Alcator C-Mod Run 1060504 Information

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Miniproposals
Miniproposal:445
Date Filed: 3/1/2006
Title: Ti measurements in ITB plasmas
First Author:Kirill Zhurovich
Session Leader:Kirill Zhurovich (shots 10-23)
Miniproposal:448
Date Filed: 4/5/2006
Title:Comparison of Small ELM regimes on C-Mod, MAST and NSTX
First Author:Rajesh Maingi
Session Leader:Amanda Hubbard (shots 1-2)
Session Leader:Rajesh Maingi (shots 3-23)

Operators
Session leader(s):Amanda Hubbard,Rajesh Maingi,Kirill Zhurovich
Physics operator(s):Ron Parker
Engineering operator(s):Andy Pfeiffer,Ed Fitzgerald,Gary Dekow

Engineering Operator Run Comment
MP 448, Comparison of Small ELM regimes on C-Mod, MAST and NSTX Session

Session Leader Plans
Entered: May 3 2006 04:03:22:057PM
Author: Amanda Hubbard
Run Plan for of 1060504, MP 448, Comparison of Small ELM regimes on C-Mod, MAST and NSTX

Session Leaders: Rajesh Maingi (PPPL) , Amanda Hubbard , Hendrik Meyer (remote from UKAEA)
Physics Operator: Ron Parker

Goal: Complete C-Mod part of Small ELM pedestal comparisons by going to high power, nu* scan


This run requires overnight boronization and all 3 RF antennas. A delayed start to resolve E-port issues is thus possible.

1) Load and repeat shot 1060407033 ; 5.45 T, 708 kA, nel 7e19 m-2.

2) Allow RF group several discharges to tune and bring up J and E power. Assess maximum available power. If 4 MW or more, continue to step 3. If not, punt and go to plan B - TBD by Steve Wolfe.

3) Density scan:
Keeping power, and hopefully beta, in its upper range, scan target density shot to shot to vary nped, Tped and thus n*. Use two power levels per shot, selected based on results of step two. Start by raising target nel (9x 1019 m-2, 1.1x 1020 m-2, 1.3x1020 m-2, 1.5x1020 m-2. Upper limit will probably be set by neutral pressure limit of J-port, or if we are lucky, a transition to Type III ELMs.

Then scan downwards, 7x 1019 m-2 ,6x 1019 m-2. The limit in this case will be losing EDA and getting either transient ELM-free H-modes or, more interestingly, discrete Type I ELMs.

Physics Operators Plans
Entered: May 3 2006 06:03:16:667PM
Author: Ron Parker
Run Plan for of 1060504, MP 448, Comparison of Small ELM regimes on C-Mod, MAST and NSTX

Session Leaders: Rajesh Maingi (PPPL) , Amanda Hubbard , Hendrik Meyer (remote from UKAEA)
Physics Operator: Ron Parker

Goal: Complete C-Mod part of Small ELM pedestal comparisons by going to high power, nu* scan


This run requires overnight boronization and all 3 RF antennas. A delayed start to resolve E-port issues is thus possible.



Overnight boronization on Wednesday 5/3/2006:

20% B2D6 / 80% He 6L bottle.
vessel temperature at 60/60/60.
60 psi to be deposited.
PEI setting to 44/70/103 (Rmin/Rres/Rmax) with no pulser.
Gas Pressures: TC3/TC6/TC9/TC6Request = [4 to 7]/150/95/150

Follow boronization with 4 hours ECDC in helium.

1) Load and repeat shot 1060407033 ; 5.45 T, 708 kA, nel 7e19 m-2.

2) Allow RF group several discharges to tune and bring up J and E power. Assess maximum available power. If 4 MW or more, continue to step 3. If not, punt and go to plan B - TBD by Steve Wolfe.

Engineering setup:
Power systems as on 1060407033
A-coil configuration: normal [+Dtop -Dbot -Jtop +Jbot] and enabled.
C-coil Start=0.3sec, Invert=2.0sec

all ICRF systems in run-on by 8:30 am.

