Alcator C-Mod Run 1051117 Information

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Miniproposals
Miniproposal:296
Date Filed: 5/14/2001
Title:Confirmation of Thomson scattering density calibration using electron cyclotron emission cutoffs
First Author:Jerry Hughes
Session Leader:Kirill Zhurovich (shots 1-32)
Miniproposal:438
Date Filed:11/17/2005
Title:J Antenna Evaluation: Operation without Faraday screen
First Author:Steve Wukitch
Session Leader:Steve Wukitch (shots 23-32)

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

Engineering Operator Run Comment
MP#296: TS/ECE cross-calibration (1/2 day) MP#438: J-antenna evaluation

Session Leader Plans
Entered: Nov 16 2005 04:24:29:473PM
Author: Kirill Zhurovich
Run plan for 1051117a (same as for 1050620a):
MP #296 (revised) 'TS/ECE density calibration'

Configure GPC2 for 4.6T operation
No RF
L-mode operation, avoid getting ohmic H-modes

Basically repeat the run 1050620a, shots 02-15, but with higher field.

Start with 1050620012, just change Bt to 4.6T.

Magnetic field and gas puff will be optimized to get ECE cutoffs for all TS spatial channels.

Physics Operators Plans
Entered: Nov 16 2005 04:58:34:927PM
Author: Robert Granetz
Engineering setup for Thursday 17 Nov 2005

MP#296: TS/ECE cross-calibration (1/2 day)
MP#438: J-antenna evaluation (1/2 day)

Session leader: T. Biewer (MP 296), S. Wukitch (MP 438)
Physics operator: R. Granetz

Overnight ECDC in D2 and bake at 60 C.
 
Run begins at 09:00 and ends at 17:00.

Power systems as on 1050620012, except the toroidal field will be raised to
4.6 T.

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     as is           Hybrid DISABLED (PG2)
   fill B-main (C-side)  with 40 psi D2  Hybrid enabled  (PG3)
   fill NINJA            with 10 psi D2  Leave DISABLED

Enable the following gate valves and shutters, assuming no vacuum problems:
  ECE, VUV, Z-bolo shutters
 
Torvac setup: Gate valves open

No between-shot boronization.

Important Diagnostics: TS, Edge TS, and GPC2 are required.  GPC and FRCECE
are desirable, if possible.  GPC2 should be configured for Btor=4.6 T.

-------------------------------------------------------------------------------
ICRF Setup: No RF for first half of the day.  Transmitter 3 needs to be in
run-on at 08:30.  The others need to be able to be turned on remotely later in
the day (go through checklist and set them up for remote control).

-------------------------------------------------------------------------------
Run plan: See the SL_PLANs in the logbook.

Session Leader Summaries
Entered: Nov 21 2005 12:20:24:680PM
Author: Kirill Zhurovich
Run summary for MP #296: "TS/ECE density calibration"

Session leader : Kirill Zhurovich
Physics Operator : Bob Granetz

First half of the day - shots 1-22

Aim: get ECE cutoff data at different radii, so that later it will be possible to derive density
calibration coefficients for TS from the calculated critical density values for ECE

Low magnetic field (~4.6T): since it's easier to get cutoffs at lower Btor
L-mode : to avoid abrupt cutoffs at the edge during L-H transition and avoid TS timing issues

Results:
We used to do this at lower field (4T) and GPC system. Since now we had to use GPC2 only, which does not have grating for this field, we were operating at 4.6T.
Got multiple cutoffs at different radii, but mainly in the core plasma region.
In order to get cutoffs at the very edge during flattop phase gas puff needs to be delayed. However, the edge was very cold at these densities, which hindered observations of the cutoffs. Moreover, we noticed that edge density was clamped during flattop phase of any discharge and somewhat independent of gas puff. Hope to pull out something from the edge data we got.
Finally, tried RF shot to induce H-mode transition and cutoffs at the edge - did not work (superb RF, 2 very brief H-modes, no cutoffs).
For details of each particular shot, see SL comments during the run.
-
Entered: Nov 21 2005 03:09:13:773PM
Author: Steve Wukitch
Run summary:

Good H-mode threshold comparison discharges on 023, 024, 028, 030.
Seems to be a fair bit of scatter in the plasma response and shot 028,
031 showed significantly disparate H-mode threshold values for D and E
versus J depending upon their time in the pulse. Better electron,
neutron, and stored energy response are seen in first RF pulse
compared to the second RF pulse independent of which antenna is first.
Radiation appears to be similar for the different antennas.

