Alcator C-Mod Run 931025 Information

Back to runs

Miniproposals
Miniproposal:
Date Filed:
Title:
First Author:
Session Leader:Bruce Lipschultz (shots 1-33)

Operators
Session leader(s):Bruce Lipschultz
Physics operator(s):John Goetz
Engineering operator(s):Joe Daigle

Engineering Operator Run Comment
divertor tests.

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Physics Operator Summaries
Entered: Jul 7 2004 04:36:50:567PM
Author: To Be Determined
Physics operator summary for 931025

EO: Daigle
PO: Goetz
SL: Lipschultz

Run 931025 was in support of Mini-Proposal #032 - Gas Puffing in the Divertor.
To this end SN discharges were run in deuterium and the divertor gas puff
system was used to put deuterium and neon into both the private flux and
common flux regions of the divertor. The divertor gas was puffed in at
different times, for varying durations and varying supply pressures. Results
from this run will be provided by the Session Leader.

The run started with a reload of shot 931021018 which was a 600 kAmp shot
that had the strike points and the x-points in somewhat the correct location.
Changes to this shot included lowering the plasma and some tweaks to
PULSE_GAS_3.

The run was plagued by alternating plasmas/duds/fizzles once the EF1 troubles
were corrected. The fields did not change significantly between these
different results. What changed? Randomness in some unknown parameter?
When the discharge decided to go, it went well. Most plasmas made it to a
successful rampdown. Toward the end of the day there were discharges with
molybdenum injections but most of the discharges were free of large injections.


Notes: There were many changes made to the V_OH1 programming through the
day to try and remove the bumps and wiggles from the current rise.
Success was had. Care must be taken to try and match the voltage
programming to the desired current level.

ZCUR was programmed to be -.03m to get the x-points in the correct
location for these plasma currents

Engineering today: There was an imbalance in the EF1's for the first ten
shots. EF1L was not following its command; it was following with some
unknown constant times the command. Changing a solid state switch
across the integration capacitor solved the problem. A nitrogen leak
was opened up after shot 23. Three blown fuses in the OH2U supply
after playing with the inversion endstop.

Scorecard: 33 shots = 16 plasmas + 5 duds + 11 fizzles + 1 test

Shot summary for Run 931025

Reload of 931021018

Changes:
S_ZCUR = -.03 @ .4s
Add PULSE_GAS_3 after .4s

Shot change result
____ _____ ______
1 P_0=1.4e-5 fizzle
2 P_0=1.2e-5 fizzle
3 fix voltage imbalance on EF1 boards fizzle
4 play with inversion end-stop on OH2's dud
5 lower OH2 inversion voltage fizzle
6 lower gain on EF1L board dud
7 split the difference on the EF1L gain change fizzle
8 raise P_ICEF1L to 4 (was 2.5) fizzle
9 swap boards for EF1U and EF1L plasma
10 raise PULSE_GAS_3 after .5s dud
11 change switch across intergrator on EF1L control board plasma
12 lower P_G_3 after .5s S_RCUR=.68 @ .2s S_ZCUR slope smoothed plasma
13 lower P_G_3 after .5s S_IP = -580000A stairstep on turn-on
of EF1 gains after .06s plasma
14 raise P_G_3 to 45V from .3 to .7s more stairsteps on IC_EF1 plasma
15 lower P_G_3 to 42V Raise V_OH1 to 100V from .07 to .11 plasma
16 raise P_G_3 to 47V from .3 to .7s raise V_OH1 to 150V plasma
17 raise P_G_3 to 52V from .3 to .5s rasie V_OH1 to 200V dud
18 P_0 = 1.4e-5 plasma
19 turn off P_G_3 @ .3s V_OH1 = 220V from .07 to .11s plasma
20 turn off P_G_3 @ .25s V_OH1 = 200V @.052s; 240V @ .11s fizzle
21 P_0 = 1.3e-5 plasma
22 lower P_G_3 to 50V S_IP = -430000 @.12s; -450000 @ .9s plasma
23 fiddle with V_OH1 to slow down current rise rate plasma
24 S_RXL ramp slowed down fiddle with V_OH1 to slow ramp fizzle
25 reload P_G_3 programming from 13 turn down LN pump speed plasma
26 reload P_G_3 programming from 15 S_IP = -805000 dud
27 P_0 = 1.5e-5 plasma
28 raise P_G_3 to 54V S_IP=-830000 fizzle
29 P_0 = 1.4e-5 fizzle
30 V_OH2 = 4V @ .024 plasma
31 no changes plasma
32 no changes fizzle
33 TF only

Session Leader Comments
Oct 25 1993 09:16:06:230AMBruce LipschultzRun of 931025
Physics Operator - John Goetz
Session Leader - B. Lipschultz

This run is based on Mini Proposal 016 - Scrapeoff Layer Characterization I.
The aim of this run is to further characterize the scrapeoff layer and the
divertor at different densities and currents. A number if such plasmas
of varying parameters were probed during the confinement run - 931021,
so we will try to fill in a few more points in the range 400-700 kA and
a range in densities. Since we have plenty of data at 800 kA we may also
try to get some data at 900 kA.

