Alcator C-Mod Run 1050427 Information

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Miniproposals
Miniproposal:415
Date Filed: 2/24/2005
Title:Rotation and H-mode Power Threshold for LSN and USN at Different IP and ne
First Author:John Rice
Session Leader:John Rice (shots 3-36)

Operators
Session leader(s):John Rice
Physics operator(s):Jim Irby
Engineering operator(s):Andy Pfeiffer,Gary Dekow,Ed Fitzgerald

Engineering Operator Run Comment
MP 415: Rotation and H-mode Power Threshold for LSN and USN at Different

Session Leader Plans

Physics Operators Plans
Entered: Apr 27 2005 06:09:49:453AM
Author: Jim Irby
Engineering setup for Wednesday, 27 Apr 2005

MP 415: Rotation and H-mode Power Threshold for LSN and USN at Different
Ip and ne

Session leader: John Rice
Physics operator: Jim Irby

ECDC in D2 at 2e-4 Torr overnight at 60 C

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

We will start with a standard fiducial (1050426001) with 2 MW of rf
The gatevalves should be setup to toggle closed --- bypass at 160 clicks

For MP415 we will start off with 1050330024 (800 kA, LSN)

A-coil configuration: normal [+Dtop -Dbot -Jtop +Jbot] and enabled.

Gas Setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 2 psi Ar Hybrid enabled (PG1)
leave B-side upper with whatever Hybrid disabled
fill B-main (C-side) with 40 psi D2 Hybrid enabled (PG3)

fill NINJA with 10 psi D2 but leave disabled

Enable the following gate valves: ECE, VUV, Z-bolo shutters

ICRF Setup: All transmitters in run on at 8:30

***************************************
Starting around 05:00 lower hybrid conditioning is planned before the
run. This activity should stop at 08:00 and ECDC should be started
and run for 30 minutes.
***************************************

Session Leader Summaries
Entered: Apr 28 2005 09:54:43:090AM
Author: John Rice
Session Leader Run Summary for 1050427 MP415 Rotation and H-mode Power Threshold

Before mapping out the rotation and H-mode power threshold at plasma currents other than 0.8 MA,
LSN 0.8 MA discharges were run in order to touch base with previous results. Several discharges
were run with increasing ICRF power in order to determine the H-mode power theshold. Today it
was near 2.1 MW, considerably higher than the 0.8 MW of previous results. Following that, several
USN discharges were run and the threshold was determined to be 3.1 MW, only slightly higher than
the previous result of 2.9 MW. However, the H-mode transition in all of these USN plasmas was
preceded by a giant sawtooth, which was not seen previously. Since these results were not in agreement
with previous experiments, little progress was made. The final shot was a 1.0 MA 'fiducial' which
had a low threshold of about 0.8 MW, much lower than the 0.8 MA result, and this discharge had
considerable argon puffing. It is a mystery why the previous results could not be reproduced;
the H-mode transition seems to occur when the core rotation passed through 0, but why the threshold
power was so much higher will require further investigation.

Physics Operator Summaries
Entered: Apr 28 2005 05:37:27:940PM
Author: Jim Irby
The machine ran well. Startups were very reproducible once the
physop realized the prefill was too low following the first plasma.
We began with the ICRF 1 MA, ramp to 3 MW, fiducial discharge on shot 3
following 2 cycle tests to make sure the data system was okay. The
L-H transition power was pretty high at around 2 MW for this
discharge, probably because of an injection. H/(H+D) was very low at 3
to 3.5%. The last shot of the day (36) was also a fiducial, but the
transition power was back to a more reasonable 850 to 900 kW.
Unfortunately the LN configuration picked to run the mini-proposal
required considerably more power to get into H-Mode and several shots
were required for us to scan the ICRF power, drop the density, and
make other adjustments to get reasonable data for the mini-proposal.

On shot 21 we switched easily over to upper null operation.
Unfortunately neither the PO or the SL told Brian about the change,
and we did some damage to the scanning probes. The gaps were not the
same as the shot that was loaded and a couple of discharges were
required to tune up the plasma before the probes could be run again.

H/(H+D) stayed at the 4% or lower level most of the day.

Lower hybrid vacuum conditioning was run from about 05:00 to 08:00
before this run. About 30 minutes of ECDC in deuterium followed the
conditioning in case there was something to "clean-up". The RGA
showed very little other than D and H. The lower hybrid system was
also run during the plasma discharges starting at 1.4 s. There was no
indication that either the vacuum conditioning or the plasma operation
affected the run.

