Alcator C-Mod Run 1040324 Information

Back to runs

Miniproposals
Miniproposal:305
Date Filed: 6/18/2002
Title:ITB - Access Conditions and Hysteresis
First Author:Martin Greenwald
Session Leader:Martin Greenwald (shots 1-34)

Operators
Session leader(s):Martin Greenwald
Physics operator(s):Steve Wolfe
Engineering operator(s):Bill Parkin,Gary Dekow,Bill Cochran

Engineering Operator Run Comment
MP# 305 Hysteresis in ITB (off- vs on-axis power)/Wolfe/[g]/Cochran/Deko

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:03:943PM
Author: Martin Greenwald
Run Summary for MP 305 ITB access conditions and hysteresis

Session Leader - Greenwald
Phys Op - Wolfe

Plan:

Run at 5.55 T, 0.8 MA, standard shape
The principal variation is in the RF programming

- back transition -

1. Begin with 2-3 MW at 70 MHz steady, beginning at 0.6 sec, establish ITB

2. Assuming the barrier forms promptly, begin ramping power at 0.9 seconds
70 MHz ramps down to reach 0.5 MW at 1.5 second
80 MHz ramps up at identical rate to keep total power fixed

3. Assuming barrier is quenched sometime during the ramp, adjust timing and
ramp rate to get more precise measure of back transition threshold

- forward transition -

4. Begin with about 1.25 MW in each of 70 and 80 MHz, start at 0.6 sec
ramp 80 down - at rate which will reach 0 MW at 1.1 seconds
ramp 70 up - at same rate - keep total power constant
(after 1.1 seconds keep 70 flat til 1.5 seconds)

5. Assuming barrier forms at some point during ramp, adjust timing at ramp rates
to get more precise measure of forward threshold


Results:

Not very productive. We had trouble getting barriers with the planned
scenario. We had weak ITBs on 014 and 015 but with early back transition.
Putting on central power should have helped reduce impurity build-up and
sustained the barriers, but we got no barriers at all in these cases.

Starting with shot 024 we dropped the field to 4.55 and switched the RF waveforms.
(This is our nominal ITB scenario). We had better luck getting ITBs but
were still not able to sustain them. The results were similar to yesterday's
run.

Physics Operator Summaries
Entered: Jul 7 2004 04:36:49:600PM
Author: Steve Wolfe
Physics Operator Summary for Wed. 3/24/2004

MP#305 ITB Hysteresis
SL: Greenwald
PO: Wolfe
EO: Cochran,Dekow,Parkin

Engineering setup:
------------------
ECDC overnight in D2, stopping two hours before the run.

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

Power supplies as on 1040323017

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 with 15 psi He3 Hybrid DISABLED (PG2)
fill C-side with 30 psi D2 Hybrid enabled (PG3)
fill NINJA (lower cap) leave as is

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

RF: Transmitters #1,2,3 and 4 in RUN-ON by 08:30

Run Plan:
---------

Load from any shot from 1040323.
Change tf current program in seg2 to 154kA, aiming for Btor=5.55T.
Set nl04 program to 0.8 or 0.9e20.

1. Begin with 2-3 MW at 70 MHz steady, beginning at 0.6 sec, establish ITB

2. Assuming the barrier forms promptly, begin ramping power at 0.9 seconds
70 MHz ramps down to reach 0.5 MW at 1.5 second
80 MHz ramps up at identical rate to keep total power fixed

3. Assuming barrier is quenched sometime during the ramp, adjust timing and
ramp rate to get more precise measure of back transition threshold

- forward transition -

4. Begin with about 1.25 MW in each of 70 and 80 MHz, start at 0.6 sec
ramp 80 down - at rate which will reach 0 MW at 1.1 seconds
ramp 70 up - at same rate - keep total power constant
(after 1.1 seconds keep 70 flat til 1.5 seconds)

5. Assuming barrier forms at some point during ramp, adjust timing at ramp rates
to get more precise measure of forward threshold

Results
---------

The machine ran pretty well today, but we didn't get much out of the MP. We
started with low-field side resonance, as planned. The first real sign of an
ITB did not come until shot 14, after a lot of trouble getting the RF to stay
on. On shot#15 we got what looked like a good ITB starting before 1sec, so we
started the ramp program. However, we then saw no more convincing ITB's, even
with the central power delayed significantly and at low ramp rates, and with
the off-axis rf started earlier, at .5sec.

