Alcator C-Mod Run 1040423 Information

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Miniproposals
Miniproposal:203
Date Filed: 2/20/1998
Title:8 T H-mode Discharge Development with 3He Minority Heating
First Author:Steve Wukitch
Session Leader:Yijun Lin (shots 1-18)

Operators
Session leader(s):Yijun Lin
Physics operator(s):Dmitri Mossessian
Engineering operator(s):Gary Dekow

Engineering Operator Run Comment
MP#203 He3 heating at 8T; SL:Lin; PO:Mossesian; EO:Dekow/Byford/Fitz

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:05:053PM
Author: Yijun Lin
MP#203 He3 Heating at 8T (Cont'd)

Run Plan:

Start with 1040421001, 5.4 T. After tests load 1040421012, nl04 0.75e20
m^-2. for 8T operation

The goal is to have good D(He3) heated H-mode.
If time permits, we will also have
a few shots for mode conversion current drive study.

1. Scan He3 puff until mode conversion is observed. Using moderate RF power
(~3.5 MW) Ip = 1.2 MA, BT~7.9 T, nl_04~0.75e20 m^-2.
2. Scale back He3 level using the information from 1 and try to have 2-4%
He3. Optimize the minority heating.
3. Scan density to optimize target for H-mode.
4. If we get a few reproducible good H-mode (or we are unable to get good
H-mode however we try), the last few shots will go for MC current drive at
higher He3 level (Need MSE in this part)
-

Run summary:

Due to the small number of good plasmas (10 shots: shot 3, 4, 6, 7, 8,
14, 15, 16, 17, 18), only the first part of the
run plan was carried out. He3 puff was increased shot by shot, from 30 ms to
200 ms (15 PSI He3, B-side upper). The heating seemed to be best when puffing
rate was about 60 ms. However, No significant fall-off in heating was
observed at larger puffing (<200 ms).
No apparent mode conversion was observed in the GPC2 signals, while
other signals including PCI are being evaluated.
H-modes were easily obtained, unlike the previous D(He3) attempts in this
campaign. A few of them lasted longer than 100 ms (shot 7
and 8). However, the performance of these H-mode was generally poor. The
L-H transition power threshold was around 3.5 MW.

Shot by shot list:
shot 1: TF test.

shot 2: 5.4 Telsa plasma.
D: .7 MW ramp [.6,1.2] sec
E: .7 MW ramp [.6,1.2] sec
J: 2.2 MW ramp [0.6,1.2] sec. Digital phase +152,
two programed notches [.9, .91] and [1.1, 1.11] sec
result: plasma. Full length.
Wmhd up to 180 kJ at 3.6 MW power. It was an excellent shot.
Next: try 8 Tesla.

shot 3: Bt = 7.9 Telsa, Ip = 1.2 MA, nl04 = 0.75 e20m^-2
D: .7 MW ramp [.6,1.2] sec
E: .7 MW ramp [.6,1.2] sec
J: 2.2 MW ramp [0.6,1.2] sec. Digital phase +152, [0, pi, pi, 0]
Two programed notches [.9, .91] and [1.1, 1.11] sec
He3 puff 30 ms.
result: plasma. full length.
Many tiny H-modes. maybe some mode convertion seen.
Next: raise he3 puff to 40 ms.

shot 4: Bt = 7.9 Telsa, Ip = 1.2 MA, nl04 = 0.75 e20m^-2
D: .7 MW ramp [.6,1.2] sec
E: .9 MW ramp [.6,1.2] sec
J: 2.2 MW ramp [0.6,1.2] sec. Digital phase +152, [0, pi, pi, 0]
Two programed notches [.9, .91] and [1.1, 1.11] sec
He3 puff 40 ms.
result: plasma. full length.
Lasting H-mode from 0.82 to 0.9 sec. Transition right before
the notch.

Next: repeat. Notches from J antenna removed. Raise E power.

shot 5: Data system shot. No plasma.

shot 6: Bt = 7.9 Telsa, Ip = 1.2 MA, nl04 = 0.75 e20m^-2
D: .8 MW ramp [.6,1.2] sec
E: 1. MW [.6,1.2] sec
J: 2.4 MW [0.6,1.2] sec. Digital phase +152, [0, pi, pi, 0]
He3 puff 40 ms.
result: plasma. full length.
2 H-modes between 0.7 to 0.9 sec. Both last about 60 ms.
2 more H-modes later.

