Alcator C-Mod Run 1060623 Information

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Miniproposals
Miniproposal:447
Date Filed: 4/4/2006
Title:MCCD experiments during current ramp-up
First Author:Alexandre Parisot
Session Leader:Alexandre Parisot (shots 1-17)

Operators
Session leader(s):Alexandre Parisot
Physics operator(s):Ian Hutchinson
Engineering operator(s):Ed Fitzgerald,Gary Dekow

Engineering Operator Run Comment
MP#447 Mode conversion current drive during startup PO:Hutchinson SL:Par

Session Leader Plans
Entered: Jun 22 2006 03:57:41:813PM
Author: Alexandre Parisot
Engineering setup for Friday 23-June-2006
SL: Parisot, Wukitch
PO: Hutchinson

Overnight ECDC in D2, and bake at 60 C.

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

Power systems as on 1060620013

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)
fill B-side upper with 25 psi 3He Hybrid enabled
*** (INCREASE FROM 15 psi TO 25 psi) ***
fill B-main (C-side) with 40 psi D2 Hybrid enabled (PG3)
fill NINJA with 12 psi D2 Enabled

** 3He 75 msec puff at 0.0 sec

*** Boronization system set up for between-shot boronization before
the run but do not open the diborane bottle.

*** All between shot boronizations (BSB) 10 minutes. Each sweep 200
seconds with a 20 second pause. All sweeps are 65-75 cm with pause
at 70 cm. Boronization pressure set to 5 mTorr.

Enable the following gate valves and shutters, assuming no vacuum problems:
ECE, VUV, Z-bolo shutters; these must be disabled for between-shot boronization

The A-Side TV camera shutter must be CLOSED before the boronizations
(before the run and for the rest of the day).
The MSE shutter must be CLOSED before the start of the run, and remain closed
throughout the day.

Important Diagnostics: FRC-ECE, He II monitor

ICRF Setup: All 4 transmitters on run-on by 8:30

------------------------------------------------------------------
Run plan

MP#447: Mode conversion current drive during startup

This is a continuation of 1060620. We want to reproduce shots
1060620013 and 1060620014, with between shot boronization to lower
Zeff, and higher 3He concentration to optimize the electron heating
(high B side upper pressure).

1] Start with 1060620013. Scan 3He puff duration 75ms,100ms,150ms

With J-port [70ms-300ms] at 2 MW with notches, monitor electron
heating and adjust Bt to obtain on-axis mode conversion with n3He ~
20-25%. (4-5 shots)

2] Boronize 10 min.

Add D&E-port 2 MW [70ms-300ms]. Scan co-current, counter-current
drive and heating phasing. (3shots)

If Zeff increases between the shots, repeat the scan, but boronize
10 min between each shot. (3shots)

3] Scan BT to investigate impact on CD and sawteeth.

Depending on the results, continue on MP#447, or switch to MP440 (SL: Wukitch)

4) Boronization erosion dependence on antenna
1) BSB followed by a D/E heating shot (1060621025 except BT=5.4 T, 50 msec 3He puff @0.2 sec)
2) J heating shot (1060621025 except BT=5.0 T, Ip->0.92 MA)
3) BSB followed by J heating shot
4) D/E heating shot
5) BSB followed by two D/E heated discharges
6) BSB followed by two J heated discharges

may repeat 1-4 depending upon results
5) use -90 and +90 and repeat
6) (5 shots) Upper single null plasma, H-mode power threshold
comparison. (1060620002 except Ip-> 1 MA)

Physics Operators Plans

Session Leader Summaries
Entered: Jun 23 2006 05:28:56:900PM
Author: Alexandre Parisot

We had a lot of unexpected events today, and consequently very few shots.
We did a scan of the 3He puff duration on the first 3 discharges, since the pressure
in the B-side-upper plenum was increased to 25 psi. We sucessfully puffed 3He starting
40 ms before breakdown, in an effort to get a sufficient 3He fraction in the plasma
and thus mode conversion earlier in the ramp-up.

However, these efforts were made useless by poor J-port performance in the ramp-up, much
like last Wednesday (1060620). We put the run on standby the do one hour of multipactor
conditionning on J-port, but this did not help. Therefore we decided to switch again
to flattop MCCD experiments, attempting to keep Zeff down by boronizing between shots.

These experiments were done at higher field than previously, so that the 3He concentration
was closer to 25 %. This should give us better electron heating than before, although minority
heating from D and E was quite uneffective at this field. After boronizing 10 minutes, heavy rain
forced us to put the run on standby again for almost 2 hours in order to pump out water around
the RF transmitters.