On shot#24 we gave up on the low field resonance and went back to 4.5T, with
D+E off-axis. With this setup we got two h-modes, each with ITB's and
radiating to an H-L in each case. Turning on the ramps failed to stop the
first ITB from radiating away, but prevented formation of an ITB in the second
H-mode. This was the case for all ramp rates tried.

Late in the run we ran into serious slowdowns in the data cycle. Josh thinks
there was a network problem, but as of this writing it has not been tracked
down. The symptom is that the data stores were a factor of about five longer
than normal. INIT was also slow.

I didn't need to touch the startup all day. I did play around some with the
glitch at segment switch, and got some improvement by increasing the current
program for the first two points in seg2, and moving the second point
earlier. However, this did not prevent the glitch/injection in all cases. I
did note that all the Xpoint locations see a substantial error
signal at seg switch, and would possibly be better if they were changed to
there values later in the shot. I also noticed that the ip offset in seg2 is
presently set to -15000 instead of the more recent value of -30000. I didn't
bother to fix this.

Scorecard
----------

tests/no-power 2
duds 0
fizzles 0
plasmas 29
========== ==
Shots 31

After the run additional cycles were taken and Josh and Henry determined that
a network switch had a mismatch that seems to have been the cause of the data
slowdown.

Session Leader Comments
Mar 24 2004 08:35:44:610AMMartin GreenwaldMP 305 ITB access conditions and hysteresis
Session Leader - Greenwald
Phys Op - Wolfe

Run at 5.55 T, 0.8 MA, standard shape
The principal variation is in the RF programming

- back transition -

1. Begin with 2-3 MW at 70 MHz steady, beginning at 0.6 sec, establish ITB

2. Assuming the barrier forms promptly, begin ramping power at 0.9 seconds
70 MHz ramps down to reach 0.5 MW at 1.5 second
80 MHz ramps up at identical rate to keep total power fixed

3. Assuming barrier is quenched sometime during the ramp, adjust timing and
ramp rate to get more precise measure of back transition threshold

- forward transition -

4. Begin with about 1.25 MW in each of 70 and 80 MHz, start at 0.6 sec
ramp 80 down - at rate which will reach 0 MW at 1.1 seconds
ramp 70 up - at same rate - keep total power constant
(after 1.1 seconds keep 70 flat til 1.5 seconds)

5. Assuming barrier forms at some point during ramp, adjust timing at ramp rates
to get more precise measure of forward threshold
Mar 24 2004 05:59:42:670PMMartin Greenwald
Results:

Not very productive. We had trouble getting barriers with the planned
scenario. We had weak ITBs on 014 and 015 but with early back transition.
Putting on central power should have helped reduce impurity build-up and
sustained the barriers, but we got no barriers at all in these cases.

Starting with shot 024 we dropped the field to 4.55 and switched the RF waveforms.
(This is our nominal ITB scenario). We had better luck getting ITBs but
were still not able to sustain them. The results were similar to yesterday's
run.

