Alcator C-Mod Run 1040123 Information

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Miniproposals
Miniproposal:375
Date Filed:11/25/2003
Title:Rotation and H-mode Threshold vs. SSEP
First Author:John Rice
Session Leader:John Rice (shots 1-35)

Operators
Session leader(s):John Rice
Physics operator(s):Steve Wolfe
Engineering operator(s):Ed Fitzgerald,Gary Dekow,Bill Byford

Engineering Operator Run Comment
MP#375 Rotation and threshold vs SSEP; SL:Rice; PO:Wolfe; EO:Dekow/Byfor

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:02:430PM
Author: John Rice
Session Leader Run Summary for 1040123 MP375 Rotation and H-mode Threshold vs SSEP

The first part of the run was achieved: the variation of the ambient L-mode rotation
velocity was determined as a function of SSEP, in 2 mm steps. There is a very abrupt
change in the core rotation velocity, going from about -18 km/s with an SSEP of -3 mm to
-38 km/s with an SSEP of +1 mm. The trend of the rotation in the SOL is awaiting further
analysis. This suggests that care should be taken about what one considers to be truly
Double Null. The second part of the run, to determine the H-mode power threshold for the
same discharges, was not achieved because the ICRF power level was limited to 3 MW since
the J-port transmitter was out of service. This was not enough to induce H-mode
with SSEP greater than +2 mm.


Physics Operator Summaries
Entered: Jul 7 2004 04:36:48:693PM
Author: Steve Wolfe
Physics Operator Summary for Friday, Jan 23, 2004

MP#375 Rotation and threshold vs SSEP
SL: Rice
PO: Wolfe
EO: Dekow,Fitzgerald,Byford

ECDC Overnight in D2, stopping by 07:00
60C Bake (optional, check with Irby and/or Bill Burke)

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

Engineering setup
-----------------

Power Systems as on 1031125008

Gas System 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 as is Hybrid DISABLED (PG2)
fill C-side with 30 psi D2 Hybrid enabled (PG3)
fill NINJA (lower cap) with 6psi Helium

Gate valve permissives for the usual suspectsd (ECE,VUV,DNB) assuming no
vacuum problems


RF: Transmitters #1 and 2 in RUN-ON by 08:00

PCS Setup:
Seg 1: from 1040122???
Seg 2: from 1031125008 (on for shot 1)
Seg 4: from 1031125018 (off for shot 1), change TF to 150000 (B=5.4)
put a dummy clearin on wire9
referencing the upper null to check offset,etc.

Run Plan
---------
For all shots, RF program ramp from 0 to 3.0MW (or max available) between 0.9
and 1.5 sec.

Start with 800kA LSN as on 1031125008 (2 shots)

Switch to seg4 to run near DN like 1031125018 and adjust gaps per
LaBombard, Hughes (? shots)

Scan SSEP from -.01m to +.01m in 1mm steps (21 shots). Try to keep gaps
constant by changing to upper xpoint reference on clearin once we get to
SSEP>0.


----------------------------------------------------------------------------
Results:

We ended up getting a pretty good scan of SSEP, though not quite at the
resolution called for in the MP. The RF was limited to 3MW max, and this
turned out to be insufficient to get H-modes in the solidly upper null part of
the scan. John and Brian did get good data on the rotation in the core and SOL
over the whole range, with some pretty good statistics.

Once again, control with SSEP proved to be somewhat problematic, in this case,
when we started trying to use positive values. As in previous runs, once the
plasmas became upper null the CLEARIN control was lost. I attempted to improve
this by changing the xpoint reference of CLEARIN to zxa=+.395. This worked
close to DN, with an offset of 9000 (rather than 12700 for zxa=-.395), but at
larger positive SSEP>.005 or so, the ZXU position had moved so far down that
the gap control was again lost, and control of SSEP was poor. The problem
seems to be that the SSEP controller is essentially controlling ZXU, but for
SSEP>0 it would be better to control ZXL. A more symmetric control scheme
would be preferable, with both ZXL and ZXU gains turned down and the SSEP
controller allowed to vary both.

An attempt to change the SSEP controller to move ZXL in place of ZXU led to an
early disruption (#28).

Finally, to get values of SSEP>.008m we went to an upper null equilibrium from
1031125030 in segment 3 (#29), and varied ZXL between -.04 and -.02. To avoid
a disruption which may have been caused by touching the nose, the RXL value
was moved from -.01 to 0.

A final beam-into-gas shot was taken (#34) after 5:00PM to allow the MSE to
evaluate their system response to unpolarized light.

