Alcator C-Mod Run 1000817 Information

Back to runs

Miniproposals
Miniproposal:
Date Filed:
Title:
First Author:
Session Leader:Steve Wolfe (shots 1-19)

Operators
Session leader(s):Steve Wolfe
Physics operator(s):Robert Granetz
Engineering operator(s):Bill Parkin,Bill Cochran

Engineering Operator Run Comment
Begin Plasma Operation After July Shutdown.Wolfe/Granetz/Cochran.

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:24:633PM
Author: To Be Determined
Plasma Startup (first run since June 2000)
SL: wolfe
PO: granetz
EO: cochran,parkin

The main goal of this run is to re-establish plasma operation after the July
vent. Once this is done, we will be running standard discharges for the
purpose of machine conditioning and for bringing diagnostics back online. RF
is not ready to fire today.

Yesterday's power system tests were completed successfully, and an initial
plasma attempt (1000816029) resulted in a late breakdown.

The G-port Ratiomatic gauge was still being worked on this morning. The A-port
camera has been reinstalled and is displayed on the monitor at the front of
the control room.

Results:
--------

A problem with the ACCESS CONTROL system delayed the start of the run until
after 11:00.

The first shot was a short, resistive plasma which disrupted at 0.2sec. After
a couple of fizzles, which had very high CII and Z-meter signals, and a few
tweaks which may not have made any difference, we got a nearly full length
shot on #5, which lasted into rampdown.

Shot 5 was followed by a lot of fizzles interspersed with a feq short
disruptive shots. These seemed to be characterized by uncontrolled density
increases with the gas valve off.

The next good shot was 15, which ran to 1.87 sec, essentially full
length. Shot 17 was another good, long shot. H/D was high, still at 1.2 on
shot 17. Startup seems to have gotten into alternating sequence by the end of
the run, which is usually a sign that we are beginning to get the walls
cleaned up.

Other notable points:

The eight RF-limiter BP coils that Joe Snipes put on integrators are giving
good data. EFIT was run using these signals for shot 5, results in tree
EFIT01_1000817005. A preliminary comparison indicates the new data tends to
move the outboard edge in by ~4mm. A mode 7 snap file efit_snap.dat_rfbp is
now in the default directory; it specifies EFIT01 as MDS_TREE.

The interferometer analysis program stopped working sometime between shot 5
and shot 13. Jim discovered that the wrong channel was being used to determine
the end of shot time, and fixed it.

The OH2L coax resistance began the day at over 2uOhms, but dropped to less
than 0.4uOhm by the end of the day.

The G-side Ratiomatic worked after a lot of work in the cell this morning, but
the auto-reset feature still isn't working, so it had to be reset
manually. Brian and Bruce indicated that there is probably still a flakey
connection in the controller as well; they got it to work by tapping it with a
screwdriver!

Power Systems performed well all day. There were some glitches on other
engineering systems, notably the TF scanner.


Physics Operator Summaries
Entered: Jul 7 2004 04:37:11:723PM
Author: To Be Determined
Physics operator summary for run 1000817:

MP ? -- Restart plasma operation after July maintenance shutdown.

Session leader: S. Wolfe
Physics operator: R. Granetz
Engineering operators: B. Cochran/B. Parkin

Summary: Typical startup day. After 2 hours of troubleshooting various
problems, the run proceeded without further troubles. We got into
the familiar plasmas/fizzle/plasma alternating pattern by the end
of the day. There were several full length plasmas (5, 15, 17), and
Stu Zweben got some good helium images of turbulent edge structures
on shots 15 and 17.

Scorecard: 7 plasmas
12 fizzles
0 duds
0 tests
0 aborted
----------
19 total

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

Engineering setup for Thursday, 17 August 2000:

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

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

Power system setup as on 1000816029.

Gas setup - fill B-top with 6 psi of D2 Hybrid enabled
fill B-side lower with 1 psi of Ar Hybrid enabled
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

DNB gate valve will be DISABLED today, since the beamline is not under vacuum.

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

Overnight ECDC in D2 was done, stopping 2 hours prior to the run

Hybrid coldstart done; no errors found

Loaded shot 1000816029 (set up by Jim Irby; 0.8 MA, 5.3 T)

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

The run was delayed nearly 2 hours due to various small problems in the
cell (ratiomatic gauge) and with the access control system.

