Alcator C-Mod Run 1040430 Information

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Miniproposals
Miniproposal:361
Date Filed:11/13/2003
Title:Identity experiments with JET on error field locked mode thresholds
First Author:T.C. Hender
Session Leader:T.C. Hender (shots 1-6)
Session Leader:Steve Wolfe (shots 24-28)
Miniproposal:386
Date Filed: 2/5/2004
Title:Locked Mode Threshold in Upper Null Configurations
First Author:Ian Hutchinson
Session Leader:Ian Hutchinson (shots 7-23)

Operators
Session leader(s):T.C. Hender,Ian Hutchinson,Steve Wolfe
Physics operator(s):Jim Irby
Engineering operator(s):Gary Dekow

Engineering Operator Run Comment
MP 371 & MP 386 SL:Hender/Wolfe/Hutchinson; PO:Irby; EO:Dekow/Byford/Par

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:05:460PM
Author: Steve Wolfe
Run Summary for Parts A and C of 1040430

MP#361 : C-Mod/JET error field identity experiment
SL: Hender/Wolfe
PO: Irby

The experiments today on MP#361 were done in two parts, shots#1-6 and
shots#24-28. All of these shots were done in the JET shape at 6.3T, 1.3MA
(q95=3.2). The shots in between were part of another locked mode study, by
Hutchinson and Wolfe under MP#386, at 5.4T and 1MA.

The aim of the first few shots (1-6) was to complete the JET/C-Mod locked
mode identity experiment dataset with some low density points. Operation
at low density proved relatively easy and the data was obtained with no
significant problems. The key shots are (no. 4) which had no LM at full
A-coil current and shot 5 which had slightly lower density than shot 4 and
formed a locked mode (this defines the local locked mode boundary very
well).

The second set of shots used an alternate A-coil configuration, (+Dtop +Dbot
-Jtop -Jbot). This arrangement has a mode spectrum similar to the JET spectrum,
though not as close as (+Btop -Dbot -Gtop +Jbot) used in all the earlier runs
for this MP. The advantage of this configuration is that the phase of the
applied 2/1 field is quite different, and so can provide additional
information on the orientation of the intrinsic error field, which we have
found is reasonably closely aligned to the primary configuration. The
disadvantage is that the 2/1 amplitude is smaller. We got four datapoints with
this configuration at moderate density:

Shot# NL04 Acoil tlock
------ ------ ------ ------
24 1.5 3000 NO LOCK acoil on at 0.8sec
26 1.2 3500 1.05 acoil on at 0.8sec
27 1.15 1500 0.81 acoil on at 0.6sec
28 1.3 3500 1.1 acoil on at 0.6sec

These densities are uncomfortably close to the intrinsic threshold found
earlier, but the 3000A point at nl04=1.5e20 indicates there isn't much of a
window and helps bound the intrinsic error.

Entered: Jul 7 2004 03:49:05:647PM
Author: Ian Hutchinson
Session Leader Report:

Summary of shots with locked modes for 1040430
______________________________________________

We were successful in getting shots in the three areas of interest to
fill in the locked-mode density versus applied 2/1 field plot.

We also found, not surprisingly perhaps, that there is a low density
below which one gets locking regardless of the value of the A-coil
current. This we interpret as a sign that the intrinsic field is
incompletely compensated by the applied field either because of phase
(which we think is not perfectly matched) or because of mode spectrum.


A-coil config was (-Dtop +Dbot +Jtop -Jbot) which is written as
negative current, since it is the opposite of the usual stabilizing
direction.

Time is lock time. Parameters are values then, except that when
there's no lock we give the lowest sustained density that is relevant.
Time 9999 means no lock.

Data from 30 Apr

Shot IA time nl04 BT Ip

7 -1300 9999 14.6 5.4 .966
8 -2600 .84 14.5 5.4 .96
9 -2000 .81 13.3 5.4 .97
10 -2000 1.17 14.8 5.4 .97
11 -0 .64 7.1 5.4 .96
12 -0 .81 5.0 5.4 .99

14 +3500 .7 6.0 5.4 .98
15 +1000 1.0 4.0 5.4 .98
16 +1000 1.02 3.9 5.4 .98
17 +1000 1.27 4.3 5.4 .98
18 +1000 1.23 4.2 5.4 .98
19 +1600 1.21 2.1 5.4 .98
20 +2700 .62 2.5 5.4 .98
21 +3160 .60 2.7 5.4 .99
22 +2100 .84 2.3 5.4 .99
23 +2100 9999 3.7 5.4 .99

12 has a funny event at 1.1s ?unlock? not sure.

