Alcator C-Mod Run 1000831 Information

Miniproposals

Miniproposal: 271

Date Filed: 5/12/2000

Title: Scaling of H-mode pedestal parameters with global plasma parameters

First Author: Dmitri Mossessian

Session Leader: Dmitri Mossessian (shots 1-27)

Operators
Session leader(s):	Dmitri Mossessian
Physics operator(s):	Ian Hutchinson
Engineering operator(s):	Ed Fitzgerald,Bill Cochran

Engineering Operator Run Comment
MP 271: Pedestal scalings,SL Mossessian,PO Wolf/Hutchinson,Cochran,Fitzg

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:24:727PM

Author: To Be Determined

Run summary for 1000831 - MP 271: Pedestal scalings

The idea was to complete MP271 (some results were obtained on 05/25, 06/01,
06/16 and 06/29). Previous runs gave some data on pedestal scaling with input
power and plasma current for EDA. One of the main remaining questions is whether
there is a dramatic difference between pedestal parameters in EDA and ELM-free H-modes, or
there is just a dependance on plasma current. So the goal of this run was to
obtain ELM-free H-modes at high current and perform RF power scans.
Unfortunately, RF was not at its best, plus the H/D ratio was very high during
most of the run (up to 14%). No power higher than 2 MW could be input into plasma,
and multiple trips were occurring during RF pulses higher than 1 MW.
Still, some useful results were obtained. Running at 1.2 MA, 0.9e20 m^-2 target
density produced H-modes that had ELM-free character judging by D-alpha level, rate of
impurity accumulation and density build-up. However, reflectometer shows that the 120kHz
fluctuation, which is supposed to be an EDA signature, is still there. Lowering target slightly
(to 7e19) lead to suppression of the fluctuation, and we had several H-mode that
were ELM-free according to all indicators. We then lowered the current, keeping same target
density, to observe changes in the pedestal parameters at ELM-free - EDA transition.
We also attempted to do the target density scan at const Ip, which would be the last
goal of the MP, but failed.

No dramatic difference between ELM-free and EDA pedestals was observed, but further data
analysis is necessary to make any definite conclusions.

List of useful shots with short descriptions follows:

----------------------------------------------------------------------------
1000831001 Good shot. 1.5 MW (noisy), density climbs to 3.5e20. But still EDA (according
to reflectometer).
Plasma is fine, so we'll be scanning RF for next several shots.
For shot 2 - try to get 2-1.5 MW steps.
----------------------------------------------------------------------------
1000831002 RF is not very good. H-modes are EDA (100 Khz QC fluctuations).
Repeat for better RF waveform.
-----------------------------------------------------------------------------
1000831003 One short H-mode at 2 MW level, then RF drops to below 1 MW.
Although the QC feature is still there, it's much broader and less pronounced
then before. Is it ELM-free ?
-----------------------------------------------------------------------------
1000831004 RF trips. Long H-mode, with QC feature starting at 0.8 sec, but D-alpha
level low and density accumulating constantly during H-mode (up to 4e20).
GradP_e is peaked when there is no QC feature, then going down steadily.
-----------------------------------------------------------------------------
1000831005 Current flat top starts only at .75 sec. We'll start RF later in the shot
(0.8 sec) and go to 1.4 sec with step from 1.5 to 1 MW at 1.1 sec.
The H-mode on this one started late in 1.5 MW phase, and still looks like
EDA according to reflectometer, while everything else indicates that it's ELM-free.
-----------------------------------------------------------------------------
1000831007 All H-modes look marginally ELM-free. We'll attempt to get better ELM-free
character by lowering target density to .7e20. RF will have 2 and 1.5 MW steps for next shot.
-----------------------------------------------------------------------------
1000831008 ELM-free according to reflectometer (no 100KHz feature).RF trips early.
Try have 2MW steady RF for next shot.
-----------------------------------------------------------------------------
1000831009 ELM-free according to reflectometer again. RF is not steady.
Next couple of shots - try to get better RF at 2 MW level.
-----------------------------------------------------------------------------
1000831010 Same as shot 9
-----------------------------------------------------------------------------
1000831020 RF went to lower power, but still has problems. 3 ELM-free H-modes
-----------------------------------------------------------------------------
1000831021 ELM-free H-modes, problems with RF
-----------------------------------------------------------------------------
1000831022 ELM-free H-modes, problems with RF.
Lower current for next shot to 1 MA, keeping density and RF power same.
-----------------------------------------------------------------------------
1000831023 RF has fewer trips, there is one H-mode, that look like ELM-free in terms
of impurity accumulation, density rise and D-alpha level, but has the 100 KHZ
fluctuation again.
-----------------------------------------------------------------------------
1000831024 Same as 23, but only 1 MW of RF.
Go down to 0.8 MA for next shot
-----------------------------------------------------------------------------
1000831025 Two EDA H-modes.

Physics Operator Summaries

Entered: Jul 7 2004 04:37:11:863PM

Author: To Be Determined

1000831

MP 271: Pedestal scalings

SL Mossessian
PO Wolfe/Hutchinson

Summary
_______

RF struggled today probably because of H/D ratio up to 15%. Never got
more than 2MW in mostly much less.

A 1.2 MA disruption due to runaway gas puff on shot 12 caused some
subsequent breakdown problems.

Physop stuff
____________
Got the Chopper and fast feedback going earlier. This should improve
vertical control after about 25ms. Shots 21 on have the final segment
1 configuration. Recommended for future use.

Tried for earlier diverting discharges with some success, except that shots
26-7 pushed my luck too hard and got vertical instabilities. These seemed
to be caused by EF1 voltage limits (shot 26) and EF2 current (shot 27).
Therefore a more careful approach is necessary beyond shot 24/5. Further
development should probably start with shot 24.