I suspect the He3 level is too small and it drops too much
in H-mode at higher density so that the H-modes are short-lived.

Next: raise He3 puff to 50 ms. Reduce D port power.

shot 7: Bt = 7.9 Telsa, Ip = 1.2 MA, nl04 = 0.75 e20m^-2
D: .5 MW ramp [.6,1.2] sec
E: 1. MW [.6,1.2] sec
J: 2.4 MW [0.6,1.2] sec. Digital phase +152, [0, pi, pi, 0]
He3 puff 50 ms.
result: plasma. full length.
3 H-mode.
Wmhd to 147 kJ. 1st H-mode lasted about 100 ms.

Next: He3 puff 60 ms.

shot 8: Bt = 7.9 Telsa, Ip = 1.2 MA, nl04 = 0.75 e20m^-2
D: .4 MW ramp [.6,1.2] sec
E: 1. MW [.6,1.2] sec
J: 2.4 MW [0.6,1.2] sec. Digital phase +152, [0, pi, pi, 0]
He3 puff 60 ms.
result: plasma. disrupted .92 sec.

H-mode lasted 100 ms. Wmhd to 151 kJ, Prf at 4.2 MW.
Better than last shot.

Next: He3 puff at 80 ms.

shot 9: Alternator test.

shot 10: After 3 hours delay on engineering check-up, the shot
was a reload of shot 2 at 5.4 tesla.
FMIT #1 had a problem at run-on. Something prevents the filement to
be ready. No power from this transmitter. (Charley will look at it).

shot 11: early disruption. 7.9 T.

shot 12: EF3 breaker problem. No plasma.

shot 13: early disruption. 7.9 T.

shot 14:
Bt = 7.9 Telsa, Ip = 1.2 MA, nl04 = 0.75 e20m^-2
D: off.
E: 1. MW [.6,1.2] sec
J: 2.4 MW [0.6,1.2] sec. Digital phase +152, [0, pi, pi, 0]
He3 puff 80 ms.
result: plasma. full length.
many tiny H-modes (dithering). power 3.7 MW.

RF power may not be enough.
Next: repeat. With D power.

shot 15:
Bt = 7.9 Telsa, Ip = 1.2 MA, nl04 = 0.75 e20m^-2
D: 0.4 MW, [.6, 1.2] sec.
E: 1. MW [.6,1.2] sec
J: 2.4 MW [0.6,1.2] sec. Digital phase +152, [0, pi, pi, 0]
He3 puff 80 ms.
result: plasma. full length.
an H-mode lasted 50 ms. D port dropped early.

Next: 100 ms He3 puff to see whether we can still get H-mode
Added notches on J-antenna to check MC.

shot 16:
Bt = 7.9 Telsa, Ip = 1.2 MA, nl04 = 0.75 e20m^-2
D: 0.4 MW, [.6, 1.2] sec.
E: 1. MW [.6,1.2] sec
J: 2.4 MW [0.6,1.2] sec. Digital phase +152, [0, pi, pi, 0]
Two programed notches [1.0, 1.01] and [1.1, 1.11] sec
He3 puff 100 ms.
result: plasma. full length.
a couple H-modes lasting about 50 ms.
The first H-mode looks no different than the one in shot 8 before
the H-L transition.

Next: He3 puff 200 ms.

shot 17:
Bt = 7.9 Telsa, Ip = 1.2 MA, nl04 = 0.75 e20m^-2
D: 0.4 MW, [.6, 1.2] sec.
E: 1. MW [.6,1.2] sec
J: 2.4 MW [0.6,1.2] sec. Digital phase +152, [0, pi, pi, 0]
Two programed notches [1.0, 1.01] and [1.1, 1.11] sec
He3 puff 200 ms.
result: plasma. disrupted 1.2 sec.
a couple H-modes. The first one last about 80 ms.