Shot 01 -- Plasma, but short shot. Terminated at t=0.19 s. Pressure gauge
didn't work. OH2L coax resistance was 2.2 uohms. Initial current
rise was rather slow.

Next shot: reduce Bz0 (-15 amps on IC_EF4). Reduce nl_04 to
0.5e20 m-2.

Shot 02 -- Fizzle. Null looks okay. Pressure reading was >0.08 mTorr.
High signals on CII and Tang. Z-meter. OH2L coax = 2.2 uohms again.

Next shot: reduce pre-fill puff from 26 to 21 ms.

Shot 03 -- Fizzle. Null looks okay. Pre-fill pressure came down to 0.065
mTorr.

Next shot: reduce pre-fill some more, reduce Bz0 a little more.

Shot 04 -- Fizzle. Everything looks okay.

Next shot: reduce RCUR offset in segment 1 from 5500 to 5000, as
requested by Steve.

Shot 05 -- Plasma. Good shot. Made it halfway down the current ramp.
Density was somewhat higher than programmed. The gas valve was
actually off for nearly the entire shot. Carbon level at breakdown
was half of the previous shot.

Next shot: lower pre-fill another 2 ms. Turn off argon.

Shot 06 -- Fizzle.

Next shot: put pre-fill back to what it was for shot 05.

Shot 07 -- Plasma. Terminated at t=0.60 s. Density took off at 0.5 s for
no apparent reason.

Next shot: reduce pre-fill 2 ms (Steve's request)

Shot 08 -- Fizzle.

Next shot: put pre-fill back to what it was for shots 05 and 07.

Shot 09 -- Fizzle.

Next shot: no changes

Shot 10 -- Fizzle.

Next shot: reduce Bz0 (subtract 15 amps from IC_EF4).

Shot 11 -- Fizzle. Null looks okay.

Next shot: gas tweak (shorten by 4 ms) <-- Wrong! see next entry.

Shot 12 -- Fizzle. Oops! I added 4 ms to the gas puff instead of subtracting
4 ms!

Next shot: subtract 8 ms from pre-fill gas puff (now at 15 ms).

Shot 13 -- Plasma. Terminated at t=0.34 s. Still has a significant hesitation
during the intial current rise. Pressure is reading 0.045 mTorr,
but Bruce is not sure if the gauge calibration is still correct.

Next shot: reduce pre-fill puff another 2 ms.

Shot 14 -- Fizzle.

Next shot: put pre-fill puff back to 15 ms.

Shot 15 -- Plasma. Full shot. Stu Zweben got some interesting helium images
showing blobby structures.

Next shot: no changes

Shot 16 -- Fizzle.

Next shot: no changes

Shot 17 -- Plasma. Good shot. nl_04=7.3e19 m-2.

Next shot: no changes

Shot 18 -- Fizzle (as expected)

Next shot: no changes

Shot 19 -- Plasma, but short. Disrupted at t=0.32 s. VDE.

End of run.

Session Leader Comments
Aug 17 2000 11:11:36:140AMSteve WolfePlasma Startup (first run since June 2000)
SL: wolfe
PO: granetz
EO: cochran

The main goal of this run is to re-establish plasma operation after the July
vent. Once this is done, we will be running standard discharges for the
purpose of machine conditioning and for bringing diagnostics back online. RF
is not ready to fire today.

Yesterday's power system tests were completed successfully, and an initial
plasma attempt (1000816029) resulted in a late breakdown.

The G-port Ratiomatic gauge was still being worked on this morning. The A-port
camera has been reinstalled and is displayed on the monitor at the front of
the control room.

A problem with the ACCESS CONTROL system delayed the start of the run until
after 11:00.
Aug 17 2000 11:31:00:247AM1000817001Steve WolfeShot #1: Plasma attempt.
plasma to 190 msec

OH2L coax resistance is at 2.2uohm

plasma very resistive. Try dropping density.
Aug 17 2000 11:57:07:920AM1000817003Steve WolfeShot#3: fizzle. cii is up to .02 (was ~.006)
Need to clean up.