Wolfe reports having discovered the Rcur error in that PCS uses a different
reference center than the predictor. Still running with the much smaller
rcur offset in PCS makes the rampdowns very impressive.

Significant Bz drift occurred. It would help physop-ing if we could
prevent that.

Scorecard
_________

Shot,Duration(s),Ipmax(MA) Shot,Duration(s),Ipmax
1 1.921 1.186 2 1.925 1.194
3 1.929 1.189 4 1.929 1.194
5 1.928 1.186 6 1.928 1.178
7 1.929 1.184 8 1.938 1.189
9 1.937 1.194 10 1.938 1.189
11 0.000 0.037 12 1.515 1.168
13 0.000 0.029 14 0.000 0.032
15 0.000 0.034 16 1.515 1.179
17 1.505 1.184 18 0.000 0.039
19 1.939 1.182 20 1.937 1.186
21 1.935 1.189 22 1.935 1.186
23 1.941 0.994 24 1.939 0.992
25 1.939 0.805 26 0.248 0.787
27 0.254 0.787
Finished summary for 1000831 Total of 27 shots.
27 shots. 22 plasmas. 5 fizzles. 0 duds.

Details
________

----------------------------------------------------------------------------
1000831xxx hutch PHYSICS_OPERATOR Aug 31 2000 8:34:35:340AM
. . . . . . . . . . . . . . . . . . . .

MP 271: Pedestal scalings

SL Mossessian
PO Wolfe/Hutchinson
Run Plan:

Assuming that E and D ports are capable of putting out 2.5 - 3 MW, continue
with MP 271 - Pedestal scalings. Study H-mode pedestal parameters scalings at
high current (1.2 - 1.4 MA) varying input power. The main goal would be to
obtain pedestal data in ELM-free H-modes to compare with previous EDA measurements.

Start with 1.2 MA, 9e19 m^-2, 5.4T, 2.5 MW RF. Perform RF power scan, varying
power from shot to shot in 0.5 MW steps (from 2.5 MW to 0.5 MW). Repeat at 1.4 MA.

Overnight ECDC in Deuterium.

Cold Start. OK.
----------------------------------------------------------------------------
1000831xxx hutch PHYSICS_OPERATOR Aug 31 2000 9:03:30:670AM
. . . . . . . . . . . . . . . . . . . .
PCS setup.

Copy segment 2 to segment 4.
Raise current to 1.2MA.
TF current to -151000 A.
Load.
----------------------------------------------------------------------------
1000831001 hutch PHYSICS_OPERATOR Aug 31 2000 9:20:23:170AM
. . . . . . . . . . . . . . . . . . . .
Plasma. Long sustained H-mode. 150kJ with 1.4MW RF.

Move RCUR out by 2mm at .7s to .662 from .6602. RCUR is not
giving us what we ask for with this offset configuration.
----------------------------------------------------------------------------
1000831002 wolfe PHYSICS_OPERATOR Aug 31 2000 9:33:18:780AM
. . . . . . . . . . . . . . . . . . . .
Wolfe taking over for Ian as of shot 3.
Shot 2: 1.2 MA Plasma, full length, 2H-modes this time
RF up to 1.6MW, but one drops out.
Gap is now between 1cm after .7 sec, still swinging a bit before
that, probably due to high current gain. It jerks down to
near zero at .43 (crossover) and .53 (ip gain step)

Next shot: delay step in IP gain to .7sec
----------------------------------------------------------------------------
1000831003 wolfe PHYSICS_OPERATOR Aug 31 2000 9:42:45:733AM
. . . . . . . . . . . . . . . . . . . .
Shot 3: delay step in IP gain to .7sec to try to fix one of the position lurches
plasma, full length. 1 short (.2sec) h-mode; so far shot 1 is the best of the day.
That cured the .5sec lurch, but now it slides in, following Ian's changed demand.

Next shot: Make RCUR program flat again, except hold it in further around crossonver.
----------------------------------------------------------------------------
1000831004 wolfe PHYSICS_OPERATOR Aug 31 2000 10:02:41:763AM
. . . . . . . . . . . . . . . . . . . .
Shot 4: Make RCUR program flat again, except hold it in further around crossover.
plasma, full length, RF trip

RCUR is flatter, still a little excursion.

Ian's back, Wolfe signing off
----------------------------------------------------------------------------
1000831005 hutch PHYSICS_OPERATOR Aug 31 2000 10:30:22:076AM
. . . . . . . . . . . . . . . . . . . .
Plasma. RF 1.4 MW dropping to 1MW. 0.5s H-mode. H/D creeps up to 9%

Initial plasma is going down. Br offset to .001 from .0005T.
----------------------------------------------------------------------------
1000831006 hutch PHYSICS_OPERATOR Aug 31 2000 10:45:14:343AM
. . . . . . . . . . . . . . . . . . . .
Plasma. Initial vertical position a bit better. Breakdown a tad earlier.
No D-port power. H-mode triggered by ramp-down.

Move EFC start time to -20ms from -5ms.
----------------------------------------------------------------------------
1000831007 hutch PHYSICS_OPERATOR Aug 31 2000 11:04:45:310AM
. . . . . . . . . . . . . . . . . . . .
Plasma. Sustained H-mode. 1.5MW dropping to 1MW.
Chopper seems to do as desired.

Add an extra gain step in Ip to help it at .5s.
Chopper initiation to -30ms.
nl04 to .7e20.
Add fast zcur P=.2 at 20ms.
----------------------------------------------------------------------------
1000831008 hutch PHYSICS_OPERATOR Aug 31 2000 11:24:27:436AM
. . . . . . . . . . . . . . . . . . . .
Plasma. Ratiomatic drops to .1mtorr from .25. Divertor ~14mtorr.
Density/radiation ramp rate is higher. Closer to ELM-free.
1.8MW but many trips.
Chopper comes on earlier but is held off by the PCS programming.