Physics Operator Summaries
Entered: Jul 7 2004 04:36:50:177PM
Author: Jim Irby
Physop Run Summary for 1040430, Friday, 30th April

MP 361 (con't): JET/C-Mod locked mode identity

MP 386 (con't): Locked Mode threshold

Session leader: Hender/Wolfe and/or Hutchinson/Wolfe
Engineerin Operators: Dekow, Byford, Parkin
Physics operator: Irby


Summary:

A very good day. I made no startup tweaks, but we had 100%
startup. We made very good progress on both mini-proposals. Final
points were added to Ian's LM plot, and we obtained good data under
the JET identity conditions. Some time was spent mid day fixing a
control power problem in an oh supply (control +-15 volt supply needed
to be power cycled.

We still had our leak at k-hor. It was mass 28 at a partial pressure
of about 5.e-8 Torr. This level is a factor of two lower than we had
yesterday (Tommy added a helium purge this morning).


Score:

plasmas 01,02,03,04,05,06,07,08,09,10,
11,12,14,15,16,17,18,19,20,21,
22,23,24,25,26,27,28

test 13


---------------------------------------------------------------------
---------------------------------------------------------------------


Engineering Setup and Run Plan for Friday, 30th of April, 2004

MP 361 (con't): JET/C-Mod locked mode identity

MP 386 (con't): Locked Mode threshold

Session leader: Hender/Wolfe and/or Hutchinson/Wolfe
Engineerin Operators: Dekow, Byford, Parkin
Physics operator: Irby

Overnight ECDC in D2, stopping two hours before the run.

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

Power systems as on 1040413029

A-coil (Btop-Dbot-Gtop+Jbot)
A-coil PLC limits set to 3 kA, 600 V.
Start time set to 0.3 s, invert 2.0 s.
**** note change in start time ****

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 disabled
fill C-side with 30 psi D2 Hybrid enabled (PG3)
pump out J-bot Hybrid disabled

Disable NINJA

Enable the following gate valves: ECE, VUV, DNB

Necessary diagnostics: ECE set for 6.3 T

*** No RF required ***



A. Run Plan for continuation of MP 361:
------------------------------------

q95=3.2 (I=1.3MA, B=6.3T, "JET shape")

With(+Btop-Dbot-Gtop+Jbot) get LM data at low density:

4. Repeat 1040413013 (nl04~7e19) but with an A-coil=2kA square wave
from 0.3 to 1.28s.

5.a Repeat 1040413010 (nl04~8.5e19) with no A-coil

5.b Repeat 1040413010 (nl04~8.5e19) but with A-coil starting at 0.1s
before intrinsic time from item5a to 1kA and then at 0.2s after
instrinsic time ramp to 3kA and back to zero at 1.28s. Tweak the
timing of second ramp so we can reach full 3.5kA without a locked
mode. (the aim of this shot is to always achieve sufficient
intrinsic error field compensation to make no locked mode).

5c. When we get success we 5b. turn off the density so it falls from
1s and we find critical density for a locked mode with near full
A-coil current.

B. MP#386 - locked mode thresholds at 1MA (C-Mod shape) These shots
will be at 5.4T, 1MA. Since the GPC2 is going to still be set for
high field, we'll be using the FRCECE for our core ECE signals.

Change A-coil configuration to (-Dtop +Dbot +Jtop -Jbot),
i.e. reversed from our "normal" connection.

1. Load 1040317025 and raise nl04 to 1.4e20. Set A-coil current to
1200A (program 1700A). This is point {3} on Ian's graph.

2. Raise or lower A-coil current setting to bracket threshold.

3. Load seg 2 from 1030715027 aiming for nl04~2.5e19, A-coil turned
off. It will probably take a few shots to get the density
down. The trick is going to be to prevent the shot from locking
early; starting with a higher density and letting it drop seems
better than having it low throughout (as we did on
1040414033). Also probably want to have significant pg3 puff in
seg1. We expect a locked mode after .6sec with no A-coil current.

4a.If we don't get an intrinsic locked mode at step 3, turn on the
A-coil (still in the "adverse" direction and raise the current
until we do. Ideally we want to find the current that gives a
locked mode at the time when oh1 is close to 18kA.

4b.If we did get an intrinsic locked mode in step 3, reverse the
A-coil connection (just reverse the supply leads) to (+Dtop -Dbot
-Jtop +Jbot). Set A-coil current to 1000A (program 1500A). This
is Ian's point {1}. We expect this to lock. If it doesn't,
decrease the A-coil current until it does; if it does lock,
increase acoil current to 2000A, which should be unlocked
(confirming the open green point on the graph).

