Alcator C-Mod Run 950118 Information

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Miniproposals
Miniproposal:049
Date Filed: 4/8/1994
Title:2D Neutral Density Profile Measurements by Charge Exchange Recombination
First Author:John Rice
Session Leader:John Rice (shots 1-33)

Operators
Session leader(s):John Rice
Physics operator(s):John Goetz
Engineering operator(s):Vinny Bertolino

Engineering Operator Run Comment
2D neutral density

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:11:990PM
Author: To Be Determined

From: LEADER::RICE
Date: 18-JAN-1995 17:23:41
Description: Physics Operator Summary for 950118

Run Summary for 950118

The curse of MP049A continues...The first 3 hours of the run were
spent trying to recover from previous friday run. There followed a period
of the cycle plasma-fizzle-fizzle-plasma, which was finally broken with
plasmas on the last 4 shots, although the density feedback got lost on one
of those. Concerning the program for MP049A, there were 7 shots, which
allowed for confirmation of the previously observed up-down neutral density
asymmetry. These were not enough shots to provide for a quantitative vertical
neutral density profile, but on the positive side, the total number of useable
shots increased by a factor of 3.5.
The RF was increased to a level of 3.5 MW with ion temperatures over
4 keV.

Scorecard:

1 Dud
2 Tests
11 Plasmas
18 Fizzles

Physics Operator Summaries
Entered: Jul 7 2004 04:36:52:880PM
Author: To Be Determined
Physics operator summary for 950118

EO: Bertilino
PO: Goetz
SL: Rice

Run 950118 was in support of Mini-Proposal #049A - 2D Neutral Density
Profile Measurements by Charge Exchange Recombination Spectroscopy. The goal
of this mini-proposal is to measure the 2D neutral hydrogen density profile.

Program for this run:
- Setup a lower SN discharge with parameters: Ip=0.8MA; Nel_04=0.6e20;
- Puff argon and measure high n transitions in He-like Ar
- Setup a D-shaped limited discharge and repeat

Only the first two steps of the program were accomplished, and then just
barely. Seven shots were deemed useable by the SL (see the Session Leader's
summary for the physics results).

Some things discovered today:
1) The values of the commutation resistors are very important for a
robust startup. The OH1 resistor was not returned to its correct
value after Run 950113. It took until shot 950118028 to determine
that it was indeed a mismatched commutation resistor that was the
cause of the copious fizzles. The flux plots indicated that the fields
had too much curvature and the Bz ramp rate was too fast for the given
current rise. It was suspected that something left over from Run
950113 was affecting the OH2 supplies, but it was the OH1 voltage
that was causing the curvature of the fields.
2) A startup scenario with the OH1 commutation resistor 10% below the
correct value was achieved, but this scenario was not robust. The
fizzles today were too cold to register on the GPC and there generally
was no current rise. Data from the z-meter array indicate that the
plasmas were starting up inside and moving in further. This led to
increased carbon influx, no current rise, and fizzles. Thus the
pattern of fizzles/plasmas.
3) The first few shots today were wasted due to operator error. I
thought I had been working on setting up modifications to shot
950112031, but instead I was working on the model left over from
950113. Thus, the startup scenario was wrong, and segment 1 was
loaded from 950112031. After working on the startup (due to point 1)
and finally getting a plasma, it was discovered that segment 2 was
wrong, and the correct segment was loaded.
4) The RF group can inject greater than 3.5MW of power into the plasma,
creating ions and electrons approaching 5keV.

Engineering and diagnostics today: The OH1 commutation resistor was not
returned to its nominal value after Run 950113. This effectively
cost this run 26 shots and 7.5 hours. The interferometer lost a
fringe and resulted in a very low density discharge.

Scorecard: 33 shots = 12 plasmas + 18 fizzles + 1 dud + 2 p.s. tests
only 7 plasmas were useable for the S.L.