Mar 24 2004 09:13:15:730AM1040324001Martin GreenwaldPlasma - RF not tuned yet
no H-mode, no ITB
Mar 24 2004 09:23:12:777AM1040324002Martin GreenwaldGood Plasma - RF power still low
Mar 24 2004 09:41:19:773AM1040324003Martin GreenwaldRF up to 1 MW
brief H-mode
Mar 24 2004 09:53:03:400AM1040324004Martin GreenwaldPrf to 1 MW
brief H-mode
Mar 24 2004 10:09:28:003AM1040324005Martin GreenwaldRF cleaning up - power to 1.5 MW - lasts longer
two h-mode phases
hint of ITB on second H-mode
Mar 24 2004 10:24:33:510AM1040324006Martin GreenwaldRF power reaches 2 MW
H-mode for 0.3 sec
Mar 24 2004 10:39:46:927AM1040324007Martin Greenwalddisruption at 1.4 sec - spark from J antenna?
two brief h-modes




Mar 24 2004 10:56:28:890AM1040324008Martin GreenwaldRF up to 2 MW
(still ramping at beginning)
H-mode but no ITB
Mar 24 2004 11:09:21:470AM1040324009Martin GreenwaldRF still ragged
h-modes but no ITB
Mar 24 2004 11:27:04:310AM1040324010Martin Greenwaldbreaker problem
Mar 24 2004 11:47:17:013AM1040324011Martin GreenwaldBt raised to 5.62 T
otherwise results similar to 09
Mar 24 2004 11:59:25:110AM1040324012Martin GreenwaldMultiple H-modes, RF trips
Hint of ITB at 1.2-1.3 sec?
Mar 24 2004 12:11:14:637PM1040324013Martin GreenwaldNo power test
Mar 24 2004 12:26:08:440PM1040324014Martin GreenwaldRF steady at 2 MW
weak itb beginning at 1.2 sec
Mar 24 2004 12:40:36:010PM1040324015Martin GreenwaldPower to 2.2 MW
Good ITB - starts at about 0.95 sec
Mar 24 2004 12:56:35:143PM1040324016Martin GreenwaldFirst shot with RF ramps
started 80 MHz (on-axis) at 1 sec
no evidence of itb
Mar 24 2004 01:10:33:133PM1040324017Martin Greenwaldreduced ramp rate
still no sign of itb
Mar 24 2004 01:27:29:927PM1040324018Martin Greenwaldramp delayed til 1.1 sec
still no ITB
Mar 24 2004 01:42:00:040PM1040324019Martin Greenwaldearly trips on RF (tried to get a bit more power)
no itb
Mar 24 2004 02:00:36:790PM1040324020Martin GreenwaldRF cleaner - but still early trip
no itb
Mar 24 2004 02:16:17:203PM1040324021Martin GreenwaldEarly disruption - before 0.9 sec
Mar 24 2004 02:29:07:457PM1040324022Martin GreenwaldSteady H-mode
but no sign of ITB
Mar 24 2004 03:23:10:697PM1040324024Martin GreenwaldSwitched to 4.55 T (reversing role of 70 & 80 MHz)
Got decent itbs - interupted by back transition
Mar 24 2004 03:23:37:493PM1040324025Martin GreenwaldStarted RF ramp
didn't save first itb which still collapsed
second was much weaker
Mar 24 2004 04:03:49:040PM1040324026Martin GreenwaldMore power into J
Similar to shot 25
Mar 24 2004 04:03:30:603PM1040324028Martin Greenwaldmore power into J
similar result - back transition at 1.05
Mar 24 2004 04:19:43:330PM1040324029Martin Greenwaldsame as last shot
Mar 24 2004 05:15:43:993PM1040324031Martin GreenwaldJ port moved earlier - to 0.7 sec
no itb at all

Physics Operator Comments
Mar 24 2004 08:18:57:770AMSteve WolfePCS Setup for 1040324

Load from 1040323036
Raise tf current in seg2 to -154000
Contrary to run plan, leave nl04 at 1e20, since this shot did run well.
Adjust second seg2 ip point to [.15,-.8e6]
Load at 24-Mar-2004 08:18:48.00
Open tree /home/wolfe/pcs_scratch -1
Open tree done
Mar 24 2004 09:08:33:987AM1040324001Steve Wolfeshot#1: plasma full length. Hardly any RF.
F-side pressure is a little high.
B-field is a tad high:5.61 vs 5.55
next shot: decrease tf current to -152100
Mar 24 2004 09:22:22:820AM1040324002Steve Wolfeshot#2: decrease tf current to -152100
plasma full length, still no rf.

next shot: drop nl04 to 0.9e20
Mar 24 2004 09:40:37:910AM1040324003Steve Wolfeshot#3: drop nl04 to 0.9e20
plasma full length, brief h-mode(?)
RF faulting above 1MW.