5. Raise A-coil current to 3500A (program 4000A). This is Ian's point
{2}. This should again be locked. If it isn't, we're done; if it
is, reduce current to refine the upper bound of the stable region.

C. Resumption of MP#361 (JET shape) with alternative A-coil set

6. If time permits: Change A-coil configuration to

(+Dtop +Dbot -Jtop -Jbot)

and obtain threshold current with as many as possible of
nl04=.7e20, .85e20, 1e20, 1.4e20.

7. If there is still time left (highly unlikely) reverse the A-coil
current and repeat step 6.

Session Leader Comments
Apr 30 2004 07:46:47:537AMSteve WolfeA. Run Plan for continuation of MP 361:
------------------------------------

q95=3.2 (I=1.3MA, B=6.3T, "JET shape")

With(+Btop-Dbot-Gtop+Jbot) get LM data at low density:

4. Repeat 1040413013 (nl04~7e19) but with an A-coil=2kA square wave
from 0.3 to 1.28s.

5.a Repeat 1040413010 (nl04~8.5e19) with no A-coil

5.b Repeat 1040413010 (nl04~8.5e19) but with A-coil starting at 0.1s
before intrinsic time from item5a to 1kA and then at 0.2s after
instrinsic time ramp to 3kA and back to zero at 1.28s. Tweak the timing
of second ramp so we can reach full 3.5kA without a locked mode.
(the aim of this shot is to always
achieve sufficient intrinsic error field compensation to make no
locked mode).

5c. When we get success we 5b. turn off the density so it falls from 1s
and we find critical density for a locked mode with near full A-coil
current.

B. MP#386 - locked mode thresholds at 1MA (C-Mod shape)
These shots will be at 5.4T, 1MA. Since the GPC2 is going to still be
set for high field, we'll be using the FRCECE for our core ECE signals.

Change A-coil configuration to (-Dtop +Dbot +Jtop -Jbot),
i.e. reversed from our "normal" connection.

1. Load 1040317025 and raise nl04 to 1.4e20. Set A-coil current to
1200A (program 1700A). This is point {3} on Ian's graph.

2. Raise or lower A-coil current setting to bracket threshold.

3. Load seg 2 from 1030715027 aiming for nl04~2.5e19, A-coil turned
off. It will probably take a few shots to get the density
down. The trick is going to be to prevent the shot from locking
early; starting with a higher density and letting it drop seems
better than having it low throughout (as we did on
1040414033). Also probably want to have significant pg3 puff in
seg1. We expect a locked mode after .6sec with no A-coil current.

4a.If we don't get an intrinsic locked mode at step 3, turn on the
A-coil (still in the "adverse" direction and raise the current
until we do. Ideally we want to find the current that gives a
locked mode at the time when oh1 is close to 18kA.

4b.If we did get an intrinsic locked mode in step 3, reverse the
A-coil connection (just reverse the supply leads) to (+Dtop -Dbot
-Jtop +Jbot). Set A-coil current to 1000A (program 1500A). This is
Ian's point {1}. We expect this to lock. If it doesn't, decrease
the A-coil current until it does; if it does lock, increase acoil
current to 2000A, which should be unlocked (confirming the open
green point on the graph).

5. Raise A-coil current to 3500A (program 4000A). This is Ian's point
{2}. This should again be locked. If it isn't, we're done; if it
is, reduce current to refine the upper bound of the stable region.

C. Resumption of MP#361 (JET shape) with alternative A-coil set

6. If time permits: Change A-coil configuration to (+Dtop +Dbot -Jtop
-Jbot)
and obtain threshold current with as many as possible of
nl04=.7e20, .85e20, 1e20, 1.4e20.

7. If there is still time left (highly unlikely) reverse the A-coil
current and repeat step 6.



Apr 30 2004 09:15:16:173AM1040430001Steve Wolfeshot#1: Set up for 7e19 shot like 1040413013 (Jim is going to use tci feedback
today, instead of nl_zmeter).
plasma, no locked mode, disrupts in rampdown.
nl04~9e19 -

next shot: lower density
Apr 30 2004 09:43:48:523AM1040430002Steve Wolfeshot#2: lower density (reduce pg3 pre-prog)
early disrupted .72
locked mode around .68 to .7sec
Apr 30 2004 09:54:45:253AM1040430003Steve Wolfeshot#3: Moving to a modified 5b:
nl04 .9e20 (like #1), step from 2000 to 3500 at .9sec
plasma to 1.37sec