Shot summary for Run 950111

Reload of 950120031

Changes to shot 950120031:
NL_04 draw to 0.6e20
ZCUR=-.02
PG1=(90V x .04sec) @ .3sec

Shot change result
____ _____ ______
1 OH test shot

2 OH test shot

3 dud - OH2's out of balance
due to segment 1 from 950113

4 load segment 1 from 950112031 fizzle - null looks o.k.
no signals on the GPC

5 P_0=1.3e-5 fizzle - null looks o.k.

6 P_0=1.7e-5 fizzle - too much Bz ramp

7 V_OH1=90V@.005; 106V@.01; 106@.015 fizzle - Bz ramp o.k. but
Bz is too high

8 IC_EF4=-1100A (was -1075A) fizzle
null somewhat better - Bz=8mT
still no current formation

9 IC_EF4=-1115A; P_0=1.4e-5 fizzle - null better
moves in - no current formed

10 IC_EF4=-1125A; P_0=1.2e-5 fizzle - null looks worse -
some evidence of a Br problem

11 offset on BR_0=7e-3 (was 6.5e-3) plasma - disr. @ .354sec
radiative collapse

12 move PG2 to 0.4sec plasma - disr. @ .35
EF2's on the rail
segment 2 appears to be 950113

13 load segment 2 from 950112031 plasma - disr. @ 1.04
radiation rising through shot

14 hold NL_04 until .95 sec fizzle - no current rise

15 slide PG3 +.002sec fizzle - slight current rise

16 P_0=1.5e-5 fizzle - barely a flash

17 P_0=1.2e-5; slide PG3 +.002sec plasma - disr. during rampdown

18 no changes fizzle - weak Halpha

19 P_0=1.7e-5 plasma - disr @ 1.3
Halpha still weak

20 no changes plasma - disr. @ 1.06
moves out and down

21 slow down NL_04 ramp-down fizzle - no current rise

22 no changes fizzle - a little current rise

23 no changes plasma - disr. @ 1.31
very disruptive throughout

24 slide PG3 -.002sec; NL_04 break @ 1.1 fizzle - no current rise

25 no changes plasma - disr. @ 1.13
moves out at 1.0sec

26 slide PG3 -.001sec fizzle - no current rise

27 no changes fizzle - a little current rise

28 no changes fizzle - no current rise

29 change OH1 commutation resistor fizzle - no current rise
to 44.7mOhms Bz too negative

30 IC_EF4=-1085A plasma - 'normal startup'
disrupts @ 1.33

31 no changes plasma - disrupts @ .51
density loses fringe @ .155
comb. of RF and pellet killed it

32 EF3 invert time = 1.5sec plasma - disrupts @ 1.1
quick fin

33 NL_04 ramps @0.99sec; Li pellet @1.0 plasma - disrupts @ 1.25

Session Leader Comments
Jan 22 1995 03:26:44:090PMJim TerryThe H_alpha signal from the camera viewing from the right side
of H port was abnormally low for this run, presumably because
the view was being obscured by ice (frost) on the camera and/or
window. This is signal \SPECTROSCOPY::TOP.Z_METER:INCAA16:INPUT_05
(uncalibrated) or \SPECTROSCOPY::top.uvis:HA_2_BRIGHT
(calibrated). The other camera on H port
\SPECTROSCOPY::TOP.Z_METER:INCAA16:INPUT_02 (uncalibrated) or
\SPECTROSCOPY::top.uvis:HA_1_BRIGHT (calibrated) may have been affected
as well.

Physics Operator Comments
Jan 18 1995 08:34:43:960AMJohn GoetzRun 950118 - MiniProposal #049A
2D Neutral Density Profile Measurements by Charge Exchange
Recombination Spectroscopy

Run Plan:
Run lower SN divertor discharges and puff argon
Run D-shaped limited discharges and puff argon

Start from 950112031:
changes:
NL_04=0.5e20
ZCUR=-.02
PG1=(90V x .04sec) @ 0.3sec