Add fast ZCUR control P=.5 at 20ms.
Tweak Ip to rise faster before cross-over.
Add ECE Bt ramp at .85s-.95s
----------------------------------------------------------------------------
1000831009 hutch PHYSICS_OPERATOR Aug 31 2000 11:42:18:763AM
. . . . . . . . . . . . . . . . . . . .
Plasma. 2MW tripping to 1MW. Strong n_e accumulation.
Chopper starts at 20ms. H/D ratio still creeping up. 12%.

Fast ZCUR P to .7 at 20ms.
Start EFC-V ramp at 40ms cf 48.
Move plasma out by 1.5mm for RF coupling.
----------------------------------------------------------------------------
1000831010 hutch PHYSICS_OPERATOR Aug 31 2000 11:53:06:920AM
. . . . . . . . . . . . . . . . . . . .
Plasma. Single H-mode at 2MW, trip at 1s.

Increase Ip at .3s again.
I think my ZCUR control change reported at shot 9 was to the wrong
segment. Do it right this time. P to 0.7 at 20ms.
----------------------------------------------------------------------------
1000831011 hutch PHYSICS_OPERATOR Aug 31 2000 12:21:56:686PM
. . . . . . . . . . . . . . . . . . . .
Fizzle. Not obvious why. Breakdown is rather late.
Discover that fizzle detector was set way late.

Br to .0005T.
Chopper ramp start to 30ms. This is another previous change that
I did to the wrong segment. Oops!
----------------------------------------------------------------------------
1000831012 hutch PHYSICS_OPERATOR Aug 31 2000 12:45:56:826PM
. . . . . . . . . . . . . . . . . . . .
Plasma. Ip starts to ramp down at 1.3s.
No Thomson. GV had closed.
Other gate-valves were also closed. No nl-feedback. Gas puff continuous
throughout shot. Presumably this is a density limit shot. If only we had
some diagnostics! Z-meter reports the equivalent of nl01=2e20.

Fast Zcur D to 30ms from 38.
Chopper current ramp start at 20ms.
Increase OH1V at 200ms.
----------------------------------------------------------------------------
1000831013 hutch PHYSICS_OPERATOR Aug 31 2000 1:00:29:200PM
. . . . . . . . . . . . . . . . . . . .
Fizzle. Late breakdown at 7ms. Big C and Tangential Z-meter sigs.

Drop fill to 20ms from 23ms puff.
----------------------------------------------------------------------------
1000831014 hutch PHYSICS_OPERATOR Aug 31 2000 1:10:00:466PM
. . . . . . . . . . . . . . . . . . . .
Fizzle. Breakdown still late.

EF4 current to -1302 from -1292, 10A more negative.
Add -10V to OH2 Voltages at 5 and 7ms.
fill puff to 21ms.
----------------------------------------------------------------------------
1000831015 hutch PHYSICS_OPERATOR Aug 31 2000 1:23:59:373PM
. . . . . . . . . . . . . . . . . . . .
Fizzle. Breakdown still late. Bz still seems high

EF4 to 1310A
Further -10V to OH2 at 7ms.
----------------------------------------------------------------------------
1000831016 hutch PHYSICS_OPERATOR Aug 31 2000 1:45:43:340PM
. . . . . . . . . . . . . . . . . . . .
Plasma. Disrupts at 1.5s, not obvious why. Seems to be an internal
reconnection event (on GPC)!
No H-mode. 0.7MW RF.
Zcur fast control is now operative at 30ms.

ZCUR D to 20ms.
----------------------------------------------------------------------------
1000831017 hutch PHYSICS_OPERATOR Aug 31 2000 2:07:25:466PM
. . . . . . . . . . . . . . . . . . . .
Plasma. Disrupts at almost the same time. Still can't see why.
Small H-mode.
Bz is drifting down at initiation somewhat, but the bdwn is 5.5ms.

Further OH2V tweak negative.
Move fast magnetics later to catch it.
Reduce early fast zcur gain to reduce oscillation.
----------------------------------------------------------------------------
1000831018 hutch PHYSICS_OPERATOR Aug 31 2000 2:25:59:390PM
. . . . . . . . . . . . . . . . . . . .
Fizzle. Bz seems too negative.Magic current ratio exceeds 6 for 5ms.

ICEF4 to -1300A.
Remove the OH2 tweaks. They give too fast a current ramp.
Tweak OH1 slightly instead.
----------------------------------------------------------------------------
1000831019 hutch PHYSICS_OPERATOR Aug 31 2000 2:45:34:500PM
. . . . . . . . . . . . . . . . . . . .
Plasma. Ramps down.
Bz now slightly high. It is bouncing around. Breakdown slightly later.

No change.
----------------------------------------------------------------------------
1000831020 hutch PHYSICS_OPERATOR Aug 31 2000 3:04:28:716PM
. . . . . . . . . . . . . . . . . . . .
Plasma several H-modes at 1MW RF.

Fill puff to 22ms.
fast zcur early P to .7
Chopper ramp to 950 at 20ms.
----------------------------------------------------------------------------
1000831021 hutch PHYSICS_OPERATOR Aug 31 2000 3:27:25:763PM
. . . . . . . . . . . . . . . . . . . .
Plasma. 3 H-modes.

Make penultimate Ip gain step at .45s
----------------------------------------------------------------------------
1000831022 hutch PHYSICS_OPERATOR Aug 31 2000 3:43:07:216PM
. . . . . . . . . . . . . . . . . . . .
Plasma. 2 H-modes ~1MW RF.

