Alcator C-Mod Run 950609 Information

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Miniproposals
Miniproposal:117
Date Filed: 4/18/1995
Title:3He Minority Heating at 7.9T
First Author:Yuichi Takase
Session Leader:Yuichi Takase (shots 1-18)

Operators
Session leader(s):Yuichi Takase
Physics operator(s):Robert Granetz
Engineering operator(s):Joe Daigle,Vinny Bertolino

Engineering Operator Run Comment
8T final run shutdown/granetz, takase

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:13:930PM
Author: To Be Determined
950609 (last run of Phase II-B)
MP #117 He3 minority heating at 8T
Density scan

Despite several problems encountered during the run, we were able to
accomplish the objective of this run. On shots 11-13 Li pellet was
injected prior to RF (pellet timing was changed to optimize the neutron
rate and the stored energy), with successful results. W_EFIT=130kJ,
Ti=3.6keV, and 8e13 neutrons/sec was achieved on shot 13 with Li pellet
injection 15ms before RF turn-on. We also observed a clear H-mode
transition at a record value of nebar*BT=23e20(m-3*T).

For the last three shots, we attempted the low He3 concentration
H-He3 mode conversion heating by switching to H majority and lowering
the field to 7.3T (at this field the H fundamental resonance is out of
the plasma, unlike at 6.5T). On shot 18 some electron heating was observed.
Power deposition was probably not central (He3 concentration was probably
too low). We need to reinvestigate this scenario in the fall.

Shot
01 fiz
02 pl disrupt @ 0.76s (OH1 pulled out)
shot delayed - computer problems, CRYO temp reading problem, etc.
03 pl 7.9T, 1MA, nel_04=1.1e20, E-port only, P_RF=1MW
04 pl nel_04=1.2e20, E-port only, P_RF=1.2MW
05 pl nel_04=1.1e20, D-port tripped, P_RF=2.3MW, W_EFIT=61-83kJ
TF didn't get to flattop
shot delayed - N2 leak
06 pl nel_04=0.9e20, D-port tripped, P_RF=1.1MW
07 pl nel_04=0.9e20, D-port tripped, P_RF=1.2MW
going up in density, enable Li pellet @ 1.1s
08 pl nel_04=1.4->1.3e20, D-port tripped, P_RF=1.3MW, disrupt @ 0.93s
disable D-port arc det from the cell (still have transmitter arc det)
09 pl nel_04=1.5->1.2e20, got both RF, P_RF=2.1MW
10 pl nel_04=1.6->1.4->1.5e20, got both RF, P_RF=2.3MW
11 pl PEP mode (Li pellet @ 0.75s), nel_04=3->1.3e20, P_RF=2.3MW
W_EFIT=60->115kJ, Ti_HIREX=3.6keV, Te0=3keV (sawtooth suppressed)
6e13neuts/s, little H-mode @ 0.85s
12 pl PEP mode (Li pellet @ 0.74s), nel_04=2.7->1.3e20, P_RF=2.5MW
W_EFIT=60->110kJ, Ti_HIREX=3.6keV, Te0=3keV (sawtooth suppressed)
6e13neuts/s (not as good)
13 pl PEP mode (Li pellet @ 0.76s), nel_04=3->1.3e20, P_RF=2.5MW
W_EFIT=60->130kJ, Ti_HIREX=3.6keV, Te0=3keV (sawtooth suppressed)
8e13neuts/s, H-mode @ 0.825s ("ELM-free" @ 0.845s)
14 dud
15 pl nel_04=0.9e20, P_RF=2.1MW
no spectroscopy data
7.3T H-He3
16 fiz
17 pl disrupt @ 0.58s, H/H+D=0.6->0.2 (CX)
18 pl nel_04=0.9e20, D-port tripped, P_RF=1.2->0.85MW
some electron heating (not so great)


Physics Operator Summaries
Entered: Jul 7 2004 04:36:54:707PM
Author: To Be Determined
Physics Operator's summary for run 950609.

MP #117 He3 minority heating at 7.9 T

SL: Y. Takase
PO: R. Granetz
EO: V. Bertolino/J. Daigle

This is a continuation of runs 950530 and 950531. Plasma operation
will be diverted, lower x-point, in deuterium at 1 MA and 8 T, with
He3 minority added for ICRF heating. The primary goal of today's run
is to study RF heating over a range of densities.

Summary:

Successfully obtained data with Prf=2.3 MW at several densities in
deuterium at 7.9 tesla and 1 MA (nl_04=0.8, 1.0, 1.3, 1.5e20 m-2). The
last shot was in hydrogen at 7.3 tesla and nl_04=1.0e20 m=2. There were
also many shots with lithium pellet injection. Even a brief H-mode (??) at
7.9 tesla and nl_04=1.5e20 !.

