:11:427PM
Author: To Be Determined
Run Plan and Engineering Setup for 1000621

MP 268: ICRF Commissioning
MP 225: Impurity Screening

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

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

Engineering Setup:

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

Run begins at 9:00 and ends at 17:00.

Power system setup: Same as for 1000616001

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 2 psi Krypton Hybrid DISABLED ** NOTE!!
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, HIREXjr

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

Run Plan:

For first shot, load from 1000512016 (1 MA, 5.2 T)

Most shots will be inner wall limited

1. Emissive probe comparison, right gap ~2 cm, nl_04 ~ 1.0
Staircase RF power. Similar to shot 1000512016 (2 Shots)

2. Sources/core impurity comparison.
Staircase RF power, with shot similar to 1000512016 (3 Shots)

3. Perform Power Ramp Studies (1-250 kW each) for loading studies,
with right gap at ~0.5, 1.0, 1.5, 2.0 cm. Similar to shot 1000614004
(5 Shots)

4. Pabs measurement with right gap set at 1.5 cm for each antenna. Shot
similar to 1000614013

5. Emissive probe comparison scan. Ip=0.6, 0.8, 1.2 MA. (3 Shots).
-----------------------------------------------------------

RUN SUMMARY

A very frustrating run with many fizzles. Nevertheless some useful data
were obtained.

All shots except the last were limited in order to avoid changes in loading
due to onset of H mode.

The first 9 shots were patterned after 1000512016 and, except for minor tuning
of the startup phase, were identical. The first 5 shots ran perfectly, lulling
the Physop into thinking this would be an easy day. However, shot 6 fizzled,
shot 7 ran as programmed, and shot 8 fizzled again, followed by a normal shot 9.
At this point, shot 1000614004 was loaded to check RF loading as a function of
right gap. The pattern of every other shot fizzling (sp?) continued. Even so
useful data were produced on the comparison of D and E antennas with the
reconfigured J port antenna. On shot 16, a problem developed during the
countdown with the OH 1 power supply, causing a 1 hour delay. Apparently, the
problem fixed itself. Shot 17 ran as programmed, but shot 18 was a dud. At
this point, Steve Wolfe noticed a strong 28 peak on the RGA and we suspected
a leak, a suspicion that was confirmed after the run. The last 2 shots, 19 and
20 ran as programmed, with shot 20 being diverted at the request of B.
Lipschultz. It was noted that on shot 20, the BZ(0) was 0, to within measurement
accuracy, but was about 1 mT on some of the fizzles. Thus variability in the
BZ null could, in addition to the effects of the leak, have caused the large
number of fizzles (5) and the one dud. As mentioned, the leak was confirmed
and traced to F port, due to inadequate heating of the seal. Hopefully it will
not be a problem for the rest of the campaign. One should also keep an eye on
the BZ null variability, presumably connected with differential cooling of the
upper and lower coils.



Session Leader Comments
Jun 21 2000 09:02:54:827AMBruce LipschultzPO - Parker
EO - Cochrane
SL - Wukitch/Lipschultz

The primary goal of today's run is to evaluate the effect of changes made
in the J-Port antenna. The 2 outer straps were shorted to ground and the
inner 2 straps will be operated as a single 2-strap antenna. The idea is
that most of the parasitic loading, which the RF group thinks is leading
to the reduced power coupled to the plasma, is due to power launched
at the back of the antenna at the high voltage regions associated with the
2 outer straps.