Go to 1 MA.
ICEF4 to -1305A
RXL moved out 2mm during 200ms period.
----------------------------------------------------------------------------
1000831023 hutch PHYSICS_OPERATOR Aug 31 2000 4:02:06:233PM
. . . . . . . . . . . . . . . . . . . .
Plasma. 1.3 and 0.8MW. at 1MA.

Raise RXL further and up the early gain.
Move the clearin ramp 30ms earlier.
----------------------------------------------------------------------------
1000831024 hutch PHYSICS_OPERATOR Aug 31 2000 4:19:13:263PM
. . . . . . . . . . . . . . . . . . . .
Plasma. 3 H-modes. 1MW RF.
Got earlier diversion.

Move clearin ramp to .1 to 1.8s.
RXL increased some more early.
Ip to .8MA
----------------------------------------------------------------------------
1000831025 hutch PHYSICS_OPERATOR Aug 31 2000 4:40:55:496PM
. . . . . . . . . . . . . . . . . . . .
Plasma. 1.4MW H-mode

RCUR gain ramped up in first 50ms.
Rcur set to .64m at 50ms (was .62)
Increase early ZXL gain.
nl04 to 1.2e20 at .5s.
----------------------------------------------------------------------------
1000831026 hutch PHYSICS_OPERATOR Aug 31 2000 5:00:01:810PM
. . . . . . . . . . . . . . . . . . . .
Plasma. Early disruption at .23s.
EF1 demand seems to be a major part of the problem.
This is probably caused by the zxl change.

Load zxl wire from shot 25.
----------------------------------------------------------------------------
1000831027 hutch PHYSICS_OPERATOR Aug 31 2000 5:15:43:233PM
. . . . . . . . . . . . . . . . . . . .
Plasma disrupts early again at .24s. Sorry!

Session Leader Comments

Aug 31 2000 09:41:51:077AM 1000831001 Dmitri Mossessian Good shot. 1.5 MW (noisy), density climbs to 3.5e20. But still EDA (according
to reflectometer).
Plasma is fine, so we'll be scanning RF for nextseveral shots.
For shot 2 - try to get 2-1.5 MW steps.

Aug 31 2000 09:43:09:590AM 1000831002 Dmitri Mossessian RF is not very good. H-modes are EDA (100 Khz QC fluctuations).
Repeat for better RF waveform.

Aug 31 2000 09:44:51:077AM 1000831003 Dmitri Mossessian One short H-mode at 2 MW level, then RF drops to below 1 MW.
Repeat.

Aug 31 2000 10:00:11:373AM 1000831003 Dmitri Mossessian Although the QC feature is still there, it's much broader and less pronounced
then before. Is it ELM-free ?

Aug 31 2000 10:10:13:513AM 1000831004 Dmitri Mossessian RF trips. Long H-mode, with QC feature starting at 0.8 sec, but D-alpha
level low and density accumulating constantly during H-mode (up to 4e20).
GradP_e is peaked when there is no QC feature, then going down steadily.

Aug 31 2000 10:26:38:093AM 1000831005 Dmitri Mossessian Current flat top starts only at .75 sec. We'll strart RF later in the shot
(0.8 sec) and go to 1.4 sec with step from 1.5 to 1 MW at 1.1 sec.
The H-mode on this one started late in 1.5 MW phase, and still looks like
EDA according to reflectometer, while everything else indicates that it's ELM-free.

Aug 31 2000 10:59:31:000AM 1000831007 Dmitri Mossessian All H-modes look marginally ELM-free. We'll attempt to get better ELM-free
character by lowering target density to .7e20. RF will have 2 and 1.5 MW steps for next shot.

Aug 31 2000 11:21:50:733AM 1000831008 Dmitri Mossessian ELM-free according to reflectometer (no 100KHz feature).RF trips early.
Try have 2MW steady RF for next shot.

Aug 31 2000 11:56:39:250AM 1000831009 Dmitri Mossessian ELM-free according to reflectometer again. RF is not steady.
Next couple of shots - try to get better RF at 2 MW level.

Aug 31 2000 02:34:05:530PM 1000831010 Dmitri Mossessian Same as shot 9

Aug 31 2000 02:59:47:903PM 1000831020 Dmitri Mossessian RF went to lower power, but still has problems. 3 ELM-free H-modes

Aug 31 2000 03:29:35:450PM 1000831021 Dmitri Mossessian ELM-free H-modes, problems with RF

Aug 31 2000 03:30:06:043PM 1000831022 Dmitri Mossessian ELM-free H-modes, problems with RF.
Lower current for next shot to 1 MA, keeping density and RF power same.

Aug 31 2000 04:04:21:450PM 1000831023 Dmitri Mossessian RF has fewer trips, there is one H-mode, that look like ELM-free in terms
of imputrity accumulation, density rise and D-alpha level, but has the 100 KHZ
fluctuation again.

Aug 31 2000 04:10:56:750PM 1000831024 Dmitri Mossessian Sama as 23, but only 1 MW of RF.
Go down to 0.8 MA for next shot

Aug 31 2000 04:25:32:280PM 1000831025 Dmitri Mossessian Two EDA H-modes.
Go to higher density for next shot, same Ip

Physics Operator Comments

Aug 31 2000 08:34:35:340AM Ian Hutchinson
MP 271: Pedestal scalings

SL Mossessian
PO Wolfe/Hutchinson
Run Plan:

Assuming that E and D ports are capable of putting out 2.5 - 3 MW, continue
with MP 271 - Pedestal scalings. Study H-mode pedestal parameters scalings at
high current (1.2 - 1.4 MA) varying input power. The main goal would be to
obtain pedestal data in ELM-free H-modes to compare with previous EDA measurements.

Start with 1.2 MA, 9e19 m^-2, 5.4T, 2.5 MW RF. Perform RF power scan, varying
power from shot to shot in 0.5 MW steps (from 2.5 MW to 0.5 MW). Repeat at 1.4 MA.

