Alcator C-Mod Run 1060502 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 1-28)

Operators
Session leader(s):Kirill Zhurovich
Physics operator(s):Jim Irby
Engineering operator(s):Bill Cochran,Sam Pierson,Bill Parkin

Engineering Operator Run Comment
automatically entered by signon - please replace with real comment

Session Leader Plans
Entered: May 1 2006 05:55:10:020PM
Author: Kirill Zhurovich
MP #445 "Ti measurements in ITB plasmas"

The purpose of this experiment is to understand triggering mechanism for producing off-axis ICRF internal transport barriers. The question of whether ITB formation can be explained in the framework of suppressing ITG turbulence via increasing ion temperature scale length to the critical scale length is the target.
This idea will be tested by varying Bt and thus shifting the RF resonance location on shot-to-shot basis.

This is an extension and continuation of the MP 422 and run 1050707.

Required diagnostics: all standard core diagnostics, especially TS, ECE, HIREX, PCI, reflectometery +CHERS (if available)

Set up GPC for ~6.2T, GCP2 for 5.4-5.8T and FRCECE for 5.4T.
ICRF - 80MHz, D&E only, 2.8MW (fault-free and constant for all discharges, see 1050707 run). ICRF power will be adjusted during first plasma shots.

Proposed Bt, Ip scan:

Bt Ip
5.4 0.9
5.5 0.917
5.6 0.933
5.7 0.95
5.8 0.967
5.9 0.983
6.0 1.0
6.1 1.017
6.2 1.033
6.3 1.05
6.4 1.067
6.45 1.075

First, establish an ITB at higher field. 1050707019 is a good candidate.
Then start Bt scan with 0.2T increment/decrement, filling the gaps later in the day as time allows.

Physics Operators Plans
Entered: May 1 2006 06:10:36:960PM
Author: Jim Irby
Physop plan and engineering setup for Tues, 02-May-2006

MP #445 "Ti measurements in ITB plasmas"
SL: Zhurovich
PO: Irby

Overnight boronization on Monday 5/1/2006:

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.

Engineering setup:
-------------------
Power system setup as on 1050707019
Gas Setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar Hybrid DISABLED (PG1)
leave B-side upper with 15psi He3. Hybrid enabled (PG2)
fill B-main (C-side) with 40 psi D2 Hybrid enabled (PG3)
fill NINJA with 10psi D2 (Disable)

We will want to be ready to use between-shot boronization during the run,
but do not open the bottle until requested.

Enable the following gate valves and shutters: ECE, VUV, Z-bolo shutters; these must be disabled for between-shot boronization MSE shutter should be CLOSED before the run and remain closed.

FMIT#1,2 in Run-on by 8:30AM; turn on earlier if requested by RF

Session Leader Summaries
Entered: May 2 2006 06:17:24:630PM
Author: Kirill Zhurovich
MP #445 "Ti measurements in ITB plasmas"
SL: Kirill Zhurovich
PO: Jim Irby

Struggled with the radiation for the most part of the day. At the beginning spent a few shots to tune RF. Got some ITBs at higher Bt (not the best ones though), while on a couple of them there was no HIREX measurements, unfortunately. By the middle of the day had troubles getting nice long H-mmode. Instead due to RF trips and injections had multiple back transitions. On a couple of occasions observed very late H-modes. HIREX got some data for several shots at different fields. However, the H-modes and ITBs were not the ones we'd like to have. Overall, pretty unsuccessful run, which we'd like to repeat with better machine performance.

Physics Operator Summaries
Entered: May 2 2006 05:28:27:550PM
Author: Jim Irby
Had continued difficulty with injections, apparently off the inner wall. Several early disruptions were associated with the injections. We also had a large number of fizzles today. Several of these also seemed to be related to very early injections of some material or gas (seen most clearly on h-alpha signal). The h-alpha did not burn out and in fact increased after the initial breakdown on many shots, ending up a factor of two higher than normal at 10 ms.

Shots 03, 04, 05, and 06 were fairly good discharges, though 05 had a strange density increase starting about 1.0 s. Then shots 07, 08 disrupted with injections clearly seen on wide 2. Shot 09 was full length but didn't get into h-mode until very late, for no clear reason.

