Alcator C-Mod Run 1050209 Information

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Miniproposals
Miniproposal:298a
Date Filed: 5/20/2002
Title:C-Mod Plasma Startup
First Author:Jim Irby
Session Leader:Jim Irby (shots 1-21)

Operators
Session leader(s):Jim Irby
Physics operator(s):Bill Rowan
Engineering operator(s):Bill Byford,Ed Fitzgerald

Engineering Operator Run Comment
C-Mod Plasma Startup/Cochran

Session Leader Plans
Entered: Feb 9 2005 10:08:06:867AM
Author: Jim Irby
We will continue plasma conditioning today.

Begin with lower null diverted for a couple of shots to get us going again. Then
sweep strike point across outer divertor. Eventually go from lower to upper null during
the discharge. Look for changes in h/d, gas evolution etc.

Physics Operators Plans
Entered: Feb 9 2005 08:03:08:167AM
Author: Bill Rowan
Purpose: Startup/Conditioning
PO: Rowan
SL: Irby

Power systems as for 1050208020

Run Plan
Start with a lower null.
Sweeps will be used during the run.
The sweeps may include x-point position in snl and snl to snu.

Session Leader Summaries
Entered: Feb 9 2005 07:14:38:620PM
Author: Jim Irby
Lots of plasma seconds today. We were able to sweep the lower divertor strike point by +- 2 cm and see
changes in h/d and density. h/(h+d) started out around 20% and then climbed to 30 or 40% during the
run. Density feedback became operational again today. It was used for the first time on shot
14. Extra gas reduced h/(h+d) to 25% or so early, but it rose back to 35% by 1.4 s. A disruption
on shot 16 filled the vessel to about 25 mTorr and should give good RGA data on hydrogenic content.
Impurity levels indicated by the RGA were relatively low. Following the disruption on shot 16 we had
fizzles until shot 21 which ran well into rampdown. ECDC was tried between shots 19 and 20, but did
not seem to help. Shot 21 had h/(h+d) of 20%, either because of ECDC or a helpful distruption and
series of fizzles (time between discharges).

Physics Operator Summaries
Entered: Feb 10 2005 07:10:38:753AM
Author: Bill Rowan
Purpose: Startup/Conditioning
PO: Rowan
SL: Irby
EO: Cochran, Byford, Fitzgerald,

Power systems as for 1050208020

Run Plan
Start with a lower null.
Sweeps will be used during the run.
The sweeps may include x-point position in snl and snl to snu.

Results
The first shot was used to test flux loops and was OH only. The next six
were SNL attempts. There were 2 fizzles followed by 4 full length shots.
The longer shots displayed soft x-ray bursts such as might result from small
pieces dropping into the plasma. The gas feed on these shots was programmed
and turned off. There was no droop in the density at late times so the wall
contribution was significant.

Starting with shot 008, the lower x-point was swept to expose the lower part
of the vacuum vessel to plasma for cleaning.
At shot 013, the nl_04 feedback was turned on. The plasma density was
controlled successfully. The density demand was increased to 1.0e+20 for shot
016. A disruption occurred at 1.3s. The next 4 shots were fizzles.
ECDC was used between the third and fourth of these. The last shot of the
day was a plasma.

There was no attempt at upper nulls.

Plasmas 12 (004,005,006,007,008,009,010,012,013,014,
016(late disruption),021)
Diagnostic test 1 (001)
Engineering fault 1 (011, no TF)
Fizzles 7 (002,003,015,017,018,019,020)
Duds 0

Total 21

Session Leader Comments
Feb 9 2005 11:26:40:977AMJim IrbyThe neuts/hards x-ray detector is finally in its proper position in the k-tan igloo opening.

The density feedback gain has been increased by a factor of two. After a couple of discharges
to check that it is operating properly we can go to density feedback.

We will attempt to get some rf power from fmit#2 today.
Feb 9 2005 11:43:21:570AMJim IrbyThe gatevalve-toggle will be enabled for the first shot today. We will manually close GV1
at the beginning of INIT to get a baseline on the RGA.