Overnight ECDC in Deuterium.

Cold Start. OK.

Aug 31 2000 09:03:30:670AM Ian Hutchinson PCS setup.

Copy segment 2 to segment 4.
Raise current to 1.2MA.
TF current to -151000 A.
Load.

Aug 31 2000 09:20:23:170AM 1000831001 Ian Hutchinson Plasma. Long sustained H-mode. 150kJ with 1.4MW RF.

Move RCUR out by 2mm at .7s to .662 from .6602. RCUR is not
giving us what we ask for with this offset configuration.

Aug 31 2000 09:33:18:780AM 1000831002 Steve Wolfe Wolfe taking over for Ian as of shot 3.
Shot 2: 1.2 MA Plasma, full length, 2H-modes this time
RF up to 1.6MW, but one drops out.
Gap is now between 1cm after .7 sec, still swinging a bit before
that, probably due to high current gain. It jerks down to
near zero at .43 (crossover) and .53 (ip gain step)

Next shot: delay step in IP gain to .7sec

Aug 31 2000 09:42:45:733AM 1000831003 Steve Wolfe Shot 3: delay step in IP gain to .7sec to try to fix one of the position lurches
plasma, full length. 1 short (.2sec) h-mode; so far shot 1 is the best of the day.
That cured the .5sec lurch, but now it slides in, following Ian's changed demand.

Next shot: Make RCUR program flat again, except hold it in further around crossonver.

Aug 31 2000 10:02:41:763AM 1000831004 Steve Wolfe Shot 4: Make RCUR program flat again, except hold it in further around crossover.
plasma, full length, RF trip

RCUR is flatter, still a little excursion.

Ian's back, Wolfe signing off

Aug 31 2000 10:30:22:077AM 1000831005 Ian Hutchinson Plasma. RF 1.4 MW dropping to 1MW. 0.5s H-mode. H/D creeps up to 9%

Initial plasma is going down. Br offset to .001 from .0005T.

Aug 31 2000 10:45:14:343AM 1000831006 Ian Hutchinson Plasma. Initial vertical position a bit better. Breakdown a tad earlier.
No D-port power. H-mode triggered by ramp-down.

Move EFC start time to -20ms from -5ms.

Aug 31 2000 11:04:45:310AM 1000831007 Ian Hutchinson Plasma. Sustained H-mode. 1.5MW dropping to 1MW.
Chopper seems to do as desired.

Add an extra gain step in Ip to help it at .5s.
Chopper initiation to -30ms.
nl04 to .7e20.
Add fast zcur P=.2 at 20ms.

Aug 31 2000 11:24:27:437AM 1000831008 Ian Hutchinson Plasma. Ratiomatic drops to .1mtorr from .25. Divertor ~14mtorr.
Density/radiation ramp rate is higher. Closer to ELM-free.
1.8MW but many trips.
Chopper comes on earlier but is held off by the PCS programming.

Add fast ZCUR control P=.5 at 20ms.
Tweak Ip to rise faster before cross-over.
Add ECE Bt ramp at .85s-.95s

Aug 31 2000 11:42:18:763AM 1000831009 Ian Hutchinson Plasma. 2MW tripping to 1MW. Strong n_e accumulation.
Chopper starts at 20ms. H/D ratio still creeping up. 12%.

Fast ZCUR P to .7 at 20ms.
Start EFC-V ramp at 40ms cf 48.
Move plasma out by 1.5mm for RF coupling.

Aug 31 2000 11:53:06:920AM 1000831010 Ian Hutchinson Plasma. Single H-mode at 2MW, trip at 1s.

Increase Ip at .3s again.
I think my ZCUR control change reported at shot 9 was to the wrong
segment. Do it right this time. P to 0.7 at 20ms.

Aug 31 2000 12:21:56:687PM 1000831011 Ian Hutchinson Fizzle. Not obvious why. Breakdown is rather late.
Discover that fizzle detector was set way late.

Br to .0005T.
Chopper ramp start to 30ms. This is another previous change that
I did to the wrong segment. Oops!

Aug 31 2000 12:45:56:827PM 1000831012 Ian Hutchinson Plasma. Ip starts to ramp down at 1.3s.
No Thomson. GV had closed.
Other gate-valves were also closed. No nl-feedback. Gas puff continuous
throughout shot. Presumably this is a density limit shot. If only we had
some diagnostics! Z-meter reports the equivalent of nl01=2e20.

Fast Zcur D to 30ms from 38.
Chopper current ramp start at 20ms.
Increase OH1V at 200ms.

Aug 31 2000 01:00:29:200PM 1000831013 Ian Hutchinson Fizzle. Late breakdown at 7ms. Big C and Tangential Z-meter sigs.

Drop fill to 20ms from 23ms puff.

Aug 31 2000 01:10:00:467PM 1000831014 Ian Hutchinson Fizzle. Breakdown still late.

EF4 current to -1302 from -1292, 10A more negative.
Add -10V to OH2 Voltages at 5 and 7ms.
fill puff to 21ms.

Aug 31 2000 01:23:59:373PM 1000831015 Ian Hutchinson Fizzle. Breakdown still late. Bz still seems high

EF4 to 1310A
Further -10V to OH2 at 7ms.

Aug 31 2000 01:45:43:340PM 1000831016 Ian Hutchinson Plasma. Disrupts at 1.5s, not obvious why. Seems to be an internal
reconnection event (on GPC)!
No H-mode. 0.7MW RF.
Zcur fast control is now operative at 30ms.

ZCUR D to 20ms.

Aug 31 2000 02:07:25:467PM 1000831017 Ian Hutchinson Plasma. Disrupts at almost the same time. Still can't see why.
Small H-mode.
Bz is drifting down at initiation somewhat, but the bdwn is 5.5ms.

