Alcator C-Mod Run 1050721 Information

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Miniproposals
Miniproposal:424
Date Filed: 5/12/2005
Title:Initial tests of disruption mitigation using a gas jet
First Author:Robert Granetz
Session Leader:Robert Granetz (shots 1-11)

Operators
Session leader(s):Robert Granetz
Physics operator(s):Steve Wolfe
Engineering operator(s):Andy Pfeiffer,Bill Byford,Ed Fitzgerald

Engineering Operator Run Comment
MP #424 -- Gas jet disruption mitigation Session leaders: R. Granetz, D.

Session Leader Plans
Entered: Jul 21 2005 07:23:39:343AM
Author: Robert Granetz
MP #424 -- Gas jet disruption mitigation
Session leaders: R. Granetz, D. Whyte
Physics operator: S. Wolfe

ECDC (requested by J. Irby); bake at 60 C.

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

Power systems as on 1050603028 (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 Hybrid DISABLED (PG1)
leave B-side upper with whatever Hybrid disabled
fill B-main (C-side) with 30 psi D2 Hybrid enabled (PG3)
No NINJA for this run.

Gas jet should have high-pressure ( >70 bar) neon bottle installed, WITH
HIGH-PRESSURE HELIUM AND ARGON BOTTLES READY TO BE SWITCHED IN DURING THE
RUN.

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
Fast PSI camera on B-horizontal, starting at t=0.800 s, Ne+0, He+0, Ar+0
filters
Thomson scattering, with adjustable timing between the two lasers
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: All transmitters in run on at 08:30, but begin the run with
ohmic discharges.

-------------------------------------------------------------------------------
Run plan: Start with neon at 70 bar, 2 ms. Get IR divertor images, AXUV
profiles, global bolometry, fast visible camera images, as well
as disruption quench data (halo currents, timescales). Then turn
on RF to get higher Wth and pressure -- same drill.

About halfway through the run, switch to helium at 70 bar, 2 ms.
Get VUV data to look at self-absorption issues.

Save the last hour of the run for argon. Compare quench times
with helium and neon.

Physics Operators Plans
Entered: Jul 20 2005 02:56:30:937PM
Author: Steve Wolfe
MP #424 -- Gas jet disruption mitigation

Session leaders: R. Granetz, D. Whyte
Physics operator: S. Wolfe

ECDC (requested by J. Irby); bake at 60 C.

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

Power systems as on 1050603028 (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  Hybrid DISABLED (PG1)
  leave B-side upper     with 15 psi He3 Hybrid disabled (PG2)
   fill B-main (C-side)  with 30 psi D2  Hybrid enabled  (PG3)
No NINJA for this run.

Gas jet should have high-pressure ( >70 bar) neon bottle installed, WITH
HIGH-PRESSURE HELIUM AND ARGON BOTTLES READY TO BE SWITCHED IN DURING THE
RUN.

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- per JT)

Necessary diagnostics:
  IR camera
  Fast PSI camera on B-horizontal, starting at t=0.800 s, Ne+0, He+0, Ar+0
    filters
  Thomson scattering, with adjustable timing between the two lasers
  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: All transmitters in run on at 08:30, but begin the run with
            ohmic discharges.

-------------------------------------------------------------------------------
Run plan: Start with neon at 70 bar, 2 ms.  Get IR divertor images, AXUV
          profiles, global bolometry, fast visible camera images, as well
          as disruption quench data (halo currents, timescales).  Then turn
          on RF, He3 puff, to get higher Wth and pressure -- same drill.

          About halfway through the run, switch to helium at 70 bar, 2 ms.
          Get VUV data to look at self-absorption issues.

          Save the last hour of the run for argon.  Compare quench times
          with helium and neon. 

Session Leader Summaries
Entered: Jul 21 2005 05:10:39:257PM
Author: Robert Granetz
We only had one shot today due to a problem with the TF scanner system.
On that shot (1050721001) we successfully fired a neon gas jet and got
a disruption that was faster than normal, as we saw on the previous gas
jet run (1050603). The AXUV is getting the entire disruption without
saturating. Mirnov coils showed a clear n=1 (and low m) just before the
quench. However, the IR camera and the fast visible camera were not
turned on for this shot, although they both were ready for shot 2, which
never happened.

We will try this run again tomorrow (Friday).

Physics Operator Summaries
Entered: Jul 21 2005 05:12:39:117PM
Author: Steve Wolfe
We only got one shot today because of a problem with the PC 
controlling the TF scanner. 1050721001 was a successful gas 
jet disruption, as programmed. 

After the shot, the TF scanner did not run, and it was found
that the TFTC PC was unresponsive and would not reboot. Eventually, 
the D-drive was replaced and restored from backup tape, but 
the labview routine would still not communicate with the HP 
scanner in the cell. By five o'clock there was some indication
that a fiber link was broken, but this has not yet been confirmed. 

We will try to run the same experiment tomorrow. 

Scorecard:
     Plasmas  1
     Fizzles  0
     Duds     0
     Tests    8
    -------  --
     Shots    9

Session Leader Comments
Jul 21 2005 07:36:13:853AMRobert GranetzI set up an XTOMO fast digitization window from t=0.795 to 0.825 s. Sampling
rate is set for 50 kHz during the fast window.
Jul 21 2005 07:50:59:707AMRobert GranetzGas jet plenum is filled with 70 bar of neon. Gas jet system is ready
to go.
Jul 21 2005 08:09:47:217AMRobert GranetzNode \xtomo::top.camac:J221:output_12 turned on (gas jet trigger).

