Alcator C-Mod Run 960905 Information

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Miniproposals
Miniproposal:150a
Date Filed: 7/23/1996
Title:3He Minority Heating at 8T
First Author:Yuichi Takase
Session Leader:Yuichi Takase (shots 1-9)

Operators
Session leader(s):Yuichi Takase
Physics operator(s):Joseph Snipes
Engineering operator(s):Joe Daigle,Frank Silva

Engineering Operator Run Comment
mp150a/takase/snipe/silva/daigle

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:16:523PM
Author: To Be Determined
MP150A D(He3) Minority Heating at 8T
SL: Takase
PO: Snipes
EO: Silva
Minority concentration scans at different densities.
Measure power absorption from RF power steps.

Overnight ECDC in D2
Transmitter #1 fixed (step start house) last night

We had two 8T shots. These shots had low He3 concentrations compared
to shots from the previous campaign (estimated to be less than 1%).
As expected, more electron heating and less ion heating were observed
(see addendum to MP150A). No parameter scans were made.
Preliminary analysis indicates an absorption efficiency of less than 50%.
At such low concentration single pass absorption is theoretically
expected to be low. There should be a maximum in single pass
absorption at somewhat higher concentration, around 5% (see addendum to
MP150A).

The run had to be terminated early because of high OH resistance reading.
See the physics operator's summary for details.

Shot
01 fiz Start from 960904038, modify to 8T, 1.2MA, nel=1.0
Start with 5ms He3 puff @ 90V (B side upper)
02 pla 7.8T, 1.2MA, nel=1.0, D: 0.85MW (crowbar @ 0.8s), E: 1.2MW,
He3 5ms @ 90V
Adjust TF, delay RF turn-on, add power notch-out for next shot.
03 pla 8.0T, nel=1.0, inj around 0.6s, didn't get to 8T till 0.8s
D: 1.0MW (crowbar), E:1.2MW
OH resistance is high
04 test OH test
05 test OH test
06 test OH test
07 test OH test
08 test OH test
09 test TF and OH test
end of run

Physics Operator Summaries
Entered: Jul 7 2004 04:36:56:753PM
Author: To Be Determined
MP150A D(He3) 8Tesla ICRF Heating

Session Leader: Yuichi Takase
Physics Operator: Joseph Snipes
Engineer in Charge: Frank Silva

Overnight ECDC in deuterium. Power systems setup as for 960904038 except TF
setup as for 960213016. Intend to run 8 T possibly up to 1.5 MA operation to
get He3 minority heating with ICRF doing He3 concentration scans at different
densities. Measurements will be made of the RF power absorption.

The OH2U resistance across the felt metal connection increased sharply after
each shot until after shot 3, it became higher than 3 uOhm and the run was
stopped for OH test shots. After several tests, the resistance reached 6 uOhm
and the run was officially cancelled.

Shot 1: Copied shot 960904002, but modified the density to 1 x 10^20 m^-2 and
made slight changes to the end of the flattop. Ip set to 1.2 MA.
TF set to 8T flattop starting at about 0.6 sec to 1.2 sec. Fizzle!
Shot 2: Reduced Br offset by 0.5 mT to 5.5 mT. Good shot. TF fault after the
plasma. Reached 1.2 MA, but only 7.8 T.
Shot 3: Reduced Br offset by another 0.5 mT to 5 mT. Moved ZXL down by 4 mm
at 0.5 sec to accomodate the Fast Scanning Probe. Asked for 7kA more
TF current to reach 8T. Good shot. Another TF fault after the plasma
and instantaneous overcurrents at the alternator! OH resistance fault
up to 3 uOhm.
Shot 4: OH test. OH resistance up to about 3.9 uOhm. Could be a problem.
Shot 5: OH test. OH resistance up to 3.95 uOhm.
Shot 6: OH test. OH resistance down to 3.92 uOhm.
Shot 7: OH test. OH resistance down to 3.89 uOhm.
Shot 8: OH test. OH resistance at 3.89 uOhm.
Shot 9: OH + TF test. Silva screwed up and ran other fields as well.
OH resistance up to 4.4 uOhm. There appears to be a real problem.

The OH2U resistance across the felt metal connection increased sharply during
the shot to about 6 uOhm. Subsequent measurments of the resistance with a
separate 100 A power supply and meters showed that the resistance is still at
6 uOhm. This level of resistance is unacceptable for operation.So, the run has
been cancelled until further tests can be made and determine how the resistance
can be returned to the normal level of less than 1 uOhm.

