Alcator C-Mod Run 1060308 Information

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Miniproposals
Miniproposal:418
Date Filed: 3/4/2005
Title:LH system commisioning
First Author:Stefano Bernabei
Session Leader:John Liptac (shots 1-5)
Miniproposal:439
Date Filed:11/16/2005
Title:Scaling of gas jet induced disruption timing with q95
First Author:Valerie Izzo
Session Leader:Robert Granetz (shots 1-28)

Operators
Session leader(s):John Liptac,Robert Granetz
Physics operator(s):Jim Irby
Engineering operator(s):Andy Pfeiffer,Bill Byford,Bill Parkin

Engineering Operator Run Comment
MP #439 -- Scaling of gas jet induced disruption timing with q95 Session

Session Leader Plans
Entered: Mar 7 2006 04:17:46:710PM
Author: Valerie Izzo
MP #439 -- Scaling of gas jet induced disruption timing with q95

Session leaders: V. Izzo, R. Granetz, D. Whyte
Physics operator: J. Irby

ECDC overnight and bake at 60 C.

Run begins at 09:00 and ends at 17:00.

Power systems as on 1050825017 (1.0 MA, 5.4 T, SNL fiducial)

A-coil configuration: normal [+Dtop -Dbot -Jtop +Jbot] and enabled.

Gas Setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar + 2 psi Ne Hybrid DISABLED (PG1)
leave B-side upper with whatever Hybrid disabled
fill B-main (C-side) with 40 psi D2 Hybrid enabled (PG3)
No NINJA for this run.

Gas jet has been set up with argon at 70 bar.
WE MAY WANT TO SWITCH THE GAS TO KRYPTON SOMETIME DURING THE DAY.

Torvac setup: unnecessary diagnostic gate valves (ECE) should be kept
closed on all gas jet shots.

Enable the following, assuming no vacuum problems:
Z-bolo shutters, VUV (yes, enable the VUV gate valve)

Necessary diagnostics:
IR camera, if possible
Fast PSI camera on B-horizontal, if possible, starting at t=0.800 s, Ar+0
filter
Thomson scattering, with timing set so that one profile is obtained just
after the edge Te collapses
Bolometry
AXUV array with reduced gain
Halo current Rogowskis
SX arrays with fast sampling window (t=0.795 to 0.820 s)
Mirnov Bp fluctuations

-------------------------------------------------------------------------------
ICRF Setup: No RF -- ohmic only

-------------------------------------------------------------------------------
Run plan: Start at 5.4 T and increment Btor on each subsequent shot, noting
the time between the gas pulse and the thermal quench. Requested
values are 5.4, 5.8, 6.3, 6.7, and possibly 7.2 and 7.6 T. Then
go back to 5.4 T and decrement the field on each subsequent shot
(5.4, 4.5, 4.1).

Physics Operators Plans
Entered: Mar 7 2006 05:28:01:960PM
Author: Jim Irby
Only addition to SL_plan is:

Backporch will be added to TF.

Session Leader Summaries
Entered: Mar 8 2006 06:04:36:110PM
Author: Robert Granetz
Session leader summary for Wednesday 08 Mar 2006

MP 439: Scaling of gas jet induced disruption timing with q95

Session leaders: V. Izzo, R. Granetz, D. Whyte
Physics operator: J. Irby

We essentially got enough of the experiment done to conclude that there
wasn't any consistent effect of the timing of the thermal quench as the
toroidal field was raised from 5.4 to 7.1 T for ohmic plasmas at
nl_04=0.8-1.0.  Relevant shots are: 1060308007, 12, 15, 17, 19, and 22.

After puzzling about this, we decided to try a quick field
scan at a lower density, since ohmic plasmas at the original density might
have had such cold edges that the NIMROD modeling wasn't really valid.  So
we had three shots with nl_04=0.3e20 m-2, and these showed a possible,
dependence on B-field of about the right time variation.  However, on the
last shot the plasma fueling valve failed completely, and so it was a very
low density runaway shot.  So it may be invalid.  The three shots are:
1060308024  7.1 T   t_spike = 0.80675 s
1060308026  5.4 T   t_spike = 0.80645 s
1060308028  4.4 T   t_spike = 0.80625 s

Small bursts of hard x-rays were observed on some shots, and this bears
further study.