The wide 2 view shows many examples of material dropping to or falling from the inner wall. It seems to be mostly streaming in from around the k or j side of the machine. Some disruptions ended in material being launched onto the outer wall around c and d ports.

Even though we boronized last night, John Rice was seeing large amounts of moly early in the day. We did have a few nice h-modes with an ITP or two.


fizzles 15,17,19,20,21,22,23,25

Session Leader Comments
May 2 2006 09:34:26:943AM1060502001Kirill ZhurovichTry plain EDA H-mode first.
1050707019 with changed parameters (lower field)
No E-antenna
Disrupted at 0.9s.
Next: Repeat
May 2 2006 09:38:11:037AM1060502002Kirill ZhurovichDisrupted at 0.39s
Sparkles on TV
May 2 2006 09:58:04:490AM1060502003Kirill ZhurovichNice long EDA H-mode.
A couple of early injections, but we survived.
No E-antenna.
May 2 2006 10:10:38:693AM1060502003Kirill ZhurovichTake a closer a look at the density profile later.
It seems like there is some kind of barrier during L-mode, when current is still penetrating (reverse shear??)
May 2 2006 10:14:39:833AM1060502004Kirill ZhurovichNice long EDA H-mode.
No E-antenna again
May 2 2006 10:45:26:863AM1060502005Kirill ZhurovichBumpy H-mode
D&E are on.
Next: Try to raise RF power by 200kW
Go for ITB (replicate 1050707019)
Enable Ar and Ne puff
May 2 2006 10:58:18:817AM1060502006Kirill ZhurovichITB starting at ~1.1s
No Ar, E is faulty.
Next: reapeat with Ar and RF
May 2 2006 11:09:36:893AM1060502007Kirill ZhurovichDisrupted at ~0.66s :(
May 2 2006 11:22:14:833AM1060502008Kirill ZhurovichDisruption at ~0.39s
May 2 2006 12:07:23:037PM1060502009Kirill ZhurovichLate brief H-mode. No ITB.
Early injections are to blame, I guess.
May 2 2006 12:35:01:453PM1060502010Kirill ZhurovichE-antenna trips caused multiple back transitions. Therefore, No ITB.
Next: Go to 6.45T and adjust the current proportionally.
May 2 2006 12:48:15:270PM1060502011Kirill ZhurovichDisruption at ~.44s
May 2 2006 01:07:25:427PM1060502012Kirill Zhurovich3 H-modes
ITB in the 3d one (check the other two)
No HIREX this shot
Repeat
May 2 2006 01:19:09:427PM1060502013Kirill ZhurovichMultiple H-modes, the last one is long enough to form an ITB.
John claims he does not see Ar.
Repeat
May 2 2006 01:32:13:863PM1060502014Kirill ZhurovichMultiple H-modes again. ITB, which seemed to survive at least one minor back transition
John says there not enough signal for HIREX
Repeat
May 2 2006 01:51:46:100PM1060502015Kirill ZhurovichFizzle
May 2 2006 02:06:21:020PM1060502016Kirill ZhurovichA couple of H-modes (EDA)
The first one is long, and probably ITB forms, but definitely not a great one
HIREX has got signal.
Next: John moves one of the HIREX channels out a bit. Repeat
May 2 2006 02:11:29:770PM1060502017Kirill ZhurovichFizzle.
May 2 2006 02:30:51:910PM1060502018Kirill ZhurovichSeveral H-modes. Too short to form an ITB.
HIREX got data.
Next: Go to 6.1T (current adjusted proportionally)
May 2 2006 03:08:23:300PM1060502019Kirill ZhurovichFizzle.
May 2 2006 03:08:29:300PM1060502020Kirill ZhurovichFizzle.
May 2 2006 03:08:32:707PM1060502021Kirill ZhurovichFizzle.
May 2 2006 03:20:02:957PM1060502022Kirill ZhurovichFizzle.
May 2 2006 03:43:14:660PM1060502023Kirill ZhurovichFizzle.
May 2 2006 04:09:49:210PM1060502024Kirill Zhurovich2 H-modes. The 2nd one, which looks more EDA-ish, is pretty late.
HIREX got data for the first H-mode.
Next: Got down to 5.9T
May 2 2006 04:12:20:850PM1060502025Kirill ZhurovichFizzle.
May 2 2006 04:26:12:723PM1060502026Kirill ZhurovichDisruption at ~0.44s
May 2 2006 04:46:06:897PM1060502027Kirill ZhurovichMultiple H-modes.
HIREX got data.
Next: 6.2T