Further OH2V tweak negative.
Move fast magnetics later to catch it.
Reduce early fast zcur gain to reduce oscillation.

Aug 31 2000 02:25:59:390PM 1000831018 Ian Hutchinson Fizzle. Bz seems too negative.Magic current ratio exceeds 6 for 5ms.

ICEF4 to -1300A.
Remove the OH2 tweaks. They give too fast a current ramp.
Tweak OH1 slightly instead.

Aug 31 2000 02:45:34:500PM 1000831019 Ian Hutchinson Plasma. Ramps down.
Bz now slightly high. It is bouncing around. Breakdown slightly later.

No change.

Aug 31 2000 03:04:28:717PM 1000831020 Ian Hutchinson Plasma several H-modes at 1MW RF.

Fill puff to 22ms.
fast zcur early P to .7
Chopper ramp to 950 at 20ms.

Aug 31 2000 03:27:25:763PM 1000831021 Ian Hutchinson Plasma. 3 H-modes.

Make penultimate Ip gain step at .45s

Aug 31 2000 03:43:07:217PM 1000831022 Ian Hutchinson Plasma. 2 H-modes ~1MW RF.

Go to 1 MA.
ICEF4 to -1305A
RXL moved out 2mm during 200ms period.

Aug 31 2000 04:02:06:233PM 1000831023 Ian Hutchinson Plasma. 1.3 and 0.8MW. at 1MA.

Raise RXL further and up the early gain.
Move the clearin ramp 30ms earlier.

Aug 31 2000 04:19:13:263PM 1000831024 Ian Hutchinson Plasma. 3 H-modes. 1MW RF.
Got earlier diversion.

Move clearin ramp to .1 to 1.8s.
RXL increased some more early.
Ip to .8MA

Aug 31 2000 04:40:55:497PM 1000831025 Ian Hutchinson Plasma. 1.4MW H-mode

RCUR gain ramped up in first 50ms.
Rcur set to .64m at 50ms (was .62)
Increase early ZXL gain.
nl04 to 1.2e20 at .5s.

Aug 31 2000 05:00:01:810PM 1000831026 Ian Hutchinson Plasma. Early disruption at .23s.
EF1 demand seems to be a major part of the problem.
This is probably caused by the zxl change.

Load zxl wire from shot 25.

Aug 31 2000 05:15:43:233PM 1000831027 Ian Hutchinson Plasma disrupts early again at .24s. Sorry!

Engineering Operator Comments

Shot Time Type Status Comment

1 09:01:58:217AM Plasma Ok

2 09:20:25:483AM Plasma Ok

3 09:35:06:343AM Plasma Ok

4 09:55:58:373AM Plasma Ok

5 10:10:16:047AM Plasma Ok

6 10:28:28:967AM Plasma Ok

7 10:44:31:717AM Plasma Ok

8 11:03:08:047AM Plasma Ok

9 11:22:15:607AM Plasma Ok

10 11:39:43:110AM Plasma Ok

11 12:00:30:920PM Plasma Ok

12 12:20:24:890PM Plasma Ok

13 12:40:32:310PM Plasma Ok

14 12:54:46:640PM Plasma Ok

15 01:08:26:797PM Plasma Ok

16 01:22:34:890PM Plasma Ok

17 01:44:24:873PM Plasma Ok

18 02:05:38:107PM Plasma Ok

19 02:24:17:747PM Plasma Ok

20 02:40:18:687PM Plasma Ok

21 03:03:03:500PM Plasma Ok

22 03:22:28:700PM Plasma Ok

23 03:40:37:437PM Plasma Ok

24 04:00:37:170PM Plasma Ok

25 04:18:46:437PM Plasma Ok

26 04:39:33:593PM Plasma Ok

27 04:57:07:937PM Plasma Ok

Session Leader Comments
Aug 31 2000 09:41:51:077AM	1000831001	Dmitri Mossessian	Good shot. 1.5 MW (noisy), density climbs to 3.5e20. But still EDA (according to reflectometer). Plasma is fine, so we'll be scanning RF for nextseveral shots. For shot 2 - try to get 2-1.5 MW steps.
Aug 31 2000 09:43:09:590AM	1000831002	Dmitri Mossessian	RF is not very good. H-modes are EDA (100 Khz QC fluctuations). Repeat for better RF waveform.
Aug 31 2000 09:44:51:077AM	1000831003	Dmitri Mossessian	One short H-mode at 2 MW level, then RF drops to below 1 MW. Repeat.
Aug 31 2000 10:00:11:373AM	1000831003	Dmitri Mossessian	Although the QC feature is still there, it's much broader and less pronounced then before. Is it ELM-free ?
Aug 31 2000 10:10:13:513AM	1000831004	Dmitri Mossessian	RF trips. Long H-mode, with QC feature starting at 0.8 sec, but D-alpha level low and density accumulating constantly during H-mode (up to 4e20). GradP_e is peaked when there is no QC feature, then going down steadily.
Aug 31 2000 10:26:38:093AM	1000831005	Dmitri Mossessian	Current flat top starts only at .75 sec. We'll strart RF later in the shot (0.8 sec) and go to 1.4 sec with step from 1.5 to 1 MW at 1.1 sec. The H-mode on this one started late in 1.5 MW phase, and still looks like EDA according to reflectometer, while everything else indicates that it's ELM-free.
Aug 31 2000 10:59:31:000AM	1000831007	Dmitri Mossessian	All H-modes look marginally ELM-free. We'll attempt to get better ELM-free character by lowering target density to .7e20. RF will have 2 and 1.5 MW steps for next shot.
Aug 31 2000 11:21:50:733AM	1000831008	Dmitri Mossessian	ELM-free according to reflectometer (no 100KHz feature).RF trips early. Try have 2MW steady RF for next shot.
Aug 31 2000 11:56:39:250AM	1000831009	Dmitri Mossessian	ELM-free according to reflectometer again. RF is not steady. Next couple of shots - try to get better RF at 2 MW level.
Aug 31 2000 02:34:05:530PM	1000831010	Dmitri Mossessian	Same as shot 9
Aug 31 2000 02:59:47:903PM	1000831020	Dmitri Mossessian	RF went to lower power, but still has problems. 3 ELM-free H-modes
Aug 31 2000 03:29:35:450PM	1000831021	Dmitri Mossessian	ELM-free H-modes, problems with RF
Aug 31 2000 03:30:06:043PM	1000831022	Dmitri Mossessian	ELM-free H-modes, problems with RF. Lower current for next shot to 1 MA, keeping density and RF power same.
Aug 31 2000 04:04:21:450PM	1000831023	Dmitri Mossessian	RF has fewer trips, there is one H-mode, that look like ELM-free in terms of imputrity accumulation, density rise and D-alpha level, but has the 100 KHZ fluctuation again.
Aug 31 2000 04:10:56:750PM	1000831024	Dmitri Mossessian	Sama as 23, but only 1 MW of RF. Go down to 0.8 MA for next shot
Aug 31 2000 04:25:32:280PM	1000831025	Dmitri Mossessian	Two EDA H-modes. Go to higher density for next shot, same Ip

