Alcator C-Mod Run 960829 Information

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Miniproposals
Miniproposal:153
Date Filed: 7/15/1996
Title:RF edge heating and RF field profiles
First Author:Chris Rost
Session Leader:Chris Rost (shots 1-40)
Session Leader:John Reardon (shots 1-40)

Operators
Session leader(s):Chris Rost,John Reardon
Physics operator(s):Earl Marmar
Engineering operator(s):Frank Silva,Joe Daigle

Engineering Operator Run Comment
mp153/marmer/silva

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:16:337PM
Author: To Be Determined
960829 Session Leader Summary -- MP 153

The purpose of today's run is to study the poloidal and pitch angle
structure of the RF edge heating observed with the CX analyzer, and and explore
the spatial structure of the attendant RF waves in scrape-off layer. The bulk
of the run will consist of two parts:

1. a series of identical shots at B_T=4.72T with low-power (< 100kW)
rf pulses; shot-to-shot scans of the PCX and rf probes

2. a series of identical shots at constant RF power, with
a TF ramp from 4.8 to 3.8T; PCX looking below the midplane
and one scan per shot of the rf fast-scanning probe

The major goals regarding the CX data were thoroughly achieved. At
constant TF, the PCX got data at 9 different positions for 8 different RF
power levels. With the ramping TF, there were 5 shots at different CX
sightlines with 100kW RF, and 4 more at 250kW. There were then 2 more at
different densities. We ended the run with 3 shots at 5.4T, low density, and
high RF power looking to drive a minority tail under the H-mode low-density
limit.

All of the rf probes were successfully scanned. During the first part
the fast-scanning probe was scanned 4 times and the A-top probe set was
scanned in Z. During the second part there were 4 more fast scans and
a scan in R of one of the J-side probe sets, and there were 4 more fast
scans over the course of the series of low-density shots that ended the run.

Almost every lower field plasma had >1MW of RF in a pulse beginning at
.35s, with H-modes.

The flattop was from .5 to 1.5s on every shot (that didn't disrupt).


Shot-by-shot:


01 TF ramp to find resonance
dud (PS?)
02 repeat (not the dud part)
dud (spoke too soon) again no EF4
03 no power test
04 disruption at .54s, H/D = 3%
05 fizzle
06 fizzle
07 dud
08 plasma -- TF ramp doesn't go low enough
09 plasma
10 fizzle
11 plasma -- now going to B_T=4.72 (constant), RF pulses, rf fast scanning
probe scan at 1.2
12 fizzle
13 plasma -- B_T = 4.66T, a little low
RF fast scanning probe is perturbing plasma around 1.2s--turn it off
Increase TF and go again.
14 plasma -- B_T 4.74T, good. H-mode at .45s. Now a few repeats.
15 plasma
16 plasma
17 plasma
18 plasma--rf fsp scan at 1.2
19 plasma--rf fsp scan at 1.2
20 plasma
21 plasma
22 plasma
23 plasma -- TF ramping 4.8 to 3.8T, RF is 100kW in flattop
24 plasma -- same TF ramp
25 plasma
26 plasma
27 plasma, 14% H, same, but RF in flattop disappeared
28 plasma, RF is back
29 strong fizzle
30 plasma, increased RF to 240kW in flattop, rf fsp scan at 1.4
31 plasma, same, rf fsp scan at 1.4
32 plasma, rf fsp scan at 1.4
33 plasma, rf fsp scan at 1.4
34 plasma, nl lowered to .8e20, rf fsp scan at 1.4
35 fizzle, nl lowered to .6e20
36 plasma, last one of this sequence, rf fsp scan at 1.4
37 plasma -- B_T=5.4T, 2MW RF (10keV central hydrogen tail with .8mW)
nl05=.7e20 before H-modes, rf fsp scan at 1.4
38 plasma, nl05=.4e20, NO H-MODES, 1.9MW RF, disr. @ 1.05s
39 fizzle
40 plasma, nl05=.4e20, H-mode at 1.15s w/ 1MW RF, rf fsp scan at .8
This one goes ALL the way down



Physics Operator Summaries
Entered: Jul 7 2004 04:36:56:707PM
Author: To Be Determined
Run Plan for 960829

MP 153 RF edge (SL's Rost/Reardon)
EO: Silva, Daigle
PO: Marmar

Engineering setup
-------------------
ECDC Overnight in Deuterium

Power systems setup as for 960828031, EXCEPT:
1) hybrid control on TF;
2) delay all power supply inversion times by 300 msec (flat top will be
extended to 1.5 seconds).

Gas setup = standard
A-side 20psi D2
B-top 5psi D2
B-side Lower 4psi Ar
Enable all for first shot (hybrid)

Run plan
--------
Start from PCS as on last shot 960828031, except extend all waveforms, voltages
and PID's to accommodate lengthened flat-top. TF on hybrid control to allow for
breakdown at 5.3 tesla and then ramp down to ~4.5 Tesla.