Mar 24 2004 09:53:21:463AM1040324004Steve Wolfeshot#4: No pcs changes; RF trying to improve match.
plasma full length, rf still tripping at the L-H transition
Mar 24 2004 10:05:44:217AM1040324005Steve Wolfeshot#5: No pcs changes; RF trying to improve match.
plasma full length,two h-modes this time.
Mar 24 2004 10:23:31:273AM1040324006Steve Wolfeshot#6: No pcs changes; RF trying to improve match.
plasma full length, two hmodes, first one lasts longer.
No ITB.
Mar 24 2004 10:39:02:923AM1040324007Steve Wolfeshot#7: No pcs changes;
plasma disrupted at 1.37sec
arcs and sparks at J-port antenna.

Mar 24 2004 10:55:43:950AM1040324008Steve Wolfeshot#8: No pcs changes;
plasma, full length
RF doing better.

next shot: RF will start to square up the rf pulse.
Mar 24 2004 11:09:19:377AM1040324009Steve Wolfeshot#9: No pcs changes;
RF will start to square up the rf pulse.

plasma full length, still not steady,
hmode starts at .7, H-L at 1.14

next shot: raise field back to 5.6
Mar 24 2004 11:20:16:113AM1040324010Steve Wolfeshot#10: raise field back to 5.6 (tfcur to -154000)
No plasma - breakers pulled out in pulse.
Mar 24 2004 11:44:20:400AM1040324011Steve Wolfeshot#11: raise field back to 5.6 (tfcur to -154000)
plasma full length, 3 or 4 H-modes, no ITB.
Mar 24 2004 11:58:16:157AM1040324012Steve Wolfeshot#12: RF squaring up
plasma full length, 3 or 4 H-modes, no ITB.
Mar 24 2004 12:09:15:727PM1040324013Steve Wolfeshot#13: No power shot - got an I2t fault in init.
Mar 24 2004 12:29:05:240PM1040324014Steve Wolfeshot#14: No changes
plasma full length, nice steady eda
Maybe an ITB starting at 1.15sec.

next shot: Martin is thinking about it
Mar 24 2004 12:44:30:920PM1040324015Steve Wolfeshot#15: raise power by .25MW
plasma full length; couple of late trips
ITB does start earlier
back transition at 1.17

next shot: start on part2, with ramps starting at 1sec
Mar 24 2004 12:57:46:363PM1040324016Steve Wolfeshot#16: start on part2, with ramps starting at 1sec
plasma full length.
Nice long eda, falling density during the on-axis ramp
but no ITB formation before the ramps.

next shot: weaker ramps

Mar 24 2004 01:11:26:430PM1040324017Steve Wolfeshot#17: weaker ramps
plasma full length,
J has dropout at 1.2sec, drops out of H-mode.
No sign of an ITB.

next shot: delay ramps

Mar 24 2004 01:26:46:347PM1040324018Steve Wolfeshot#18: delay ramps; raise Ip at .1sec to .65 and move next
point to .120,-.8e6 (glitch was back on 17)

plasma full length, glitch is gone again.
No ITB evident.

next shot: Try to get J back to 2.5MW

Mar 24 2004 01:41:56:713PM1040324019Steve Wolfeshot#19: Try to get J back to 2.5MW
plasma full length multiple H-modes.
Lots of rf faulting early

next shot: try again

Mar 24 2004 02:03:52:060PM1040324020Steve Wolfeshot#20: try again

plasma full length, rf fault late,
one early fault. long eda but no ITB.