There were many operational difficulties today.  The main fueling valve
("C-side") was not doing a good job of following its command, and it
completely failed to open by the end of the day.  (It will be replaced
before tomorrow's run.)  And we also had many post-disruption fizzles,
which is notably uncharacteristic of previous gas jet runs.  The RGA showed
lots of hydrocarbons.  This may be because we're still only very early into
the campaign.


Physics Operator Summaries
Entered: Mar 8 2006 05:23:23:517PM
Author: Jim Irby
MP #439 -- Scaling of gas jet induced disruption timing with q95

Session leaders: V. Izzo, R. Granetz, D. Whyte
Physics operator: J. Irby
EOs: Pfeiffer, Byford, Parkin

Lots of fizzles today. This problem was probably a combination of a dirty machine responding to the disruptions and the prefill being too high.



Problems today:

Fill pressure was probably too high much of the day, which may have increased the fizzle rate. There was some thought yesterday that the gauge calibration was incorrect, but the calibration is in fact correct.

The B-Main piezo valve (PG3) was "stuck" closed until 0.5 s or so, and we therefore were w/o density control during most of the shot. This problem should be fixed by tomorrow's run. The valve failed completely on shot 28.

The machine was pretty dirty with lots of carbon being evolved from the disruptions. The carbon level was probably the primary reason for the high fizzle rate.

Session Leader Comments
Mar 8 2006 08:04:40:310AMRobert GranetzFilling gas jet plenum with 70 bar of argon. Fast valve is sealed.
The rest of the system is at 0.2 mTorr.
Mar 8 2006 08:12:31:390AMRobert GranetzCXRS toroidal background shutter (upper push-pull pair) is now open, and will
remain open for today's run so that Aaron can get some spectra.
Mar 8 2006 08:13:27:937AMRobert GranetzThe first plasma shot will be a non-disruptive shot for John Liptac and Ron Parker to
complete yesterday's run. After that, it's no holds barred.
Mar 8 2006 09:55:18:763AM1060308004Robert GranetzAll the programmable amplifiers for all the core x-ray arrays are working.
Mar 8 2006 10:16:09:997AM1060308004John LiptacBob and Valerie have graciously given us the first shot of the day to complete the run from yesterday.

Gap scan, reload of shot 1060307019 with 60 degree ideal CD phase for six segments. 20kW/klystron to match yesterdays run. LH set to go at 0.695 s.

Network problem broke connection to alcdata no LH power.

Gas valve issue, rise that was seen at about 0.85 s yesterday was seen at about 0.6 s, before the LH power. nl04 goes up to 0.6 as opposed to 0.4 range, the antenna probe density goes from 4-2e18 m-3 over the gap scan, not a bad range, but different than yesterday's 2-1e18 m-3.


Mar 8 2006 09:57:34:903AM1060308005John LiptacFizzle, continue with Bob's run. Try to pick up scan on next LH run.

Move launcher back to 1700 counts, ~ 1cm behind limiter, to protect is from disruptions.


Mar 8 2006 09:56:16:890AM1060308006Robert GranetzGas jet run will begin on this shot. I've turned on the fast valve trigger node,
and enabled the torus valve.
Mar 8 2006 10:22:59:950AM1060308006Robert Granetz
Shot 06 -- Fizzle.  Argon gas jet fired at t=0.800 s.