Gas Setup:
----------
fill B-top 6psi D2 Hybrid enabled (PG4)
fill B-side lower 1 psi Argon Hybrid Disabled (PG1)
fill B-side Upper as is, Hybrid Disabled (PG2)
fill B-main 40psi D2 Hybrid Enabled (PG3)
NINJA: 12psi D2

Enable ECE, VUV, Z-bolo shutter assuming no vacuum problems

Session Leader Summaries
Entered: May 4 2006 03:59:22:800PM
Author: Amanda Hubbard
We essentially followed the plan below. The target discharge worked reliably from shot 1 and was not varied; very good shape match and in general long, steady, fairly clean-looking EDA H-modes were obtained.

The morning was spent on Step 2, attempting to bring up the RF. After numerous attempts and some vacuum conditioning, D and E port were getting ~ 2 MW combined, with some E-port trips. But, J-port was tripping at only ~ 0.6 MW. Since the total power was insufficient to raise beta_ped, it was decided after shot 9 (about 1 pm) to turn the run over to Kirill for ITB studies.

Step 3 thus remains to be attempted on another day.
*****************************************************************************



Run Plan for of 1060504, MP 448, Comparison of Small ELM regimes on C-Mod, MAST and NSTX

Session Leaders: Rajesh Maingi (PPPL) , Amanda Hubbard , Hendrik Meyer (remote from UKAEA)
Physics Operator: Ron Parker

Goal: Complete C-Mod part of Small ELM pedestal comparisons by going to high power, nu* scan


This run requires overnight boronization and all 3 RF antennas. A delayed start to resolve E-port issues is thus possible.

1) Load and repeat shot 1060407033 ; 5.45 T, 708 kA, nel 7e19 m-2.

2) Allow RF group several discharges to tune and bring up J and E power. Assess maximum available power. If 4 MW or more, continue to step 3. If not, punt and go to plan B - TBD by Steve Wolfe.

3) Density scan:
Keeping power, and hopefully beta, in its upper range, scan target density shot to shot to vary nped, Tped and thus n*. Use two power levels per shot, selected based on results of step two. Start by raising target nel (9x 1019 m-2, 1.1x 1020 m-2, 1.3x1020 m-2, 1.5x1020 m-2. Upper limit will probably be set by neutral pressure limit of J-port, or if we are lucky, a transition to Type III ELMs.

Then scan downwards, 7x 1019 m-2 ,6x 1019 m-2. The limit in this case will be losing EDA and getting either transient ELM-free H-modes or, more interestingly, discrete Type I ELMs.
Entered: May 4 2006 05:13:53:283PM
Author: Kirill Zhurovich
Second half of the day:

MP 445 "Ti measurements in ITB plasmas"
SL: Kirill Zhurovich
PO: Ron Parker

The run was delayed by ~2hrs due to some problems with TF power supply.

Machine performance was better than on 1060502, but still worse than in the past.
We got a couple of ITBs at 6.45T and 6.3T. H-modes at 6.1T and 5.9T were long with multiple minor back transitions. Got HIREX measurements for these cases. Looks like we've got 4 useful shots for comparison of Ti gradients for ITB vs. non-ITB cases.

Physics Operator Summaries
Entered: May 4 2006 05:18:32:970PM
Author: Ron Parker
The run was disappointing because of the lack of power from the J-port antenna. This resulted in terminating the planned MP after 9 shots, and switching to a backup MP with Kirill as session leader. Several good shots were obtained and a systematic scan of field and current was carried out. There was one extended outage due to failure and repair of a PLC module used to control the TF. This resulted in a delay lasting almost 2 hours. After repair, the TF and the machine ran reasonably well for the remainder of the run.

Scorecard: 23 shots, 2 fizzles, 1 disruption, 2 no-TF shots, 1 TF power test and 17 full length plasmas.