Jan 18 1995 08:35:43:830AM950118001John GoetzShot 950118001:
OH test shot

For 002:
another test shot

Jan 18 1995 08:45:03:840AM950118002John GoetzShot 950118002:
OH test shot

For 003:
begin run

Jan 18 1995 09:05:43:740AM950118003John GoetzShot 950118003:
dud
programming for segment 1 is from Run 950113 - OH2's are
way out of balance

For 004:
load segment 1 from 950112031

Jan 18 1995 09:22:10:210AM950118004John GoetzShot 950118004:
fizzle
null looks o.k. - breakdown at .005
no signals on the GPC - a wimpy fizzle

For 005:
P_0=1.3e-5

Jan 18 1995 09:37:16:970AM950118005John GoetzShot 950118005:
fizzle
null looks o.k. - breakdown at .005
no signals on the GPC - a wimpy fizzle

For 006:
P_0=1.7e-5

Jan 18 1995 09:57:50:530AM950118006John GoetzShot 950118006:
fizzle
Bz ramp rate is too high early in the shot
(compared to 950112031)

For 007:
Change OH1 voltage early to slow Bz ramp rate
90V@.005; 106V@.01; 106V@.015

Jan 18 1995 10:10:27:370AM950118007John GoetzShot 950118007:
fizzle
Bz ramp rate o.k. but Bz is too high

For 008:
IC_EF4=-1100A (was -1075A)

Jan 18 1995 10:34:15:380AM950118008John GoetzShot 950118008:
fizzle
null a bit better - Bz now 8mT

For 009:
IC_EF4=-1115A
P_0=1.4e-5

Jan 18 1995 10:50:42:180AM950118009John GoetzShot 950118009:
fizzle
null better - this one bounces but no current formation -
z-meter says it moves inward

For 010:
IC_EF4=-1125A
P_0=1.2e-5

Jan 18 1995 11:04:18:480AM950118010John GoetzShot 950118010:
fizzle
null worse - no current formation - z-meter says it moves inward
some evidence of a radial field problem

For 011:
offset on BR_0 = 7.0e-3

Jan 18 1995 11:20:56:950AM950118011John GoetzShot 950118011:
plasma - disruption @ .354sec - radiative collapse
probably due to too much argon

For 012:
move PG2 to 0.4sec

Jan 18 1995 11:48:41:600AM950118012John GoetzShot 950118012:
plasma - disruption @ .35sec - EF2's on the rail
it appears that segment 2 is also from 950113 and has
slot divertor programming

For 013:
load segment 2 from 950112031

Jan 18 1995 12:01:40:730PM950118013John GoetzShot 950118013:
plasma - disruption @ 1.04sec - radiation was rising
density was falling

For 014:
hold NL_04 until 0.95sec

Jan 18 1995 12:13:29:860PM950118014John GoetzShot 950118014:
fizzle - bounces at .013sec - no current rise

For 015:
slide PG3 +.002sec

Jan 18 1995 12:29:55:400PM950118015John GoetzShot 950118015:
fizzle - bounces at .015sec - slight current rise

For 016:
P_0=1.5e-5

Jan 18 1995 12:46:20:330PM950118016John GoetzShot 950118016:
fizzle - barely a flash

For 017:
P_0=1.2e-5
slide PG3 +.002sec

Jan 18 1995 01:01:14:160PM950118017John GoetzShot 950118017:
plasma - disruptive during rampdown - final disr. @ 1.31

For 018:
no changes

Jan 18 1995 01:16:07:510PM950118018John GoetzShot 950118018:
fizzle - no current rise - very weak Halpha signal

For 019:
P_0=1.7e-5

Jan 18 1995 01:32:25:660PM950118019John GoetzShot 950118019:
plasma - disr. @ 1.3
Halpha signal remains weak, but this one goes

For 020:
no changes

Jan 18 1995 01:50:23:650PM950118020John GoetzShot 950118020:
plasma - disr. @ 1.06
plasma moves down and out beginning at 1.0sec

For 021:
slow down the NL_04 ramp-down

Jan 18 1995 02:11:28:980PM950118021John GoetzShot 950118021:
fizzle - no current rise