Plenum gas: argon
Pulse length (ms): 2.0
Plenum pre -pulse pressure (bar): 70
Plenum post-pulse pressure (bar): 66
Plenum change in  pressure (bar): 04

Mar 8 2006 10:57:09:233AM1060308007Valerie Izzo
Btor=5.4 T, q95=3.7, Thermal quench at t=0.8065 s. A little later than previous argon gas jet shots at this toroidal field. Repeat with same Btor to adjust Thomson timing.
Mar 8 2006 10:58:03:123AM1060308007Robert GranetzX-ray arrays didn't look the same as what I'm used to seeing. Might be because these
are only ohmic shots (60 kJ), with low x-ray emission in the periphery.
Mar 8 2006 11:18:22:420AM1060308009Robert GranetzFizzle. Gas jet fired.
Mar 8 2006 11:48:33:467AM1060308010Robert GranetzFor this shot, I've changed the magnetics sampling rate to 10 kHz for t = -0.1 to +0.9 s
(since the plasma will terminate at t=0.81 s). This keeps the number of samples the
same.
Mar 8 2006 12:26:52:263PM1060308012Valerie Izzo
Btor=5.4 T, q95=3.7. Thermal quench at 0.806 s. Thomson was a little too late this time. Next shot, increase to Btor=5.8 T
Mar 8 2006 12:29:20:607PM1060308012Robert GranetzThe x-ray data looks more like what I would expect, although I think it's
still evident that there's less emission from the periphery compared to
RF-heated shots.
Mar 8 2006 12:33:48:873PM1060308012Robert Granetz
Shot 12 -- Good shot.  Argon gas jet fired at t=0.800 s.
Btor = 5.4 T.
Current quench starts at t=0.8064 s.
Current quench duration is about 1.5 ms.
I_halo=116 kA.

Prf=0.0 MW (ohmic)
Wth=55 kJ.

Plenum gas: argon
Pulse length (ms): 2.0
Plenum pre -pulse pressure (bar): 70
Plenum post-pulse pressure (bar): 66
Plenum change in  pressure (bar): 04

Mar 8 2006 12:31:43:983PM1060308013Robert GranetzThe toroidal field will be 5.8 T for this shot.
Mar 8 2006 01:13:56:543PM1060308015Robert Granetz
Shot 15 -- Good shot.  Argon gas jet fired at t=0.800 s.
Btor = 5.8 T.
Current quench starts at t=0.8064 s.
Current quench duration is about 1.3 ms.
I_halo=120 kA.

Prf=0.0 MW (ohmic)
Wth=56 kJ.

Plenum gas: argon
Pulse length (ms): 2.0
Plenum pre -pulse pressure (bar): 70
Plenum post-pulse pressure (bar): 66
Plenum change in  pressure (bar): 04

Mar 8 2006 01:16:05:700PM1060308015Robert GranetzX-ray data during the quench looks bizarre!
Mar 8 2006 01:21:56:717PM1060308015Valerie IzzoBtor=5.8 T, q95=3.9. Thermal quench at 0.8062 s. Little or no apparent change in quench timing. Thomson shows cooling in as far as rho=0.6 at .806 s.
Mar 8 2006 01:28:57:780PM1060308015Robert GranetzNext shot will be at 6.3 T.
Mar 8 2006 01:50:14:327PM1060308017Robert Granetz
Shot 17 -- Good shot.  Argon gas jet fired at t=0.800 s.
Btor = 6.3 T.
Current quench starts at t=0.8065 s.
Current quench duration is about 1.3 ms.
I_halo=111 kA.

Prf=0.0 MW (ohmic)
Wth=107 kJ.

Plenum gas: argon
Pulse length (ms): 2.0
Plenum pre -pulse pressure (bar): 70
Plenum post-pulse pressure (bar): 66
Plenum change in  pressure (bar): 04

Mar 8 2006 01:54:09:623PM1060308017Robert GranetzThe x-ray plunge occurs at about 0.8062 s, which is about 200 microseconds later
than on shot 12 (at 5.4 T).
Mar 8 2006 02:04:17:110PM1060308017Valerie IzzoBtor=6.3 T, q95=4.3. No change in timing is apparent.

Mar 8 2006 02:21:20:483PM1060308019Robert Granetz
Shot 19 -- Good shot.  Argon gas jet fired at t=0.800 s.
Btor = 6.7 T.
Current quench starts at t=0.8066 s.
Current quench duration is about 1.5 ms.
I_halo=111 kA.