OH coax resistance now down to 1.87
Aug 17 2000 12:23:06:950PM1000817004Steve WolfeShot#4: another fizzle
Aug 17 2000 12:43:38:497PM1000817005Steve WolfeShot#5: tweak rcur offset (5500->5000)
plasma to 1.66sec
H/D=0.7
Aug 17 2000 01:08:15:717PM1000817006Steve WolfeShot#6: fizzle.
Aug 17 2000 01:22:09:607PM1000817007Steve WolfeShot#7: short plasma to ~.6sec
density takes off at 0.5 sec, possible sharkfin?

OH2l coax resistance is now down to 1.33
Earl disabled H/D for this shot to look at his Zeeman BTOR meter.
Aug 17 2000 01:56:40:733PM1000817008Steve WolfeShot#8: fizzle.

oh2l resistance now down to .95uOhm.
Aug 17 2000 02:00:12:123PM1000817009Steve WolfeShot#9: fizzle.

Aug 17 2000 02:17:36:903PM1000817010Steve WolfeShot#10: another fizzle.

oh2l resistance down to .69uOhms, in range of the others.
Cii reaches .025
Bz has crept up a bit.

Aug 17 2000 02:35:43:857PM1000817011Steve WolfeShot#11: fizzle.
breakdown is a little earlier

oh2l coax now down to .57uOHm, oh2u ~.67
Aug 17 2000 02:52:09:543PM1000817012Steve WolfeShot#12: and another fizzle.

Bob added 4msec to the gas instead
of subtracting; oh well, that would have
been the next experiment.
Aug 17 2000 03:14:42:860PM1000817013Steve WolfeShot#13: plasma to .45sec, similar to 7 but ends sooner
current rise is maybe a little better, still too slow.

oh2l coax is down to .396uOhm, now lowest of the three.
Aug 17 2000 03:27:55:047PM1000817014Steve WolfeShot#14: and another fizzle. Can't possibly get two in a row.
Aug 17 2000 03:58:11:437PM1000817015Steve WolfeShot#15: plasma, full length 1.85 sec
interferometer signal stops at .2 sec again, like on shot 13.

Aug 17 2000 04:10:58:047PM1000817016Steve WolfeShot#16: fizzle, of course.
Aug 17 2000 04:36:38:920PM1000817017Steve WolfeShot#17: plasma, full length
H/D is still 1.2
Aug 17 2000 04:50:52:907PM1000817018Steve WolfeShot#18: fizzle. Let's take one more and see if they alternate.
Aug 17 2000 05:06:16:687PM1000817019Steve WolfeShot#19: early disruption, .32 sec; the thrash finally got us.
Anyhow the startups are now in alternating sequence, so we must
be beginning to clean up.

Physics Operator Comments
Aug 17 2000 08:43:10:280AMRobert GranetzEngineering setup for Thursday, 17 August 2000:

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

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

Power system setup as on 1000816029.

Gas setup - fill B-top with 6 psi of D2 Hybrid enabled
fill B-side lower with 1 psi of Ar Hybrid enabled
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

DNB gate valve will be DISABLED today, since the beamline is not under vacuum.
Aug 17 2000 08:43:32:263AMRobert Granetz Overnight ECDC in D2 was done, stopping 2 hours prior to the run

Hybrid coldstart done; no errors found

Loaded shot 1000816029 (set up by Jim Irby; 0.8 MA, 5.3 T)
Aug 17 2000 01:39:03:153PM1000817001Robert GranetzThe run was delayed nearly 2 hours due to various small problems in the
cell (ratiomatic gauge) and with the access control system.

Shot 01 -- Plasma, but short shot. Terminated at t=0.19 s. Pressure gauge
didn't work. OH2L coax resistance was 2.2 uohms. Initial current
rise was rather slow.

Next shot: reduce Bz0 (-15 amps on IC_EF4). Reduce nl_04 to
0.5e20 m-2.
Aug 17 2000 11:45:28:687AM1000817002Robert GranetzShot 02 -- Fizzle. Null looks okay. Pressure reading was >0.08 mTorr.
High signals on CII and Tang. Z-meter. OH2L coax = 2.2 uohms again.

Next shot: reduce pre-fill puff from 26 to 21 ms.
Aug 17 2000 11:58:08:390AM1000817003Robert GranetzShot 03 -- Fizzle. Null looks okay. Pre-fill pressure came down to 0.065
mTorr.

