Alcator C-Mod Run 930819 Information

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Miniproposals
Miniproposal:
Date Filed:
Title:
First Author:
Session Leader:Yuichi Takase (shots 1-30)

Operators
Session leader(s):Yuichi Takase
Physics operator(s):Steve Horne
Engineering operator(s):Frank Silva

Engineering Operator Run Comment

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:08:553PM
Author: To Be Determined
Run 930819
Physics Operator Summary. (Horne)
Session Leader -- Y. Takase
Engineer -- Frank Silva

Last night, discharge cleaned in D.

OPERATORS NOTE -- I loaded the "LABEL" node in the pulse_gas_* drawables
with labels appropriate to this run. If you load one of these shots for a later run,
you may need to change them.

This was an RF run. Physics objective was to get repeatable plasmas in D2,
or mostly D2.

The first 9 shots were with H2 fill; 3-9 had D puff.
Then we switched to D fill and D puff on B_top.
It took several shots
to evolve the gas valve programming (shots 10-17) with success, more or less, on shot 18.
From then on the gas programming was adjusted gently shot by shot to improve the initial
current rise; shot 23 looks about like a typical shot in H from yesterday.
I was concerned that the plasma seemed nearly diverted onto the limiter
near OH2; on shot 27 the OH2 voltage programming waws adjusted to fix that. There was no
obvious change in plasma quality as a result.
Shots 29 and 30 we programmed the plasma radial position to move out against the limiter
to get a sweep of RF loading -- with predictable results. (Plasma died against the limiter,
and the RF failed to fire.)

A scatterplot of any later shot today against yesterday's run, shows no glaring differences.
The only difficulty during the run was in developing a gas valve program for D which
gives the same pressure evolution in the machine as we had in H.

See the Session Leader's summary for the RF news.

================

Gas connections --- they WERE:

PULSE_GAS_3 = A_SIDE (H2)
PULSE_GAS_1 = B_SIDE_LOWER (Ar)
PULSE_GAS_2 B_SIDE_UPPER (H2)

For this run, they are:

PULSE_GAS_3 = B_TOP (D2)
PULSE_GAS_1 = B_SIDE_LOWER (Ar)
PULSE_GAS_2 = B_SIDE_UPPER (H2)

Shot
1 fill and puff from B side upper,1.2e-5. limiter at 93 cm.
short, probably too much gas

2 reduce puff, fill = 1.e-5, ==>xrays.

3 add d2 puff
move -2 cm down
Still lots of hards
got zcur=-1.5 cm

4 fill 1.3e-5 H
more d2, earlier
zcur=-.03 cm
Got the zcur, but still lots of hards

5 same fill
h2 puff from (.003,34) to (-.008,50)
efc V to 750 (was 700)
Good shot. Scatterplot shows that 1'st 4 shots had low gas.
This shot nominal compared to yesterday.

6 Change d2 puff . (-.008,50) (+.1,50) (+.102,0)
Good shot. Definite change in ratiomatic signal at 100 msec -- -5.0 last shot,
-4.8 this shot.
Density higher than nominal

7 Change d2 puff . (-.008,50) (+.2,50) (+.202,0)
Drop h2 puff late in time.
Died early, density increase at 250 msec. Gas or RF?

8 disable PG2, B side upper, h2. Change d2 puff a bit,
A dud -- no flash. No obvious magnetics problem; gas a hair high on scatterplot.

9 Drop fill to 1.1e-5 (was 1.3). Adjust d2 programming -- 100 v 10 msec puffs
at -.03 and zero, then maintainance. Hards again.
scatterplot shows gas and density decrease (compared to yesterday) at 30 msec or
so.

10 Switch fill to D2. Add D puff at -50 msec., 2 burps, then ramp.
Fill at 1.1 e-5 in D, not H, so gauge factor difference makes it 1.4 or so.
Still hards.

11 Add another d2 puff at -80 msec. Fill at 1.3e-5.
Better, but not great -- like shots 3,4. First d2 puff is in at t=0.

12 More d2 early.
Fizzle. Probably overshot with gas.

13 Shift d2 programming forward in time by 15 msec. This value based on getting 1.5e-5
on ratiomatic at breakdown.
Fizzle -- probably not far enough.

14 move d2 programming 10 msec later. This should be close.
good shot, but xrays again.

15 Increase gas with ramp -- (-.065,50), (-.04,55) and so forth.
Fizzle.

16 Reduce d2 a bit. Better, but still a fizzle.

17 Take a divot out of gas at -40 msec. Fizzle, but better still.

18 Bigger divot. That did it. This was a change in gas programming at -50 msec!.
First cmod shot in D2.

19 Repeat. Few hards, not as good current rise. Scatterplot shows faster initial
density rise than yesterday. Density nice initially, then drops.