10 to 15 minute delay getting alternator up to speed --- NSTAR related


test 01,02 02

dud 04,05,08 03

fizzle 18 01

plasma 03,06,07,09,10,11,12,13,14,15
16,17,19,20,21,22,23,24,25,26
27,28,29,30,31,32,33,34,35,36 30

total cycles 36

Session Leader Comments
Apr 27 2005 09:29:38:750AM1050427003John Ricefiducial
Apr 27 2005 09:33:16:860AM1050427004John Rice'that was a definite dud'
Apr 27 2005 09:48:15:053AM1050427005John Rice'that was a definite dud'
Apr 27 2005 10:02:53:160AM1050427006John Rice0.8 MA, LSN
Prf = 0.69 MW, no H-mode
Apr 27 2005 10:21:25:037AM1050427007John Rice0.8 MA, LSN
Prf = 0.6 MW, no H-mode
Apr 27 2005 10:27:28:863AM1050427008John Ricedud
Apr 27 2005 10:43:14:410AM1050427009John Rice0.8 MW, LSN
1.0 MW, no H-mode
Apr 27 2005 11:04:12:583AM1050427010John Rice0.8 MW, LSN
1.4 MW, no H-mode ?????
Apr 27 2005 11:22:47:393AM1050427011John Rice0.8 MW, LSN
2.1 MW, no H-mode ?????
Apr 27 2005 11:34:34:333AM1050427012John Rice0.8 MW, LSN
2.1 MW, no H-mode ?????
Apr 27 2005 11:48:14:550AM1050427013John Rice0.8 MW, LSN
2.1 MW, no H-mode ?????
Apr 27 2005 12:04:15:600PM1050427014John Rice0.8 MW, LSN
2.1 MW, crappy H-mode, Ar off
Apr 27 2005 12:15:39:113PM1050427015John Rice0.8 MW, LSN
1.3 MW, L-mode, Ar off
Apr 27 2005 12:30:31:457PM1050427016John Rice0.8 MW, LSN
1.6 MW, L-mode, Ar off
Apr 27 2005 01:05:06:550PM1050427017John Ricedisrupted
Apr 27 2005 01:05:16:427PM1050427018John Ricefizzle
Apr 27 2005 01:10:28:833PM1050427019John Rice0.8 MA, LSN
1.8 MW RF, H-mode
disrupted 0.86 s
Apr 27 2005 01:25:45:550PM1050427020John Rice0.8 MA, LSN
1.7 MW RF, H-mode
Apr 27 2005 02:00:22:300PM1050427021John Rice0.8 MA, USN
1.7 MW RF, L-mode
Apr 27 2005 02:00:39:707PM1050427022John Rice0.8 MA, USN
3.1 MW RF, H-mode
Apr 27 2005 02:29:38:677PM1050427023John Rice0.8 MA, USN
3.1 MW RF, H-mode
Apr 27 2005 02:29:48:193PM1050427024John Rice0.8 MA, USN
3.1 MW RF, H-mode
Apr 27 2005 02:42:27:113PM1050427025John Rice0.8 MA, USN
2.9 MW RF, H-mode
Apr 27 2005 03:05:38:333PM1050427026John Rice0.8 MA, USN
2.6 MW RF, L-mode
Apr 27 2005 03:23:07:973PM1050427027John Rice0.8 MA, LSN
2.5 MW RF, H-mode
Apr 27 2005 03:27:45:050PM1050427028John Ricedisrupted early
Apr 27 2005 03:50:43:770PM1050427029John Rice0.8 MA, LSN
RF ramp 0-2.6 MW
H-mode at 2.05 MW
Apr 27 2005 03:59:19:630PM1050427030John Rice0.8 MA, LSN
RF ramp 0-2.6 MW
H-mode at 2.2 MW
Apr 27 2005 04:11:19:440PM1050427031John Rice0.8 MA, LSN
RF ramp 0-2.6 MW
H-mode at 2.2 MW
Apr 27 2005 04:28:43:190PM1050427032John Rice0.8 MA, USN
RF ramp 1.5-2.8 MW
no H-mode
Apr 27 2005 04:38:21:723PM1050427033John Rice0.8 MA, USN
RF ramp 1.5-4.0 MW
H-mode at 3.7 MW
Apr 27 2005 04:48:18:770PM1050427034John Rice0.8 MA, USN
RF ramp 1.5-4.0 MW
H-mode at 3.4 MW
Apr 27 2005 04:58:56:630PM1050427035John Rice0.6 MA, USN
RF ramp 1.-3.0 MW
no H-mode
Apr 27 2005 05:14:35:863PM1050427035John Rice1.0 MA, USN
RF ramp 0.5-3.0 MW
H-mode 0.7 MW

