Alcator C-Mod Run 1050505 Information

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Miniproposals
Miniproposal:417
Date Filed: 2/24/2005
Title:Plasma performance, boronization and ICRF heating effectiveness with high-Z antenna guards and all-m
First Author:Yijun Lin
Session Leader:Yijun Lin (shots 1-22)

Operators
Session leader(s):Yijun Lin
Physics operator(s):Bill Rowan,Ian Hutchinson
Engineering operator(s):Bill Cochran,Ed Fitzgerald,Bill Parkin

Engineering Operator Run Comment
Continuation of MP417?

Session Leader Plans
Entered: May 5 2005 12:15:15:357PM
Author: Yijun Lin
Continue on 1050504. Try to get plasmas.
If we get good plasmas, we will run MP417 to evaluate the boronization.

We did He flow in 200 torr and 600 Torr in the morning in the machine (total
about 4 hours). Thomson scattering saw fewer dust events comparing the
beginning (0 events in 10 shots in compared with 3-4 events per shot).

Hopefully, we will get significantly less dust in plasma attempts.

Physics Operators Plans

Session Leader Summaries
Entered: May 6 2005 09:33:18:597AM
Author: Yijun Lin
SL summary:

Getting longer plasmas than the previous two runs. shot 16 got to 0.9 sec
and shot 22 got to 0.72 sec.
Apparently, He4 flow in the morning did not help much. We are in
the same slow progress as the last two runs.

---------
On the TiD2 powder theory:

Supportive evidence:
'Sand' piles are observed in the LH camera view on the grill. It is
consistent with the speculation by D. Whyte that there might be
16 gram of TiD2 powder (from the estimation of total degasing in run 1050504).

these sand piles may also be Boron hydride or boron after the boronization.

Contradictory evidence:

Dave Gwinn and Bob Childs performed a test on the Ti alloy we used on the
couplers. A sample was put in our vacuum oven, baked at 90C to drive off
the water, and then brought back down to 60 C. The chamber was then filled
with 500 T of D2 and left 20 hours or so. The sample and a control sample
left out of the oven look identical both by eye and under the microscope.
No indication of dust or flaking. No change in weight of the oven sample.

the test may not have reproduced the evironment on the vessel.
Some other things
must have helped. We can count them: boronization, ECDC in He4 and/or
ECDC in D2. But we have no idea on how this actually could help.
-----------


Physics Operator Summaries
Entered: May 5 2005 05:08:43:793PM
Author: Ian Hutchinson
Two plasmas lasted over .5 seconds.
There was some progress but the dust and deuterium is still overwhelming.

Session Leader Comments
May 5 2005 12:27:59:873PM1050505001Yijun Linfizzle
May 5 2005 12:50:11:077PM1050505002Yijun Lin260 ms. 560 kA. (encourging)
May 5 2005 12:55:30:077PM1050505003Yijun Lin fizzle. to 75 ms.

May 5 2005 01:12:30:623PM1050505004Yijun Linplasma to 130 ms, i_max = 280 kA. Stuff coming from the LH launcher
and other places.
Next shot: 1050505005, interesting number --> good plasma?

May 5 2005 01:27:28:077PM1050505005Yijun Linfizzle.
Apparently, an interesting shot number did not guarrantee a good plasma.
The machine does not know the beauty of numbers.
May 5 2005 01:34:22:717PM1050505006Yijun Linfizzle
May 5 2005 01:51:14:327PM1050505007Yijun Lin340 ms. 600 kA. (the longest plasma this week/month. better than 1050504041)
Still stuff came off the LH grill.
May 5 2005 02:01:36:263PM1050505008Yijun Lin170 ms. 300 kA.
May 5 2005 02:32:58:077PM1050505009Yijun Lin 300 ms. 570 kA. One of the best plasmas we have had since 1050503.
there were a few LH camera frames that did not show any dust.

It looks like 'sand'piling on the LH grill from the camera view (frame 9).
More 'sand' is on the lower part than the upper part. Is it just optical illusion?
It was definitely not there last week.
May 5 2005 02:28:50:107PM1050505010Yijun Lin210 ms. 360 kA
May 5 2005 02:48:45:670PM1050505011Yijun Lin340 ms. 600 kA. Same sand piles seen in LH view (e.g. frame 9)
Next: try inner wall limited plasma to get plasma longer.

May 5 2005 02:51:36:717PM1050505012Yijun Lintrying innner wall limited plasma. Fizzle

May 5 2005 03:14:39:373PM1050505013Yijun Lin370 ms. 600 kA. (longest plasma today so far)

May 5 2005 03:20:05:480PM1050505014Yijun Linto 70 ms. fizzle.
May 5 2005 03:44:27:920PM1050505015Yijun Linto 140 ms, 360 kA.
May 5 2005 03:55:55:043PM1050505016Yijun Linto 0.93 sec, 600 kA. inner wall limited. (good shot!)
No LH camera data. H/D~1%
Note: This was the 100th shot this week/month.
Maybe shot numbers do matter.
May 5 2005 04:04:55:107PM1050505017Yijun Linto 70 ms. fizzle
May 5 2005 04:11:45:560PM1050505018Yijun Linto 120 ms.
May 5 2005 04:36:33:140PM1050505019Yijun Linshot 19: plasma till 340 ms, 570 kA.
Camera data is back. It is hard to tell whether the 'sand' piles
have been getting bigger or smaller. They are about the same size
as yesterday.