locked mode at 1.1sec, but there is an injection there.
Try retaking this one.
Apr 30 2004 10:11:10:903AM1040430004Steve Wolfeshot#4: Raise nl04 program to 1.0 and repeat
locked mode in rampdown at 1.36

treat that as no locked mode case and go to 5c
Apr 30 2004 10:27:49:647AM1040430005Steve Wolfeshot#5: case 5c - begin dropping the density feed back at 0.9sec
Move acoil ramp earlier by .1 sec as well
disrupts at 1.27sec
locks at 1.03sec, around nl04 of .9sec

next shot: pick up 5a
Apr 30 2004 10:37:55:330AM1040430006Steve Wolfeshot#6: pick up 5a -- density as on #4, acoil off.
locked mode at 0.6sec

We should be done with part A.
Apr 30 2004 11:09:03:083AM1040430007Steve Wolfeshot#7: On to Part B -
Load 1040317025 , raise nl04 to 1.4e20, acoil program to 1700 (should get 1200)

disrupted at 1.45
acoil current at 1250A
No locked mode, density rise is slow but is up by about 1sec.
This gives us Ian's point 3.

next shot: program acoil to 3000 and raise density a little faster
Apr 30 2004 11:21:02:800AM1040430008Steve Wolfeshot#8: program acoil to 3000 and raise density a little faster
plasma to 1.1sec, locked mode at 0.85
bracketing looks pretty good

next shot: split the difference on the acoil
Apr 30 2004 11:41:59:217AM1040430009Steve Wolfeshot#9: program acoil to 2400
disrupts at 1.04 sec,
locks at .803sec, but there are injections at the same time.
Not sure if this is a good datapoint or not.

next shot: delay acoil to 0.8 sec
Apr 30 2004 11:48:14:767AM1040430010Steve Wolfeshot#10: delay acoil to 0.8 sec, still at 2400
plasma to 1.5sec,
locked mode at 1.2 or so.

Move on to B3.
Apr 30 2004 12:11:40:010PM1040430011Steve Wolfeshot#11: Move on to B3 (load seg2 from 1030715027) and turn off acoil
disrupts at .65sec

probable locked mode at 0.646, density is at 7e19.
Apr 30 2004 12:35:58:707PM1040430012Steve Wolfeshot#12: repeat to get the density down
plasma full length, seems to lock at 0.8 at nl04=.5
Something happens at 1.1, maybe an injection?

Go on to 4b
Apr 30 2004 12:48:20:383PM1040430012Steve WolfeThere will be a delay tto fix a bad shunt signal
in the OH2L power supply.
Apr 30 2004 01:26:36:257PM1040430013Steve Wolfeshot#13: OH power supply test
Long check state, probably going to get a dpcs error
OH's look ok.
Apr 30 2004 01:45:40:327PM1040430014Steve Wolfeshot#14: Acoil reversed and programmed to 1500A (to get ~1000A)
in stabilizing direction

disrupts at 1.29sec
Locked mode at .71sec, nl04=6e19
acoil was programmed to 4000, so we actually got 3500A (~10G)
This point is a high density edition of point #2 (a variant of
step 5)

next shot: really try to do 4b
Apr 30 2004 01:57:30:190PM1040430015Steve Wolfeshot#15: Acoil program to +1500A

plasma to 1.44sec
locks at 1.02sec at nl04=3.8e19
There was an injection at 0.47sec, that raised the density.
A good data point, but not at quite low enough density.

Try this one again and see if the injection goes away.
Apr 30 2004 02:08:47:913PM1040430016Steve Wolfeshot#16: Acoil program again at 1500A

plasma, full length.
locks at 1.1sec, nl04=3.8e19, very like the previous shot,
and on this one there is no injection.

Try moving the turnoff of gas an nl04 from .6 to .5sec
Apr 30 2004 02:25:00:263PM1040430017Steve Wolfeshot#17:Try moving the turnoff of gas an nl04 from .6 to .5sec
plasma full length
locked mode at 1.26 but nl04 came up to 4.5e19

need to get the density down somehow.

next shot: ask beam to turn off (they were going at 0.4sec)
also decrease pg3 puff to 20V
Apr 30 2004 02:32:59:190PM1040430018Steve Wolfeshot#18:ask beam to turn off (they were going at 0.4sec)
also decrease pg3 puff to 20V

plasma full length
same thing, locks at 1.23 nut nl04=4.4e19

next shot: drop the program nl04 to 3e19 and get rid of pg3 program
Apr 30 2004 02:48:16:273PM1040430019Steve Wolfeshot#19: drop the program nl04 to 3e19 and get rid of pg3 program
also raise acoil current prog to 2000A.