Next: repeat 200 ms puff. Raise nl04 to see whether the H-mode can
stay longer.

shot 18:
Bt = 7.9 Telsa, Ip = 1.2 MA, nl04 = 0.9 e20m^-2
D: 0.4 MW, [.6, 1.2] sec.
E: 1. MW [.6,1.2] sec
J: 2.4 MW [0.6,1.2] sec. Digital phase +152, [0, pi, pi, 0]
Two programed notches [1.0, 1.01] and [1.1, 1.11] sec
He3 puff 200 ms.
result: plasma.
Dithering. D port faulted out early. Prf at 3.7 MW.
Maybe the power threshold is right at this level.
No conclusion can be drawn yet.

End of run.

Physics Operator Summaries
Entered: Jul 7 2004 04:36:50:100PM
Author: Dmitri Mossessian
int k=part,j=high;
p summary for 1040423


Engineering Setup and Run Plan 1040423

Purpose: MP#203 He3 heating at 8T (Cont'd)

SL: Lin
PO: Mossessian

Engineering Setup:

Power systems the same as 1040421001 for 5.4 T plasmas
After magnet tests and test plsama(s) at 5.4 T switch to 8 T - adjust TF
limit appropriately.

Overnight ECDC in D2 at 2e-4 Torr

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

A-coils should be configured for standard operation

Gas setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar Hybrid enabled (PG1)
leave B-side upper with 15 psi He3 Hybrid enabled (PG2)
fill C-side with 30 psi D2 Hybrid enabled (PG3)

Enable the following gatevalves: ECE, VUV, DNB

Diagnostics:
GPC2 set for 8 T, TCI, PCI, FRECE (5.4 T discharge)
McPherson/Chromex to monitor He3
halo current diagnostics, TF scanner
OH coax resistance and thermocouple instrumentation
MSE from DNB
----------------------------------------------------------------------------
--
RF Setup: All four transmitters in RUN-ON by 08:00, all at 80 MHz
----------------------------------------------------------------------------
---

Run Plan:

Start with 1040421001 - 5.4 T. After tests load 1040421012, nl04 0.75e20
m^-2. for 8T operation

The goal is to have good D(He3) heated H-mode. If time permits, we will also have a few shots for mode conversion current drive study.

1. Scan He3 puff until mode conversion is observed. Using moderate RF power ~3.5 MW) Ip = 1.2 MA, BT~7.9 T, nl_04~0.75e20 m^-2.
2. Scale back He3 level using the information from 1 and try to have 2-4% He3. Optimize the minority heating.
3. Scan density to optimize target for H-mode.
4. If we get a few reproducible good H-mode (or we are unable to get good H-mode however we try), the last few shots will go for MC current drive at higher He3 level (Need MSE in this part)
-______________________________________________________________
Summary:

It would have been a good run if we have not had a long delay due to some alternator problem that caused alternator voltage to go down in the middle of shot 8, which led to forced inversion of EF3 power supply and to a disruption.
Power supply fuses were thoroughly and frequently checked and we did not have problems with breakers. Only on shot 12 did EF3 breaker open.
From shot 10, that was 5.4 T test after alternator problem was fixed, to shot 13 there was a large injection around the time when x-point is formed. The injection led to disruptions on shots 11 and 13. Moving RXL 1 cm in, and, therefore, moving outer strike point down the divertor plate, helped.
There were no particular problems with startup, other than soem runaways on shot 15, which were suppressed by increasing the prepuff slightly.
Overall, there were 10 good shots and He3 puff was scanned from 40 to 200 msec.

Total:

18 shots
12 @ 8 T
2 @ 5.4 T
4 tests

Details:


----------------------------------------------------------------------------
1040423001 Test OK.

Next shot - 5.4 T plasma
----------------------------------------------------------------------------
1040423002 Plasma. Greta shot. 180 kJ max W for 3.5 MW RF. Clear burst of ELMs when T_ped jumps up above 500 eV.