20 Increase size of divot in gas programming, raise maintainance level to
fill in density.
Poor current rise early. BZ looks too negative.

21 Add 40 A to ef4. Fix ef4 programming to be flat from -.5 sec.
Better -- still not a nice current rise.

22 Less gas from about -50 msec on. Good shot, a few xray sparkles.
Current rise from 30 msec on looks fine, but from 10-30 is low.

23 Increase the width of the divot -- both earlier and (a bit) later.
Looks better -- best so far. Note that early gas was reduced but early density was
higher. (around 30 msec or so.)

24 Raise maintance gas a bit for more
density later. That worked but there's a peculiar density rise
at .5 sec -- possibly due to RF or to vertical shift of plasma.

25 Delicate gas tweak early; move upward jog to .56 msec or so.
Ok, a few xrays. Disrupts on the way down.

26 Add a pinch of gas early, drop it late. OK.

27 remove about 2000 A from the OH2 coils around 200-300 msec,
to try to be more solidly limited. Earlier shots are nearly diverted, on the
inner wall. Probably worked.

28 Gas twiddle, essentially a repeat. Loose plasma early, sharks in the water.

29 Less gas late to try to submerge the shark fin. Also, ramp the plasma out
radially from (.2,.66) to (.3,.69), then back to (.4,.66)
That worked, plasma died shortly after kissing the RF limiter.

30 repeat.

Entered: Jul 7 2004 03:49:08:570PM
Author: To Be Determined
Run Summary for 930819

ICRF coupling studies in D(H) plasma.

Session Leader: Takase
Physics Operator: Horne
Engineering Operator: Silva

Objective of today's run was to obtain loading data as functions of
1) H/D concentration ratio
2) Plasma-antenna distance
3) Plasma shape
4) Plasma density

ECDC was done with deuterium this morning.
We loaded 930818023 and evolved it into a plasma with fairly good match to the
antenna and the limiter. We started with H fill and H puff, substituting D puff
for H puff gradually, and eventually D fill and D puff. It took a while to set up
the D plasma, trying to find a window between runaway shots and fizzles. (see
physics operator's summary.) Antenna loading did not seem to change appreciably
as the H/D ratio is changed, but we don't have a good way of measuring the H/D ratio
at the moment. Catherine did see some thermonuclear neutrons today.
We scanned the antenna position from 96cm to 91cm and the limiter position
from 93cm to 90cm. On the last two shots (29 and 30) the plasma was shifted radially
so that R_out(FFIT) varied from 84 to 90cm (the limiter was at 90cm and the antenna
was at 91cm). However, because we did not have the time to retune after moving the
antenna in (at the moment we need a few plasma shots to do this), rf faulted on
high reflection. We did observe significant loading increase when the antenna was
moved from 92cm to 91cm with the limiter placed at 90cm.

Loading results:

Initial analysis indicates that the loading is 4-6 Ohms when the antenna is 2cm
behind the limiter, but 10-15 Ohms when it is 1cm behind the limiter. This is to
be compared with the vacuum loading which is about 0.2 Ohm. This result is consistent
with our predictions based on code modeling. We will be refining our determination of
loading by making additional measurements (voltage probe array and antenna current probe)
after the August break.

Coupling results:

We have successfully injected at least 1/4 MW (250 kW) into the plasma. At the moment
we have an uncertainty in our power measurement which needs to be resolved during the
August break. According to another measurement the power was 1/2 MW (500kW).
We did see some signs of rf effects on soft X-rays, density, radiated power, and
edge probes (and maybe others too). We also made an ICRF plasma after a disruption
(it is most obvious on the vertically-viewing camera on F port, but also shows up
on visible Brems, H alpha, antenna loading, and maybe interferometer. All diagnostitians
are encouraged to look at your signals for rf effects and rf pick-up. Good shots to
look at are shots 930819018 and 930819024. The rf power can be found in
\rf::top.antenna.results:pwr_net (calibration needs to be resolved, and can be a factor
of two lower than this signal indicates). According to this measurement, shot 024 had
500 kW leaving the antenna. So where did all that power go? Possibly in the edge plasma
(there are modifications to the density, the floating potential, and maybe temperature),
but no nasty impurity effects were observed. My personal feeling is that the antenna
needs to be closer to the plasma.


Physics Operator Summaries

Session Leader Comments
Aug 19 1993 09:16:09:850AMYuichi TakaseICRF coupling studies in D(H) plasma.

