Alcator C-Mod Run 990218 Information

Back to runs

Miniproposals
Miniproposal:230
Date Filed: 1/15/1999
Title:Effect of Divertor Baffling on Confinement, Thresholds
First Author:Spencer Pitcher
Session Leader: Unknown (shots 1-28)

Operators
Session leader(s): Unknown
Physics operator(s):Ron Parker,Ian Hutchinson
Engineering operator(s):Frank Silva

Engineering Operator Run Comment
MP#230 Parker,Hutch/Silva

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:19:163PM
Author: To Be Determined
Run Plan for 990218

Miniproposal 230: Effect of Divertor Baffling on Confinement, Thresholds and
the ELM-free/EDA Boundary

Physop: Parker/Hutchinson

Overnight ECDC in D2

Engineering Setup:

Power supply setup as in shot 990217025
TF under hybrid control

Gas setup:

B-top 6 psi D2 Hybrid enabled
C-side 30 psi D2 Hybrid enabled
B-side lower 1 psi of Ar Hybrid disabled

Plan: Begin with MP 214; then move into miniproposal 230
when proper conditions are established.

MP 230 Effect of Divertor Baffling on Confinement

PURPOSE:

Obtain information on, (1) effect of the flapper on confinement in
L-mode, ELM-free and EDA discharges

(2) effect of the flapper on neutral densities
at the midplane and divertor under these
conditions

We will run pairs of discharges, first with flapper closed for
the entire discharge and then flapper open in a comparison discharge.

start: Ip = 0.8 MA, Bt = 5.3 T, D2, nl04 target
1.0e20, two phases of RF heating 0.3 s long each (1 MW and
2 MW approx).

after: vary nl04 target density and Ip to get our target
regimes, L-mode, ELM-free and EDA

argon: start with no argon, then later standard puff at 0.3

key diag's: all pressure gauges, div RGA, HIREX, chromex

In addition to the gas setup specified in Parker's bulletin, I strongly
suggest that we have the capability to run between-shot ECDC in Helium through
B-side-upper valve (as was done 990202, for example).

We may need H in one of the plenums because the H/D fraction was the
lowest yet yesterday.

D-port waveform:
[0.,0.,2.6,3.2,2.8,2.8,3.,3.,2.7,2.7,3.,3.,0.,0.],
*,[0.,.9,.90001,1.1,1.1001,1.125,1.12501,1.15,1.15001,1.175,1.17501,1.2,1.20001,1.4089]

E-port
waveform:[0.,0.,0.,.3,1.2,1.2,.8,.8,1.2,1.2,.6,.6,1.2,1.2,.4,.4,1.,1.,0.,0.,0.],
*,
[0.,.1,.5,.5001,.75,.78,.78001,.8,.8001,.82,.82001,.84,.84001,.86,.86001,.88,.88001,.9,.90001,1.20001,4.]

E-port coefficients: [-.754546,.520706,-2.83353]

ST1: 565 PS1: 424 ST2: 2502 PS2: 985

Vacuum conditioning before start of run

ST1: 662 PS1: 327 ST2: 2892 PS2: 454

128 .5->1.5 .8->1.0
129 1.5->2 .8->1.0

ST1: 565 PS1: 424 ST2: 2502 PS2: 985

001 power supply problem
002 early disruption - chopper supply failed
003 EFC test
004 fizzle
005 fizzle
006 fizzle
007 fizzle
008 fizzle
009 fizzle
010 fizzle
011 fizzle
012 plasma good RF ramps
three faults on #1 the first two were MIT Arc and phase balance
the last was MIT arc, pppl arc and phase balance
from the fast scope, the reflected power is spiking up when
the MIT arc detector fires.

Calculated MW_coefficients for
D-port: [-2.0398731,-0.11517370,-0.73490295]
E-port: [-0.95418678,0.099974625,-2.5148038]

013 fizzle
014
015
016
017-025 fizzle
026 plasma
good H->L neutron event beginning @1.146 sec
1.109 sec voltage limit and MIT arc detect
1.116 sec MIT arc,voltage limit, and phase balance
1.125 sec voltage limit and phase balance

027 plasma
no JOEGER_2 data - ie no tuned RF power

Using 026 and 027, MW_coefficients were calculated once again:

D-port: [-2.1884471,-0.38350071,-0.22212792]
E-port: [-1.24188,0.029231706,-1.9403619]

*****************
*** SUMMARY ***
*****************

With three discharges, improvement was incremental in D and E-port
ICRF systems. We have eliminated the false phase balance faults
resulting from antenna mutual coupling (induced power was exceeding
threshold power when the antenna was supposed to be off). We also
verified that the MIT arc detection was faulting properly on reflected
power using fast digital scope to monitor forward and reflected power
on a fast time base. The FPA screen current tracked forward power
instead of reflected power. The fault indications on #2 which occur
without power are not causing real fault actions (turning off the rf).
The fault indication board is probably oversensitive. Issues
associated with the power feedback were not tested well enough to draw
conclusions. Preliminary indications suggest that power feedback is
still insufficient. The remaining issue to be addressed tomarrow is
to run the transmitters together with 1.25 MW out of each with
controlled RF power.