Physics Operator Summaries
Entered: Nov 17 2005 04:54:18:180PM
Author: Robert Granetz
Physics operator summary for Thursday 17 Nov 2005:

MP#296: TS/ECE cross-calibration (1/2 day)
MP#438: J-antenna evaluation (1/2 day)

Session leader: T. Biewer (MP 296), S. Wukitch (MP 438)
Physics operator: R. Granetz

Tough day in the physop chair.  The TS/ECE MP basically required density
ramps to the disruption limit.  This resulted in an alternating
disruption/fizzle/disruption/fizzle sequence which persisted throughout
their portion of the run.  Because of the high OH2U coax readings, there
were also a number of OH+TF shots required as well.  The core ECE channels
were successfully cut off, but the edge channels were rather cool, so it's
difficult to find the cut off for them.

Around 14:00 we switched to the 2nd MP.  J-antenna ran very well (up to 3
MW), as did D+E.  Various comparisons of heating efficiency and H-mode
access between J and D+E were done.  See the session leaders' summaries for
more details.

Even during the 2nd part of the day, the startups were not robust, and
there were lots of shots with runaways. 

Scorecard: 15 plasmas
            3 duds
           10 fizzles
            4 power supply tests
           --------------
    Total: 32 shot cycles

Session Leader Comments
Nov 17 2005 09:16:18:980AM1051117001Kirill ZhurovichGood cutoffs at R~71.3-76.5, 79.5, 83.7
next: correct TS alignment and increase Btor to 4.6T
Nov 17 2005 09:18:20:450AM1051117002Kirill Zhurovichno plasma
Nov 17 2005 09:45:54:887AM1051117003Kirill ZhurovichCutoffs for R~68.5cm, 72.5-77.7, 81, and it's trickier at the edge, since there is not much signal there
Nov 17 2005 09:46:28:743AM1051117004Kirill Zhurovichno plasma (as Bob's predicted)
Nov 17 2005 09:58:41:137AM1051117005Kirill ZhurovichGood cutoffs at R~69.2-78.5 cm, 81.6cm
Nov 17 2005 10:10:20:683AM1051117006Kirill Zhurovichno plasma
again there is shot/fizzle pattern due to disruptions
Nov 17 2005 10:33:24:387AM1051117007Kirill Zhurovichearly disruption
Nov 17 2005 10:47:02:887AM1051117008Kirill Zhurovichfizzle
Nov 17 2005 11:09:50:540AM1051117009Kirill ZhurovichCutoffs for R~69.2-78.4cm, 81.6
next: delay the gas puff by ~100ms
Nov 17 2005 11:14:08:667AM1051117010Kirill Zhurovichfizzle
Nov 17 2005 11:32:31:103AM1051117011Kirill Zhurovichno plasma shot
next: in addition to the puf delay decrease the overall density to 2 (nl values) to avoid disruptions
Nov 17 2005 11:44:16:497AM1051117012Kirill Zhurovichno plasma
Nov 17 2005 12:06:52:527PM1051117013Kirill Zhurovichno plasma
Nov 17 2005 12:42:45:117PM1051117014Kirill ZhurovichCutoffs at R~69.2-78.4cm, 81.6cm
No edge cutoffs
Nov 17 2005 12:47:08:440PM1051117015Kirill Zhurovichno plasma
next increase plasma current to 1MA
decrease Btor to 4.55T
Nov 17 2005 12:57:31:147PM1051117016Kirill Zhurovichstrange shot
no cutoffs at all
Nov 17 2005 01:09:01:243PM1051117017Kirill Zhurovichno plasma
Nov 17 2005 01:51:57:803PM1051117018Kirill ZhurovichCutoffs at R~71.5-76.7,79.8, 83.9 and probably 86.4
Nov 17 2005 01:49:37:553PM1051117019Kirill Zhurovichno plasma
next :add RF to get H-mode and cutoffs at the edge
Nov 17 2005 02:33:14:447PM1051117022Kirill ZhurovichNice RF!
a couple of H-mode blips, no cutoffs
that's it for ECE calibration today
Nov 17 2005 02:52:49:680PM1051117023Steve Wukitch023 BT~4.5 T, Ip~1 MA, nl_04~0.8
D: ramp to 1 MW [1.1,1.5] sec
E: ramp to 1 MW [1.1,1.5] sec
J: ramp to 2 MW [0.6,1] sec
result: plasma
D: ran max faults at high power
E: ran
J: ran 2 faults