Physics Operator Comments
Apr 27 2005 08:17:56:673AM1050427001Jim IrbyCAMAC cycle test --- looks okay

ratiomatic was off as usual
Apr 27 2005 08:53:15:610AM1050427002Jim Irby2nd cycle test to make sure XTOMO Granetz crate is operational --- bad amp board loading crate

gas okay (a little high as usual during cycle test)
Apr 27 2005 09:30:03:423AM1050427003Jim IrbyECDC in D2 overnight followed by LH conditioning from 05:00 to 08:00, followed by
30 minutes of ECDC in D2 for cleanup. LH conditioning produces only D2 and H2 as
determined by RGA scans.

loaded seg 2 from 1050426001 (fiducial) into seg 3 (segment on)

loaded seg 4 from 1040409028 (800 kA, LN) into seg 2 (segment off)

loaded seg 3 from 1040409019 (800 kA, UN) into seg 4 (segment off)

Will start with fiducial shot and ramping ICRF

plasma into rampdown --- high L to H transition power

lower hybrid firing at 1.4 s

h/(h+d) at 3%
Apr 27 2005 09:41:42:067AM1050427004Jim Irbyswitched to seg 2 (800 kA, LN), but also left seg 4 ON.

dud --- gas too low

Apr 27 2005 09:48:19:867AM1050427005Jim Irbyincreased prepuff by 3 ms

dud --- pressure still low
Apr 27 2005 10:19:24:067AM1050427006Jim Irbyincreased prepuff another 2 ms, removed strange ramp early

turned off gatevalve toggle

plasma into rampdown

Apr 27 2005 10:24:55:113AM1050427007Jim Irbyplasma into rampdown --- still some work required to get rf going

pressure looks good

lh operation going well --- no light from grill
Apr 27 2005 10:32:25:850AM1050427008Jim Irbyrepeat DPCS

dud --- pressure dropped relative to shot 6

Apr 27 2005 10:47:41:050AM1050427009Jim Irbyincreased prepuff 2 ms (now 20 ms)

basepressure at pulse 6.5e-7 Torr

plasma into rampdown

Apr 27 2005 12:15:08:067PM1050427009Jim Irbyincreased prepuff 2 ms (now 20 ms)

basepressure at pulse 6.5e-7 Torr

plasma into rampdown
Apr 27 2005 12:16:00:833PM1050427010Jim Irbyno DPCS changes

adding some icrf power

good shot

more icrf but no h-mode

Steve Wolfe noted offset in SSEP --- zeoroed for next shot

-
Apr 27 2005 12:16:28:300PM1050427011Jim Irbyzeroed SSEP offsets
more icrf

shot okay but still no h-mode
-
Apr 27 2005 12:16:44:317PM1050427012Jim Irbyargon puff from 50 to 30 ms

good shot --- no h-mode

-
Apr 27 2005 12:16:57:740PM1050427013Jim Irbynl_04 request to 9e19 from 9.5e10 / m^2

no h-mode?
-
Apr 27 2005 12:10:44:537PM1050427014Jim Irbyargon puff disabled

no lh for next couple of shots

nl_04 request from 9 to 8.5e19 / m^2

good shot --- h-modes at last

Apr 27 2005 12:23:38:613PM1050427015Jim Irbyrepeat with a little less icrf

good shot --- no h-mode
Apr 27 2005 12:35:54:317PM1050427016Jim Irbyrepeat --- more icrf

good shot --- no h-modes

Apr 27 2005 12:52:35:787PM1050427017Jim Irbyrepeat with more icrf

disruption at 0.44 s

Apr 27 2005 01:05:19:770PM1050427018Jim Irbyrepeat

fizzle --- pressure and fields okay


Apr 27 2005 01:14:40:707PM1050427019Jim Irbytry again --- no DPCS changes

basepressure 6.5e-7 Torr

scanning probe overheating --- may have caused disruption at 1.2 s

argon was enabled for this shot
Apr 27 2005 01:25:51:880PM1050427020Jim Irbyreduced prepuff by 2 ms