Next shot - 8 T, 1.2 MA, nl 7.5e19, 30 msec He3 puff. TF current to 219 kA for 7.9 T.
Loaded 1040421012. Changed He3 puff (PG2) to 30 msec starting at 0.3 sec. Changed nl.
PLC TF limit to 230, starting point to -1.5 sec

----------------------------------------------------------------------------
1040423003 Plasma. Good 8 T shot.

Next shot - reduce additional puff before 0.1 sec to slow down density rise at the beginning. He3 to 40 msec
----------------------------------------------------------------------------
1040423004 Plasma. Short H-mode terminated by a preprogramed drop in RF

Next shot - repeat
----------------------------------------------------------------------------
1040423005 No power shot due to TCI feedback problems.

Next shot - plasma
----------------------------------------------------------------------------
1040423007 Plasma.

Next shot - He3 puff to 60 msec
----------------------------------------------------------------------------
1040423008 Plasma. Terminated at 0.9 sec - breakers problem.

Next shot - He3 to 80 msec.
----------------------------------------------------------------------------
1040423008 EF3 went into forced inversion at 0.82 sec, because the alternatotor voltage was going down. At that point
position control was lost and plasma disrupted. So it looks like the main problem was ramping down of
the alternator voltage that started at 0.4 sec for the reason that is so far unknown.
----------------------------------------------------------------------------
1040423008 Long delay due to the alternator problem.

Next shot will be no power shot - testing alternator excitation.
----------------------------------------------------------------------------
1040423009 Next shot - 5.4 T, loaded 1040421001 again.
----------------------------------------------------------------------------
1040423012 EF3 breaker opened. This will be no power shot.
----------------------------------------------------------------------------
1040423013 Disruption at 0.36 sec. It looks like it is caused by a large injection off the divertor
outer plate that happens right when X-point is formed.

Next shot - reduce RXL by 1 cm to move outer strike point in.
----------------------------------------------------------------------------
1040423014 Plasma. No disruption this time. Moving strike point a little bit down the plate helped.

Next shot - no change
----------------------------------------------------------------------------
1040423015 Plasma.

Next shot - He3 to 100 msec. Prepuff 16 -> 18 msec to get rid of runaways at 0.2 s
----------------------------------------------------------------------------
1040423016 Plasma. No runaways.

Next shot - He3 to 200 msec
----------------------------------------------------------------------------
1040423017 Plasma. Disrupted at 1.2 sec.

Next shot - RXL down 0.5 cm after 1 sec. nl up to 9e19
----------------------------------------------------------------------------
1040423018 Plasma. Ramps down to 0.




Session Leader Comments
Apr 23 2004 09:17:07:903AM1040423001Yijun Lin50 kA TF test.
Apr 23 2004 09:30:19:513AM1040423002Yijun Linshot 2: 5.4 Telsa plasma.
D: .7 MW ramp [.6,1.2] sec
E: .7 MW ramp [.6,1.2] sec
J: 2.2 MW ramp [0.6,1.2] sec. Digital phase +152,
two programed notches [.9, .91] and [1.1, 1.11] sec
result: plasma. Full length.
Wmhd up to 180 kJ at 3.6 MW power. It was an excellent shot.
Next: try 8 Tesla.
Apr 23 2004 09:48:20:487AM1040423003Yijun Linshot 3: Bt = 7.9 Telsa, Ip = 1.2 MA, nl04 = 0.75 e20m^-2
D: .7 MW ramp [.6,1.2] sec
E: .7 MW ramp [.6,1.2] sec
J: 2.2 MW ramp [0.6,1.2] sec. Digital phase +152, [0, pi, pi, 0]
Two programed notches [.9, .91] and [1.1, 1.11] sec
He3 puff 30 ms.
result: plasma. full length.
Many tiny H-modes. maybe some mode convertion seen.
Next: raise he3 puff to 40 ms.
Apr 23 2004 10:12:09:327AM1040423004Yijun Linshot 4: Bt = 7.9 Telsa, Ip = 1.2 MA, nl04 = 0.75 e20m^-2
D: .7 MW ramp [.6,1.2] sec
E: .9 MW ramp [.6,1.2] sec
J: 2.2 MW ramp [0.6,1.2] sec. Digital phase +152, [0, pi, pi, 0]
Two programed notches [.9, .91] and [1.1, 1.11] sec
He3 puff 40 ms.
result: plasma. full length.
Lasting H-mode from 0.82 to 0.9 sec. Transition right before
the notch.