Nov 17 2005 03:13:19:337PM1051117024Steve Wukitch024 BT~5.2 T, Ip~1 MA, nl_04~0.9
D: ramp to 0.8 MW [1.1,1.5] sec
E: ramp to 1.2 MW [1.1,1.5] sec
J: ramp to 2 MW [0.6,1] sec
result: plasma H-mode threshold
D: ran 1 fault
E: ran 1 fault
J: ran

Nov 17 2005 03:31:36:587PM1051117025Steve Wukitchfizzle
Nov 17 2005 03:34:29:850PM1051117026Steve Wukitchdud
Nov 17 2005 03:57:30:913PM1051117027Steve Wukitchdud
Nov 17 2005 04:25:59:243PM1051117028Steve Wukitch028 BT~5.2 T, Ip~1 MA, nl_04~0.9
D: ramp to 0.8 MW [1.1,1.5] sec
E: ramp to 1.2 MW [1.1,1.5] sec
J: ramp to 2 MW [0.6,1] sec
result: plasma
D: ran
E: ran
J: ran
good comparison
swap order of antennas

Nov 17 2005 04:26:15:320PM1051117029Steve Wukitchfizzle
Nov 17 2005 04:47:58:913PM1051117030Steve Wukitch030 BT~5.2 T, Ip~1 MA, nl_04~0.9
D: ramp to 0.8 MW [0.6,1] sec
E: ramp to 1.2 MW [0.6,1] sec
J: ramp to 2 MW [1.1,1.5] sec
result: plasma
D: ran
E: ran
J: ran
good comparison

Nov 17 2005 04:47:22:540PM1051117031Steve Wukitch031 BT~5.2 T, Ip~1 MA, nl_04~0.9
D: ramp to 0.8 MW [0.6,1] sec
E: ramp to 1.2 MW [0.6,1] sec
J: ramp to 2 MW [1.1,1.5] sec
result: plasma
D: ran
E: ran
J: ran
good comparison
H mode for J but not for D+E
something to the order making it difficult to get into H-mode

Nov 17 2005 05:00:57:493PM1051117032Steve Wukitchfizzle

Physics Operator Comments
Nov 16 2005 06:08:05:207PMRobert GranetzLoaded DPCS segment 2 from 1050620012 segment 3 (yes, 3). Re-called all the magnetics
predictors to get the new BP16 coil.

Then changed Btor in segment 2 to 4.6 T (123900 kA).

Saved in /home/granetz/pcs_scratch shot 1051117000.

Also loaded into model.
Nov 17 2005 09:12:46:590AM1051117001Robert GranetzPlasma. Good shot. Density ramped up to get the ECE cutoff at t=1.37 s, followed
shortly thereafter by a density limit disruption. Btor=4.5 T (wanted 4.6).
The new IR pyrometer peaks at 560 C on the disruption. It also sees the marfe
start up just before the disruption. Lots of early runaways.

Next shot: increase Btor to 4.6 T (126400 A). Also add 1 ms to prefill.
Nov 17 2005 09:18:11:340AM1051117002Robert GranetzFizzle.

Next shot: no changes
Nov 17 2005 09:36:54:790AM1051117003Robert GranetzPlasma. Good shot. Density limit disruption after the ECE cutoff.
Btor=4.6 T. Good startup, almost no runaways. Inner wall gets to 560 C.

