Alcator C-Mod Run 960208 Information

Back to runs

Miniproposals
Miniproposal:128a
Date Filed:11/28/1995
Title:Nitrogen Injection Plume Study
First Author:D Jablonski
Session Leader:D Jablonski (shots 1-36)

Operators
Session leader(s):D Jablonski
Physics operator(s):Earl Marmar
Engineering operator(s):Joe Daigle,Vinny Bertolino

Engineering Operator Run Comment
marmer

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:15:133PM
Author: To Be Determined
Session Leader Report for 8 February 1996
Run 960208
For Miniproposal 139
Earl Marmar, Physics Operator
David Jablonski, Session Leader

The run went reasonably well, though perhaps not all that was hoped to be
accomplished was accomplished. The new Nitrogen filters appear to not work
terribly well. In shot 3, we performed a Nitrogen injection at the inner-wall
midplane, observing through a N-I filter (868nm) with the B-side Culham camera.
Nothing but a blank screen was observed. This even though the Chromex saw the
868 line to be rather bright. The reason for this failure is not known at the
moment (the CCD camera should be sensitive to this wavelength). The
attempts to observe flow reversal by reducing the outer gap while puffing
through the outer limiter capillary were also not succesfull. The Helium II
and Nitrogen II plumes were still observed to go towards the strike-point
(shots 5-8). It was hoped that flow reversal might be seen with the plumes, as
is seen with the scanning probe often in low density shots. A number of decent
Helium II plumes were observed in the bottom half of the machine with the top
Culham camera (shots 9-13). These observations were made possible by the
installation of a new He-II filter in the B-top filter wheel.

The efforts to perform upper x-point discharges met with decidedly negative
results. Shot 19 was perhaps the bast upper x-point, there was no NINJA puff
for it. Shots 20, 24, 32, and 33, the first two with Helium puffing at the
inner-wall, the second two with Nitrogen puffing at the inner-wall, were
moderately succesful, with disruptions ending the shots prematurely. Shot 35,
with a Nitrogen puff at the inner-wall midplane, gave a rather good upper
x-point, with the plasma going the distance. The plumes on these shots were
not quite what was expected. They tended to be somewhat symmetric, and in some
frames seem to show actual flow reversal. The reason for the odd behaviour
(compared with the lower x-point shots, and the Carbon plume upper x-point
shots performed last year) is not known, and will require analysis. The
pictures taken with the A-side camera (with a C-III filter) will also be useful
in analyzing these shots.

Shot 31 provides what might be characterized as the best 'Viewgraph Shot' of
the day. Nitrogen was puffed on the top of the inner and outer divertor noses
simultaneously, while viewed by the top Culham camera through a N-II filter.
The plumes produced go in opposite directions (CW and CCW, as appropriate),
towards the appropriate strike point.

Many of the shots also provided for the taking of interesting data with the
McPherson, Chromex, and Scanning Probe systems. A shot by shot breakdown is
given below. 'Plenum' gives the gas and pressure in torr in the NINJA plenum.
'Capil' the capillary puffed through. 'Trig' the NINJA valve trigger time and
pulse length. 'Filts' the filters used on the Culham cameras. 'Cam' which
Culham camera is hooked up to the optical recording system.