______________________

On the whole, a very successful run. After a slow start, with some fizzles and
duds, we settled into a day of mostly good shots. Playing with the RCUR offset
seemed to be the key to success, ending up more or less where Steve Wolfe was
for the early part of the run yesterday (960828), with startups that looked
fitful but usually went. We had at least 2 shots with breakdown at 12 msec that
formed into full plasmas. There should be many useful data for the
mini-proposal. The early parts of many shots were used for RF tuning, and net
power levels up to nearly 3 MW were achieved. At the end of the day, we took
several shots at decreasing density, with an eye to looking at hydrogen tail
formation. We continued to get H-Modes with moderate RF power, even down to
nl_04=.4e20 (a new low density H-Mode record for C-Mod) with .9 MW ICRF.

The edge Thomson scattering system was also being tested, and the first
plasma-scattered photons were observed.

Engineering systems performed well after an initial problem with the EF4 PLC,
which caused two duds and some early delay. Hybrid control of the TF was used
all day without incident. The X-ray tomo CAMAC crates were left off-line for
the whole day, because of yesterday's CAMAC errors.


Shot-by-shot:

1. reload 980828031, copy segment 2 into 3, turn 2 off, 3 on, extend
programming to give flat top to 1.5, turn off rf RCUR feedback; PS dud; no EF4.
2. retry; ps dud; no EF4
3. test; appears EF4 PLC in some funny mode, not properly enabled.
4. retry; plasma; disrupt at .53 s; something fell in.
5. no changes; fizzle
6. B_r offset to 6 mT from 6.5; fizzle; late b-d
7. B_r offset to 7 mT; initial puff to 16 msec from 19; dud
8. B_r offset to 6.5 mT; initial puff to 18 ms; RCUR seg 1 offset to 8000 from
9000; plasma; disrupt at .4 MA in rampdown; H-mode near end of shot
9. repeat; plasma;
10. fizzle
11. Rcur offset to 7500; plasma;
12. B_T programmed to 4.73 Tesla from .5 to 1.5 s; fizzle
13. retry; plasma, very late bd
14. pre-puff to 17 ms; plasma
15. twiddle ZXL late (between .8 and 1.2 s); plasma;
16. plasma;
17. twiddle RXL, to ramp out 5 mm by 1.2 s; plasma
18. plasma; disrupt at 1.3 s; RF probe?, something fell in?
19. plasma; disrupt at 1.19;
20. plasma; RF scanning probe not going in
21. plasma
22. plasma
23. ramp TF during flat top; plasma
24. plasma
25. tweak the TF ramp a little lower at 1.5 s; plasma
26. plasma
27. fiddle with I_p rampdown rate (speed it up); zcur tweak in rmp-dwn; plasma
28. plasma
29. more twiddling with rampdown; 80 kA fizzle
30. plasma; disrupted earlier than normal; RF probe fired at about 1.4 s
31. reload 27; move argon pulse 50 msec earlier & add 5 msec; plasma
32. plasma
33. fiddle with RXL during rampdown (don't pull it in so far); plasma
34. nl_04 prog to .8e20, lower voltage preprog on valve; plasma
35. nl_04 prog to .6e20, lower voltage preprog on valve; 80 kA fizzle
36. repeat; plasma
37. 5.3 tesla straight across; plasma, .8 MW RF, in and out of H-Mode
38. nl_04 prog to .4e20; plasma; disrupt at 1.1 seconds; very late breakdown;
big brick?; fast disruption; some gate valves closed.
39. fizzle
40. reduce pre-puff by 1 msec to 16 ms; plasma; H-mode at nl_04=.4e20; ramped all the
way down.

39 attempts = 29 plasmas + 2 PS duds + 2 strong fizzles (80 kA) + 5 weak fizzles +
1 gas-head dud


Session Leader Comments
Aug 29 1996 10:22:43:830AM960829001Chris Rost01 First a TF ramp to pinpoint our resonance -- dud

Aug 29 1996 10:23:24:130AM960829002Chris Rost02 repeat -- dud

Aug 29 1996 10:24:28:660AM960829003Chris Rost03 power supply test

Aug 29 1996 10:25:01:670AM960829004Chris Rost04 plasma - disruption at .54s

Aug 29 1996 10:25:15:850AM960829005Chris Rost05 fizzle

Aug 29 1996 10:27:09:920AM960829006Chris Rost06 fizzle

Aug 29 1996 10:36:42:150AM960829007Chris Rost07 dud

Aug 29 1996 11:04:54:820AM960829008Chris Rost08 plasma -- need TF ramp to go lower

Aug 29 1996 11:13:08:150AM960829009Chris Rost09 plasma -- PCX problem (fixed), repeat shot

Aug 29 1996 11:08:29:150AM960829010Chris Rost10 fizzle

Aug 29 1996 11:18:19:600AM960829011Chris Rost11 plasma -- now going to B_T=4.72 (constant), RF pulses

Aug 29 1996 11:26:10:340AM960829012Chris Rost12 fizzle

Aug 29 1996 11:38:01:080AM960829013Chris Rost13 plasma -- B_T = 4.66T, a little low
RF fast scanning probe is perturbing plasma around 1.2s
Increase TF and go again.