Prf=0.0 MW (ohmic)
Wth=61 kJ.

Plenum gas: argon
Pulse length (ms): 2.0
Plenum pre -pulse pressure (bar): 65
Plenum post-pulse pressure (bar): 61
Plenum change in  pressure (bar): 04

Mar 8 2006 02:26:03:687PM1060308019Valerie IzzoBtor=6.7 T, q95=4.4. Thermal quench at about 0.8065 s. Thomson show cooling extends only to rho=0.7 at 0.806 s. Thermal quench and current quench may be getting progressively later, but by a very small amount which may not be outside the error bars.
Mar 8 2006 02:29:39:827PM1060308019Robert GranetzX-rays didn't behave the same as the last few shots, so it's difficult to
compare timing.
Mar 8 2006 02:29:53:030PM1060308019Robert GranetzNext shot will be 7.2 T.
Mar 8 2006 03:09:07:857PM1060308022Robert Granetz
Shot 22 -- Good shot.  Argon gas jet fired at t=0.800 s.
Btor = 7.1 T.
Current quench starts at t=0.8065 s.
Current quench duration is about 1.8 ms.
I_halo=116 kA.

Prf=0.0 MW (ohmic)
Wth=50 kJ.

Plenum gas: argon
Pulse length (ms): 2.0
Plenum pre -pulse pressure (bar): 70
Plenum post-pulse pressure (bar): 66
Plenum change in  pressure (bar): 04

Mar 8 2006 03:14:55:060PM1060308022Valerie IzzoBtor=7.1T, q95=4.6. Thermal quench at 0.8063 s. Thomson shows more cooling by 0.806 s than lower field shots.
Mar 8 2006 04:06:47:267PM1060308024Robert Granetz
Shot 24 -- Good shot.  Argon gas jet fired at t=0.800 s.
Btor = 7.1 T.
Note that this shot had nl_04=0.3e20 m-2, instead of 0.9e20 m-2.
Current quench starts at t=0.8067s.
Current quench duration is about 1.5 ms.
I_halo=99 kA.

Prf=0.0 MW (ohmic)
Wth=42 kJ.

Plenum gas: argon
Pulse length (ms): 2.0
Plenum pre -pulse pressure (bar): 70
Plenum post-pulse pressure (bar): 66
Plenum change in  pressure (bar): 04

Mar 8 2006 04:11:08:020PM1060308024Robert GranetzX-ray arrays still don't provide a clear thermal quench time.
Mar 8 2006 04:18:18:567PM1060308024Robert GranetzFor this shot, and the remainder of today, the density programming was
reduced to nl_04=0.5e20 m-2, instead of 1.0e20 m-2 (which was the request
for all earlier shots today).
Mar 8 2006 04:18:44:127PM1060308024Robert GranetzThe next shot will be at 5.4 T, with nl_04=0.5e20 m-2.
Mar 8 2006 04:45:06:380PM1060308026Robert Granetz
Shot 26 -- Good shot.  Argon gas jet fired at t=0.800 s.
Btor = 5.4 T.
nl_04=0.3e20 m-2
Current quench starts at t=0.80645 s.
Current quench duration is about 1.6 ms.
I_halo=124 kA.

Prf=0.0 MW (ohmic)
Wth=38 kJ.

Plenum gas: argon
Pulse length (ms): 2.0
Plenum pre -pulse pressure (bar): 70
Plenum post-pulse pressure (bar): 66
Plenum change in  pressure (bar): 04

Mar 8 2006 04:45:24:440PM1060308026Robert GranetzNext shot will be at 4.0 T, and nl_04=0.5e20 m-2.
Mar 8 2006 05:00:13:610PM1060308027Robert Granetz
This shot disrupted, but it wasn't us.  The disruption was at t=0.7 s.  Maybe it was
a low-q issue (q95=2.8), maybe something else.

For the next shot, increase Btor a bit to 4.3 T.  This will be the last shot of
the day.