After all these efforts, we were able to get four comparison discharges with different phasing.
Shot 14 co-current drive
Shot 15 counter-current drive
Shot 16 heating phasing
Shot 17 co-current drive
These discharges will be analyzed to find indications of MCCD based on loop voltage differences and
changes in the period and amplitude of sawtooth oscillations.







Physics Operator Summaries
Entered: Jun 23 2006 05:13:32:047PM
Author: Ian Hutchinson
Today was pretty boring from the Physop twiddling viewpoint.
The small number of shots was an effect of the large number of problems.
These included breaker replacement, storm-drain backup into the RF area, together with boronization. That said, zero duds or fizzles.

Scorecard:
__________
  Shot,Duration(s),Ipmax(MA),Result  Shot,Duration(s),Ipmax,Result
  |   01   1.388   0.814   Plasma  |   02   1.382   0.812   Plasma  |
  |   03   1.381   0.811   Plasma  |   04   0.315   0.794   Plasma  |
  |   05   1.964   1.000   Plasma  |   06   1.953   1.004   Plasma  |
  |   07   1.972   0.694   Plasma  |   08   1.974   0.709   Plasma  |
  |   09   1.309   0.699   Plasma  |   10   1.977   0.674   Plasma  |
  |   11   1.328   0.661   Plasma  |   12   1.926   0.635   Plasma  |
  |   13   1.972   0.665   Plasma  |   14   1.973   0.712   Plasma  |
  |   15   1.974   0.696   Plasma  |   16   1.974   0.694   Plasma  |
  |   17   1.972   0.696   Plasma 
Date 1060623:  17 shots.  17 plasmas.   0 fizzles.   0 duds.   0 System Error.
        (Plasma = Ip gt 50.0 kA   Dud = H_alpha lt  0.40 V)
Total plasma duration: 28.74 s (exceeding  -81 kA)

Session Leader Comments
Jun 23 2006 09:25:30:133AM1060623001Alexandre Parisot120 ms 3He puff. J-port has many faults.
Good on-axis heating is observed.
Nl04 rise is comparable to 1060620013 and we have more pressure in B-side upper, yet the 3He monitor has less signal than 013. Why?

Next: Puff 150ms.
Jun 23 2006 09:41:26:053AM1060623002Alexandre Parisot150 ms 3He puff. Thompson is back.
Signal is saturated on He II monitor, higher than 1060620013.
Gate valve was closed after shot (left-over from yesterday).
J is still struggling.

Next: Puff -40 to 110 ms.
Jun 23 2006 10:23:11:063AM1060623003Alexandre ParisotPuffing 3He earlier than break-down works !
Concentration estimate: 25-30 %, more than what we want. The heating is off-axis.
The rise in He II signal is shifted by 40 ms.

Next. Multipactor 1h hoping that this will bring J-port back in shape.
Consequently, THERE WILL BE NO PLASMA ATTEMPTS FOR 1 1/2 HOURS.
Jun 23 2006 12:00:25:140PM1060623004Alexandre ParisotDisrupted at 0.3 sec. Large injection.
RF still struggled. No RF cell data, match looks good.
3He puff -40 to 90ms.

Next: Load 1060621025. Puff 3He 50 ms [.2-.25]
Jun 23 2006 12:08:37:890PM1060623005Alexandre ParisotRF ran clean. Not sure 3He went in, heating is very weak.
No Thompson.

Next. Go back to 100ms 3He puff.

Jun 23 2006 12:26:07:323PM1060623006Alexandre ParisotRF ran clean again.

Next. Load 1060620008 (MP#356 - Flattop MCCD experiments)

Jun 23 2006 12:38:17:883PM1060623007Alexandre ParisotJ-port faulted at 0.81 s. D&E ran at 0.5 MW.
No break-in-slope data. Puff time was 200ms.

Next: Retune J-port.


Jun 23 2006 12:58:35:923PM1060623008Alexandre ParisotJ ran with some faults.
Pellet at 1.04 sec.

Next: bt0 to 5.8T and 3He puff duration to 180ms.


Jun 23 2006 01:11:11:217PM1060623009Alexandre ParisotGood shot.

Next. Change phasing.


Jun 23 2006 01:27:00:980PM1060623010Alexandre ParisotInjections early, density is different than in 009.

Next. Heating phase.