Physics Operator Comments
May 2 2006 09:31:26:690AM1060502001Jim IrbyBoronization seems to have gone well last night.

loaded seg 2 of shot 1050707019 into seg 2
tweaked P_08 and did a load/clean
ef4 currently at -1305 A

start time for TF changed from -1.5 to -1.0 in seg 1.

loaded Ip 900 kA in seg 2
loaded Bt 150 kA in seg 2

loaded seg 3 wire 9 into seg 2 wire 9: enabled a-coil feedback
zeroed a-coil request in all-v seg 2
integrator C start from 0.5 to 0.3 s
load/clean

prepuff from 23 to 18 ms

disruption at 0.908 s

injection very early killed density rise


May 2 2006 09:48:55:020AM1060502002Jim Irbywent in cell before this shot and tweaked TCI alignment

increased pg3 seg 1 gas


lost plasma at 0.4 s --- possibly because magnetics needed recalculation
May 2 2006 10:04:41:473AM1060502003Jim Irbyrecalculated rcur to zxu

slowed down density rise

problems with iris shutter at a-port -- running blind

plasma into rampdown --- good eda, but nearly lost it again with early injections


May 2 2006 10:24:47:427AM1060502004Jim Irbyassuming that we are hitting something on the outer wall: reduced early rcur:
0.258 s to 0.65 m
0.377 s to 0.6566 m
0.5335 s to 0.661 m

plasma into rampdown --- early injections much reduced --- good eda, but no e-port power

still have lots of sparkles showing up on wide 2.



May 2 2006 10:33:04:440AM1060502005Jim Irbyno DPCS changes

enabled argon from 0.35 to 0.39 s

ninja puffing during rampdown

plasma into rampdown --- big injection starting at 0.28 s, but still good eda


May 2 2006 10:57:47:897AM1060502005Jim Irbyasked for 1 psi Argon and 2 psi neon

Attempt to get an ITB
Ip request to 1 MA --- same as 1050707019
Bt request copied over from 1050707019 --- 6.27 T

TF current limit to 180 kA

plasma into rampdown --- good ITB

I only had 10 volts on the argon puff!


May 2 2006 11:16:55:440AM1060502007Jim Irbyargon puff to 100 V from 0.35 to 0.39 s (was 10 V)

repeat of 06 otherwise

disruption at 0.6804 s

lose control of density at about 0.6 s when 2Pi also takes off as rf comes on (e-port)

lots of material coming in below c-hor (wide 2 view)


May 2 2006 11:34:04:830AM1060502008Jim IrbyDPCS repeat

igt at 2.1e-6 Torr in check

disruption at 0.39 s --- 2Pi starts up at 0.34 s

power glitch in cell --- many go in, some return

sparker current 1880 uA






May 2 2006 12:25:26:447PM1060502009Jim Irbytry again --- no DPCS changes

plasma into rampdown, good rf, but no h-mode until very late??

Jerry claims ideal condtions for h-mode, but...

TCI signals very low ---- DNB transformer was opened up in the rf lab --- SF6 fills power room and cell even though they pumped it out to 50 mTorr before vent to air. Meter indicates strong SF6 flow out of rf lab into the power room



May 2 2006 12:32:17:560PM1060502010Jim Irbyrepeat

plasma into rampdown --- h-mode a little later than on shot 6

puffing more gas to get same density

radiated power a factor of two up from shot 6 on 2 Pi (e-port power)