Mar 8 2006 05:17:33:753PM1060308028Robert Granetz
Shot  -- Good shot, except the density seemed to go to zero, and there were lots of
runaways.  Argon gas jet fired at t=0.800 s.
Btor = 4.4 T.
Current quench starts at t=0.8062 s.
Current quench duration is about 1.7 ms.
I_halo=171 kA.

Prf=0.0 MW (ohmic)
Wth=23 kJ.

Plenum gas: argon
Pulse length (ms): 2.0
Plenum pre -pulse pressure (bar): 70
Plenum post-pulse pressure (bar): 66
Plenum change in  pressure (bar): 04

Mar 8 2006 05:19:04:160PM1060308028Robert GranetzEnd of run. I'll pump out the gas jet system, and also close the CXRS shutter,
write up a short run report, and then start setting up for physopping
tomorrow's run.

Physics Operator Comments
Mar 8 2006 08:04:44:827AMJim IrbyBefore the run we will take a test shot to:

. check operation of the data system

. verify proper operation of the main gas puff

. obtain a TF scanner baseline


Mar 8 2006 09:09:29:857AM1060308001Jim IrbyThis shot is a cycle test

test:

. data system including bolometer camac
. gas puff
. bolometer camac

lost some x-tomo data

don't really have gas puff from b-side until 0.5 s
ratiomatic was off

bolometer camac opeational





Mar 8 2006 09:09:00:373AM1060308002Jim Irbysecond try on gas puff --- started a little earlier 0.31 s
ratiomatic was on for this one

Mar 8 2006 09:20:39:747AM1060308003Jim Irbyanother cycle test

a little earlier on the gas 0.285 s


Mar 8 2006 09:49:29:293AM1060308004Jim IrbyThis will be a repeat of shot 1060307019 for completion of LH run

removed 40 volt kick to PG3 in seg 2 in attempt to get density from yesterday

good shot

density too high for John.

Mar 8 2006 09:56:56:090AM1060308005Jim Irbydropped density request to 4.6e19 /m^2 as seen on 1060307019 at 0.7 s

fizzle


Mar 8 2006 10:28:42:310AM1060308006Jim Irbyloaded shot 1050825017, 5.4 T, 1 MA, LSN
loaded seg 1 from 1060307019 into seg 1
did calls on rcur, zcur,clearin,rxl,zsl,rxu,zxu, and IP to resolve new procedures
loaded seg 1 tf with backporch into seg 2.

Bob has enabled gas jet

fizzle --- possible issues with both gas and bz0
Mar 8 2006 10:46:16:293AM1060308007Jim Irbygas from 45 to 35 ms

bzo from -1340 to -1360 A

plasma

#49 high


Mar 8 2006 11:12:27:373AM1060308008Jim IrbyThis shot will be a PLC controlled 150 kA TF only test

#49 bottom at 2.19 u at 1 s (no change from yesterday)



Mar 8 2006 12:01:32:857PM1060308010Jim Irbyworking to get a backporch following disruption
TF invert to 2.8 s
TF fizzle off
Steve Wolfe has enabled seg 4 to control backporch after disruption

A few extra minutes for Joe and Yuri to mod TF fizzle delay.

TF fizzle from 1000 to 2500 ms

EF4 from -1360 to -1380 A

Bob has enabled gas jet again

fizzle --- no problem with fields or gas but...

got the backporch

#49 okay at 2 s


Mar 8 2006 12:10:41:530PM1060308011Jim Irbyno dpcs changes

fizzle --- will drop gas for next shot

#49 okay
Mar 8 2006 12:26:40:857PM1060308012Jim IrbyEF4 back to -1340 A from -1380 --- late breakdown from last shot

plasma --- actually reached programmed density after valve turned on


Mar 8 2006 12:48:04:733PM1060308013Jim IrbyBt to 5.8 T --- 161 kA

fizzle

#49 okay


Mar 8 2006 01:04:01:733PM1060308014Jim Irbyreduced pg4 from 30 to 28 ms.

closer but still fizzled

pressure was lower as requested

bounce at about 13 ms did us in
Mar 8 2006 01:21:26:513PM1060308015Jim Irbyef4 to -1350 from -1340 A

plasma --- got higher field

#49 2.88 u


Mar 8 2006 01:48:35:593PM1060308016Jim Irbychanging TFV cooling from C-Right control at -162 C to Vertical average control -184 C. TF bottom cooling to -180 C.