May 5 2005 04:37:32:983PM1050505020Yijun Linplasma to 75 ms.
May 5 2005 04:55:56:983PM1050505021Yijun Lin plasma to 220 ms.
May 5 2005 05:03:42:700PM1050505022Yijun Lin plasma to 720 ms, 600 kA. good shot

Physics Operator Comments
May 5 2005 11:32:21:390AMBill RowanAttempts during the morning to purge dust.

Start from shot 1050504055
May 5 2005 11:36:08:500AMBill Rowan
Load into PCS
Load at 5-May-2005 11:34:00.00
Open tree /home/rowan -1
Open tree done

May 5 2005 12:27:32:373PM1050505001Bill RowanFizzle
May 5 2005 12:33:56:107PM1050505001Bill Rowan
Next shot: No changes. See what it does
May 5 2005 12:44:34:250PM1050505002Bill Rowan
0.26 s

Next shot. No changes
May 5 2005 12:55:42:420PM1050505003Bill Rowan
0.07 s

Next shot. No changes
May 5 2005 12:59:15:780PM1050505003Bill Rowan
0.07 s

Next shot. No changes
May 5 2005 01:18:56:607PM1050505004Ian HutchinsonSet Rcur offset in segment 1 to 500 from 2500.
No other changes for shot 4.

Plasma till .14s

No changes.
May 5 2005 01:35:12:153PM1050505005Ian Hutchinson40kA died at 30ms. Apparently vertical position problem.

Rcur offset to 1500
Br offset to 0 from -.0005
May 5 2005 01:44:52:840PM1050505006Ian Hutchinson30kA fizzle.

No changes.
May 5 2005 02:04:28:060PM1050505007Ian HutchinsonPlasma till .35s. Choking on radiation. Probably that would have been ok if the density demand had not been so high.

Lower nl04 to 5e19.
May 5 2005 02:13:39:513PM1050505008Ian HutchinsonPlasma till .18s, 300kA.

Lower gas puff 3 in segment 1.
Rcur offset to 2500 from 1500.
May 5 2005 02:25:34:293PM1050505009Ian HutchinsonPlasma till .29s. 590kA.

No change
May 5 2005 02:39:49:090PM1050505010Ian HutchinsonPlasma to .21s.
May 5 2005 02:48:50:793PM1050505011Ian HutchinsonPlasma to .35s. 590kA.
Since the gas puff was off, this shot demonstrates that the excessive density rise is not due to puffed gas.
May 5 2005 03:00:29:560PM1050505012Ian HutchinsonAttempt at limited plasma. Clearin and Rcur adjusted to be constant for most of the shot, instead of transitioning to diverted.

Plasma to .08s.
May 5 2005 03:14:15:340PM1050505013Ian HutchinsonPlasma till .37s. Limited plasma going resistive.
May 5 2005 03:29:36:937PM1050505014Ian HutchinsonPlasma to .075s.
May 5 2005 03:31:12:750PM1050505015Ian HutchinsonPlasma to .14s.
May 5 2005 03:58:53:217PM1050505016Ian HutchinsonPlasma to .94s. Density rises steadily despite no gas.

Adjust clearin to -.03 make more circular. Raise zcur to zero.
May 5 2005 04:11:20:090PM1050505017Ian HutchinsonPlasma till .064s. Vertical position control lost because the current rise was so slow.
May 5 2005 04:17:58:280PM1050505018Ian HutchinsonPlasma till .12s. Killed by titanium radiation.
May 5 2005 04:37:29:200PM1050505019Ian HutchinsonPlasma till .34s.
May 5 2005 04:50:00:420PM1050505020Ian HutchinsonPlasma till .075s.
May 5 2005 05:03:17:670PM1050505021Ian HutchinsonPlasma till .23s.
May 5 2005 05:03:50:530PM1050505022Ian HutchinsonPlasma till .7s.

Engineering Operator Comments
ShotTimeTypeStatusComment
112:20:00:437PMPlasmaOk
212:37:08:200PMPlasmaOk
312:49:49:840PMPlasmaOk
401:04:44:950PMPlasmaOk
501:20:17:390PMPlasmaOk
601:32:48:467PMPlasmaOk
701:45:20:857PMPlasmaOk
801:58:33:967PMPlasmaOk
902:11:01:717PMPlasmaOk
1002:23:42:763PMPlasmaOk
1102:36:15:250PMPlasmaOk
1202:49:46:467PMPlasmaOk
1303:02:29:310PMPlasmaOk
1403:15:17:077PMPlasmaOk
1503:27:52:450PMPlasmaOk
1603:40:35:827PMPlasmaOk
1703:56:55:047PMPlasmaOk
1804:09:32:763PMPlasmaOk
1904:22:13:483PMPlasmaOk
2004:35:08:997PMPlasmaOk
2104:47:58:793PMPlasmaOk
2205:00:47:077PMPlasmaOk