Physics Operator Comments
Aug 31 2000 08:34:35:340AM		Ian Hutchinson	MP 271: Pedestal scalings SL Mossessian PO Wolfe/Hutchinson Run Plan: Assuming that E and D ports are capable of putting out 2.5 - 3 MW, continue with MP 271 - Pedestal scalings. Study H-mode pedestal parameters scalings at high current (1.2 - 1.4 MA) varying input power. The main goal would be to obtain pedestal data in ELM-free H-modes to compare with previous EDA measurements. Start with 1.2 MA, 9e19 m^-2, 5.4T, 2.5 MW RF. Perform RF power scan, varying power from shot to shot in 0.5 MW steps (from 2.5 MW to 0.5 MW). Repeat at 1.4 MA. Overnight ECDC in Deuterium. Cold Start. OK.
Aug 31 2000 09:03:30:670AM		Ian Hutchinson	PCS setup. Copy segment 2 to segment 4. Raise current to 1.2MA. TF current to -151000 A. Load.
Aug 31 2000 09:20:23:170AM	1000831001	Ian Hutchinson	Plasma. Long sustained H-mode. 150kJ with 1.4MW RF. Move RCUR out by 2mm at .7s to .662 from .6602. RCUR is not giving us what we ask for with this offset configuration.
Aug 31 2000 09:33:18:780AM	1000831002	Steve Wolfe	Wolfe taking over for Ian as of shot 3. Shot 2: 1.2 MA Plasma, full length, 2H-modes this time RF up to 1.6MW, but one drops out. Gap is now between 1cm after .7 sec, still swinging a bit before that, probably due to high current gain. It jerks down to near zero at .43 (crossover) and .53 (ip gain step) Next shot: delay step in IP gain to .7sec
Aug 31 2000 09:42:45:733AM	1000831003	Steve Wolfe	Shot 3: delay step in IP gain to .7sec to try to fix one of the position lurches plasma, full length. 1 short (.2sec) h-mode; so far shot 1 is the best of the day. That cured the .5sec lurch, but now it slides in, following Ian's changed demand. Next shot: Make RCUR program flat again, except hold it in further around crossonver.
Aug 31 2000 10:02:41:763AM	1000831004	Steve Wolfe	Shot 4: Make RCUR program flat again, except hold it in further around crossover. plasma, full length, RF trip RCUR is flatter, still a little excursion. Ian's back, Wolfe signing off
Aug 31 2000 10:30:22:077AM	1000831005	Ian Hutchinson	Plasma. RF 1.4 MW dropping to 1MW. 0.5s H-mode. H/D creeps up to 9% Initial plasma is going down. Br offset to .001 from .0005T.
Aug 31 2000 10:45:14:343AM	1000831006	Ian Hutchinson	Plasma. Initial vertical position a bit better. Breakdown a tad earlier. No D-port power. H-mode triggered by ramp-down. Move EFC start time to -20ms from -5ms.
Aug 31 2000 11:04:45:310AM	1000831007	Ian Hutchinson	Plasma. Sustained H-mode. 1.5MW dropping to 1MW. Chopper seems to do as desired. Add an extra gain step in Ip to help it at .5s. Chopper initiation to -30ms. nl04 to .7e20. Add fast zcur P=.2 at 20ms.
Aug 31 2000 11:24:27:437AM	1000831008	Ian Hutchinson	Plasma. Ratiomatic drops to .1mtorr from .25. Divertor ~14mtorr. Density/radiation ramp rate is higher. Closer to ELM-free. 1.8MW but many trips. Chopper comes on earlier but is held off by the PCS programming. Add fast ZCUR control P=.5 at 20ms. Tweak Ip to rise faster before cross-over. Add ECE Bt ramp at .85s-.95s
Aug 31 2000 11:42:18:763AM	1000831009	Ian Hutchinson	Plasma. 2MW tripping to 1MW. Strong n_e accumulation. Chopper starts at 20ms. H/D ratio still creeping up. 12%. Fast ZCUR P to .7 at 20ms. Start EFC-V ramp at 40ms cf 48. Move plasma out by 1.5mm for RF coupling.
Aug 31 2000 11:53:06:920AM	1000831010	Ian Hutchinson	Plasma. Single H-mode at 2MW, trip at 1s. Increase Ip at .3s again. I think my ZCUR control change reported at shot 9 was to the wrong segment. Do it right this time. P to 0.7 at 20ms.
Aug 31 2000 12:21:56:687PM	1000831011	Ian Hutchinson	Fizzle. Not obvious why. Breakdown is rather late. Discover that fizzle detector was set way late. Br to .0005T. Chopper ramp start to 30ms. This is another previous change that I did to the wrong segment. Oops!
Aug 31 2000 12:45:56:827PM	1000831012	Ian Hutchinson	Plasma. Ip starts to ramp down at 1.3s. No Thomson. GV had closed. Other gate-valves were also closed. No nl-feedback. Gas puff continuous throughout shot. Presumably this is a density limit shot. If only we had some diagnostics! Z-meter reports the equivalent of nl01=2e20. Fast Zcur D to 30ms from 38. Chopper current ramp start at 20ms. Increase OH1V at 200ms.
Aug 31 2000 01:00:29:200PM	1000831013	Ian Hutchinson	Fizzle. Late breakdown at 7ms. Big C and Tangential Z-meter sigs. Drop fill to 20ms from 23ms puff.
Aug 31 2000 01:10:00:467PM	1000831014	Ian Hutchinson	Fizzle. Breakdown still late. EF4 current to -1302 from -1292, 10A more negative. Add -10V to OH2 Voltages at 5 and 7ms. fill puff to 21ms.
Aug 31 2000 01:23:59:373PM	1000831015	Ian Hutchinson	Fizzle. Breakdown still late. Bz still seems high EF4 to 1310A Further -10V to OH2 at 7ms.
Aug 31 2000 01:45:43:340PM	1000831016	Ian Hutchinson	Plasma. Disrupts at 1.5s, not obvious why. Seems to be an internal reconnection event (on GPC)! No H-mode. 0.7MW RF. Zcur fast control is now operative at 30ms. ZCUR D to 20ms.
Aug 31 2000 02:07:25:467PM	1000831017	Ian Hutchinson	Plasma. Disrupts at almost the same time. Still can't see why. Small H-mode. Bz is drifting down at initiation somewhat, but the bdwn is 5.5ms. Further OH2V tweak negative. Move fast magnetics later to catch it. Reduce early fast zcur gain to reduce oscillation.
Aug 31 2000 02:25:59:390PM	1000831018	Ian Hutchinson	Fizzle. Bz seems too negative.Magic current ratio exceeds 6 for 5ms. ICEF4 to -1300A. Remove the OH2 tweaks. They give too fast a current ramp. Tweak OH1 slightly instead.
Aug 31 2000 02:45:34:500PM	1000831019	Ian Hutchinson	Plasma. Ramps down. Bz now slightly high. It is bouncing around. Breakdown slightly later. No change.
Aug 31 2000 03:04:28:717PM	1000831020	Ian Hutchinson	Plasma several H-modes at 1MW RF. Fill puff to 22ms. fast zcur early P to .7 Chopper ramp to 950 at 20ms.
Aug 31 2000 03:27:25:763PM	1000831021	Ian Hutchinson	Plasma. 3 H-modes. Make penultimate Ip gain step at .45s
Aug 31 2000 03:43:07:217PM	1000831022	Ian Hutchinson	Plasma. 2 H-modes ~1MW RF. Go to 1 MA. ICEF4 to -1305A RXL moved out 2mm during 200ms period.
Aug 31 2000 04:02:06:233PM	1000831023	Ian Hutchinson	Plasma. 1.3 and 0.8MW. at 1MA. Raise RXL further and up the early gain. Move the clearin ramp 30ms earlier.
Aug 31 2000 04:19:13:263PM	1000831024	Ian Hutchinson	Plasma. 3 H-modes. 1MW RF. Got earlier diversion. Move clearin ramp to .1 to 1.8s. RXL increased some more early. Ip to .8MA
Aug 31 2000 04:40:55:497PM	1000831025	Ian Hutchinson	Plasma. 1.4MW H-mode RCUR gain ramped up in first 50ms. Rcur set to .64m at 50ms (was .62) Increase early ZXL gain. nl04 to 1.2e20 at .5s.
Aug 31 2000 05:00:01:810PM	1000831026	Ian Hutchinson	Plasma. Early disruption at .23s. EF1 demand seems to be a major part of the problem. This is probably caused by the zxl change. Load zxl wire from shot 25.
Aug 31 2000 05:15:43:233PM	1000831027	Ian Hutchinson	Plasma disrupts early again at .24s. Sorry!