Next: repeat. Notches from J antenna removed. Raise E power.
Apr 23 2004 10:24:47:327AM1040423005Yijun Linshot 5: Data system shot. No plasma.
Apr 23 2004 10:46:00:913AM1040423006Yijun Linshot 6: Bt = 7.9 Telsa, Ip = 1.2 MA, nl04 = 0.75 e20m^-2
D: .8 MW ramp [.6,1.2] sec
E: 1. MW [.6,1.2] sec
J: 2.4 MW [0.6,1.2] sec. Digital phase +152, [0, pi, pi, 0]
He3 puff 40 ms.
result: plasma. full length.
2 H-modes between 0.7 to 0.9 sec. Both last about 60 ms.
2 more H-modes later.

I suspect the He3 level is too small and it drops too much
in H-mode at higher density so that the H-modes are short-lived.


Next: raise He3 puff to 50 ms. Reduce D port power.
Apr 23 2004 11:06:06:420AM1040423007Yijun Linshot 7: Bt = 7.9 Telsa, Ip = 1.2 MA, nl04 = 0.75 e20m^-2
D: .5 MW ramp [.6,1.2] sec
E: 1. MW [.6,1.2] sec
J: 2.4 MW [0.6,1.2] sec. Digital phase +152, [0, pi, pi, 0]
He3 puff 50 ms.
result: plasma. full length.
3 H-mode.
Wmhd to 147 kJ. 1st H-mode lasted about 100 ms.

Next: He3 puff 60 ms.
Apr 23 2004 11:27:36:453AM1040423008Yijun Linshot 8: Bt = 7.9 Telsa, Ip = 1.2 MA, nl04 = 0.75 e20m^-2
D: .4 MW ramp [.6,1.2] sec
E: 1. MW [.6,1.2] sec
J: 2.4 MW [0.6,1.2] sec. Digital phase +152, [0, pi, pi, 0]
He3 puff 60 ms.
result: plasma. disrupted .92 sec.

H-mode lasted 100 ms. Wmhd to 151 kJ, Prf at 4.2 MW.
Better than last shot.

Next: He3 puff at 80 ms.

Apr 23 2004 02:13:30:813PM1040423009Yijun Linshot 9: Alternator test.
Apr 23 2004 02:13:39:733PM1040423010Yijun Linshot 10: After 3 hours delay on engineering check-up, the shot
was a reload of shot 2 at 5.4 tesla.
FMIT #1 had a problem at run-on. Something prevents the filement to
be ready. No power from this transmitter. (Charley will look at it).
Apr 23 2004 02:36:51:740PM1040423011Yijun Linshot 11: early disruption. 7.9 T.
Apr 23 2004 02:52:25:047PM1040423012Yijun Linshot 12: EF3 breaker problem. No plasma.
Apr 23 2004 03:05:00:263PM1040423013Yijun Linshot 13: early disruption. 7.9 T.
Apr 23 2004 03:31:06:673PM1040423014Yijun Linshot 14:
Bt = 7.9 Telsa, Ip = 1.2 MA, nl04 = 0.75 e20m^-2
D: off.
E: 1. MW [.6,1.2] sec
J: 2.4 MW [0.6,1.2] sec. Digital phase +152, [0, pi, pi, 0]
He3 puff 80 ms.
result: plasma. full length.
many tiny H-modes (dithering). power 3.7 MW.

Next: repeat. With D power.
Apr 23 2004 04:23:20:497PM1040423016Yijun Linshot 16:
Bt = 7.9 Telsa, Ip = 1.2 MA, nl04 = 0.75 e20m^-2
D: 0.4 MW, [.6, 1.2] sec.
E: 1. MW [.6,1.2] sec
J: 2.4 MW [0.6,1.2] sec. Digital phase +152, [0, pi, pi, 0]
Two programed notches [1.0, 1.01] and [1.1, 1.11] sec
He3 puff 100 ms.
result: plasma. full length.
a couple H-modes lasting about 50 ms.
The first H-mode looks no different than the one in shot 8 before
the H-L transition.