Session Leader: Takase
Physics Operator: Horne
Engineering Operator: Silva

Objective for today's run is to obtain loading data as functions of
1) H/D concentration ratio
2) Plasma-antenna distance
3) Plasma shape
4) Plasma density

1) will only be qualitative since we don't have a good way of measuring the H/D ratio
2) we will spend some time on, since moving the antenna and changing the edge
plasma will change tuning
3) and 4) will be done if time allows.

R_limiter = 93cm
R_antenna = 96cm
for the first shot. But we will be moving them during the run.

B top has D2
B side upper has H2
B side lower has Ar

Start from 930818023 with some changes.

Aug 19 1993 09:17:53:800AM930819001Yuichi TakaseShot 01
H fill, H puff
short plasma (disrupt at 0.18s)

Aug 19 1993 09:42:35:710AM930819002Yuichi TakaseShot 002
H fill, H puff
good plasma, tuning a little off

Aug 19 1993 09:55:57:990AM930819003Yuichi TakaseShot 003
H fill, H puff and D puff
good plasma, tuning a little better
Rlim=93, Rant=95

Aug 19 1993 10:07:01:980AM930819004Yuichi TakaseShot 004
a little more D puff
a little better tune
Rlim=92.5, Rant=94.5

Aug 19 1993 10:34:55:150AM930819005Yuichi TakaseShot 005
good shot, a lot less HX
Rlim=92, Rant=94

Aug 19 1993 10:49:14:250AM930819006Yuichi TakaseShot 006
good shot, nel=4
Rlim=91.5, Rant=93.5

Aug 19 1993 11:00:09:430AM930819007Yuichi TakaseShot 007
attempt to raise D
disrupt at 0.36, too much gas
Rlim=91, Rant=93

Aug 19 1993 11:26:30:160AM930819008Yuichi TakaseShot 008
dud, vacuum loading 0.2 Ohms
starts faulting after 0.4sec power step-up
Rlim=91, Rant=93

Aug 19 1993 11:43:15:890AM930819009Yuichi TakaseShot 009
runaway shot
Rlim=91, Rant=93

Aug 19 1993 12:50:56:950PM930819010Yuichi TakaseShot 010
disrupt @ 0.26sec
Rlim=91, Rant=93

Aug 19 1993 12:52:25:510PM930819011Yuichi TakaseShot 011
runaways, rf faulted at 0.3sec
Rlim=91, Rant=93

Aug 19 1993 12:52:54:020PM930819012Yuichi TakaseShot 012
fizzle
Rlim=91, Rant=93

Aug 19 1993 12:53:05:590PM930819013Yuichi TakaseShot 013
fizzle
Rlim=91, Rant=93

Aug 19 1993 12:59:01:800PM930819014Yuichi TakaseShot 014
runaway shot, rf faulted at 0.23sec
Rlim=91, Rant=93

Aug 19 1993 01:19:27:820PM930819015Yuichi TakaseShot 015
fizzle again
Rlim=91, Rant=93

Aug 19 1993 01:23:44:940PM930819016Yuichi TakaseShot 016
fizzle again
Rlim=92, Rant=94

Aug 19 1993 01:42:32:450PM930819017Yuichi TakaseShot 016
fizzle again, almost there
Rlim=92, Rant=94

Aug 19 1993 02:07:59:240PM930819019Yuichi TakaseShot 018
good shot, a lot of rf
Rlim=92, Rant=94

Aug 19 1993 02:09:57:910PM930819019Yuichi TakaseShot 018
good shot, good rf shot
Rlim=92, Rant=94

Aug 19 1993 02:10:48:430PM930819019Yuichi TakaseShot 019
transmitter tripped
Rlim=92, Rant=94

Aug 19 1993 02:30:33:340PM930819020Yuichi TakaseShot 020
disruptive plasma, rf faulted on minor disruption
Rlim=92, Rant=94

Aug 19 1993 03:17:00:520PM930819021Yuichi TakaseShot 021
plasma disrupted at 0.3
Rlim=92, Rant=94

Aug 19 1993 03:17:42:740PM930819022Yuichi TakaseShot 022
good shot, but lots of rf interrupts
Rlim=92, Rant=94

Aug 19 1993 03:50:36:910PM930819023Yuichi TakaseShot 023
good shot, but high rf reflection
Rlim=92, Rant=94

Aug 19 1993 03:52:54:760PM930819024Yuichi TakaseShot 024
good tune, lots of rf power (1/4-1/2MW at the end)
Rlim=92, Rant=94

Aug 19 1993 04:09:23:280PM930819025Yuichi TakaseShot 025
good shot, but rf faulted
Rlim=91, Rant=93