good shot --- h-modes


Apr 27 2005 01:47:52:990PM1050427021Jim Irbyargon pulse to 50 ms at 1 psi
increased prepuff 2 ms

switch to upper null --- seg 4 --- forgot to tell Brian

good shot --- upper null
Apr 27 2005 02:07:17:723PM1050427022Jim Irbyclearin increased by 0.007 m

good shot --- h-mode
Apr 27 2005 02:19:53:850PM1050427023Jim Irbyclearin increased by 0.004 m

added 20 more ms of argon at 1 psi

good shot --- more h-modes

Apr 27 2005 02:29:18:600PM1050427024Jim Irby20 ms more of argon

good shot --- a few h-modes

Apr 27 2005 02:45:41:600PM1050427025Jim Irbyrepeat with lower icrf power

good shot --- still got h-modes
Apr 27 2005 03:02:37:190PM1050427026Jim Irbyrepeat with lower icrf power

good shot
Apr 27 2005 03:22:07:440PM1050427027Jim Irbyswitch back to seg 2 for lower single null
modified argon puff in seg 2 to match seg 4

good shot --- many h-modes
Apr 27 2005 03:36:52:223PM1050427028Jim Irbyrepeat with icrf ramp

disruption at 0.363 s

event in outer divertor seen on wide2

Apr 27 2005 03:44:32:130PM1050427029Jim Irbyreduced prepuff 2 ms

good shot --- one h-mode

Apr 27 2005 03:57:40:287PM1050427030Jim Irbyadded 2 ms to prepuff

added 20 ms to argon puff at 1 psi

good shot --- one h-mode
Apr 27 2005 04:12:46:957PM1050427031Jim Irby20 ms added to argon puff

ramped out rcur by 0.005 m from 1.6 to 1.85 s --- better GPI view

good shot --- one h-mode
Apr 27 2005 04:31:33:190PM1050427032Jim Irbyswitched back to seg 4 --- upper null

copied argon gas puff from seg 2 to seg 4

Apr 27 2005 04:32:59:800PM1050427033Jim Irbyrepeat with larger icrf ramp

good shot --- late h-mode
Apr 27 2005 04:52:11:457PM1050427034Jim IrbyIp request to 600k but applied to wrong segment...

plasma
Apr 27 2005 04:57:53:690PM1050427035Jim Irby600 kA request in seg 4 loaded

good shot --- 600 kA




Apr 27 2005 05:17:25:207PM1050427036Jim Irbyturned on seg 3 --- fiducial shot from this morning

good shot --- early elm-free h-mode at only 880 kW

Engineering Operator Comments
ShotTimeTypeStatusComment
108:09:05:987AMTestOk
208:49:24:907AMTestOk
309:17:03:143AMPlasmaOk
409:31:08:733AMPlasmaOk
509:43:53:530AMPlasmaOk
609:56:25:050AMPlasmaOk
710:12:20:100AMPlasmaOk
810:25:31:647AMPlasmaOk
910:38:10:490AMPlasmaOk
1010:58:35:380AMPlasmaOk
1111:15:44:160AMPlasmaOk
1211:29:15:723AMPlasmaOk
1311:43:41:097AMPlasmaOk
1411:58:09:973AMPlasmaOk
1512:11:04:787PMPlasmaOk
1612:24:05:613PMPlasmaOk
1712:39:03:583PMPlasmaOk
1812:52:44:880PMPlasmaOk
1901:05:15:190PMPlasmaOk
2001:20:16:113PMPlasmaOk
2101:32:45:333PMPlasmaOk
2201:55:43:020PMPlasmaOk
2302:10:02:597PMPlasmaOk
2402:22:59:160PMPlasmaOk
2502:35:31:550PMTestBad
2602:51:04:083PMPlasmaOk
2703:10:04:097PMPlasmaOk
2803:25:38:393PMPlasmaOk
2903:38:12:520PMPlasmaOk
3003:51:46:707PMPlasmaOk
3104:04:12:333PMPlasmaOk
3204:16:47:113PMPlasmaOk
3304:29:06:707PMPlasmaOk
3404:41:42:613PMPlasmaOk
3504:54:08:647PMPlasmaOk
3605:09:35:490PMPlasmaOk