Jun 23 2006 01:33:56:713PM1060623011Alexandre ParisotDisrupted at 1.22sec.

Next. Boronize 10 minutes. Repeat with co-current drive.


Jun 23 2006 03:49:48:823PM1060623012Alexandre ParisotMARFE early. J has many faults (mismatched ?)
nl04 higher than before.

Big storm. Needs to check if there is any water around FMIT# 3 & 4.
"There is water all over the place". We can't run with that.

Close off the diborane bottle and try to dry out the transmitter area,
hopefully before the next storm. Assuming no more water problems in the meantime, we will resume plasma attempts at 4:20 (30min filament warmup on FMIT#3 and 4).
Jun 23 2006 04:30:39:300PM1060623013Alexandre ParisotPlasma. Runaways early.
Faulty RF, apparently post-boronization pathology.

Next: Cross fingers and repeat
Jun 23 2006 04:33:45:957PM1060623014Alexandre ParisotPlasma. J has 4 faults.

Next. Go counter-CD.




Jun 23 2006 04:44:33:210PM1060623015Alexandre ParisotPlasma. Clean RF.

Next. Heating phasing.




Jun 23 2006 04:59:10:127PM1060623016Alexandre ParisotPlasma. Clean RF.

Next. One more shot, co-current drive phasing.




Jun 23 2006 05:11:05:563PM1060623017Alexandre ParisotPlasma. 2 faults on J-port, one early, one late.

End of run.




Physics Operator Comments
Jun 23 2006 09:11:32:810AMIan HutchinsonLoad from 1060620013. This is running in segment 4. 0.8MA upper null.
He3 pressure is 25psi instead of 15, so we should get more He3.
Load into model.
Jun 23 2006 09:36:48:287AM1060623001Ian HutchinsonPlasma.

He3 gas puff to 150ms (from 120).
Jun 23 2006 09:49:59:740AM1060623002Ian HutchinsonPlasma.

He3 puff to -40ms to +110ms.
Jun 23 2006 10:12:38:110AM1060623003Ian HutchinsonPlasma.
He3 is present in the monitor at breakdown, but the total fill pressure is not significantly changed by it.
Jun 23 2006 12:00:41:437PM1060623004Ian HutchinsonPrior to this shot we do multipacting of J-port antenna for about 1 hour to try
to improve its performance.
He3 puff to -40ms to 90ms.

Plasma disrupts at .31s. Density is quite high. Big radiative event near time of last RF trip. Fill puff gives only a very low fill pressure because the plenum was depleted to 2psi instead of 6psi.

Load from 1060621025. Change He3 puff to 50ms total (.2-.25s)
Jun 23 2006 12:24:45:057PM1060623005Ian HutchinsonPlasma.

He3 puff to 100ms (.2-.3s). Enable LPI gate valve.
Jun 23 2006 12:33:22:963PM1060623006Ian HutchinsonPlasma

Load 1060620008. Load.
Jun 23 2006 12:49:23:053PM1060623007Ian HutchinsonPlasma.
Jun 23 2006 01:12:22:403PM1060623008Ian HutchinsonPlasma. Found that not all gate valves were open for the last 3 shots, which
explains the high base pressure.

TF to 160kA (5.8T). He3 puff to 180ms from 200ms.
Jun 23 2006 02:10:04:813PM1060623011Ian HutchinsonPlasma.Disrupts at 1.3s


Boronize for 10 minutes.
Lower fill puff to 8ms.
Wait for base pressure to reach 4e-6.
Jun 23 2006 02:32:29:483PM1060623011Ian HutchinsonPlasma.

Fill puff to 11ms.
Thunderstorm fills the RF trench with water and calls a halt.

Engineering Operator Comments
ShotTimeTypeStatusComment
109:10:06:207AMPlasmaOk
209:24:05:397AMPlasmaOk
309:41:24:990AMPlasmaOk
411:46:14:797AMPlasmaOk
512:01:16:047PMPlasmaOk
612:15:05:373PMPlasmaOk
712:30:51:290PMPlasmaOk
812:47:34:133PMPlasmaOk
901:01:42:050PMPlasmaOk
1001:16:39:810PMPlasmaOk
1101:29:20:450PMPlasmaOk
1202:12:42:483PMPlasmaOk
1304:17:31:110PMPlasmaOk
1404:30:06:503PMPlasmaOk
1504:42:33:257PMPlasmaOk
1604:55:53:520PMPlasmaOk
1705:08:23:080PMPlasmaOk