Aug 19 1993 05:10:22:550PM930819026Yuichi TakaseShot 026
good shot, but rf faulted (mistuned)
Rlim=91, Rant=93

Aug 19 1993 05:26:49:210PM930819027Yuichi TakaseShot 027
good shot, but rf faulted (mistuned)
Rlim=91, Rant=93

Aug 19 1993 05:28:22:730PM930819028Yuichi TakaseShot 028
good shot, short rf pulse
Rlim=91, Rant=92

Aug 19 1993 05:30:04:200PM930819029Yuichi TakaseShot 029
good shot (sweeping R_out to the limiter), disrupts after contacting limiter
rf faulted
Rlim=91, Rant=92

Aug 19 1993 05:31:08:950PM930819030Yuichi TakaseShot 030
good shot (sweeping R_out to the limiter), plasma dies after contacting limiter
rf faulted
Rlim=91, Rant=92

Aug 19 1993 06:34:48:650PM930819030Yuichi TakaseLimiter and Antenna positions entered for shots 26-30 were wrong.
Correct positions are:
Shot Lim Ant
026 90 92
027 90 92
028 90 91
029 90 91
030 90 91

Physics Operator Comments
Aug 19 1993 09:17:40:790AM930819001Steve Horne
RUN 930819 -- RF.


Gas connections --- they WERE:

V14 = PULSE_GAS_3 = A_SIDE (H2)
V15 = PULSE_GAS_1 = B_SIDE_LOWER (Ar)
V16 = PULSE_GAS_2 B_SIDE_UPPER (H2)



For this run, they are:

V14 = PULSE_GAS_3 = B_TOP (D2)
V15 = PULSE_GAS_1 = B_SIDE_LOWER (Ar)
V16 = PULSE_GAS_2 = B_SIDE_UPPER (H2)



Shot
1 fill and puff from B side upper,1.2e-5. limiter at 93 cm.
short, probably too much gas





Aug 19 1993 09:40:42:010AM930819001Steve HorneShot 2 -- reduce puff, drop fill to 1.e-5
Got hard x-rays.





Aug 19 1993 10:07:26:790AM930819004Steve Horne
4 fill 1.3e-5 H
more d2, earlier
zcur=-.03 cm
Got the zcur, but still lots of hards





Aug 19 1993 10:32:03:350AM930819005Steve Horne
5 same fill
h2 puff from (.003,34) to (-.008,50)
efc V to 750 (was 700)
Good shot. Scatterplot shows that 1'st 4 shots had low gas.
This shot nominal compared to yesterday.


Aug 19 1993 10:48:49:720AM930819006Steve Horne6 Change d2 puff . (-.008,50) (+.1,50) (+.102,0)
Good shot. Definite change in ratiomatic signal at 100 msec -- -5.0 last shot,
-4.8 this shot.





Aug 19 1993 11:10:32:230AM930819007Steve Horne
7 Change d2 puff . (-.008,50) (+.2,50) (+.202,0)
Drop h2 puff late in time.
Died early, density increase at 250 msec. Gas or RF?





Aug 19 1993 11:30:40:020AM930819008Steve Horne
8 disable PG2, B side upper, h2. Change d2 puff a bit,
A dud -- no flash. No obvious magnetics problem; gas a hair high on scatterplot.


Aug 19 1993 11:52:55:710AM930819009Steve Horne9 Drop fill to 1.1e-5 (was 1.3). Adjust d2 programming -- 100 v 10 msec puffs
at -.03 and zero, then maintainance. Hards again.
scatterplot shows gas and density decrease (compared to yesterday) at 30 msec or
so.


Aug 19 1993 12:26:51:250PM930819010Steve Horne
10 Switch fill to D2. Add D puff at -50 msec., 2 burps, then ramp.
Fill at 1.1 e-5 in D, not H, so gauge factor difference makes it 1.4 or so.
Still hards.


Aug 19 1993 12:27:12:090PM930819011Steve Horne11 Add another d2 puff at -80 msec. Fill at 1.3e-5.
Better, but not great -- like shots 3,4. First d2 puff is in at t=0.


Aug 19 1993 12:40:12:150PM930819013Steve Horne13 Shift d2 programming forward in time by 15 msec. This value based on getting 1.5e-5
on ratiomatic at breakdown.
Fizzle -- probably not far enough.

Aug 19 1993 01:08:46:810PM930819014Steve Horne14 move d2 programming 10 msec later. This should be close.
good shot, but xrays again.

Aug 19 1993 01:46:38:260PM930819015Steve Horne15 Increase gas with ramp -- (-.065,50), (-.04,55) and so forth.
Fizzle.