Shot X-P Plenum Capil Trig Filts Cam nl04 Comments
==== === ====== ===== ==== ===== === ==== ========
01 Dwn N2/307 -- -- H-A sid -- Fiducial, Fizzle
02 Dwn N2/307 -- -- H-A sid 1.2e20 Fiducial, H-A lks horrible
03 Dwn N2/307 B16-001 .4/.1 N-I sid 9.5e19 See Nothing in N-I
See plume on Jim's A-Side
04 -- -- -- -- -- -- -- Hybrid Test
05 Dwn N2/306 B33-001 .4/.1 N-II top 1.1e20 sg,CCW so-so Plume
06 Dwn N2/306 B33-001 .4/.1 N-II top 9.5e19 sg,CCW so-so Plume
07 Dwn N2/306 B33-001 .4/.1 N-II top 8.0e19 sg,CCW so-so Plume
08 Dwn He/601 B33-001 .4/.1 He-II top 1.0e20 sg,CCW so-so Plume
09 Dwn He/601 B33-001 .4/.1 He-II top 1.1e20 ng,Very diffuse
10 Dwn He/600 B22-022 .4/.1 He-II top 1.1e20 A couple frames of decent plume
A31-014 .8/.1
11 Dwn He/600 B31-086 .4/.1 He-II top 1.0e20 A couple frames of okay plume
A31-014 .4/.1
12 Dwn He/596 B31-086 .4/.1 He-II top 1.2e20 A couple okay frames, dis .65
13 Dwn He/596 B31-086 .4/.1 He-II top 1.6e20 See almost nothing
14 Dwn He/596 B16-001 .4/.1 N-I sid 1.3e20 Wrong Filt, redo next
B20-001
15 Dwn He/596 B16-001 .4/.1 He-I sid 1.1e20 Nice Pinpoints of He-I
B20-001
16 Up He/595 -- -- H-A sid -- Lasts About 200 msec
17 Up He/595 -- -- He-I sid -- Lasts About 200 msec
18 Up He/595 -- -- He-II sid -- Lasts About 300 msec
19 Up He/592 -- -- H-A sid 1.0e20 H-A picture grainy
20 Up He/592 B16-001 .4/.1 He-II sid 1.0e20 (Sym) Plume, Dis .65
21 Up He/591 B16-001 .4/.1 He-II sid -- Power System Failure
22 Up He/591 B16-001 .4/.1 He-II sid -- Dis .4, no He in
23 Up He/591 B16-001 .4/.1 He-II sid -- Fizzle
24 Up He/590 B16-001 .4/.1 He-II sid 1.1e20 Nice Plume,Sym&Wrong Dir
25 Dwn He/590 B16-001 .4/.1 He-II sid -- Big Fizzle
A31-014 .8/.1 He-II
26 Dwn He/588 B16-001 .4/.1 He-II sid 1.0e20 Okay Plume,Straight Accross,
A31-014 .8/.1 He-II See tail going around on A-Side
27 Dwn N2/325 B26-019 .4/.1 N-II top -- Big Fiz
28 Dwn N2/325 B26-019 .4/.1 N-II top -- Big Fiz
29 Dwn N2/325 B26-019 .4/.1 N-II top 8.0e19 Nice Shot,See some Divertor Lt
30 Dwn N2/322 B31-038 .4/.1 N-II top -- Big Fiz
31 Dwn N2/320 B22-022 .4/.1 N-II top 8.0e19 Nice Double Plume!
B31-086 'Viewgraph' Shot
32 Up N2/320 B16-001 .4/.1 N-II sid 8.5e19 Strge Plume,Sym,Dis at .72
See nice on A-side too (W)
33 Up N2/318 B16-001 .4/.1 N-II sid 8.5e20 Same as 32, See multi-strm on A
Amazing A-movie, inc reversal
34 Up N2/316 B16-001 .3/.1 N-II sid -- Big Fiz
35 Up N2/315 B16-001 .3/.1 N-II sid 8.7e19 Same as 33,full shot,Amaz on A
36 Dwn -- -- -- H-A sid -- Fiducial,Early Dis

Physics Operator Summaries
Entered: Jul 7 2004 04:36:56:067PM
Author: To Be Determined

From: PHYSOP::MARMAR
Date: 8-FEB-1996 18:52:20
Subj: Physics operator's run summary 960208

Physics Operator Summary for Thursday, 960208

MP 139 Plumes
EO Bertolino/Daigle
PO Marmar
SL Jablonski

Engineering setup:

Discharge clean in deuterium for 1 hour before the run

A-side (actually K-side) plenum: 19-20 psi of deuterium
B-top plenum: 5 psi of deuterium.
B-side-lower plenum: 4 psi of argon.
NINJA plenum: 300 torr nitrogen
Enable hybrid control of A-side and B-top valves for start
of run.
Enable the ECE, VUV, Moly monitor, PCX, and TCX valves, assuming status of
each is okay.

Use engineering settings from shot 960202001 (a fiducial shot); enable hybrid
control of toroidal field current.

Generally an ok run, but:
we had difficulty making upper x-point shots that were vertically stable;
fizzles became a problem after shot 22 [disruptions?, nitrogen? (puffed
intentionally through NINJA), karma?];
glitches on hybrid outputs returned, affecting the TF time history on shots 2
and 3 (Wolfe monitored this through the run, and made numerous
entries into the hybrid topic in the logbook)

See the session leader's summary for discussion of the plume measurements.

There was a problem with EF4 on shot 20, after the disruption (high current
through varistors for a short time); on shot 21, EF4 supply blew a fuse due to
a bad SCR (presumably caused by shot 20).

