Alcator C-Mod Run 1031119 Information

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Miniproposals
Miniproposal:363
Date Filed:11/13/2003
Title:Investigation of the L-H threshold conditions in Lower null, Double null, Upper Null and Limiter Con
First Author:Amanda Hubbard
Session Leader:Amanda Hubbard (shots 1-8)

Operators
Session leader(s):Amanda Hubbard
Physics operator(s):Robert Granetz
Engineering operator(s): Unknown

Engineering Operator Run Comment
MP #363 L/H Threshold in lower null, upper null, double null and limiter

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Physics Operator Summaries
Entered: Jul 7 2004 04:37:19:753PM
Author: Robert Granetz
Physics operator summary for run 1031119 (Wednesday):

Purpose: MP 363 - L/H Threshold in lower null, upper null, double null, and
limiter configurations

Session leader: A. Hubbard
Physics operator: R. Granetz
Engineers in charge:

Summary: The run had to be cancelled because of a meltdown of the Linux
cluster. The computers weren't revived until late in the
afternoon. This MP will probably be re-scheduled for next week.

Scorecard: 0 plasmas
0 fizzles
0 duds
0 test or no-power shot cycle
0 aborted and/or screwed up by computer problems
----------
0 total

-------------------------------------------------------------------------------
Engineering setup for Wednesday, 19 Nov 2003

MP #363 - L/H Threshold in lower null, upper null, double null, and limiter
configurations

Session leader: A. Hubbard
Physics operator: R. Granetz

ECDC overnight in D2 at 2e-4 Torr, stopping by 07:00.
Bake at 60 C overnight as well.

Run begins at 09:00 and ends at 17:00.

Power systems the same as on 1031118007 (0.8 MA, 5.4 T, UPPER single null)

A-coils should be hooked up as on 1031114027 (+Dtop -Dbot -Jtop +Jbot), and
the power supply should be enabled.

Gas setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar Hybrid enabled (PG1)
leave B-side upper as is Hybrid DISABLED (PG2)
fill C-side with 30 psi D2 Hybrid enabled (PG3)

NO NINJA!

Enable the following gate valves, assuming no vacuum problems:
ECE, VUV, DNB

Necessary diagnostics: Edge TS, GPC, HIREX, TCI, Langmuir probes (ASP, FSP,
and ISP operated in a Mach-flow mode)
Desirable: CXRS, FRCECE, Vis. Brem., Chromex looking at He+1 Doppler flow
through toroidal fiber views of inner and outer SOL

-------------------------------------------------------------------------------
RF Setup: All 4 transmitters in Run On by 08:00. We will need Prf > 3 MW on
many shots.

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

Run Plan: 1) Establish the optimum shape for USN plasmas which gives the
best pedestal region coverage and signal/noise on edge TS.
Start from on of the upper null shots from Brian's MP
(possibly 1031118007, except with nl_04=0.9e20 m-2). Adjust
shape as indicated by Jerry; cell access to adjust fibre
positions if needed. This will determine kappa and delta for
the other configurations.

2) Switch to LSN. 800 kA, ~ 5.4 T. 3-4 shots.
a) Power ramp up to ~ 3 MW, to determine L-H threshold.
b) Discharge with fixed power just below threshold, for
100-200 ms, followed by high power phase (4-5 MW). Repeat
as needed for probe, HIREX.

3) Switch to DN . 5-6 discharges.
a) 2 Discharges at power which gave L-H threshold in LSN
(eg. 1 MW). Document ETS profiles, flows, rotation.
b) Power ramp to maximum available (5 MW>) to determine the
new L-H threshold.
c) As above, make discharges with power just below L-H
transition for ~ 200 ms, followed by higher power to get
H-mode phase.

4) Switch to upper single null (if there's time).

5) Switch to inner wall limiter configuration (if there's time).

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

ECDC was done overnight, as well as a 60 C bake.

Hybrid coldstart done by the engineering group; no errors found

Loaded PCS (all segments) from shot 1031118007 (1.0 MA, 5.4 T, single
null upper), but raised nl_04 to 0.9e20 m-2.

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

Unix cluster melted down again around 08:40. We're in a holding pattern until
Tom can resurrect it.

Tom reports that the delay due to computer problems will take at least a couple
of hours to fix.

14:30 -- The computers are still not working. Run cancelled.

Session Leader Comments

Physics Operator Comments
Nov 18 2003 09:17:39:090PMRobert GranetzEngineering setup for Wednesday, 19 Nov 2003

MP #363 - L/H Threshold in lower null, upper null, double null, and limiter
configurations

Session leader: A. Hubbard
Physics operator: R. Granetz

ECDC overnight in D2 at 2e-4 Torr, stopping by 07:00.
Bake at 60 C overnight as well.

Run begins at 09:00 and ends at 17:00.

Power systems the same as on 1031118007 (0.8 MA, 5.4 T, UPPER single null)

A-coils should be hooked up as on 1031114027 (+Dtop -Dbot -Jtop +Jbot), and
the power supply should be enabled.

Gas setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar Hybrid enabled (PG1)
leave B-side upper as is Hybrid DISABLED (PG2)
fill C-side with 30 psi D2 Hybrid enabled (PG3)

NO NINJA!

Enable the following gate valves, assuming no vacuum problems:
ECE, VUV, DNB

Necessary diagnostics: Edge TS, GPC, HIREX, TCI, Langmuir probes (ASP, FSP,
and ISP operated in a Mach-flow mode)
Desirable: CXRS, FRCECE, Vis. Brem., Chromex looking at He+1 Doppler flow
through toroidal fiber views of inner and outer SOL

-------------------------------------------------------------------------------
RF Setup: All 4 transmitters in Run On by 08:00. We will need Prf > 3 MW on
many shots.

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

Run Plan: 1) Establish the optimum shape for USN plasmas which gives the
best pedestal region coverage and signal/noise on edge TS.
Start from on of the upper null shots from Brian's MP
(possibly 1031118007, except with nl_04=0.9e20 m-2). Adjust
shape as indicated by Jerry; cell access to adjust fibre
positions if needed. This will determine kappa and delta for
the other configurations.

2) Switch to LSN. 800 kA, ~ 5.4 T. 3-4 shots.
a) Power ramp up to ~ 3 MW, to determine L-H threshold.
b) Discharge with fixed power just below threshold, for
100-200 ms, followed by high power phase (4-5 MW). Repeat
as needed for probe, HIREX.

3) Switch to DN . 5-6 discharges.
a) 2 Discharges at power which gave L-H threshold in LSN
(eg. 1 MW). Document ETS profiles, flows, rotation.
b) Power ramp to maximum available (5 MW>) to determine the
new L-H threshold.
c) As above, make discharges with power just below L-H
transition for ~ 200 ms, followed by higher power to get
H-mode phase.

4) Switch to upper single null (if there's time).

5) Switch to inner wall limiter configuration (if there's time).
Nov 19 2003 08:55:23:073AMRobert GranetzUnix cluster melted down again around 08:40. We're in a holding pattern until Tom and/or Josh can
resurrect it.
Nov 19 2003 09:20:39:800AMRobert GranetzTom reports that the delay due to computer problems will take at least a couple of
hours to fix.
Nov 19 2003 02:43:31:173PMRobert Granetz14:30 -- The computers are still not working. Run cancelled.

Engineering Operator Comments
ShotTimeTypeStatusComment
103:14:19:850PMTestOk
203:22:50:817PMTestOk
303:32:47:093PMTestOk
403:42:23:323PMTestOk
503:51:46:260PMTestOk
604:03:10:190PMTestOk
704:22:49:747PMTestOk
804:30:18:663PMTestOk