I reduced the gas a few times to try to get rid of post-disruption
fizzles. PG4 started the day at 18ms and ended up at 14ms. No other startup
changes were made. I also tweaked the early current in seg 3 and 4 to try to
get rid of some turnaround effects (programmed ip
Scorecard
----------

tests 1 (beam-into-gas)
duds 0
fizzles 4
plasmas 29 (1 early disruption)
======= ==
shots 34



Session Leader Comments

Physics Operator Comments
Jan 23 2004 07:10:36:373AMSteve WolfeSetting up for run 1030123
MP#375 Rotation and threshold vs SSEP
SL: Rice
PO: Wolfe

PCS setup:
loadfrom 1031125008
import seg1 from 1040122018 (.8MA, SNL)
import seg4 from 1031125018 (.8MA, SSEP control)
change tf from -147500 to -150000
copy wire 9 from wire 4 (clearin) and
turn off gains
call alg with zxa=.395; factor is 2.3e-5
call controller alg with zxa=.395, get rate 3.1688, common rate=3.
build seg4: get a factor page for ic_ef4u
load/clean - no warnings

Filling in configuration /12-NOV-2003 08:00:23.00/
Cleaning PCS tree in /home/wolfe/pcs_scratch
about to ask alcdata to copy /home/wolfe/pcs_scratch/pcs_model to /cmod/trees/models/pcs/pcs_model
Load at 23-Jan-2004 07:10:00.00
Open tree /home/wolfe/pcs_scratch -1
Open tree done


Jan 23 2004 07:17:35:920AMSteve WolfeRun Plan:
---------

For all shots, RF program ramp from 0 to 3.0MW (or max available) between 0.9
and 1.5 sec.

Start with 800kA LSN as on 1031125008 (2 shots)

Switch to seg4 to run near DN like 1031125018 and adjust gaps per
LaBombard, Hughes (? shots)

Scan SSEP from -.01m to +.01m in 1mm steps (21 shots). Try to keep gaps
constant by changing to upper xpoint reference on clearin once we get to
SSEP>0.


Jan 23 2004 09:10:05:873AM1040123001Steve Wolfeshot#1: Seg2 from 1021125008 (snl 800kA, 8e19); rf ramp starting at 0.9sec
plasma full length. No signals on the bus rogowski's. EFIT will fail.

Run EFIT manually, but results will be suspect anyway.
There is a big injection around .12sec, almost kills it.

next shot: repeat, with the probe (and hopefully bus rogs)
Jan 23 2004 09:29:46:203AM1040123002Steve Wolfeshot#2: Repeat with the scanning probe
drop seg 1 field to 150000 (was left at 5.6T from yesterday)

fizzle. Huge CII signal. Gas is way up. NO obvious reason.

next shot: tweak gas, lower TF to 149 in seg1,2,4 (it's coming out 5.46
Jan 23 2004 09:55:37:277AM1040123003Steve Wolfeshot#3: pg4 from 18msec to 15ms, lower TF to 149kA in seg1,2,4
plasma, probe, hmode; Bt=5.43T
looks good to me.

next shot: go to DN (seg4)
Jan 23 2004 10:15:07:747AM1040123004Steve Wolfeshot#4: go to DN (seg4 should look like 1031125018)
plasma full length, h-mode at 1.3sec, ssep about -1mm
the upper null referenced clearin is reading 6000 lower than the normal one.
try putting the offset at 6000?

next shot: raise zcur 2mm for jwhughes
Jan 23 2004 10:27:51:950AM1040123005Steve Wolfeshot#5: raise zcur from -.01 to -.008
plasma full length, hmodce at 1.28sec, ssep -1mm->0
clearin signals agree, so the right offset for zxa=.395 is +6000
compared to 12,700 for the normal zxa.

next shot: decrease ssep by .01m
Jan 23 2004 10:42:03:740AM1040123006Steve Wolfeshot#6: decrease ssep by .01m to [-.011,-.012]
plasma, disrupts at 1.67sec. tci feedback screwed up. No h-mode
no d-port. ssep=-1.4cm according to efit.
upper clearin ref is -11600 from nominal for this ssep.

next shot: repeat, try for correct density

Jan 23 2004 11:00:57:307AM1040123007Steve Wolfeshot#7: repeat, try for correct density
disruption at 1.17sec. looks like abn injection?

try again

Jan 23 2004 11:09:06:333AM1040123008Steve Wolfeshot#8: repeat
plasma, full length, hmode at 1.22sec


next shot: ssep up 2mm
Jan 23 2004 11:24:11:443AM1040123009Steve Wolfeshot#9: ssep up 2mm to [-.009,-.010]

plasma full length, hmode at 1.29sec,ssep=-1cm

next shot: decrease clearin by 2mm at .65sec, increase ssep by 2mm
Jan 23 2004 11:40:54:803AM1040123010Steve Wolfeshot#10: decrease clearin by 2mm , to -.002 early,rcur by 1mm to .656,.655,
increase ssep by 2mm to [-.007,-.008]

plasma, full length, hmode at 1.25sec
ssep is still at -1cm? Looks like the ssep didn't change.
I think it's because I have another ssep on wire 12, and it found the wrong one?