Shot summary:

1. Fiducial; fizzle
2. B_r offset to 6.2mT, add 1 ms to PG4 prepuff; plasma; disrupt on injection
near end of flat-top (1.03 s); loaded into fiducial databases (ohmic and RF)
3. nl_04 to .75e20, clearin to +.003; plasma; glitches on hybrid; got nl_04 ~
.95e20; TF on hybrid control to test gentle rampdown
4. hybrid test; seems ok
5. fiddle with gaps; TF on PLC control; plasma
6. increase right gap 1 cm; plasma
7. decrease right gap 5 mm; argon enabled; some early impurity injections;
plasma
8. repeat; He puff on NINJA; plasma
9. gaps from shot 3; plasma; ohmic H-Mode early, followed by imp. injection at
.54 s
10. early tweak on EF2byEF4 prop gain, to help Wolfe with diagnosis of hybrid
glitches; plasma
11. repeat; plasma; H-mode .54 to .63 s
12. nl_04 programmed to 2e20; plasma; disrupt at .61 s
13. reduce gaps by 2 mm, move down 1 cm; plasma; disrupt on rampdown (.6MA)
14.nl_04 programmed to .9e20; plasma
15. nl_04 prog to .6e20; plasma; H-mode returned
16. attempt upper x-point; argon and NINJA disabled; plasma; disrupt at .24s
(first down, then lost it up)
17. raise current limit on EF3's; program ZCUR to go up faster; plasma; lost it
down at .22 s
18. reload segment 3 from 951213025, add a little early gas; lower nl_04 to
.88e20; plasma; starts oscillating vertically at .205, finally lose it down
19. delay strkpsi control to .4 s; plasma; made it to below .2MA on rampdown
20. lower nl_04; NINJA on; plasma; disrupt; heads up at .605, lose it down; EF4
problem after the disruption (current through varistors)
21. lower zcur by 1 cm; raise ZXU programming to match x-pt better; dud; ef4
fault at -1 second
22. retry; plasma; disrupt; start oscillating after .4, finally lose it up
23. fiddle with RXL (move out); move ZCUR up 5 mm; fizzle
24. reduce pre-puff to 10 msec; plasma; disrupt .73 s (up)
25. back to lower x-point; fizzle
26. reduce pre-puff to 9 ms; plasma
27. retry; fizzle
28. Br offset to 6.8 mT; fizzle
29. Br offset to 6.0 mT; plasma; slight hesitation on Ip rise
30. raise pre-puff to 10 ms; fizzle
31. retry; plasma
32. upper x-point; plasma; disrupt at .72 (up)
33. ramp Ip a little faster between .5 and .8 MA; lower late strkpsi prog gain
slightly; plasma; disrupt @.75 s (down)
34. reduce clearin by 4 mm; fizzle
35. retry; plasma; this was the only upper x-point shot of the day with NINJA
that made it through ramp-down
36. fiducial; fizzle


35 plasma attempts, 26 plasmas, 8 fizzles, 1 power supply dud
1 hybrid test

Session Leader Comments

Physics Operator Comments

Engineering Operator Comments
ShotTimeTypeStatusComment
108:33:27:210AMPlasmaOk
208:44:03:470AMPlasmaOk
308:59:45:380AMPlasmaOk
409:15:06:840AMTestOk
509:28:02:840AMPlasmaOk
609:39:18:400AMPlasmaOk
709:49:53:550AMPlasmaOk
810:06:34:660AMPlasmaOk
910:17:36:770AMPlasmaOk
1010:51:16:050AMPlasmaOk
1111:02:24:160AMPlasmaOk
1211:13:26:400AMPlasmaOk
1311:27:15:850AMPlasmaOk
1411:38:29:680AMPlasmaOk
1511:49:13:180AMPlasmaOk
1612:07:53:330PMPlasmaOk
1712:26:55:400PMPlasmaOk
1812:41:57:000PMPlasmaOk
1901:01:59:340PMPlasmaOk
2001:13:59:810PMPlasmaOk
2101:46:30:430PMPlasmaBadef4 ioc
2202:12:51:130PMPlasmaOk
2302:29:56:730PMPlasmaOk
2402:37:41:060PMPlasmaOk
2502:54:07:840PMPlasmaOk
2603:03:08:120PMPlasmaOk
2703:16:35:470PMPlasmaOk
2803:24:52:240PMPlasmaOk
2903:34:53:860PMPlasmaOk
3003:46:11:090PMPlasmaOk
3103:56:41:420PMPlasmaOk
3204:11:29:720PMPlasmaOk
3304:24:44:830PMPlasmaOk
3404:41:05:910PMPlasmaOk
3504:49:39:540PMPlasmaOk
3605:01:31:090PMPlasmaOk