Next shot: reduce pre-fill some more, reduce Bz0 a little more.
Aug 17 2000 12:24:15:280PM1000817004Robert GranetzShot 04 -- Fizzle. Everything looks okay.

Next shot: reduce RCUR offset in segment 1 from 5500 to 5000, as
requested by Steve.
Aug 17 2000 12:41:16:780PM1000817005Robert GranetzShot 05 -- Plasma. Good shot. Made it halfway down the current ramp.
Density was somewhat higher than programmed. The gas valve was
actually off for nearly the entire shot. Carbon level at breakdown
was half of the previous shot.

Next shot: lower pre-fill another 2 ms. Turn off argon.
Aug 17 2000 01:40:06:950PM1000817007Robert GranetzShot 07 -- Plasma. Terminated at t=0.60 s. Density took off at 0.5 s for
no apparent reason.

Next shot: reduce pre-fill 2 ms (Steve's request)
Aug 17 2000 01:51:28:450PM1000817008Robert GranetzShot 08 -- Fizzle.

Next shot: put pre-fill back to what it was for shots 05 and 07.
Aug 17 2000 02:04:40:983PM1000817009Robert GranetzShot 09 -- Fizzle.

Next shot: no changes
Aug 17 2000 02:17:56:467PM1000817010Robert GranetzShot 10 -- Fizzle.

Next shot: reduce Bz0 (subtract 15 amps from IC_EF4).
Aug 17 2000 02:52:59:793PM1000817011Robert GranetzShot 11 -- Fizzle. Null looks okay.

Next shot: gas tweak (shorten by 4 ms) <-- Wrong! see next entry.
Aug 17 2000 02:53:09:247PM1000817012Robert GranetzShot 12 -- Fizzle. Oops! I added 4 ms to the gas puff instead of subtracting
4 ms!

Next shot: subtract 8 ms from pre-fill gas puff (now at 15 ms).
Aug 17 2000 03:13:35:247PM1000817013Robert GranetzShot 13 -- Plasma. Terminated at t=0.34 s. Still has a significant hesitation
during the intial current rise. Pressure is reading 0.045 mTorr,
but Bruce is not sure if the gauge calibration is still correct.

Next shot: reduce pre-fill puff another 2 ms.
Aug 17 2000 03:25:45:983PM1000817014Robert GranetzShot 14 -- Fizzle.

Next shot: put pre-fill puff back to 15 ms.
Aug 17 2000 03:56:42:843PM1000817015Robert GranetzShot 15 -- Plasma. Full shot. Stu Zweben got some interesting helium images
showing blobby structures.

Next shot: no changes
Aug 17 2000 04:14:34:937PM1000817016Robert GranetzShot 16 -- Fizzle.

Next shot: no changes
Aug 17 2000 04:32:31:717PM1000817017Robert GranetzShot 17 -- Plasma. Good shot. nl_04=7.3e19 m-2.

Next shot: no changes
Aug 17 2000 04:52:56:607PM1000817018Robert GranetzShot 18 -- Fizzle (as expected)

Next shot: no changes
Aug 17 2000 05:33:35:140PM1000817019Robert GranetzShot 19 -- Plasma, but short. Disrupted at t=0.32 s. VDE.

End of run.

Engineering Operator Comments
ShotTimeTypeStatusComment
111:15:19:060AMPlasmaOk
211:33:54:403AMPlasmaOk
311:48:24:437AMPlasmaOk
412:11:38:670PMPlasmaOk
512:29:22:937PMPlasmaOk
612:58:31:250PMPlasmaOk
701:14:27:733PMPlasmaOk
801:38:53:590PMPlasmaOk
901:54:29:780PMPlasmaOk
1002:09:10:920PMPlasmaOk
1102:30:28:390PMPlasmaOk
1202:45:19:310PMPlasmaOk
1303:07:04:873PMPlasmaOk
1403:20:50:233PMPlasmaOk
1503:43:44:123PMPlasmaOk
1604:09:29:437PMPlasmaOk
1704:23:04:873PMPlasmaOk
1804:48:41:233PMPlasmaOk
1905:01:29:090PMPlasmaOk