The evaluation of the antenna performance will include a number of
steps, which must be dealt with around the fact that there is a review
of the potential changes for the J-port antenna. This review will be
ocurring in parallel with the run and so the order of occurrence may
vary from the shot plan posted.
Jun 21 2000 09:34:51:077AM1000621001Bruce Lipschultzshot 1: shot went with some difficulty in current rise. D and E fired, but not J.
Jun 21 2000 09:51:41:793AM1000621002Bruce Lipschultzshot 2: Repeat of 1. Stll no J power.
Jun 21 2000 10:09:21:310AM1000621003Bruce Lipschultzshot 3: no changes - still no J port
Jun 21 2000 10:48:07:717AM1000621004Bruce Lipschultzshot 4: some amount of J-port power this time. They can now attempt to
tune it.
Jun 21 2000 10:48:24:890AM1000621004Bruce Lipschultzshot 4: some amount of J-port power this time. They can now attempt to
tune it.
Jun 21 2000 11:09:00:763AM1000621005Bruce Lipschultzshot 5: 0.8 MW on J. Tuning to continue.
Jun 21 2000 11:21:31:263AM1000621006Bruce Lipschultzshot 6: fizzle
Jun 21 2000 11:51:47:217AM1000621007Bruce Lipschultzshot 7: SOme arcs on J, still tuning.
Jun 21 2000 12:08:35:530PM1000621008Bruce Lipschultzshot 8: fizzle
Jun 21 2000 12:30:05:497PM1000621009Bruce Lipschultzshot 9: still limited power on J-port - 1 MW. Transmitter issues.
Jun 21 2000 12:30:16:653PM1000621009Bruce Lipschultzshot 9: still limited power on J-port - 1 MW. Transmitter issues.
Jun 21 2000 02:20:12:310PM1000621010Bruce Lipschultzshot 10: J-port limited to 900 kW. So this shot switched over to power ramps to
get the loading resistance
Jun 21 2000 02:20:44:343PM1000621011Bruce Lipschultzshot 11: fizzle
Jun 21 2000 02:22:16:763PM1000621012Bruce Lipschultzshot 12: power ramps, outer gap at 1.5 cm
Jun 21 2000 02:22:26:030PM1000621013Bruce Lipschultzshot 13: fizzle
Jun 21 2000 02:23:10:903PM1000621014Bruce Lipschultzshot 14: power ramp, outer gap = 1. cm
Jun 21 2000 02:43:27:480PM1000621015Bruce Lipschultzshot 15: OH test
Jun 21 2000 04:03:48:857PM1000621016Bruce Lipschultzshot 16: fizzle
Jun 21 2000 04:13:29:967PM1000621017Bruce Lipschultzshot 17: ok shot. J, D and E at 1 MW each square wave 300 ms each. This is
to determine the heating efficiency of each antenna by looking at the Te
decay at shutoff. This shot was inner wall limited and 1.5 cm outer gap.
Neutrons from each seem similar which would indicate that the antenna
change to J has helped.
Jun 21 2000 04:34:50:077PM1000621018Bruce Lipschultzshot 18: fizzle
Jun 21 2000 04:53:01:530PM1000621019Bruce Lipschultzshot 19: a repeat of 17 to look at power absorption.

Physics Operator Comments
Jun 21 2000 09:38:43:263AM1000621001Ron ParkerShot 1 was programmed from shot 1000516001. It ran as programmed but
with a somewhat erratic startup. Fill pressure and BZ(0) will be tuned
for next shot.
Jun 21 2000 09:36:23:593AM1000621002Ron ParkerShot 2 was a repeat of shot 1, with some tuning of the startup.
Initial fill pulse was extended by 2 msec to 20 msec and IC4 was
decreased by 10 A to -1290.
Jun 21 2000 10:11:13:750AM1000621003Ron ParkerShot 3 was another repeat -- no changes from shot 2. Startup still erratic
around crossover. SW points out that current rise is exceeding programmed waveform, which
may cause the hesitations in the current rise. For next shot, the demand for Ip will be
increased. Also, clearin decreased by a few mm.
Jun 21 2000 10:49:51:403AM1000621004Ron ParkerShot 4 was again a repeat, with the changes noted in the entry for the last shot.
Current rise was improved as a result of setting the demand closer to the actual
early rate of rise. I/B seems to be getting a little higher in the early phase, so
EF4 current increased by 10 A to -1280.

Problem noted with Ross relay in power room, requiring power room entry.
15 minute delay as a result.

No changes for next shot.
Jun 21 2000 11:30:22:123AM1000621005Ron ParkerShot 5 ran as programmed. Current rise still a little erratic, with demand running
behind actual. Demand will be increased slightly on next shot. Breakdown and startup
look good.

Next shot: no changes, except as noted above.
Jun 21 2000 11:31:47:030AM1000621006Ron Parker
Shot 6 was a fizzle, with slower current rise than earlier shots.
Next shot: pulse gas fill increased by 2 msec to 22 msec.
Jun 21 2000 11:49:44:293AM1000621007Ron ParkerPlasma came back, but breakdown is still slower than in earlier shots.