For 022:
no changes

Jan 18 1995 02:12:13:210PM950118022John GoetzShot 950118022:
fizzle - a little current rise - bounces at .018sec

For 023:
no changes

Jan 18 1995 02:27:13:620PM950118023John GoetzShot 950118023:
plasma - disruptive during rampdown - final disr. @ 1.31

For 024:
NL_04 break point at 1.1sec
slide PG3 -.002sec

Jan 18 1995 02:36:13:060PM950118024John GoetzShot 950118024:
fizzle - no current rise - bounces at .014sec

For 025:
no changes

Jan 18 1995 02:53:59:420PM950118025John GoetzShot 950118025:
plasma - disr. @ 1.13
plasma jumps out at the current ramp down

For 026:
slide PG3 -.001sec

Jan 18 1995 03:15:21:490PM950118026John GoetzShot 950118026:
plasma - no current rise

For 027:
no changes

Jan 18 1995 04:03:07:320PM950118027John GoetzShot 950118027:
plasma - bounce at .014 - no current rise

For 028:
no changes

Jan 18 1995 04:04:42:190PM950118028John GoetzShot 950118028:
fizzle - bounce at .014 - no current rise

For 029:
OH1 commutation resistor now 44.7mOhms

Jan 18 1995 04:05:28:010PM950118029John GoetzShot 950118029:
fizzle - bounce at .016 - no current rise
Bz too negative according to scatterplot

For 030:
IC_EF4=-1085A

Jan 18 1995 04:21:38:200PM950118030John GoetzShot 950118030:
plasma - disrupts @ 1.33
RF input power ~ 3.4MW

For 031:
no changes

Jan 18 1995 04:32:11:120PM950118031John GoetzShot 950118031:
plasma - disrupts @ 0.51
density feedback goes nuts @ .155sec due to no density signals
dead by combination of RF, Li pellet, and no density

For 032:
EF3 invert time = 1.5sec

Jan 18 1995 04:46:47:440PM950118032John GoetzShot 950118032:
plasma - disrupts @ 1.1 - looks like a quick fin

For 033:
NL_04 ramp starts @ .99sec
Li pellet @ 1.0

Jan 18 1995 05:13:05:090PM950118033John GoetzShot 950118033:
plasma - disrupts @ 1.25
still moving out during rampdown

Engineering Operator Comments
ShotTimeTypeStatusComment
108:26:19:080AMTestOkcoax test
208:36:58:910AMTestOkcoax test
308:48:20:980AMPlasmaOkno faults
409:10:59:100AMPlasmaOkno faults
509:25:12:060AMPlasmaOkno faults
609:39:57:210AMPlasmaOkno faults
709:58:14:110AMPlasmaOkno faults
810:16:04:210AMPlasmaOkno faults
910:36:18:290AMPlasmaOkno faults
1010:52:52:770AMPlasmaOkno faults
1111:07:28:010AMPlasmaOkno faults
1211:24:13:450AMPlasmaOkno faults
1311:47:34:780AMPlasmaOkno faults
1412:06:31:680PMPlasmaOkno faults
1512:18:21:670PMPlasmaOkno faults
1612:30:27:400PMPlasmaOkno faults
1712:45:40:300PMPlasmaOkno faults
1801:02:01:330PMPlasmaOkno faults
1901:17:45:440PMPlasmaOkno faults
2001:33:41:880PMPlasmaOkno faults
2101:52:06:070PMPlasmaOkno faults
2202:03:15:600PMPlasmaOkno faults
2302:15:23:550PMPlasmaOkno faults
2402:29:19:480PMPlasmaOkno faults
2502:43:49:390PMPlasmaOkno faults
2603:05:09:740PMPlasmaOkno faults
2703:18:59:590PMPlasmaOkno faults
2803:29:03:870PMPlasmaOkno faults
2903:53:02:850PMPlasmaOkno faults
3004:07:47:860PMPlasmaOkno faults
3104:21:50:950PMPlasmaOkno faults
3204:37:13:990PMPlasmaOkno faults
3304:53:52:550PMPlasmaOkno faults