Timing is set for 2 ms pulse starting at t=0.8000 s.
Jul 21 2005 08:59:38:243AMRobert GranetzWe're ready to go, but Jim Terry and Dennis Whyte have not arrived yet, so I
don't know the status of the fast PSI camera and the IR camera.
Jul 21 2005 09:47:49:927AM1050721001Robert GranetzShot 01 -- Good shot. Gas jet worked. Thermal quench started around t=0.809 s.
I_halo=150 kA. AXUV got the entire quench without saturating. Joe Snipes sees
an n=1 (probably), with low m. Part of xtomo array_3 has no finite signal. Halo
inboard toroidal array didn't trigger.

Plenum gas: neon
Pulse length (ms): 2.0
Plenum pre -pulse pressure (bar): 70.5
Plenum post-pulse pressure (bar): 63.5
Plenum change in pressure (bar): 7.

Jul 21 2005 10:12:15:530AM1050721001Robert GranetzWe're in a hold between shots 1 and 2 in order to fix a problem with
the TF scanner.
Jul 21 2005 11:22:50:303AM1050721001Dennis WhyteInjected neon inventory from bottle: ~1600 Torr-L
B-Bottom MKS gives us ~1200 Torr-L based on 4.06 m3 vessel volume.
So we still have a discrepancy in the gas inventory, but
it looks less than that last run 06/03

Jul 21 2005 10:11:38:230AM1050721002Robert Granetz3 MW of ICRF will turn on at t=0.7 for this shot, and probably for the
rest of the run.

Physics Operator Comments
Jul 21 2005 07:19:26:437AMSteve Wolfe
We had overnight ECDC and 60C bake

Setup for 2nd gas jet run
Load from 1050603028
 Startup has 27ms pg4, Br0=+.00025,ic_ef4u=-1320
 This was robust on 1050603, so leave it for now, 
 except decrease pg4 to 21msec

 Seg2 is 1MA, 5.4T, nl04=1e20, no pg3 puff
  change tf to 144000A (~5.2T) for better D(He3)
Load at 21-Jul-2005 07:18:52.00
Open tree /home/wolfe/pcs_scratch      -1
Open tree done


Jul 21 2005 09:07:21:147AM1050721001Steve Wolfe
Shot#1: Bob's ready; JT and DW not in yet. 
First shot will be with gas jet at 0.8
plasma disrupted at 0.8sec
Very late breakdown 10msec

next: ef4 to -1310, br0 to 0
Dennis and JT are now in the room

Jul 21 2005 10:12:17:870AM1050721001Steve Wolfe
Shot#2: ef4 from -1320 to -1310, br0 to from +.00025 to 0
Over 60 minute delay while people get set up and there is a
problem with the TF scanner PC

Jul 21 2005 10:40:21:230AM1050721002Steve Wolfe
Shot#2: ef4 from -1320 to -1310, br0 to from +.00025 to 0
He3 puff on at .3 off at .4 and enable b-side upper
Add 2psi Ne to the 1psi Ar in b-side lower and enable
  (pg1 puff=50ms)
Delay for the TF scanner computer will be at least another hour
(from 10:40AM)

Jul 21 2005 11:46:46:303AM1050721002Steve Wolfe
Shot#2: No Power shot to see if TF scanner PC is really fixed.
It wasn't. There will be another delay while files are 
redirected to the disk that is still alive

Jul 21 2005 12:00:45:117PM1050721003Steve Wolfe
Shot#3: Another No Power shot to see if TF scanner PC is fixed now.
It ran for awhile, then stopped? 


Jul 21 2005 12:15:35:790PM1050721004Steve Wolfe
Shot#4: Another No Power shot to see if TF scanner PC is fixed now.
Still not working. maybe understood. Will try once more.


Jul 21 2005 12:31:04:197PM1050721005Steve Wolfe
Shot#5: Another No Power shot to see if TF scanner PC is fixed now.
No joy. try putting in a new D-drive. 


Jul 21 2005 01:14:36:273PM1050721006Steve Wolfe
Shot#6: Another No Power shot to see if TF scanner PC is fixed by
putting in a new D-drive. 
Still not working. 

Jul 21 2005 01:49:33:930PM1050721007Steve Wolfe
Shot#7: Another No Power shot to test TF scanner 
Not working and the debugger isn't working on it. 

Jul 21 2005 02:48:02:180PM1050721008Steve Wolfe
Shot#8: They found a cable not connected; try another no power
shot. Not working yet. 

Reboot the thing in the cell and the computer and try again

Jul 21 2005 05:06:43:167PM1050721009Steve Wolfe
Shot#9: Reboot the thing in the cell and the computer and try again
There is still a communication problem. 

Jul 21 2005 05:52:33:727PM1050721010Steve Wolfe
Shot#10: post-run test shot after the TF scanneeeer seemed to work
in manual tests. 

It seems to have worked. 


Jul 21 2005 05:59:50:260PM1050721011Steve Wolfe
Shot#11: 2nd post-run test shot after the TF scanner seemed to work
in manual tests. 

Worked a second shot (with no PEI current, so it is basically
showing bitnoise/bitnoise, but the data do show up.)


Engineering Operator Comments
ShotTimeTypeStatusComment
109:01:59:540AMPlasmaOk
211:31:49:337AMTestBadTF scanner Failed
311:53:39:150AMTestBadTF Scanner Problems
412:08:38:087PMTestOkTF Scanner test
512:22:26:133PMTestOkTF Scanner Test
601:04:40:883PMTestOkTF Scanner Test
701:24:59:853PMTestOkTF Scanner Test
802:21:49:507PMTestOkThis was a no power test shot
903:57:51:930PMTestOkThis was a no power test shot.
1005:44:57:727PMTestOk
1105:53:41:320PMTestOk