Scorecard
9 shots
2 plasmas
1 fizzle
6 tests

Session Leader Comments
Sep 5 1996 09:19:44:780AMYuichi TakaseMP150A D(He3) Minority Heating at 8T
SL: Takase
PO: Snipes
EO: Silva
Minority concentration scans at different densities.
Measure power absorption from RF power steps.

Sep 5 1996 09:30:02:550AM960905001Yuichi TakaseShot 001 fiz
Start from 960904038, modify to 8T, 1.2MA, nel=1.0
Start with 5ms He3 puff @ 90V (B side upper)

Sep 5 1996 09:33:18:630AM960905002Yuichi TakaseShot 002 plasma
7.8T, 1.2MA, nel=1.0, D: 0.85MW (crowbar @ 0.8s), E: 1.2MW
He3 5ms @ 90V

Adjust TF, delay RF turn-on, add power notch-out for next shot.

Sep 5 1996 09:58:40:950AM960905003Yuichi TakaseShot 003 plasma
8.0T, nel=1.0, inj around 0.6s, didn't get to 8T till 0.8s
D: 1.0MW (crowbar), E:1.2MW

Sep 5 1996 09:59:06:340AM960905004Yuichi TakaseShot 004 OH test

Physics Operator Comments
Sep 5 1996 08:28:54:990AMJoseph SnipesMP150A D(He3) 8Tesla ICRF Heating

Session Leader: Yuichi Takase
Physics Operator: Joseph Snipes
Engineer in Charge: Frank Silva

Overnight ECDC in deuterium. Power systems setup as for 960904038 except TF
setup as for 960213016. Intend to run 8 T possibly up to 1.5 MA operation to
get He3 minority heating with ICRF doing He3 concentration scans at different
densities. Measurements will be made of the RF power absorption.


Sep 5 1996 08:54:35:280AM960905001Joseph SnipesShot 1: Copied shot 960904002, but modified the density to 1 x 10^20 m^-2 and
made slight changes to the end of the flattop. Ip set to 1.2 MA.
TF set to 8T flattop starting at about 0.6 sec to 1.2 sec. Fizzle!


Sep 5 1996 09:30:27:600AM960905002Joseph SnipesShot 2: Reduced Br offset by 0.5 mT to 5.5 mT. Good shot. TF fault after the
plasma. Reached 1.2 MA, but only 7.8 T.



Sep 5 1996 09:47:49:270AM960905003Joseph SnipesShot 3: Reduced Br offset by another 0.5 mT to 5 mT. Moved ZXL down by 4 mm
at 0.5 sec to accomodate the Fast Scanning Probe. Asked for 7kA more
TF current to reach 8T. Good shot. Another TF fault after the plasma
and instantaneous overcurrents at the alternator! OH resistance fault
up to 3 uOhm.


Sep 5 1996 10:02:10:950AM960905004Joseph SnipesShot 4: OH test. OH resistance up to about 3.9 uOhm. Could be a problem.

Sep 5 1996 11:01:09:280AM960905005Joseph SnipesShot 5: OH test. OH resistance up to 3.95 uOhm.

Sep 5 1996 11:14:17:610AM960905006Joseph SnipesShot 6: OH test. OH resistance at 3.92 uOhm.

Sep 5 1996 11:20:53:770AM960905007Joseph SnipesShot 7: OH test. OH resistance at 3.89 uOhm.

Sep 5 1996 11:28:07:460AM960905008Joseph SnipesShot 8: OH test. OH resistance at 3.89 uOhm.

Sep 5 1996 11:53:26:040AM960905009Joseph SnipesShot 9: OH + TF test. Silva screwed up and ran other fields as well.
OH resistance up to 4.4 uOhm. There appears to be a real problem.


Sep 5 1996 01:57:41:990PM960905009Joseph SnipesThe OH2U resistance across the felt metal connection increased sharply during
the shot to about 6 uOhm. Subsequent measurments of the resistance with a
separate 100 A power supply and meters showed that the resistance is still at
6 uOhm. This level of resistance is unacceptable for operation.So, the run has
been cancelled until further tests can be made and determine how the resistance
can be returned to the normal level of less than 1 uOhm.


Engineering Operator Comments
ShotTimeTypeStatusComment
108:43:14:690AMPlasmaOkno faults
208:54:58:360AMPlasmaOkall pf dedendant supplies show low line phase seq..
309:30:19:160AMPlasmaOkTimmed Overcurrent from alt. late in shot.
409:53:56:470AMTestOkOH2U reading 3.89Micro Ohms.
510:54:21:230AMTestOkOH2U 3.9519 Micro ohms. @ 5.0 KA
611:07:59:140AMTestOkoh temp test
711:15:33:110AMTestOkoh test temp
811:22:52:340AMTestOkoh temp tests
911:40:09:610AMTestOkoh test see log