The relatively low number of shots was primarily due to long cooldown
times at the higher field, but there were also a fair number of problems
as well: several DAQ failures, one OH1 fault, a leaky port seal, and
several INIT failures. Nothing major though.

This is the last run until autumn, due to the planned summer shutdown.

Scorecard: 15 plasmas
2 fizzles (first D2 shot and first H2 shot)
1 dud, maybe (camac init failure)
----------
18 total

Run setup:

Discharge clean as usual in deuterium before the run

Fill A-side plenum with 19-20 psi of deuterium
Fill B-side-upper plenum with 19-20 psi of Helium-3 (This plenum probably
already contains Helium-3, so it may not need to be purged. This stuff
is expensive, after all.)
Set pre-fill at 1.8e-5 torr.
Start from shot 950531010, (an 8 tesla, 1 MA shot).
Adjust fizzle detector appropriately.
Set TF inversion at 1.1 s.

Set density to nl_04=1.0e20 m-2.

Detailed shot log:

Shot 01 -- Fizzle. Reasonably good null.
Next shot: reduce pre-fill from 1.8 to 1.6e-5 torr.

Shot 02 -- Plasma, but OH1 faulted around 0.36 s, causing plasma current to
droop, and terminating shot at 0.76 s in a CENTERED disruption.
Next shot: repeat. RF should start at 0.8 s.

MAX (and it's camac highway) crashed during the init for shot 03. Long pause
while MAX reboots.

Fault occurred during the (second) init attempt. Long pause.

Shot 03 -- Plasma, good shot. 1 MA, 8 T. Prf=1 MW, from t=0.77 to 1.00 s.
Next shot: turn on FSP control, with the programmed location just
about where it was on this shot at 0.6 s. Also move He3 gas pulse
earlier by 0.1 s.

Shot 04 -- Plasma, disrupted at 1.02 s due to excessive elongation (kappa=1.8).
This problem was caused by the FSP control. Prf=1 MW.
Next shot: raise FSP strike point by 8 mm. If this results in
a problem, I'll disable it.

Shot 05 -- Plasma, good shot. Prf=2.3 MW. Some heating, but not too
impressive. Good control of FSP strike point. Toroidal field
did not quite reach 7.9 T, and thus did not flattop. Probably
due to an excessively warm TF core.
Next shot: lower the requested density from 1.0 to 0.8e20 m-2.

Nitrogen leak, probably on E-port seal. There will be a very long pause, since
the TF core is warm, but the cooling had to be reduced to close up the leaking
seal.

Shot 06 -- Plasma, good shot. Lower density, as requested. Prf=1.1 MW.
Next shot: Change RCUR control to include a tiny amount of
feedback based on the RF antenna loading (after t=1.1 s).
No other changes.

Shot 07 -- Plasma, good shot, except for some hard x-rays.
Next shot: raise pre-fill from 1.7 to 1.9e-5 torr, raise density
to nl_04=1.3e20 m-2, and zero out the RCUR feedback on RF antenna
loading. Also turn on lithium pellet injector at 1.1 s.
Also, due to intense lobbying by Ian, who doesn't like the quality
of the breakdown, I lowered Br by 0.5 mT and raised Bz by 1 mT for
the next shot.

Shot 08 -- Plasma, disrupted at 0.93 s. EF2's were at their current limit.
Density was higher, as requested.
Next shot: turn off FSP control (and the fast scanning probe) and
try again.

Shot 09 -- Plasma, good shot. Prf=2.0 MW. Lithium pellet at 1.1 s.
Next shot: raise density to nl_04=1.5e20 m-2. Also turn on feedback
of RCUR using the RF antenna loading, but with a very small
coefficient again. Also, set up the impurity injector to shoot
in niobium at 0.9 s.

Shot 10 -- Plasma, good shot. Prf=2.3 MW. Lithium pellet at 1.1 s.
Higher density, as requested.
Next shot: repeat. Change RCUR feedback on antenna loading to
turn on at 0.9 s, rather than 1.1 s, since it looks like it may
be working properly.

Shot 11 -- Plasma, good shot. Prf=2.3 MW. Big lithium pellet at 0.75 s causes
a doubling of the density. There's some rumbling from the RF guys
about a very short H-mode from 0.85 to 0.86 s, but I don't believe
it.
Next shot: repeat. Change sign of the coefficient of the antenna
loading in the RCUR predictor.