May 2 2006 12:54:55:443PM1060502011Jim Irbygoing to 6.45 T --- 179.080 kA
request 1.02 MA for Ip

disruption at 0.4419 s

900 kW spike on 2Pi, density starts up at 0.34 s


May 2 2006 01:11:27:003PM1060502012Jim Irbyput a ramp from 10 to 100 V on argon from 0.35 to 0.39 s

plasma into rampdown --- multiple h-modes

continue to see injections from upper-inner wall on j/k side of machine


May 2 2006 01:17:54:753PM1060502013Jim Irbyrepeat

plasma into rampdown --- ITB

not enough argon or neon


May 2 2006 01:33:48:613PM1060502014Jim Irbyargon full on at 100 V from 0.36 to 0.39 s

still not enough argon

plasma into rampdown
May 2 2006 01:51:22:850PM1060502015Jim Irbyargon from 0.36 to 0.41 s
repeat otherwise

fizzle --- fields good --- gas low


May 2 2006 02:05:31:037PM1060502016Jim Irbyprepuff from 18 to 20 ms

plasma into rampdown --- single h-mode late

good hirex signal

May 2 2006 02:14:02:520PM1060502017Jim Irbyrepeat for hirex

fizzle --- injections around 12 ms seem to kill startup


May 2 2006 02:31:50:583PM1060502018Jim Irbyno changes --- assuming injections caused last fizzle

plasma into rampdown --- three h-modes --- no ITB


May 2 2006 02:41:05:647PM1060502019Jim IrbyBt to 6.1 T, 169.36 kA
Ip to 966 kA
EF4 from -1305 to -1315 A

fizzle


May 2 2006 03:13:25:020PM1060502020Jim Irbyloaded seg 1 from 1060425033 into seg 1 --- previous startup tuned up for high field run.

fizzle --- injection again
May 2 2006 03:14:32:740PM1060502021Jim Irbyrepeat

fizzle??
May 2 2006 03:30:11:083PM1060502022Jim Irbyreduced prepuff to 18 ms from 20 ms
raised br0 from -0.0005 to 0.0000 T

fizzle --- still seeing rise in h-alpha for 10 ms or so rather than a drop


May 2 2006 03:49:18:880PM1060502023Jim Irby10 minutes of ECDC in D2

Bt start from -1.5 to -1.0

fizzle again ---- h-alpha looks a little better



May 2 2006 03:58:40:850PM1060502024Jim IrbyBr0 back to -0.0005 T
Bz0 from -1335 to -1345 A

plasma into rampdown
May 2 2006 04:16:11:567PM1060502025Jim IrbyBt to 5.9 T, 163.81 kA
Ip to 934.09 kA

fizzle --- injection at 10 ms

gas a little low compared to 1060425 run


May 2 2006 04:32:08:800PM1060502026Jim Irbyprepuff from 18 to 20 ms

disruption at 0.4462 s

injection begins by 0.426 s


May 2 2006 04:47:19:160PM1060502027Jim Irbyno DPCS changes

plasma into rampdown --- multiple h-modes

wide 2 shows inner wall activity still
May 2 2006 05:11:46:707PM1060502028Jim IrbyBt to 6.2 T, 172.139 kA
Ip to 981.59 kA

nl04 request to 1.2e20 at 0.5 s --- try to get higher target density

plasma for 1.72 s


Engineering Operator Comments
ShotTimeTypeStatusComment
109:12:39:910AMPlasmaOk
209:35:16:753AMPlasmaBadOH Fault
309:51:54:817AMPlasmaOk
410:09:09:660AMPlasmaOk
510:25:47:643AMPlasmaOk
610:51:47:050AMPlasmaOk
711:04:38:240AMPlasmaOk
811:17:37:787AMPlasmaOk
911:54:41:740AMPlasmaOk
1012:25:27:650PMPlasmaOk
1112:43:48:800PMPlasmaOk
1212:56:46:847PMPlasmaOk
1301:10:40:300PMPlasmaOk
1401:23:35:130PMPlasmaOk
1501:43:33:007PMPlasmaOk
1601:56:24:007PMPlasmaOk
1702:09:08:753PMPlasmaOk
1802:21:56:020PMPlasmaOk
1902:37:42:850PMPlasmaOk
2002:51:32:473PMPlasmaOk
2103:04:21:973PMPlasmaOk
2203:17:22:520PMPlasmaOk
2303:41:01:473PMPlasmaOk
2403:53:42:287PMPlasmaOk
2504:09:49:067PMPlasmaOk
2604:22:27:473PMPlasmaOkPF breaker pulled after disruption
2704:37:14:740PMPlasmaOk
2805:03:52:550PMPlasmaOk