Aug 29 1996 11:53:53:330AM960829014Chris Rost14 plasma -- B_T 4.74T, good. H-mode at .45s. Now a few repeats.

Aug 29 1996 12:06:47:640PM960829015Chris Rost15 plasma

Aug 29 1996 12:41:56:500PM960829016Chris Rost16 plasma

Aug 29 1996 12:42:27:260PM960829017Chris Rost17 plasma

Aug 29 1996 01:41:51:280PM960829023Chris Rost23 plasma -- TF ramping 4.8 to 3.8T

Aug 29 1996 01:51:27:760PM960829024Chris Rost24 plasma -- same TF ramp

Aug 29 1996 02:17:23:040PM960829025Chris Rost25 plasma -- same, but end-of-ramp TF a little lower than in 24

Aug 29 1996 02:17:37:000PM960829026Chris Rost26 plasma -- same

Aug 29 1996 02:29:21:870PM960829027Chris Rost27 plasma -- same, but RF in flattop disappeared

Aug 29 1996 02:53:03:000PM960829029Chris Rost29 strong fizzle

Aug 29 1996 03:05:07:740PM960829030Chris Rost30 plasma, increased RF to 240kW in flattop

Aug 29 1996 03:17:09:030PM960829031Chris Rost31 plasma, same

Aug 29 1996 03:30:13:030PM960829032Chris Rost32 plasma

Aug 29 1996 03:51:26:560PM960829034Chris Rost34 plasma nl lowered to .8e20

Aug 29 1996 04:16:41:040PM960829036Chris Rost36 plasma, last one of this sequence

Aug 29 1996 04:28:16:840PM960829037Chris Rost37 plasma -- B_T=5.4T, 2MW RF (10keV central hydrogen tail with .8mW)
nl05=.7e20 before H-modes

Aug 29 1996 04:54:04:510PM960829038Chris Rost38 plasma, nl05=.4e20, NO H-MODES, 1.9MW RF

Aug 29 1996 04:54:32:770PM960829039Chris Rost39 fizzle

Aug 29 1996 05:05:42:660PM960829040Chris Rost40 plasma, nl05=.4e20, H-mode at 1.15s w/ 1MW RF

Physics Operator Comments

Engineering Operator Comments
ShotTimeTypeStatusComment
108:52:30:640AMPlasmaOkno ef4
209:18:37:970AMPlasmaOkcomm fault/no ef4
309:43:24:450AMPlasmaOkno power ef4 test
409:58:36:960AMPlasmaOkoh1 self powered ckt. fired
510:08:19:230AMPlasmaOkno faults
610:18:08:950AMPlasmaOk
710:27:55:960AMPlasmaOk
810:36:28:110AMPlasmaOkno faults
910:50:39:270AMPlasmaOkno faults
1011:03:47:380AMPlasmaOkno faults
1111:12:05:540AMPlasmaOkno faults
1211:22:57:330AMPlasmaOkno faults
1311:31:02:700AMPlasmaOkno faults
1411:45:58:060AMPlasmaOkno faults
1511:57:38:640AMPlasmaOkno faults
1612:10:09:150PMPlasmaOkno faults
1712:21:31:370PMPlasmaOkno faults
1812:42:18:000PMPlasmaOkno faults
1912:53:46:150PMPlasmaOkno faults
2001:03:33:390PMPlasmaOkno faults
2101:16:02:010PMPlasmaOkno faults
2201:26:15:350PMPlasmaOkno faults
2301:38:54:140PMPlasmaOkno faults
2401:49:07:370PMPlasmaOk
2502:04:16:950PMPlasmaOk
2602:14:35:710PMPlasmaOk
2702:24:43:520PMPlasmaOk
2802:36:47:960PMPlasmaOk
2902:46:46:870PMPlasmaOk
3002:55:34:980PMPlasmaOk
3103:07:57:950PMPlasmaOk
3203:22:06:420PMPlasmaOk
3303:33:09:410PMPlasmaOk
3403:44:13:450PMPlasmaOk
3503:56:53:210PMPlasmaOk
3604:06:33:400PMPlasmaOk
3704:17:16:200PMPlasmaOk
3804:36:36:210PMPlasmaOk
3904:49:11:560PMPlasmaOk
4004:58:21:100PMPlasmaOkno faults/last shot1700 hrs