Next shot: increase Btor to 4.65 (127800 A)
Nov 17 2005 09:45:04:040AM1051117004Robert GranetzFizzle. This is alternating just like the last time this run was tried on 1050620.

Next shot: no changes.
Nov 17 2005 09:57:59:277AM1051117005Robert GranetzPlasma. Good shot. Got ECE cutoff and density limit disruption.

Next shot: Change unused wire 9 to be the usual B21 A-coil feedback (copy from
recent shot). Also reduce prefill by 4 ms to see if we can get out of this
alternating shot/fizzle/shot/fizzle pattern.
Nov 17 2005 10:09:31:277AM1051117006Robert GranetzDud.

Next shot: add the 4 ms back to the prefill.
Nov 17 2005 10:37:06:683AM1051117007Robert GranetzPlasma. Disrupted early due to an injection. Didn't get to the ECE cutoff. OH2U coax
is okay.

Next shot: reduce prefill by 2 ms.
Nov 17 2005 10:53:29:510AM1051117008Robert GranetzFizzle.

Next shot: add 2 ms back to prefill.
Nov 17 2005 11:09:04:777AM1051117009Robert GranetzPlasma. Good shot. Got the ECE cutoff and a density-limit disruption.
Lots of early runaways.

Next shot: no changes. I've tried to get out of the alternating fizzle pattern, but
nothing has helped. Delay the density ramp programming by 100 ms.
Nov 17 2005 11:25:25:900AM1051117010Robert GranetzFizzle. What a surprise.

Next shot: OH + TF only shot to tighten the OH2U coax back up, just to be
on the safe side.
Nov 17 2005 11:32:38:870AM1051117011Robert GranetzTest shot; OH + TF only. OH2U coax looks good.

Next shot: reduce nl_04 to 2.0e20 m-2, hopefully to get edge channel cutoff without
getting to density limit disruption.
Nov 17 2005 11:45:51:557AM1051117012Robert GranetzDud. OH2U didn't commutate. Steve Wolfe noticed that its switch didn't
close at t = -0.7 s.

Next shot: try again, after checking the supply.
Nov 17 2005 12:11:38:010PM1051117013Robert GranetzAnother OH + TF only shot.

Next shot: go for plasma again. The density will be 2.0e20 m-2, so that
we'll get the edge ECE channels cut off, but hopefully we won't get a
density-limit disruption.
Nov 17 2005 12:33:21:090PM1051117014Robert GranetzPlasma. Good shot. It's still difficult to determine whether the edge channels
show a cut off, or whether they're just cold.

Next shot: increase Ip to 1.0 MA (was 0.9), and decrease nl_04 to 1.9e20 m-2.
Nov 17 2005 12:47:14:177PM1051117015Robert GranetzFizzle. Still in the alternating pattern.

Next shot: reduce Btor to 4.55 T (125000 A). (Was 4.65 T)
Nov 17 2005 01:14:04:553PM1051117016Robert GranetzPlasma. Big burst of runaways from t=0.5 to 0.7 s. Density was under better control,
but the plasma still disrupted.

Next shot: Increase early density to 0.7e20 m-2 to see if we can avoid the
runaways. Also reduce pre-fill by 1 ms, but it'll be a fizzle anyway.
Also increase the OH1 and OH2's reverse PLC current limits to -30 kA.
Nov 17 2005 01:12:50:430PM1051117017Robert GranetzFizzle.

Next shot: decrease Btor to 4.50 T (123600 A).
Nov 17 2005 01:24:03:820PM1051117018Robert GranetzPlasma. Still disrupted at t=1.5 s.

Next shot: fizzle.
Nov 17 2005 01:47:31:680PM1051117019Robert GranetzFizzle.

Next shot: Turn on the RF in order to try and get an H-mode to enhance
the edge temperature. Reduce nl_04 to 0.9e20 m-2. Keep Btor at 4.5 T.
Nov 17 2005 01:51:46:320PM1051117020Robert GranetzFizzle. This is the first time today that we've had two fizzles in a row.

Next shot: OH + TF only shot.
Nov 17 2005 02:22:50:413PM1051117021Robert GranetzOH + TF only test. Good OH2U resistance.