No change for next shot.
Jun 21 2000 12:04:18:280PM1000621008Ron ParkerShot 8 was again a fizzle. Breakdown is ~1 msec late and current rise hesitates.
For next shot, decrease EF4 current from 1280 to 1290 A.
Jun 21 2000 12:52:11:123PM1000621009Ron ParkerShot came back as initial breakdown occurred at 6.5 msec, compared to
7.7 msec on last shot which fizzled.

Power room and cell access. 25 minute delay for RF deliberations and access to
power room.


Jun 21 2000 01:05:43:780PM1000621010Ron ParkerShot 1000614004 was loaded for this shot, and ran as programmed.

We are now varying the right gap, beginning with 2 cm on this shot.

Next shot: similar, but right gap should be 1.5 cm (RCUR increasd by 3 mm).
Jun 21 2000 01:27:56:763PM1000621011Ron Parker
Another fizzle! Too much gas?
Next shot will have the fill pulse reduced in duration from 25 to 20 msec.

Note: Fill pulse should have been reduced when shot 1000614004 was loaded.
Jun 21 2000 01:43:00:730PM1000621012Ron ParkerShot ran with right gap at ~ 1.4 cm. Initial fill pressure dropped to ~0.042 mT and
initial breakdown and current rise were good.

Next shot: right gap set for ~ 1 cm. No change in startup conditions.
Jun 21 2000 02:03:42:560PM1000621013Ron ParkerAnother fizzle--every other shot! Why?

Try a little less EF4 current at -1295 A.
Jun 21 2000 02:31:51:763PM1000621014Ron ParkerThis shot ran as programmed, EF4 current at -1295 A.

Next shot: Right gap set @ 1.4 cm (as in shot 12)

Shot interrupted due to OH 1 power supply problem -- type 3 fault.

Count down continued, but no shot.
Jun 21 2000 02:30:59:247PM1000621015Ron ParkerShot 15 was interrupted due to OH 1 fault.
Power room entry to check problem.
Jun 21 2000 03:51:19:640PM1000621016Ron ParkerShot 16 was another fizzle. 1 hour delay due to OH 1 problem.
Jun 21 2000 04:09:21:230PM1000621017Ron ParkerShot 17 ran with a few small tunes on the startup: 1 msec more gas, from 20 to 21 msec,
and decreased BR offset from .00035 to 0.00025.

No changes for next shot.
Jun 21 2000 04:36:52:047PM1000621018Ron Parker
This shot was a dud. No apparent reason as far as field null is concerned.
There is a strong 28 peak on RGA which suggests possibility of a leak.
Also 32 peak is present and dies after each fizzle, rising after each shot.

Gas pulse increased for next shot by 2 msec.
Jun 21 2000 05:02:42:437PM1000621019Ron Parker
Shot 19 ran as programmed. Breakdown is still a little late -- 6.6 msec on
z meter. Pressure is also still a bit low, 0.04 mT.

Last shot coming up, and will be programmed to be diverted.
We continue to suspect a leak.
Jun 21 2000 05:23:02:280PM1000621020Ron Parker
Shot ran as programmed, no fizzle. Surprising was the BZ trace, essentially zero
although on shot 16, with identical settings of EF4, it was about 1 mT -- and 16
was a fizzle.

Engineering Operator Comments
ShotTimeTypeStatusComment
109:08:34:950AMPlasmaOk
209:31:58:873AMPlasmaOk
309:50:57:327AMPlasmaOk
410:15:16:903AMPlasmaOk
510:49:20:577AMPlasmaOk
611:10:40:920AMPlasmaOk
711:32:23:123AMPlasmaOk
811:52:58:530AMPlasmaOk
912:08:31:873PMPlasmaOk
1012:52:46:687PMPlasmaOk
1101:10:39:200PMPlasmaOk
1201:26:40:937PMPlasmaOk
1301:46:37:403PMPlasmaOk
1402:03:56:933PMPlasmaOk
1502:23:41:593PMPlasmaBadOH1 Type 3 Flt during Init, shot aborted.
1603:32:54:297PMPlasmaOk
1703:50:45:937PMPlasmaOk
1804:18:14:343PMPlasmaOk
1904:37:50:153PMPlasmaOk
2005:02:04:153PMPlasmaOk