Shot 12 -- Plasma, good shot. Prf=2.4 MW. Another lithium pellet at 0.74 s.
Next shot: repeat, except move lithium pellet injection to 0.76 s.

Shot 13 -- Plasma, good shot. Prf=2.4 MW. Lithium pellet at 0.76 s.
Next shot: lower the density to nl_04=0.8e20 m-2. Also re-enable
FSP control, with the strike position raised by 5 mm from shot 08.
Also increase the coefficient of the antenna loading feedback on
RCUR from -200 to -400 after t=1.0 s.

Alternator problem. Had to recycle back to recool.

Shot 14 -- No plasma, or a fizzle. Can't tell because spectroscopy DAQ failed
and all the magnetics DAQ failed. Lots of DAQ failures.
Apparently there must have been init failures.
Next shot: try again, no changes.

Shot 15 -- Plasma, good shot. Prf=2.1 MW. No lithium pellet.
No spectroscopy data again. It turns out that the spectroscopy
model was locked, due to editing by Rob Nachtrieb.
Next shot: change to hydrogen plasma, with a prefill of 2.8e-5 torr.
Lower toroidal field to 7.3 tesla. Everything else remains the
same.

Shot 16 -- Fizzle. (First hydrogen attempt today.) 50 kA. No hard x-rays.
Next shot: reduce pre-fill to 2.5e-5 torr and try again.

Shot 17 -- Plasma, disrupted at 0.57 s. Some hard x-rays. Hydrogen fraction
is about 60%
Next shot: increase hydrogen pre-fill to 2.7e-5 torr.

Shot 18 -- Plasma, good shot, until the lithium pellet at 1.05 s killed
it. Prf= 1 MW approx.

End of run. Last shot until next autumn.

Session Leader Comments
Jun 9 1995 05:50:53:440PM950609001Yuichi Takase950609 (last run of Phase II-B)
MP #117 He3 minority heating at 8T
Density scan

shot 01 fiz

Jun 9 1995 05:51:27:610PM950609002Yuichi Takaseshot 02 pl disrupt @ 0.76s (OH1 pulled out)
shot delayed - computer problems, CRYO temp reading problem, etc.

Jun 9 1995 05:51:43:110PM950609003Yuichi Takaseshot 03 pl 7.9T, 1MA, nel_04=1.1e20, E-port only, P_RF=1MW

Jun 9 1995 05:51:56:170PM950609004Yuichi Takaseshot 04 pl nel_04=1.2e20, E-port only, P_RF=1.2MW

Jun 9 1995 05:52:13:050PM950609005Yuichi Takaseshot 05 pl nel_04=1.1e20, D-port tripped, P_RF=2.3MW, W_EFIT=61-83kJ
TF didn't get to flattop

Jun 9 1995 05:52:24:380PM950609006Yuichi Takaseshot 06 pl nel_04=0.9e20, D-port tripped, P_RF=1.1MW

Jun 9 1995 05:52:34:640PM950609007Yuichi Takaseshot 07 pl nel_04=0.9e20, D-port tripped, P_RF=1.2MW

Jun 9 1995 05:54:08:370PM950609008Yuichi Takasegoing up in density, enable Li pellet @ 1.1s
shot 08 pl nel_04=1.4->1.3e20, D-port tripped, P_RF=1.3MW,
disrupt @ 0.93s
D-port problem is with the phase balance detector
disable D-port arc det from the cell (still have transmitter arc det)

Jun 9 1995 05:54:23:450PM950609009Yuichi Takaseshot 09 pl nel_04=1.5->1.2e20, got both RF, P_RF=2.1MW

Jun 9 1995 05:54:34:390PM950609010Yuichi Takaseshot 10 pl nel_04=1.6->1.4->1.5e20, got both RF, P_RF=2.3MW

Jun 9 1995 05:54:53:010PM950609011Yuichi Takaseshot 11 pl PEP mode (Li pellet @ 0.75s), nel_04=3->1.3e20, P_RF=2.3MW
W_EFIT=60->115kJ, Ti_HIREX=3.6keV, Te0=3keV (sawtooth suppressed)
6e13neuts/s, little H-mode @ 0.85s

Jun 9 1995 05:55:07:310PM950609012Yuichi Takaseshot 12 pl PEP mode (Li pellet @ 0.74s), nel_04=2.7->1.3e20, P_RF=2.5MW
W_EFIT=60->110kJ, Ti_HIREX=3.6keV, Te0=3keV (sawtooth suppressed)
6e13neuts/s (not as good)