First shot today will be a 10kA PLC controlled OH test to produce a test signal for the flux loops.
Feb 9 2005 12:24:55:023PM1050209001Jim Irby10 kA OH test for flux loop check

Offsets on OH coax voltages now very low:

oh2l +0.0005
oh2u +0.0006
oh1 +0.0002
Feb 9 2005 12:32:08:350PM1050209002Jim Irbyfizzle
Feb 9 2005 02:36:09:990PM1050209004Jim Irbyh/(h+d) at 21% at 1.4 s

Feb 9 2005 02:35:26:837PM1050209005Jim Irbyh/(h+d) at 26% at 1.4 s


Feb 9 2005 03:24:58:727PM1050209006Jim Irbyplasma into rampdown

h/(h+d) = 29%
Feb 9 2005 03:34:11:727PM1050209007Jim Irbyplasma into rampdown

h/(h+d) at 32% at 1.4 s

Feb 9 2005 03:32:33:693PM1050209008Jim Irbyplasma into rampdown

h/(h+d) at 35% at 1.4 s

Feb 9 2005 03:53:35:400PM1050209009Jim Irbyplasma into rampdown with +/- 2 cm sweep of RXL

h/(h+d) at 35% at 1.4 s

gatevalve-toggle was disabled for this shot
Feb 9 2005 04:23:26:320PM1050209010Jim Irbyplasma into rampdown

gatevalve toggle enabled

before/after rga data available as of shot 7 --- may be confusion
with gatevalve status to figure out.

h/(h+d) at 34% at 1.4 s
Feb 9 2005 04:52:26:087PM1050209012Jim Irbyplasma into rampdown

h/(h+d) at 35% at 1.4 s

Feb 9 2005 05:18:09:020PM1050209013Jim Irbysweep a little harder

next shot will try density control

plasma into rampdown
Feb 9 2005 05:27:59:760PM1050209014Jim Irbydensity feedback enabled --- 7e19 request

plasma into rampdown

h/(h+d) drops during density increase, but ends up at 37% at 1.4 s

Feb 9 2005 05:36:48:773PM1050209015Jim Irbyfizzle

puffing a little extra gas???
Feb 9 2005 05:57:30:557PM1050209016Jim Irbytry again for 1e20 nl04

disruption at 1.28 s

h/(h+d) down to 25%, but then heading up quickly at end of shot
Feb 9 2005 06:13:15:307PM1050209018Jim Irbyfizzle
Feb 9 2005 06:24:42:370PM1050209019Jim Irbyfizzle
Feb 9 2005 07:16:37:680PM1050209021Jim Irbyplasma well into rampdown

h/(h+d) at 20% early, 24% late.

before/after RGA data looks good for this shot

Physics Operator Comments
Feb 9 2005 11:15:41:507AMBill RowanLoaded shot 1050208020. Load/clean.
Feb 9 2005 12:06:49:287PMBill Rowan001. OH only for flux loop test
Feb 9 2005 12:11:32:553PM1050209001Bill Rowan
Next shot. Plasma attempt.
Feb 9 2005 12:34:02:740PM1050209002Bill Rowan
002. Fizzle

Next shot. Lowered the BR by 0.5 mT
Feb 9 2005 01:11:16:400PM1050209003Bill Rowan003. Fizzle. Slight improvement.

Next shot. Lower BR by 0.5 mT
Feb 9 2005 01:17:22:820PM1050209003Bill RowanIncrease pg4 by 2 ms
Feb 9 2005 01:38:37:383PM1050209004Bill Rowan
RF will be firing after 1 s on subsequent shots
Feb 9 2005 01:44:26:130PM1050209004Bill Rowan
Next shot. No changes
Feb 9 2005 01:59:28:460PM1050209004Bill Rowan004. Full length shot.
Prefill pressure is only slightly higher
BR lowered as expected.
Bursts of soft x-ray at 1.2 s
Feb 9 2005 02:00:21:350PM1050209005Bill Rowan005. Full length shot
Bursts of soft x-ray at 0.7 s