Session Leader Comments
May 4 2006 09:16:25:010AM1060504001Amanda HubbardLovely plasma, but very little RF. nel only 5.8e19 m-2, but it will probably rise once RF added. Retune and repeat.
May 4 2006 10:25:22:877AM1060504002 XP 448: small ELM regime comparison.
Shape: LSN with scaled poloidal cross-section matching MAST and NSTX.
Probably need ~ 4 MW RF power to see the small ELMs.
May 4 2006 10:27:00:173AM1060504003 Steady EDA, peak electron_beta@95% flux ~ 0.16
May 4 2006 10:27:42:817AM1060504004 Steady EDA again, peak electron_beta_t@95% flux ~ 0.15
May 4 2006 11:21:58:113AM1060504005 2 MW RF power, peak electron beta_t@95% up to 0.2. Probably need at least
0.35-0.4%.
May 4 2006 10:55:35:987AM1060504006Amanda HubbardGot 2 MW again, plus a little from J which RF guys think is arcing.
Stopping to vaccum condition.
This shot had impurity injections ~0.85 secs - which has been unusual today.
May 4 2006 11:23:57:440AM1060504006 Peak electron beta_t @ 95% is 0.2 again, and Temax ~ 500 eV.
No sign of small ELMs yet.
May 4 2006 12:32:03:423PM1060504008 Peak electron beta_t @ 95% is 0.15 again, and Temax ~ 400 eV.
No sign of small ELMs.
May 4 2006 12:43:20:270PM1060504009 Peak electron beta_t @ 95% is 0.2 again, and Temax ~ 500 eV.
No sign of small ELMs.
May 4 2006 01:05:40:597PM1060504010Kirill ZhurovichH-mode, but disrupted at ~0.84s
May 4 2006 01:31:59:113PM1060504011Kirill Zhurovichstrange, but bad shot: no plasma.
it is said that no TF.
May 4 2006 01:32:21:363PM1060504012Kirill ZhurovichNo plasma. No TF again.
May 4 2006 02:54:19:580PM1060504013Kirill ZhurovichTest shot - YAGs are on target
May 4 2006 03:07:58:067PM1060504014Kirill Zhurovich2 Major H-modes with a number of minor back transitions.
Looks like ITB
Next: repeat, but increase Ar puff to 40ms
May 4 2006 03:31:26:910PM1060504015Kirill ZhurovichLate H-mode, no ITB
Next: reduce target density by 10% to 1*10^20 in pcs,
Go to 6.3T (current proportionally)
May 4 2006 03:44:57:440PM1060504016Kirill ZhurovichNice long H-mode with ITB forming at ~1.2s (there is a change in H-alpha at ~1s)
Next: lower Bt to 6.1T
May 4 2006 03:52:55:440PM1060504017Kirill ZhurovichDelayed H-mode. No ITB at this field
HIREX has not got data due to HV trips
Next: repeat, but decrease target density by 10%
May 4 2006 04:05:17:270PM1060504018Kirill ZhurovichBrief H-mode due to RF trip
Next: go to 5.9T
May 4 2006 04:20:54:690PM1060504019Kirill ZhurovichLong H-mode with several minor back transitions.
Was not good shot for HIREX
Next: repeat
May 4 2006 04:25:03:783PM1060504020Kirill Zhurovichfizzle
May 4 2006 04:43:09:143PM1060504021Kirill ZhurovichLong H-mode with several minor back transitions.
Next: 5.7T
May 4 2006 04:53:26:597PM1060504022Kirill ZhurovichLong H-mode with several minor back transitions.
HIREX lost one of its channels due to HV trip
next: repeat
May 4 2006 05:02:51:317PM1060504022Kirill Zhurovichfizzle
end of run

Physics Operator Comments
May 4 2006 09:17:52:793AM1060504001Ron ParkerShot 1 ran well. Need to bring up RF power.
May 4 2006 09:26:22:747AM1060504002Ron ParkerShot 2 ran well, 1 MW of RF, Steady H-mode.
May 4 2006 09:37:01:260AM1060504003Ron ParkerShot 3 was similar to 2, RF still at 1 MW.
May 4 2006 09:48:23:293AM1060504004Ron ParkerShot 4 was good, RF still 1 MW for most of the RF pulse.
May 4 2006 09:58:53:410AM1060504004Ron ParkerShort (?) delay for power room access.
May 4 2006 10:20:12:033AM1060504005Ron ParkerShot ran well, RF power up to 2 MW.
May 4 2006 10:29:01:957AM1060504006Ron ParkerShots continue to run well. RF remains at 2 MW level.
May 4 2006 10:36:39:660AM1060504006Ron ParkerArgon-Neon injection on next shot.