Next shot: go for plasma again.
Nov 17 2005 02:36:17:913PM1051117022Robert GranetzPlasma. Made it well down the ramp. Good 3 MW RF pulse, including J3 and J4.
Only the briefest of H-modes though. No cutoff seen on the edge Te channels.

End of MP 296.

Now start with MP 438, J-antenna evaluation

Next shot: Load segment 2 from 1051116028 segment 2. (5.2 T, 0.9 MA, 0.9e20 m-2, SNL)
Nov 17 2005 02:58:34:587PM1051117023Robert GranetzPlasma. Good, full-length shot. J-antenna ramps up to 2 MW. D and E go later.
H/(H+D)=10%.

Next shot: no changes.
Nov 17 2005 03:12:48:180PM1051117024Robert GranetzPlasma. Good, full-length shot. Similar to previous shot.

Next shot: repeat, no changes.
Nov 17 2005 03:24:15:930PM1051117025Robert GranetzPlasma, but very, very short.

Next shot: OH + TF only reverse bridge shot.
Nov 17 2005 03:38:45:617PM1051117026Robert GranetzOH+TF only, reverse bridge OH2U coax resistance = 1.5 micro-ohms.

Next shot: go for plasma again. Pre-fill has been increased by 2 ms from shot 25.
Nov 17 2005 03:51:45:790PM1051117027Robert GranetzDud! I didn't expect that. Fields and gas look acceptable.

Next shot: add -10 A to IC_EF4, increase prefill by another 1 ms.
Nov 17 2005 04:07:49:210PM1051117028Robert GranetzPlasma. Good full-length shot. Good RF performance. Prf_J gets up to 3 MW, but it's
not as good as D+E in getting the plasma into H-mode. There were lots of runaways.

Next shot: add another 1 ms to prefill.
Nov 17 2005 04:17:44:023PM1051117029Robert GranetzFizzle.

Next shot: reduce pre-fill by 2 ms.
Nov 17 2005 04:31:32:570PM1051117030Robert GranetzPlasma. Good shot. J and (D+E) were swapped in time. Short H-modes. Awful
startup, but there doesn't seem to be an alternative today.

Next shot: no changes.
Nov 17 2005 04:42:01:820PM1051117031Robert GranetzPlasma. Good full-length shot. Good D,E, and J performance. Almost no runaways.

Next shot: no changes.
Nov 17 2005 04:53:31:867PM1051117032Robert GranetzFizzle.

End of run.

Engineering Operator Comments
ShotTimeTypeStatusComment
109:00:59:307AMPlasmaOk
209:14:32:840AMPlasmaOk
309:27:52:090AMPlasmaOk
409:41:02:090AMPlasmaOk
509:54:07:933AMPlasmaOk
610:07:25:917AMPlasmaOk
710:29:22:387AMPlasmaOk
810:45:00:340AMPlasmaOk
910:58:09:650AMPlasmaOk
1011:12:10:243AMPlasmaOk
1111:28:51:480AMTestOkReverse Bridge Shot
1211:41:59:370AMPlasmaBadCommutation Switch Failure
1312:04:09:307PMTestOkReverse-Bridge Shot
1412:19:26:760PMPlasmaOk
1512:36:36:650PMPlasmaOk
1612:49:53:137PMPlasmaOk
1701:06:00:697PMPlasmaOk
1801:19:16:523PMPlasmaOk
1901:32:32:163PMPlasmaOk
2001:48:52:680PMPlasmaOk
2102:11:08:960PMTestOkOH TF Reverse Bridge shot
2202:25:02:523PMTestOk
2302:46:49:320PMPlasmaOk
2403:00:13:883PMPlasmaOk
2503:13:37:587PMPlasmaOk
2603:30:39:240PMTestOkReverse-Bridge
2703:44:44:163PMPlasmaOk
2803:57:58:210PMPlasmaOk
2904:11:06:680PMPlasmaOk
3004:24:17:663PMPlasmaOk
3104:37:24:070PMPlasmaOk
3204:50:54:600PMPlasmaOk