next shot: SSEP to [-.007,-.008] and zero wire 12 so I don't get confused.
Jan 23 2004 11:54:04:637AM1040123011Steve Wolfeshot#11: SSEP to [-.007,-.008] and zero wire 12 so I don't get confused.
plasma full length, hmode at 1.24sec, ssep=-8mm.

next shot: ssep another 2mm positive
Jan 23 2004 12:14:28:270PM1040123012Steve Wolfeshot#12: SSEP to [-.005,-.006]
plasma full length, hmode at 1.30sec, ssep=-5.5mm
wire 9 clearin is now at -5500 below wire 4 value (phys aout)

next shot: another 2mm on SSEP
Jan 23 2004 12:22:45:330PM1040123013Steve Wolfeshot#13: SSEP to [-.003,-.004]
plasma full length, hmode at 1.23sec, ssep=-3.5mm

next shot: increase Ip program at 0.1sec, ssep back to [-.001,-.002]
Jan 23 2004 12:38:31:253PM1040123014Steve Wolfeshot#14: increase Ip program at 0.1sec, ssep back to [-.001,-.002]
plasma full length, hmode at 1.20sec, ssep=-1mm.
clearin errors match again.

next shot: another 2mm on ssep, should go positive.
Jan 23 2004 12:53:33:273PM1040123015Steve Wolfeshot#15:ssep to [.001,0]; no change to clearin yet.
plasma full length, hmode at 1.34sec, ssep=+2mm
Gap grew by 2mm

next shot: change clearin alg to use zxa=+.395
Jan 23 2004 01:12:09:940PM1040123016Steve Wolfeshot#16:change clearin alg to use zxa=+.395, offset=6000 in predictor.
ssep still at [.001,0.]; this may have a problem from .1 to .3sec

plasma full length, hmode at 1.31sec, ssep=1.5 to 2mm
Gaps look about the same as last time. The two clearin's differ by
3000, although the program and offset are the same. The difference
must be in the hybrid internal offsets. I think that means I should
change the offset to 9000.

next shot: change offset to 9000
Jan 23 2004 01:25:24:813PM1040123017Steve Wolfeshot#17:change clearin alg to use zxa=+.395, offset=9000 in predictor.
ssep still at [.001,0.]

disrupted at 1.4sec, hmode at 1.25sec, left gap over 2cm; wrong way.
No, the offset seems to have gone to zero, not to 9000.
the wire 12 error is now 9000 greater than wire 4?
It looks like it didn't take the change and put in zero instead.

next shot: offset on clearin to 9000
Jan 23 2004 01:34:47:733PM1040123018Steve Wolfeshot#18:change clearin alg to use zxa=+.395, offset=9000 in predictor.
and check it this time. ssep still at [.001,0.]

plasma full length,hmode at 1.32sec, ssep=.2cm, leftgap=1.3cm

next shot: ssep up another 2mm
Jan 23 2004 01:48:41:677PM1040123019Steve Wolfeshot#19: ssep to [.003,.002]

plasma to 1.6sec, tci feedback died again.
over gassed it again. SSEP didn't seem to change; did I load it?

next shot: try that again. Reload, just to be sure.
Jan 23 2004 02:02:13:133PM1040123020Steve Wolfeshot#20: ssep to [.003,.002]

fizzle. One disruption too many.

next shot: repeat
Jan 23 2004 02:19:35:257PM1040123021Steve Wolfeshot#21: ssep to [.003,.002] again
plasma full length, No H-mode. D faults at 1.44sec
ssep between 3.5 and 4mm

next shot: Go on up another 2mm on ssep
Jan 23 2004 02:31:23:313PM1040123022Steve Wolfeshot#22: ssep to [.005,.004]
plasma full length, still no h-mode
ssep=5mm

next shot: up another 2mm on ssep
Jan 23 2004 02:48:28:107PM1040123023Steve Wolfeshot#23: ssep to [.007,.006]
RF will try 3MW flat program

Distuption at 1.17sec
ssep=6mm, but inner gap is down to 1cm?
injection at 1.139 and a second big one at 1.17

next shot: increase clearin and another 2mm on ssep
Jan 23 2004 02:57:50:200PM1040123024Steve Wolfeshot#24: ssep to [.009,.008]
clearin increase by 2mm, rcur increase by 1mm

fizzle.