After that characterization data is obtained,
we plan to move on to impurity gas puffing through the divertor.
In those we studies we are looking to determine the relative trapping efficiency
of different divertor densities on different gases. We will go to
relatively high current 800-900 kA, raise the plasma and divertor
densities and puff different impurity gases through the divertor. We will
also try and puff enough impurity gas to determine if the threshold for
the flame plasma is lowered and enhancement of a radiative divertor
configuration.

The first shot will be a repeat of 931021018, but without divertor
gas puffing.

Oct 25 1993 09:34:04:900AM931025001Bruce Lipschultzshot 1: fizzle, lower the pressure and start again.

Oct 25 1993 09:45:20:610AM931025002Bruce Lipschultzshot 1: fizzle, it appears that there is an imbalance in the EF. The engineers
will take a look at it.

Oct 25 1993 10:12:29:970AM931025003Bruce Lipschultzshot 3: fizzle again. It still appears to be a power supply problem.

Oct 25 1993 12:26:04:630PM931025009Bruce Lipschultzshot 9: This shot went ok. The problem with the EF has gotten better but
is still there. It is not clear why this shot went.
The density was 2.e19 and dropping. We will try and level out
the density for the next shot and shoot the probe in to maximum
insertion at 700 ms. Hopefully
we will get a repeat of shot 9.

Oct 25 1993 12:38:54:610PM931025010Bruce Lipschultzshot 10: dud! and the power supply problem is back.

Oct 25 1993 12:55:36:510PM931025011Bruce Lipschultzshot 11: Pretty good shot. Alot of moly early in time (~100 ms) which
shows up on the bolos and hollowness in the Te profile. The density
increases during the shot up to 4.e19. The probe was not fired
on this shot.

For the next shot we will try
to level out the density and get rid of the moly. The probe will
fire.

Oct 25 1993 02:44:58:330PM931025016Bruce Lipschultzshot 16: Good shot. Flame on at 720 ms at a density of 6.8e19. After
that the density rises to 8.9e19. The radiated power was very low ~130kW
on the 2pi). For the next shot the gas puff will be increased again.

Oct 25 1993 03:58:21:570PM931025021Bruce Lipschultzshot 21: More reasonable density rise with flame starting at 575 ms
and again at 6.5e19 density. The density levels out at 9.2e19.
For the next shot we will push to lower current (450 kA)

Oct 25 1993 04:35:24:180PM931025023Bruce Lipschultzshot 23: This shot was fine at 475 kA. The density levels out at 5.3e19
without a flame. We do get a flame during rampdown at ~ 1 sec. We will
try for slightly higher density on the next shot with full probe
insertion.

Oct 25 1993 04:35:52:740PM931025024Bruce Lipschultzshot 24: fizzle

Oct 25 1993 04:59:26:810PM931025025Bruce Lipschultzshot 25: This shot had a nice low density; a low of 1.e19 rising steadily
to 3.e19. The Zeff is corr. high. The probe went in at 700 ms when the
density was 2.e19. The next shot we will raise the current to 800 kA
and the density to roughly 6.e19 with a small Neon puff triggered at
250 ms for 100 ms.

Oct 25 1993 05:41:32:300PM931025027Bruce Lipschultzshot 27: This was a good 825 kA shot. The density reached 7.2e19.
The small amount of neon injected had little effect on the plasma.
We will puff in more neon and D2 for the next shot. Note that the Neon
is being puffed throught the private flux capillary tube.

Oct 25 1993 06:36:36:680PM931025030Bruce Lipschultzshot 30: This was a good 825 kA shot. The density reached almost 1.e20.
No neon was injected but there was still some amount on the McPherson
spectrum. We will increase the Neon on the next shot keeping evrything
else constant.

Oct 25 1993 06:41:28:000PM931025031Bruce Lipschultzshot 31: This one disrupted at 575 ms. The density reached 7.4e19. The
neon didn't get injected on that shot.