Next: He3 puff 200 ms.
Apr 27 2004 08:20:14:717AM1040423017Yijun Linshot 17:
Bt = 7.9 Telsa, Ip = 1.2 MA, nl04 = 0.75 e20m^-2
D: 0.4 MW, [.6, 1.2] sec.
E: 1. MW [.6,1.2] sec
J: 2.4 MW [0.6,1.2] sec. Digital phase +152, [0, pi, pi, 0]
Two programed notches [1.0, 1.01] and [1.1, 1.11] sec
He3 puff 200 ms. (actually 168 ms, PO mistake)
result: plasma. disrupted 1.2 sec.
a couple H-modes. The first one last about 80 ms.

Next: repeat 200 ms puff. Raise nl04 to see whether the H-mode can stay longer
Apr 27 2004 08:20:02:763AM1040423018Yijun Linshot 18:
Bt = 7.9 Telsa, Ip = 1.2 MA, nl04 = 0.9 e20m^-2
D: 0.4 MW, [.6, 1.2] sec.
E: 1. MW [.6,1.2] sec
J: 2.4 MW [0.6,1.2] sec. Digital phase +152, [0, pi, pi, 0]
Two programed notches [1.0, 1.01] and [1.1, 1.11] sec
He3 puff 200 ms. (actually 168 ms, PO mistake)
result: plasma.
Dithering. D port faulted out early. Prf at 3.7 MW.
Maybe the power threshold is right at this level.
No conclusion can be drawn yet.

Physics Operator Comments
Apr 23 2004 08:56:58:320AMDmitri MossessianEngineering Setup and Run Plan 1040423

Purpose: MP#203 He3 heating at 8T (Cont'd)

SL: Lin
PO: Mossessian

Engineering Setup:

Power systems the same as 1040421001 for 5.4 T plasmas
After magnet tests and test plsama(s) at 5.4 T switch to 8 T - adjust TF
limit appropriately.

Overnight ECDC in D2 at 2e-4 Torr

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

A-coils should be configured for standard operation

Gas setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar Hybrid enabled (PG1)
leave B-side upper with 15 psi He3 Hybrid enabled (PG2)
fill C-side with 30 psi D2 Hybrid enabled (PG3)

Enable the following gatevalves: ECE, VUV, DNB

Diagnostics:
GPC2 set for 8 T, TCI, PCI, FRECE (5.4 T discharge)
McPherson/Chromex to monitor He3
halo current diagnostics, TF scanner
OH coax resistance and thermocouple instrumentation
MSE from DNB
----------------------------------------------------------------------------
--
RF Setup: All four transmitters in RUN-ON by 08:00, all at 80 MHz
----------------------------------------------------------------------------
---

Run Plan:

Start with 1040421001 - 5.4 T. After tests load 1040421012, nl04 0.75e20
m^-2. for 8T operation

The goal is to have good D(He3) heated H-mode. If time permits, we will also
have
a few shots for mode conversion current drive study.

1. Scan He3 puff until mode conversion is observed. Using moderate RF power
(~3.5 MW) Ip = 1.2 MA, BT~7.9 T, nl_04~0.75e20 m^-2.
2. Scale back He3 level using the information from 1 and try to have 2-4%
He3. Optimize the minority heating.
3. Scan density to optimize target for H-mode.
4. If we get a few reproducible good H-mode (or we are unable to get good
H-mode however we try), the last few shots will go for MC current drive at
higher He3 level (Need MSE in this part)
Apr 23 2004 08:58:31:743AMDmitri MossessianFirst shot will be PLC TF test. If the test is OK, we'll do 5.4 T plasma and then go to 8 T.

Loaded 1040421001 (5.4 T, 1 MA, 8.5e19 nl) for the first shot. Load clan OK.
Apr 23 2004 09:22:16:020AM1040423001Dmitri MossessianTest OK.

Next shot - 5.4 T plasma
Apr 23 2004 09:35:02:097AM1040423002Dmitri MossessianPlasma. Greta shot. 180 kJ max W for 3.5 MW RF. Clear burst of ELMs when T_ped jumps up above 500 eV.