next shot: drop pg4 by 1msec
Jan 23 2004 03:17:42:223PM1040123025Steve Wolfeshot#25:pg4 to 14msec, ssep at [.009,.008]
clearin,rcur as on 24
plasma full length, no hmode.
ssep=6.5mm, getting down to 1cm again.

next shot: change clearin zxa to .35
Jan 23 2004 03:28:55:437PM1040123026Steve Wolfeshot#26:clearin zxa to .350 (offset=9000), and also controller to zxa=.350
ssep at [.009,.008]
clearin,rcur as on 24

plasma full length, ssep=.7 to .9, left gap=1.4

next shot: decrease clearin by 1mm
Jan 23 2004 03:52:40:360PM1040123027Steve Wolfeshot#27:clearin smaller by 1mm. ssep to [.01,.008]
plasma, full length. No change in ssep time history.

I'm going to have to change the SSEP algorithm to go any further.
The problem seems to be that the SSEP controller is basically ZXU,
so the upper xpoint is just coming down while the zxl is fixed.
If I change that, I'll need to drop the ZXL gain as well, and
maybe change the zxa reference again.

next shot: Change SSEP controller to be orthog to ZXU, not ZXL
Jan 23 2004 03:59:36:750PM1040123028Steve Wolfeshot#28: Change SSEP controller to be orthog to ZXU, not ZXL
Early disruption. The ssep gain is on too soon.


next shot: reload shot 27 and then change to upper null.
Jan 23 2004 04:11:14:307PM1040123029Steve Wolfeshot#29: reload shot 27. Import seg 3 from 1031125030.
Change tf to -149kA. Turn on seg3. load

plasma full length, ssep>2cm

next shot: increase zxl
Jan 23 2004 04:27:28:323PM1040123030Steve Wolfeshot#30: increase zxl from -.04 to -.02

plasma disrupts at 1.25sec,
ssep=+5mm, gaps aren't bad.
Almost lost it on current rise at 0.1sec
May have hit the nose.

next shot: move xl out and back down.
Jan 23 2004 04:38:41:973PM1040123031Steve Wolfeshot#31: zxl from -.02 to -.03; rxl from -.01 to 0.0
increase ip at .15 to -800000.

fizzle.
next shot: try that again
Jan 23 2004 04:55:07:753PM1040123032Steve Wolfeshot#32: zxl from -.02 to -.03; rxl from -.01 to 0.0
increase ip at .15 to -800000.

plasma full length, no hmode, ssep=10mm

next shot: zxl to -.035
Jan 23 2004 05:07:18:747PM1040123033Steve Wolfeshot#33: zxl from -.03 to -.035

plasma full length. ssep around 1.4cm

END OF PLASMA RUN

next shot: Beam into gas only (MSE)
Jan 23 2004 05:16:40:667PM1040123034Steve Wolfeshot#34: Beam into gas only (MSE)
Load from 1040121015, f.d. on at 0.8 sec (was 0.08)
BTOP only enabled.
DNB at 0.7sec

Got over 2mTorr of gas pressure, got the beam.

END OF RUN

Engineering Operator Comments
ShotTimeTypeStatusComment
108:59:31:443AMPlasmaOk
209:22:35:247AMPlasmaOk
309:49:08:753AMPlasmaOk
410:03:21:120AMPlasmaOk
510:18:09:830AMPlasmaOk
610:32:43:400AMPlasmaOk
710:50:08:537AMPlasmaOk
811:03:59:323AMPlasmaOk
911:19:20:017AMPlasmaOk
1011:33:21:973AMPlasmaOk
1111:49:19:833AMPlasmaOk
1212:02:42:403PMPlasmaOk
1312:17:14:700PMPlasmaOk
1412:33:08:890PMPlasmaOk
1512:46:57:160PMPlasmaOk
1601:01:36:557PMPlasmaOk
1701:15:56:260PMPlasmaOk
1801:30:17:650PMPlasmaOk
1901:43:23:060PMPlasmaOk
2001:59:10:903PMPlasmaOk
2102:12:56:990PMPlasmaOk
2202:26:56:650PMPlasmaOk
2302:40:10:250PMPlasmaOk
2402:54:16:563PMPlasmaOk
2503:09:00:990PMPlasmaOk
2603:23:22:773PMPlasmaOk
2703:37:35:717PMPlasmaOk
2803:54:31:530PMPlasmaOk
2904:06:51:770PMPlasmaOk
3004:21:16:883PMPlasmaOk
3104:35:31:243PMPlasmaOk
3204:49:16:220PMPlasmaOk
3305:03:44:097PMPlasmaOk
3405:13:16:453PMTestOk
3503:31:27:243PMTestBad