Aug 19 1993 01:47:03:310PM930819016Steve Horne16 Reduce d2 a bit. Better, but still a fizzle.

Aug 19 1993 01:48:18:130PM930819017Steve Horne17 Take a divot out of gas at -40 msec. Fizzle, but better still.

Aug 19 1993 02:19:55:430PM930819018Steve Horne18 Bigger divot. That did it. This was a change in gas programming at -50 msec!.
First cmod shot in D2.

Aug 19 1993 02:20:22:740PM930819019Steve Horne19 Repeat. Few hards, not as good current rise. Scatterplot shows faster initial
density rise than yesterday. Density nice initially, then drops.


Aug 19 1993 03:34:10:590PM930819020Steve Horne20 Increase size of divot in gas programming, raise maintainance level to
fill in density.
Poor current rise early. BZ looks too negative.

Aug 19 1993 03:34:34:380PM930819021Steve Horne21 Add 40 A to ef4. Fix ef4 programming to be flat from -.5 sec.
Better -- still not a nice current rise.


Aug 19 1993 03:34:56:260PM930819022Steve Horne22 Less gas from about -50 msec on. Good shot, a few xray sparkles.
Current rise from 30 msec on looks fine, but from 10-30 is low.

Aug 19 1993 03:35:26:310PM930819023Steve Horne23 Increase the width of the divot -- both earlier and (a bit) later.
Looks better -- best so far. Note that early gas was reduced but early density was
higher. (around 30 msec or so.)

Aug 19 1993 04:14:17:590PM930819024Steve Horne24 Raise maintance gas a bit for more
density later. That worked but there's a peculiar density rise
at .5 sec -- possibly due to RF or to vertical shift of plasma.

Aug 19 1993 04:30:09:990PM930819025Steve Horne25 Delicate gas tweak early; move upward jog to .56 msec or so.
Ok, a few xrays. Disrupts on the way down.

Aug 19 1993 04:31:24:730PM930819026Steve Horne26 Add a pinch of gas early, drop it late. OK.

Aug 19 1993 04:55:43:480PM930819027Steve Horne27 remove about 2000 A from the OH2 coils around 200-300 msec,
to try to be more solidly limited. Earlier shots are nearly diverted, on the
inner wall. Probably worked. Shot ok.

Aug 19 1993 04:56:09:390PM930819028Steve Horne28 Gas twiddle, essentially a repeat. Loose plasma early, sharks in the water.

Aug 19 1993 05:09:43:520PM930819029Steve Horne29 Less gas late to try to submerge the shark fin. Also, ramp the plasma out
radially from (.2,.66) to (.3,.69), then back to (.4,.66)
That worked, plasma died shortly after kissing the RF limiter.

Aug 19 1993 05:19:01:870PM930819030Steve HorneRepeat -- same plasma, too.

Engineering Operator Comments
ShotTimeTypeStatusComment
109:03:22:780AMPlasmaOkecdc d2/shot 1 h2 st, pulse , no bd dud
209:19:26:020AMPlasmaOkplasma
309:39:14:410AMPlasmaOklots a spark
409:56:57:560AMPlasmaOkplasma/no sparks
510:14:29:050AMPlasmaOkplasma
610:30:15:680AMPlasmaOkplasma
710:51:07:690AMPlasmaOkplasma
811:11:08:200AMPlasmaOk
911:31:13:690AMPlasmaOkplasma
1011:51:26:520AMPlasmaOkd2 steady state & pulse
1112:10:37:590PMPlasmaOkplasma
1212:25:53:760PMPlasmaOkfizzle -- no faults
1312:37:13:000PMPlasmaOkfizzle -- no faults
1412:51:48:890PMPlasmaOkno faults
1501:07:22:070PMPlasmaOkno faults -- double flash!! Two shots in one.
1601:19:59:140PMPlasmaOkno faults
1701:34:26:400PMPlasmaOkfizzle
1801:47:39:730PMPlasmaOkno faults
1902:02:33:690PMPlasmaOk
2002:18:48:280PMPlasmaOkno faults
2102:40:02:390PMPlasmaOkplasma
2202:59:37:550PMPlasmaOkplasma
2303:15:53:980PMPlasmaOkplasma
2403:33:52:320PMPlasmaOkplasma
2503:52:32:640PMPlasmaOkplasma
2604:09:29:020PMPlasmaOkplasma
2704:27:00:760PMPlasmaOkplasma
2804:41:26:740PMPlasmaOkplasma
2904:55:41:170PMPlasmaOkplasma
3005:08:37:420PMPlasmaOklast shot #30