next shot: nl04 to .95e20
Mar 24 2004 02:21:49:697PM1040324021Steve Wolfeshot#21: nl04 to .95e20
plasma disrupts at .890; sparks from J
The 0.1sec glitch is back again too.

next shot: no changes
Mar 24 2004 02:36:39:733PM1040324022Steve Wolfeshot#22: no changes
plasma full length, one early rf glitch ,
no ITB. Still have the .1sec glitch

next shot: start rf at 0.5sec
Mar 24 2004 02:44:01:353PM1040324023Steve Wolfeshot#23: start rf at 0.5sec
still no itb forming

next shot: go to 4.5T
Mar 24 2004 03:05:07:590PM1040324024Steve Wolfeshot#24: go to 4.5T (-122000 tfcur), D+E only
plasma full length, some rf trips at 1sec,
looks like an itb starts at .8 and again at 1.3

next shot: start with the ramps again
Mar 24 2004 03:22:19:070PM1040324025Steve Wolfeshot#25: start with the ramps again
Still getting two h-modes, second has no ITB this time
first radiates away
Mar 24 2004 03:37:59:783PM1040324026Steve Wolfeshot#26: increase ramp rates.
plasma full length still 2 hmodes
First H-L is a little later.
No ITB in second

next shot: ramp harder
Mar 24 2004 03:52:40:977PM1040324027Steve Wolfeshot#27: increase ramp rates.
plasma full length H-L at 0.8
looks like several short itb phases.
The .1sec injection is back.
Mar 24 2004 04:06:01:060PM1040324028Steve Wolfeshot#28: accidentally did a pcs load. No changes.
RF will ramp harder.

plasma full length - looks very similar.


next shot: start J .1sec earlier
Mar 24 2004 04:19:59:067PM1040324029Steve Wolfeshot#29: start J .1sec earlier
Or Not.
plasma looks similar (not too surprising.)


Mar 24 2004 05:05:46:027PM1040324030Steve Wolfeshot#30: start J .1sec earlier

plasma - data system is frozen.
Josh is storing data manually
Looks like a late ITB, after 1sec on ECE?
No nl04 signal.
Mo rf signals.

next shot: repeat
Mar 24 2004 05:37:12:213PM1040324031Steve Wolfeshot#31: repeat
plasma full length, back transition at .82
No itb.

Engineering Operator Comments
ShotTimeTypeStatusComment
109:01:12:383AMPlasmaOk
209:17:46:347AMPlasmaOk
309:36:12:063AMPlasmaOk
409:49:56:973AMPlasmaOk
510:02:59:570AMPlasmaOk
610:19:34:050AMPlasmaOk
710:34:16:200AMPlasmaOk
810:48:58:080AMPlasmaOk
911:03:07:087AMPlasmaOk
1011:17:10:373AMPlasmaBadAll TF and PF breakers opened at pulse again
1111:38:04:593AMPlasmaOk
1211:54:13:680AMPlasmaOk
1312:08:02:973PMPlasmaBadI2T fault
1412:20:55:573PMPlasmaOk
1512:35:45:157PMPlasmaOk
1612:50:44:353PMPlasmaOk
1701:07:02:207PMPlasmaOk
1801:21:05:807PMPlasmaOk
1901:37:04:063PMPlasmaOk
2001:56:30:080PMPlasmaOk
2102:11:04:743PMPlasmaOk
2202:25:04:433PMPlasmaOk
2302:38:35:300PMPlasmaOk
2402:58:55:283PMPlasmaOk
2503:16:21:903PMPlasmaOk
2603:30:46:957PMPlasmaOk
2703:45:36:637PMPlasmaOk
2803:59:29:893PMPlasmaOk
2904:13:42:697PMPlasmaOk
3004:36:33:530PMPlasmaOk
3105:07:42:653PMPlasmaOk
3205:26:46:450PMTestBadpcdaqldx problems
3306:08:20:823PMTestOk
3406:57:32:243PMTestOk