Oct 25 1993 06:52:53:120PM931025032Bruce Lipschultzshot 32: Fizzle

Physics Operator Comments
Oct 25 1993 09:08:24:580AMJohn GoetzRun 931025

Mini-proposal 032 - Gas Puffing in the Divertor

Engineering Operator - Daigle
Physics Operator - Goetz
Session Leader - Lipschultz

Goals: 1) Density scan and current scan (0.4 - 0.7 MA)
2) Inject impurities (Ne and He) into the divertor

Start from Shot 931021018
Changes: lower ZCUR to -.03 @ .4s

Oct 25 1993 09:31:39:220AM931025001John GoetzShot 001: Fizzle
Fields as good as usual
Breakdown @ .006s

For 002: P_0 = 1.2e-5

Oct 25 1993 09:49:01:940AM931025002John GoetzShot 002: Fizzle
~150A imbalance in EF1's (was there on shot 001 also)

For 003: slight difference in voltages on EF1 boards found
corrected by engineering
no other changes

Oct 25 1993 10:20:24:870AM931025003John GoetzShot 003: Fizzle
~200A imbalance in EF1's (was there on shot 001 also)

For 004: play with inversion end-stop on OH2's
fire again

Oct 25 1993 10:52:11:380AM931025004John GoetzShot 004: Dud - OH2U dies @ -.86s - blew three fuses

For 005: replace fuses
lower inversion voltage on OH2's

Oct 25 1993 11:08:31:310AM931025005John GoetzShot 005: Fizzle - EF1L 160A too negative
barely broke down

For 006: lower gain on EF1L board

Oct 25 1993 11:51:08:880AM931025007John GoetzShot 007: Fizzle - EF1L 75A too negative
broke down @ -34cm

For 008: raise gain on IC_EF1L from 2.5 to 4

Oct 25 1993 12:06:58:980PM931025008John GoetzShot 008: Fizzle - EF1L 30A too negative
broke down @ +20cm

For 009: lower gain on IC_EF1L from 4 to 2.5
swap boards changed over the weekend

Oct 25 1993 12:22:22:500PM931025009John GoetzShot 009: Plasma .63MA successful rampdown
EF1L 30A too negative


For 010: raise PULSE_GAS_3 after .5s

Oct 25 1993 12:52:05:400PM931025010John GoetzShot 010: dud
EF1L 80A too negative



For 011: change switch across integrator on EF1L control board

Oct 25 1993 12:54:20:820PM931025011John GoetzShot 011: plasma - .63MA density rising through shot
EF1's track the best they have all day


For 012: lower P_G_3 after .5s
RCUR = .68 @ .2s
ZCUR slope straightened out

Oct 25 1993 01:10:32:510PM931025012John GoetzShot 012: plasma - .63MA - successful rampdown

For 013: lower P_G_3 after .5s
stairstep turn-on of IC_EF1 gains after .06s
S_IP = -580000A

Oct 25 1993 01:28:42:140PM931025013John GoetzShot 013: plasma - .60MA - successful rampdown

For 014: raise P_G_3 to 45V between .3 and .7s
more stairsteps for turn-on of IC_EF1 gains after .06s

Oct 25 1993 01:52:23:610PM931025014John GoetzShot 014: plasma - .62MA - successful rampdown

For 015: raise P_G_3 to 42V between .3 and .7s
raise V_OH1 to 100v from 40V .07 & .11s (smooth out
current rise)

Oct 25 1993 02:04:37:340PM931025015John GoetzShot 015: plasma - .61MA - successful rampdown

For 016: raise P_G_3 to 47V between .3 and .7s
raise V_OH1 to 150v from 100V .07 & .11s (smooth out
current rise)

Oct 25 1993 02:27:33:780PM931025016John GoetzShot 016: plasma - .61MA - successful rampdown

For 017: raise P_G_3 to 52V between .3 and .5s
lower P_G_3 after .5s to 20V
raise V_OH1 to 200V from 150V .07 & .11s (smooth out
current rise)

Oct 25 1993 02:42:00:830PM931025017John GoetzShot 017: dud - fields look acceptable

For 018: P_0 = 1.4e-5

Oct 25 1993 03:00:02:080PM931025018John GoetzShot 018: plasma .61MA disruption @ 1.1s

For 019: turn off P_G_3 at .3s
puff through divertor
V_OH1 = 220V from .07 to .11s

Oct 25 1993 03:11:03:370PM931025019John GoetzShot 019: plasma .61MA disruption @ .75s

For 020: V_OH1 = 200V @ .052s; 240V @ .11
turn off P_G_3 at .25s

Oct 25 1993 03:29:45:030PM931025020John GoetzShot 020: fizzle plasma just snuffs according to VUV