There will be a delay (~ 30 minutes?) while the J-port RF antenna is vacuum conditioned.
May 4 2006 12:14:50:423PM1060504007Jim Irbyno changes since Ron left

plasma into rampdown --- late breakdown --- gas 10% lower than on shot 006


2nd example of TCI drift problem today


May 4 2006 12:29:59:020PM1060504008Jim Irbyprepuff from 18 to 19 ms

plasma into rampdown
May 4 2006 12:45:03:423PM1060504009Ron ParkerShot 9 ran well, RF power averaged about 2 MW.
May 4 2006 12:56:56:567PM1060504009Ron ParkerIt looks like we are giving up on the run plan due to lack of performance of J-port. We are turning things over to Kirill and continuation of MP 445 (see run plan for 1060502). We'll start by loading shot 1060502014.
May 4 2006 01:07:07:237PM1060504010Ron ParkerShot 10 disrupted, not clear why.
May 4 2006 01:17:40:067PM1060504011Ron ParkerNo TF, no shot
May 4 2006 01:32:55:253PM1060504012Ron ParkerSame thing, no TF; actually TF came on a level of 0.45 T, then shut down apparently due to fizzle detection. We'll have a power room access to investigate.
May 4 2006 02:36:58:317PM1060504012Ron ParkerProblem with the TF seems to be a bad PLC module. It has been replaced and we are about to do a 50 kA TF test.
May 4 2006 02:48:56:393PM1060504013Ron ParkerTF shot at 50 kA was OK. We'll set up for plasma on next shot.
May 4 2006 03:06:58:470PM1060504014Ron ParkerShot 14 went off as programmed. Next: same shot, but Ar puff increased to 40 ms.
May 4 2006 03:32:42:753PM1060504015Ron ParkerShot 15 ran well, H-mode at RF = 2.1 MW.

Next shot: Target density lowered from 1.1e20 m-2 to 1.0e20.

Also TF lowered from 6.45 to 6.3T and Ip from 1.02 to 0.996 MA
May 4 2006 03:45:18:660PM1060504016Ron ParkerGood shot, long RF pulse at 2.1 MW

Next: reduce field from 6.3 to 6.1, current from 996 to 964 kA.
May 4 2006 03:52:03:613PM1060504017Ron ParkerGood shot. Next: same B and I, but reduce target density to 0.95e20 m-2.
May 4 2006 04:09:42:113PM1060504018Ron ParkerShot went off OK, but RF didn't hold up.

Next: Field lowered to 5.9, current to 932 kA.
May 4 2006 04:31:19:707PM1060504019Ron ParkerShot 19 went off as programmed.

No change for next shot.
May 4 2006 04:29:12:550PM1060504020Ron ParkerShot 20 fizzled. Pressure may be a bit too high, so reduce from 19 to 17 ms for next shot.
May 4 2006 04:45:45:253PM1060504021Ron ParkerShot 21 ran well. Next: 5.7 T, 900 kA
May 4 2006 04:56:36:457PM1060504022Ron ParkerShot 22 went off well, but incomplete data from Hirex. So we'll repeat.


May 4 2006 05:03:39:707PM1060504023Ron ParkerShot 23 fizzled. Machine is getting dirty.

Engineering Operator Comments
ShotTimeTypeStatusComment
109:01:46:827AMPlasmaOk
209:18:17:967AMPlasmaOk
309:30:58:887AMPlasmaOk
409:43:44:543AMPlasmaOk
510:09:29:363AMPlasmaOk
610:21:57:020AMPlasmaOk
712:07:29:910PMPlasmaOk
812:26:33:597PMPlasmaOk
912:39:38:550PMPlasmaOk
1001:02:14:753PMPlasmaOk
1101:14:52:393PMPlasmaBadTF Power Level Wrong
1201:29:34:817PMPlasmaBadTF Miss Fired
1302:46:41:923PMTestOk50 KA TF PLC Test
1402:59:17:800PMPlasmaOk
1503:14:46:097PMPlasmaOk
1603:31:39:080PMPlasmaOk
1703:44:18:410PMPlasmaOk
1803:57:00:270PMPlasmaOk
1904:09:51:707PMPlasmaOk
2004:22:18:020PMPlasmaOk
2104:34:49:097PMPlasmaOk
2204:48:06:207PMPlasmaOk
2305:00:59:720PMPlasmaOk