On the three shots, reasonable power was generated with each system
run separately. H-modes were obtained. In fact on 990218026 and 027,
H->L neutron events were observed.

Physics Operator Summaries

Session Leader Comments

Physics Operator Comments
Feb 18 1999 09:31:14:983AMIan HutchinsonRon Parker is in the chair. I am just watching.
Feb 18 1999 09:43:13:170AM990218001Josh StillermanThis shot was a dud
Feb 18 1999 09:44:58:310AM990218002Josh StillermanThis shot disrupted due to lack of chopper horizontal field control.
Feb 18 1999 10:08:00:107AM990218003Josh Stillerman
This was a test of the chopper power supply. Chopper supply appears OK.
Feb 18 1999 11:07:54:890AM990218006Ian HutchinsonHutch standing in for Parker during teaching.
Fizzle. Reached 50kA before dying.

Pulse gas fill to 6ms at -1s with pressure 20 psi
OH1 V to 150 V at 7-10ms, from 200V
OH2 to 12V from 16V.
Should increase the Bz ramp rate, although not clear this is the right thing to
do.
Feb 18 1999 11:23:32:590AM990218007Ian HutchinsonFizzle. Got to 50kA again. Got almost exactly the same fill pressure.

Do the opposite on the Bz
OH1 V to 250V, OH2 to 20V.
Feb 18 1999 11:44:41:250AM990218008Ian HutchinsonFizzle. Got a solid 50kA this time but it just hangs there.
No signal on the ECE to tell where it went.
On shot 2 which went, the ECE shows the initial plasma well inside.

Fill puff to 7ms from 6ms.
EF3 to 2200V from 2400 V at 10ms. Try to slow the Bz more. The last
change did not do much.
Feb 18 1999 12:03:01:293PM990218009Ian HutchinsonFizzle. Extremely similar to previous.

EF4 to -1275 from -1270
Feb 18 1999 12:11:55:903PM990218010Ian HutchinsonFizzle. Very similar. Nothing I do seems to change it!

Import segment 1 from 990211030. This was a good day.
EF4 to -1270. It was -1285 in that segment.
Got a warning that the name in P15 was changed. This is false. It is EF4_U
and has always been. Messages include:

About to set def back to \HYBRID::TOP
SEG_NAMES STRING = Array[2]
\HYBRID::TOP.PCS.SEG_01 \HYBRID::TOP.PCS.SEG_02
SEG_NUMS LONG = Array[2]
1 2
% Compiled module: X_COMPLAIN.
% XMANAGER: The MODAL keyword to the XMANAGER procedure is obsolete. It is
superseded by the MODAL keyword to the WIDGET_BASE function.
ST FLOAT = -3.50000
ST FLOAT = 0.100000
Filling in configuration /28-JAN-1999 08:23:22.55/
Cleaning PCS tree in SCRATCH_DISK:[HUTCH]
copying SCRATCH_DISK:[HUTCH]PCS_MODEL.TREE to CMOD$MODELS:[HYBRID.PCS]PCS_MODEL.
T
Feb 18 1999 12:55:45:483PM990218011Ian HutchinsonFizzle. TF breaker pulls. Gets to 60kA before fizzling.
Nice early breakdown at 5ms. This now looks as if it does not have enough
Bz at the current peak.
TF fuse is apparently the same one as before.

Lower OH1 to 100V from 200V and Oh2 to 8V from 16V during 5-10ms.
Feb 18 1999 01:12:04:950PM990218012Ian HutchinsonPlasma till 1.66s. Amazingly fast current rise. RF ramps seem to work.
H-mode transition at just over 1 MW. H/D=.05

No changes.
Feb 18 1999 01:34:14:217PM990218013Ian HutchinsonFizzle at 35kA. Br is .002 mT negative. Current rise rate is greatly reduced.