Next shot.
Turn on PG1 for 15 ms
Feb 9 2005 02:48:34:150PM1050209006Bill Rowan006. Full length shot.
Soft x-ray bursts at 0.7 s

Next shot.
Increase PG1 to 35 ms
Feb 9 2005 03:04:48:680PM1050209007Bill Rowan007. Full length shot

Next shot.
Increase PG1 to 45 ms
Feb 9 2005 03:30:33:867PM1050209008Bill Rowan
008. Full length shot

Next shot.
Sweep RXL +/- 2 cm
Feb 9 2005 03:50:39:507PM1050209009Bill Rowan009. Full length shot

Next shot.
Add a sweep to ZXL +/- 1 cm
Feb 9 2005 04:11:08:257PM1050209010Bill Rowan
010. Full length shot

Next shot.
Increase the RXL sweep
Feb 9 2005 04:27:24:850PM1050209011Bill Rowan011. No TF

Next shot.
No changes
Feb 9 2005 05:23:07:793PM1050209012Bill Rowan012. Full length shot

Next shot.
Increase the RXL sweep
Feb 9 2005 05:23:24:497PM1050209013Bill Rowan013. Full length shot.

Next shot
Turn on the NL_04 feedback.
Feb 9 2005 05:23:54:793PM1050209014Bill Rowan014. Full length shot
NL_04 feedback worked at 0.7e+20

Next shot
Increased argon again - increased the length of PG1 pulse
NL_04 feedback changed to 1.0e+20
Feb 9 2005 05:33:22:680PM1050209015Bill Rowan015. Fizzle
Feb 9 2005 05:34:39:210PM1050209015Bill RowanNext shot.
No changes
Feb 9 2005 05:47:59:290PM1050209016Bill Rowan016. Plasma. Disruption at 1.29s
Moves vertically at the disruption

Next shot.
Reduced the outer part of the RXL sweep to 2.0 cm
Feb 9 2005 06:37:02:570PM1050209017Bill Rowan017. Fizzle

Next shot: reduce the density demand
Feb 9 2005 06:15:21:120PM1050209018Bill Rowan018. Fizzle
Feb 9 2005 06:17:04:557PM1050209018Bill Rowan
Next shot: reduce the prefill by 2 ms
Feb 9 2005 06:19:48:023PM1050209018Bill Rowan
Turn off PG1, the argon valve
Feb 9 2005 06:26:33:070PM1050209019Bill Rowan019. Fizzle

Next shot: reduce the prefill by 2 ms
Feb 9 2005 06:38:51:260PM1050209019Bill RowanECDC for 10 minutes before the next shot.
Feb 9 2005 06:58:00:743PM1050209020Bill Rowan020. Fizzle

ECDC did not seem to help. The pressure was 1.19e-06 before this shot.

Next shot. No changes.
Feb 9 2005 07:05:13:320PM1050209021Bill Rowan21. Plasma

End of the run

Engineering Operator Comments
ShotTimeTypeStatusComment
112:04:16:290PMTestBad
212:21:20:350PMTestBad
312:59:31:507PMPlasmaOk
401:30:16:600PMPlasmaOk
501:44:50:290PMPlasmaOk
602:37:58:320PMPlasmaOk
702:56:24:413PMPlasmaOk
803:18:23:320PMPlasmaOk
903:42:53:663PMPlasmaOk
1004:03:00:320PMPlasmaOk
1104:21:48:587PMPlasmaOk
1204:35:23:743PMPlasmaOk
1304:53:18:100PMPlasmaOk
1405:13:47:863PMPlasmaOk
1505:27:23:853PMPlasmaOk
1605:40:24:150PMPlasmaOk
1705:56:10:807PMPlasmaOk
1806:09:17:883PMPlasmaOk
1906:21:53:510PMPlasmaOk
2006:50:50:710PMPlasmaOk
2107:03:15:057PMPlasmaOk