Jun 9 1995 05:55:20:800PM950609013Yuichi Takaseshot 13 pl PEP mode (Li pellet @ 0.76s), nel_04=3->1.3e20, P_RF=2.5MW
W_EFIT=60->130kJ, Ti_HIREX=3.6keV, Te0=3keV (sawtooth suppressed)
8e13neuts/s, H-mode @ 0.825s ("ELM-free" @ 0.845s)

Jun 9 1995 05:55:58:390PM950609014Yuichi Takaseshot 14 dud

Jun 9 1995 05:56:10:980PM950609015Yuichi Takaseshot 15 pl nel_04=0.9e20, P_RF=2.1MW
no spectroscopy data

Jun 9 1995 05:56:31:910PM950609016Yuichi Takase7.3T H-He3
shot 16 fiz

Jun 9 1995 05:56:44:900PM950609017Yuichi Takaseshot 17 pl disrupt @ 0.58s, H/H+D=0.6->0.2 (CX)

Jun 9 1995 05:56:58:850PM950609018Yuichi Takaseshot 18 pl nel_04=0.9e20, D-port tripped, P_RF=1.2->0.85MW
some electron heating (not so great)

Physics Operator Comments
Jun 9 1995 08:26:23:330AMRobert GranetzMP #117 He3 minority heating at 7.9 T

SL: Y. Takase
PO: R. Granetz
EO: V. Bertolino

This is a continuation of runs 950530 and 950531. Plasma operation
will be diverted, lower x-point, in deuterium at 1 MA and 8 T, with
He3 minority added for ICRF heating. The primary goal of today's run
is to study RF heating over a range of densities. A secondary goal is
to fiddle with the TF high-tap switching.

Jun 9 1995 08:26:48:880AMRobert GranetzRun setup:

Discharge clean as usual in deuterium before the run

Fill A-side plenum with 19-20 psi of deuterium
Fill B-side-upper plenum with 19-20 psi of Helium-3 (This plenum probably
already contains Helium-3, so it may not need to be purged. This stuff
is expensive, after all.)
Set pre-fill at 1.8e-5 torr.
Start from shot 950531010, (an 8 tesla, 1 MA shot).
Adjust fizzle detector appropriately.
Set TF inversion at 1.1 s.

Set density to nl_04=1.0e20 m-2.

Jun 9 1995 08:35:48:140AM950609001Robert GranetzShot 01 -- Fizzle. Reasonably good null.
Next shot: reduce pre-fill from 1.8 to 1.6e-5 torr.

Jun 9 1995 09:01:20:620AM950609002Robert GranetzShot 02 -- Plasma, but OH1 faulted around 0.36 s, causing plasma current to
droop, and terminating shot at 0.76 s in a CENTERED disruption.
Next shot: repeat. RF should start at 0.8 s.

Jun 9 1995 10:23:00:500AM950609003Robert GranetzShot 03 -- Plasma, good shot. 1 MA, 8 T. Prf=1 MW, from t=0.77 to 1.00 s.
Next shot: turn on FSP control, with the programmed location just
about where it was on this shot at 0.6 s. Also move He3 gas pulse
earlier by 0.1 s.

Jun 9 1995 10:36:46:820AM950609004Robert GranetzShot 04 -- Plasma, disrupted at 1.02 s due to excessive elongation (kappa=1.8).
This problem was caused by the FSP control. Prf=1 MW.
Next shot: raise FSP strike point by 8 mm. If this results in
a problem, I'll disable it.

Jun 9 1995 10:58:45:500AM950609005Robert GranetzShot 05 -- Plasma, good shot. Prf=2.3 MW. Some heating, but not too
impressive. Good control of FSP strike point. Toroidal field
did not quite reach 7.9 T, and thus did not flattop. Probably
due to an excessively warm TF core.
Next shot: lower the requested density from 1.0 to 0.8e20 m-2.

Jun 9 1995 11:03:01:100AM950609005Robert GranetzNitrogen leak, probably on E-port seal.

Jun 9 1995 11:48:50:520AM950609006Robert GranetzShot 06 -- Plasma, good shot. Lower density, as requested. Prf=1.1 MW.
Next shot: Change RCUR control to include a tiny amount of
feedback based on the RF antenna loading (after t=1.1 s).
No other changes.

Jun 9 1995 12:08:10:940PM950609007Robert GranetzShot 07 -- Plasma, good shot, except for some hard x-rays.
Next shot: raise pre-fill from 1.7 to 1.9e-5 torr, raise density
to nl_04=1.3e20 m-2, and zero out the RCUR feedback on RF antenna
loading. Also turn on lithium pellet injector at 1.1 s.