Raise Br offset to 4.5 mT from 3.mT
Feb 18 1999 01:44:34:140PM990218014Ian HutchinsonFizzle at 42 kA for 8 ms. Close to going.


Helium ECDC for 5 minutes.
No other changes. Back to Parker.
Feb 18 1999 02:06:04:700PM990218015Ian HutchinsonFizzle

More ECDC
Feb 18 1999 02:12:00:327PM990218016Ian HutchinsonFizzle. Somewhat worse if anything.

Lower OH1 to 50V at 5-10 ms.
Feb 18 1999 02:20:02:967PM990218016Ian Hutchinson

C-top D_alpha array seems to indicate that shots 16 and 17 end with the
light at the outboard. In other words the second lump on the signal, from
15 to 20 ms is predominant in the channels that are from .81m outwards
(These radii are quoted at the level of the nose.)
Feb 18 1999 02:33:30:577PM990218017Ian HutchinsonFizzle.

Lower the fill puff to 5(.5)ms.
Feb 18 1999 02:51:37:763PM990218018Ian HutchinsonFizzle the gas did not change. It was not loaded properly.

Make the change.
C-Top profiles from JT with calibrations accounted for seem to show
the opposite, that the plasma dies on the inside on a fizzle. On the plasma
shot the D_alpha fills in across the radius during 14-20 ms.
Feb 18 1999 02:57:28:310PM990218019Ian HutchinsonFizzle

Increase the OH1 to 200-100 from 5ms to 10 ms.
Feb 18 1999 03:31:20:030PM990218022Ian HutchinsonRelaoded shot 2, got a Dud


We forgot to reduce the fill pulse to account for the higher plenum pressure
so we got .23 mtorr, way too high.
Feb 18 1999 03:56:27:403PM990218023Ian HutchinsonFizzle with the settings from shot 2 and reasonable pressure
Bz is a little too high.

EF4 lowered to -1275 from -1260A.
Feb 18 1999 04:05:27:357PM990218024Ian HutchinsonFizzle 50 kA.

EF4 to -1285A
Feb 18 1999 04:33:29:340PM990218025Ian HutchinsonFizzle.

BR offset to 3.5mT from 4.5mT.
Feb 18 1999 04:33:54:967PM990218025Ron ParkerShots 13-25 have been fizzles, for reasons which are obscure. Various fixes have been tried: increase/decrease fill pressure,
increase/decrease EF 4 current and increase /decrease OH 1 voltage, but with no success. Return to the settings of shot 2 also did not
succeed. Finally, a 1 mT decrease BR resulted in a successful shot.
Feb 18 1999 04:34:25:513PM990218026Ian HutchinsonPlasma. Perhaps we ought to have believed in the need for a lower BR.
Shot 12 certainly had it.

No changes.
Feb 18 1999 04:47:37:937PM990218027Ron ParkerNo changes - why tamper with success? ECDC employed between shots.
Feb 18 1999 05:03:05:623PM990218028Ron ParkerBack to the fizzles!

Engineering Operator Comments
ShotTimeTypeStatusComment
109:02:43:890AMPlasmaOkCheck EFc chopper
209:20:25:793AMPlasmaOkefc no go blown fuses
310:03:00:590AMPlasmaOkEFc test ok
410:21:45:513AMPlasmaOkNo Faults
510:34:59:140AMPlasmaOkNo Faults
610:53:06:890AMPlasmaOkNo Faults
711:08:14:590AMPlasmaOkNo Faults
811:22:07:043AMPlasmaOkNo Faults
911:42:53:250AMPlasmaOkNo Faults
1011:57:54:280AMPlasmaOkNo Faults
1112:14:52:357PMPlasmaOkNo Faults
1212:53:56:590PMPlasmaOkNo Faults
1301:09:14:013PMPlasmaOkNo Faults
1401:27:16:590PMPlasmaOkno faults
1501:44:05:467PMPlasmaOkNo Faults
1602:03:40:373PMPlasmaOkno faults
1702:17:52:187PMPlasmaOkno faults
1802:28:38:530PMPlasmaOkno faults
1902:41:20:560PMPlasmaOkno faults
2002:56:11:280PMPlasmaOkno faults
2103:12:20:140PMPlasmaOkno faults
2203:25:11:420PMPlasmaOkno faults
2303:42:06:437PMPlasmaOkno faults
2403:55:06:640PMPlasmaOkno faults
2504:09:03:543PMPlasmaOkno faults
2604:22:57:983PMPlasmaOkno faults/plasma
2704:43:30:810PMPlasmaOkno faults/plasma
2804:56:40:513PMPlasmaOkno faults