TF to 6.3 T (175 kA)

TF current limit raised to 190 kA

Fizzle

#49 2.59 u

fields look good --- gas?


Mar 8 2006 01:58:04:577PM1060308017Jim Irbyprefill from 28 to 27 ms.

plasma ---

#49 2.75 u


Mar 8 2006 02:12:50:687PM1060308018Jim IrbyTF to 6.7 T (186 kA)

fizzle

#49 at 2.58 u


Mar 8 2006 02:31:48:060PM1060308019Jim Irbyprefill to 28 from 27 ms

plasma

#49 2.69 u


Mar 8 2006 02:46:22:060PM1060308020Jim IrbyTF to 7.2 T (200 kA)

TF current limit at 205 kA

prefill from 27 to 26 ms

dud --- supply problem with ef3

#49 at 2.42 u


Mar 8 2006 03:16:58:577PM1060308022Jim Irbyprefill to 23 ms --- Ian, after talking with Brian, is certain the ratiomatic calibration is correct, and we have been running very high fill pressures over the last couple of days.

plasma ---

#49 at 2.73 u


Mar 8 2006 03:56:36:487PM1060308023Jim Irbyprefill from 23 to 21 ms

fizzle --- very late breakdown
Br0 may be a little low

#49 2.5 u


Mar 8 2006 04:17:45:283PM1060308024Jim IrbyBr0 increased by 0.3 mT

plasma --- looks good --- got .5 e20


Mar 8 2006 04:30:17:470PM1060308025Jim IrbyBt to 5.4 T

fizzle

#49 2.58 u


Mar 8 2006 04:48:58:253PM1060308026Jim Irbyno dpcs changes

plasma


Mar 8 2006 04:55:10:847PM1060308027Jim IrbyBt to 4.0 T (111 kA)

plasma

#49 2.46 u


Mar 8 2006 05:22:11:033PM1060308028Jim IrbyBt to 4.3 T (120 kA)

plasma --- very low density --- lots of x-rays

looks like the piezo failed completely

#49 at 2.49 u

Engineering Operator Comments
ShotTimeTypeStatusComment
108:48:00:310AMTestOk
209:02:32:200AMTestOk
309:14:38:607AMTestOk
409:35:47:907AMPlasmaOkTF top 43&51-4.8417,49-4.45
509:50:43:310AMPlasmaOkTF top 42-6.9525, 49-5.27131
610:18:48:187AMPlasmaOkTF top 42-6.15144, 48-4.89616
710:34:32:890AMPlasmaOkTF Top 43 at 5.80435 uohms and bottom at 11.4771 uohms
810:49:17:403AMPlasmaOk
911:14:36:153AMPlasmaOk
1011:49:44:247AMPlasmaOk
1112:03:06:420PMPlasmaOk
1212:15:41:327PMPlasmaOk
1312:40:40:467PMPlasmaOk
1412:53:15:170PMPlasmaOk
1501:07:36:297PMPlasmaOk
1601:30:28:793PMPlasmaOk
1701:44:24:373PMPlasmaOk
1802:02:05:590PMPlasmaOk
1902:14:41:327PMPlasmaOk
2002:36:17:500PMPlasmaBadEF3 Breaker Opened prior to Shot
2102:50:26:467PMPlasmaOk
2203:03:08:390PMPlasmaOk
2303:47:32:280PMPlasmaOk
2404:00:30:627PMPlasmaOk
2504:22:54:253PMPlasmaOk
2604:35:39:910PMPlasmaOk
2704:48:36:457PMPlasmaOk
2805:03:27:457PMPlasmaOk