Next shot - 8 T, 1.2 MA, nl 7.5e19, 30 msec He3 puff. TF current to 219 kA for 7.9 T.
Loaded 1040421012. Changed He3 puff (PG2) to 30 msec starting at 0.3 sec. Changed nl.
PLC TF limit to 230, starting point to -1.5 sec

Apr 23 2004 09:47:13:203AM1040423003Dmitri MossessianPlasma. Good 8 T shot.

Next shot - reduce additional puff before 0.1 sec to slow down density rise at the beginning. He3 to 40 msec
Apr 23 2004 10:04:13:913AM1040423004Dmitri MossessianPlasma. Short H-mode terminated by a preprogramed drop in RF

Next shot - repeat
Apr 23 2004 10:25:18:857AM1040423005Dmitri MossessianNo power shot due to TCI feedback problems.

Next shot - plasma
Apr 23 2004 11:08:35:800AM1040423007Dmitri MossessianPlasma.

Next shot - He3 puff to 60 msec
Apr 23 2004 11:26:08:533AM1040423008Dmitri MossessianPlasma. Terminated at 0.9 sec - breakers problem.

Next shot - He3 to 80 msec.
Apr 23 2004 11:43:37:340AM1040423008Dmitri MossessianEF3 went into forced inversion at 0.82 sec, because the alternatotor voltage was going down. At that point
position control was lost and plasma disrupted. So it looks like the main problem was ramping down of
the alternator voltage that started at 0.4 sec for the reason that is so far unknown.
Apr 23 2004 01:49:24:777PM1040423008Dmitri MossessianLong delay due to the alternator problem.

Next shot will be no power shot - testing alternator excitation.
Apr 23 2004 02:05:18:910PM1040423009Dmitri MossessianNext shot - 5.4 T, loaded 1040421001 again.
Apr 23 2004 02:52:22:220PM1040423012Dmitri MossessianEF3 breaker opened. This will be no power shot.
Apr 23 2004 03:16:29:493PM1040423013Dmitri MossessianDisruption at 0.36 sec. It looks like it is caused by a large injection off the divertor
outer plate that happens right when X-point is formed.

Next shot - reduce RXL by 1 cm to move outer strike point in.
Apr 23 2004 03:30:29:410PM1040423014Dmitri MossessianPlasma. No disruption this time. Moving strike point a little bit down the plate helped.

Next shot - no change
Apr 23 2004 03:58:26:273PM1040423015Dmitri MossessianPlasma.

Next shot - He3 to 100 msec. Prepuff 16 -> 18 msec to get rid of runaways at 0.2 s
Apr 23 2004 04:21:10:513PM1040423016Dmitri MossessianPlasma. No runaways.

Next shot - He3 to 200 msec
Apr 23 2004 04:42:43:490PM1040423017Dmitri MossessianPlasma. Disrupted at 1.2 sec.

Next shot - RXL down 0.5 cm after 1 sec. nl up to 9e19
Apr 23 2004 04:59:41:030PM1040423018Dmitri MossessianPlasma. Ramps down to 0.

Engineering Operator Comments
ShotTimeTypeStatusComment
109:07:34:457AMTestOkTF 50 KA Test
209:20:03:597AMPlasmaOk
309:36:53:037AMPlasmaOk
409:59:22:547AMPlasmaOk
510:22:08:463AMTestOk
610:31:27:083AMPlasmaOk
710:54:04:190AMPlasmaOk
811:17:09:417AMPlasmaBadAlternator Field Dipped
901:50:16:477PMTestOkAlternator Excitation Test
1002:08:07:160PMPlasmaOk
1102:24:33:590PMPlasmaOk
1202:48:30:970PMPlasmaBadEF 3 Aux Power Shut OFF in INIT
1303:02:16:983PMPlasmaOk
1403:24:46:100PMPlasmaOk
1503:47:16:807PMPlasmaOk
1604:10:45:267PMPlasmaOk
1704:33:20:603PMPlasmaOk
1804:55:49:720PMPlasmaOk