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	09:01:58:217AM	Plasma	Ok
2	09:20:25:483AM	Plasma	Ok
3	09:35:06:343AM	Plasma	Ok
4	09:55:58:373AM	Plasma	Ok
5	10:10:16:047AM	Plasma	Ok
6	10:28:28:967AM	Plasma	Ok
7	10:44:31:717AM	Plasma	Ok
8	11:03:08:047AM	Plasma	Ok
9	11:22:15:607AM	Plasma	Ok
10	11:39:43:110AM	Plasma	Ok
11	12:00:30:920PM	Plasma	Ok
12	12:20:24:890PM	Plasma	Ok
13	12:40:32:310PM	Plasma	Ok
14	12:54:46:640PM	Plasma	Ok
15	01:08:26:797PM	Plasma	Ok
16	01:22:34:890PM	Plasma	Ok
17	01:44:24:873PM	Plasma	Ok
18	02:05:38:107PM	Plasma	Ok
19	02:24:17:747PM	Plasma	Ok
20	02:40:18:687PM	Plasma	Ok
21	03:03:03:500PM	Plasma	Ok
22	03:22:28:700PM	Plasma	Ok
23	03:40:37:437PM	Plasma	Ok
24	04:00:37:170PM	Plasma	Ok
25	04:18:46:437PM	Plasma	Ok
26	04:39:33:593PM	Plasma	Ok
27	04:57:07:937PM	Plasma	Ok