Jun 9 1995 12:16:13:580PM950609007Robert Granetz Also, due to intense lobbying by Ian, who doesn't like the quality
of the breakdown, I lowered Br by 0.5 mT and raised Bz by 1 mT for
the next shot.

Jun 9 1995 12:33:38:980PM950609008Robert GranetzShot 08 -- Plasma, disrupted at 0.93 s. EF2's were at their current limit.
Density was higher, as requested.
Next shot: turn off FSP control and try again.

Jun 9 1995 01:25:25:410PM950609009Robert GranetzShot 09 -- Plasma, good shot. Prf=2.0 MW. Lithium pellet at 1.1 s.
Next shot: raise density to nl_04=1.5e20 m-2. Also turn on feedback
of RCUR using the RF antenna loading, but with a very small
coefficient again. Also, set up the impurity injector to shoot
in niobium at 0.9 s.

Jun 9 1995 01:51:58:270PM950609010Robert GranetzShot 10 -- Plasma, good shot. Prf=2.3 MW. Lithium pellet at 1.1 s.
Higher density, as requested.
Next shot: repeat. Change RCUR feedback on antenna loading to
turn on at 0.9 s, rather than 1.1 s, since it looks like it may
be working properly.

Jun 9 1995 02:23:03:640PM950609011Robert GranetzShot 11 -- Plasma, good shot. Prf=2.3 MW. Big lithium pellet at 0.75 s causes
a doubling of the density. There's some rumbling from the RF guys
about a very short H-mode from 0.85 to 0.86 s, but I don't believe
it.
Next shot: repeat. Change sign of the coefficient of the antenna
loading in the RCUR predictor.

Jun 9 1995 02:50:07:660PM950609012Robert GranetzShot 12 -- Plasma, good shot. Prf=2.4 MW. Another lithium pellet at 0.74 s.
Next shot: repeat, except move lithium pellet injection to 0.76 s.

Jun 9 1995 03:25:00:340PM950609013Robert GranetzShot 13 -- Plasma, good shot. Prf=2.4 MW. Lithium pellet at 0.76 s.
Next shot: lower the density to nl_04=0.8e20 m-2. Also re-enable
FSP control, with the strike position raised by 5 mm from shot 08.
Also increase the coefficient of the antenna loading feedback on
RCUR from -200 to -400 after t=1.0 s.

Jun 9 1995 04:05:44:630PM950609014Robert GranetzShot 14 -- No plasma, or a fizzle. Can't tell because spectroscopy DAQ failed
and all the magnetics DAQ failed. Lots of DAQ failures.
Apparently there must have been init failures.
Next shot: try again, no changes.

Jun 9 1995 04:13:30:280PM950609015Robert GranetzShot 15 -- Plasma, good shot. Prf=2.1 MW. No lithium pellet.
Next shot: change to hydrogen plasma, with a prefill of 2.8e-5 torr.
Lower toroidal field to 7.3 tesla. Everything else remains the
same.

Jun 9 1995 04:36:23:720PM950609016Robert GranetzShot 16 -- Fizzle. (First hydrogen attempt today.) 50 kA. No hard x-rays.
Next shot: reduce pre-fill to 2.5e-5 torr and try again.

Jun 9 1995 04:52:07:400PM950609017Robert GranetzShot 17 -- Plasma, disrupted at 0.57 s. Some hard x-rays.
Next shot: increase hydrogen pre-fill to 2.7e-5 torr.

Jun 9 1995 05:16:37:360PM950609018Robert GranetzShot 18 -- Plasma, good shot, until the lithium pellet at 1.05 s killed
it. Prf= 1 MW approx.

End of run. Last shot until next autumn.

Engineering Operator Comments
ShotTimeTypeStatusComment
108:29:24:140AMPlasmaOk
208:46:46:050AMPlasmaBadoh1 type 2
309:33:31:340AMPlasmaOk
410:23:25:740AMPlasmaOk
510:43:15:450AMPlasmaOk
611:22:59:110AMPlasmaOk
711:54:16:070AMPlasmaOk
812:25:11:150PMPlasmaOk
912:59:38:960PMPlasmaOk
1001:35:05:630PMPlasmaOk
1102:07:59:890PMPlasmaOk
1202:35:27:270PMPlasmaOk
1303:07:10:010PMPlasmaOk
1403:30:52:030PMPlasmaOk
1503:59:02:500PMPlasmaOk
1604:26:30:770PMPlasmaOk
1704:42:41:280PMPlasmaOk
1805:02:34:380PMPlasmaOk