For 021: P_0 = 1.3e-5

Oct 25 1993 03:47:43:830PM931025021John GoetzShot 021: plasma .62MA disruption @ 1.1s

For 022: S_IP = -430000 @ .12s; -450000@.9s
lower P_G_3 to 50V @ .25s

Oct 25 1993 04:00:48:750PM931025022John GoetzShot 022: plasma .5MA disruption @ .6s

For 023: fiddle with V_OH1 to slow down current rise

Oct 25 1993 04:21:48:180PM931025023John GoetzShot 023: plasma .48MA successful rampdown

For 024: fiddle with V_OH1 to slow down current rise some more
S_RXL ramp slowed down

Oct 25 1993 04:36:20:570PM931025024John GoetzShot 024: fizzle
high partial pressure of N2

For 025: reload gas programming from 931025013
turn down LN pump speed

Oct 25 1993 04:56:12:910PM931025025John GoetzShot 025: plasma .45MA successful rampdown


For 026: reload gas programming from 931025015
S_IP = -805000

Oct 25 1993 05:09:11:030PM931025026John GoetzShot 026: dud


For 027: P_0 =1.5e-5

Oct 25 1993 06:52:32:050PM931025026John Goetzdiamgnetic baseline

Oct 25 1993 05:39:07:340PM931025027John GoetzShot 027: plasma .82MA disruption @ 1.2s


For 028: S_IP = -830000
increase P_G_3 - first point = 54V

Oct 25 1993 05:56:00:250PM931025028John GoetzShot 028: fizzle


For 029: P_0 = 1.4e-5

Oct 25 1993 06:12:50:310PM931025029John GoetzShot 029: fizzle
Br too positive @ .020 - plasma gets thrown out the top

For 030: V_OH2 = 4V @ .024

Oct 25 1993 06:32:50:070PM931025030John GoetzShot 030: plasma .87MA disruption @ 1.2s

For 031: no changes

Oct 25 1993 06:45:23:150PM931025031John GoetzShot 031: plasma .87MA disruption @ .57s

For 032: no changes

Oct 25 1993 06:52:04:680PM931025032John GoetzShot 032: fizzle

For 033: TF only

Engineering Operator Comments
ShotTimeTypeStatusComment
109:18:38:240AMPlasmaOkPlasma shot O.K.
209:33:49:240AMPlasmaOkPlasma shot O.K.
309:52:39:390AMPlasmaOkPlasma shot adjusted inv.end stop oh2u
410:17:18:110AMPlasmaBadOH2u com fault& IOC fault Loss three fuses
510:52:19:370AMPlasmaOkPlasma shot No faults.
611:11:54:110AMPlasmaOkPlasma shot O.K . change Margin angle to 51 EF1l
711:26:08:720AMPlasmaOkplasma shot ok
811:53:58:730AMPlasmaBadEF1l seems to have a gain problem.
912:05:48:780PMPlasmaOkPlasma shot EF1 gain still?
1012:24:25:380PMPlasmaOkPlasma shot EF1 Gain problem.
1112:39:29:550PMPlasmaOkPlasma shot O.K.
1212:55:25:920PMPlasmaOkno faults
1301:13:20:420PMPlasmaOkno faults
1401:31:11:860PMPlasmaOkno faults
1501:51:17:220PMPlasmaOkPlasma shot O.K.
1602:09:15:470PMPlasmaOkPlasma shot O.K.
1702:28:20:010PMPlasmaOkno faults
1802:42:02:010PMPlasmaOkPlasma shot O.K.
1902:58:29:750PMPlasmaOkPlasma shot O.K.
2003:15:37:110PMPlasmaOkPlasma shot Fizzle
2103:31:02:610PMPlasmaOkPlasma shot O.K.
2203:48:18:190PMPlasmaOkPlasma shot O.K.
2304:04:46:730PMPlasmaOkplasma shot ok
2404:23:43:300PMPlasmaOkFizzle; may be due to increase in 28 peak prior to shot
2504:37:08:110PMPlasmaOkGood shot; 28 peak still slightly elevated
2604:58:13:680PMPlasmaOkDud!
2705:20:40:570PMPlasmaOkgood 800 kA shot
2805:39:57:410PMPlasmaOkFizzle
2905:57:02:000PMPlasmaOkFizzle
3006:14:18:370PMPlasmaOkGood 850 kA shot
3106:31:43:490PMPlasmaOkDisrupted at .57 seconds; induced comm. fail in EF1L
3206:47:49:420PMTestBad
3307:12:23:890PMTestOkTF test for Artur's gas gauge