plasma full length,
locked mode at 1.20sec, nl04=2.2e19
OK, got a valid point #1.

next shot: program 3000A and hope it's not too far
Apr 30 2004 03:02:01:420PM1040430020Steve Wolfeshot#20: program 3000A; this should be either stable or a point #2
plasma full length with lots of late runaways
No locked mode down to nl04 of 1.3e19

next shot: go up to 3500 (Program) and raise nl04 prog to 2.5e19
Apr 30 2004 03:08:25:717PM1040430020Steve WolfeCorrection, shot 20 may have locked at .65sec and nl04=2.1e19.
Apr 30 2004 03:14:44:050PM1040430021Steve Wolfeshot#21: go up to 3500 (Program) and raise nl04 prog to 2.5e19
plasma full length, fewer hards

locked mode at .6, I think, nl04=2.6e19
I believe the last two shots are type#2, still looking
for a stable field at this density

next shot: Acoil prog 2500, if this isn't stable, raise nl0r to 3e19
Apr 30 2004 03:32:26:197PM1040430022Steve Wolfeshot#22: Acoil prog 2500, if this isn't stable, raise nl0r to 3e19
cycle is hung, there was an ack failure in init.
Josh fixed it.

plasma full length
No locked mode? nl4=2.2e19
No it's locked at .84sec

raise nl04 to 3.5e19
Apr 30 2004 03:42:02:920PM1040430023Steve Wolfeshot#23: raise nl04 to 3.5e19
plasma full length

nl04=3.5e19, no lock

next shot: Move on to C-6
Apr 30 2004 04:17:22:353PM1040430024Steve Wolfeshot#24: load seg 2 of #6, acoil square at 3500 (drawn) .8sec to 1.28sec
nl04 to 1.6e20

plasma full length:
No locked mode?

next shot: drop density, raise acoil to full.
Apr 30 2004 04:30:47:360PM1040430025Steve Wolfeshot#25: drop density to nl04=1.2, raise acoil to 4000 (program)
Strange early disruption at 0.4sec.
tci feeddback went berserk? No, the current is very low early,
lots of hards, only gets to 200kA at 100msec

Seems to be a startup problem.
This is like that strange on on 3/25 I think.
Just try again
Apr 30 2004 04:43:50:037PM1040430026Steve Wolfeshot#26: drop density to nl04=1.2, raise acoil to 4000 (program)
Early marfe, plasma to 1.5
locked mode at 1.05 sec
not obvious on magnetics, but there is on the ece and nl
at 1.2e20

next shot: acoil current to 2000A (prog) start earlier
Apr 30 2004 04:53:29:100PM1040430027Steve Wolfeshot#27: acoil current to 2000A (prog) start earlier

plasma to 1.4sec into rampdown
locks at 0.81, nl4=1.15

back up to 1.4 and raise current to max
Apr 30 2004 05:05:11:153PM1040430028Steve Wolfeshot#28: back up to 1.4e20 and raise current to max

plasma to 1.5sec, locked at 1.1sec, 1.3e20 , 3500A

END OF RUN.
Apr 30 2004 06:28:50:920PM1040430028Steve WolfeAt about 18:00, after everybody had left, the HEAT autodialer alarm
started calling out. HEAT seemed to be running amok, claiming 102 open TC's,
power over 100kW and the vessel temp read as high as 190 C.

I managed to contact Gary Dekow and Jim Irby. At their suggestions, I shut down
the heater breaker and also turned off the LN2 Pump.

Messages left for Joe Bosco, Bill Burke, and Yuri Rokhman.

Physics Operator Comments
Apr 30 2004 08:31:27:690AMJim IrbyEngineering Setup and Run Plan for Friday, 30th of April, 2004

MP 361 (con't): JET/C-Mod locked mode identity

MP 386 (con't): Locked Mode threshold

Session leader: Hender/Wolfe and/or Hutchinson/Wolfe
Physics operator: Irby

Overnight ECDC in D2, stopping two hours before the run.

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

Power systems as on 1040413029

A-coil (Btop-Dbot-Gtop+Jbot)
A-coil PLC limits set to 3 kA, 600 V.
Start time set to 0.3 s, invert 2.0 s.
**** note change in start time ****

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 disabled
fill C-side with 30 psi D2 Hybrid enabled (PG3)
pump out J-bot Hybrid disabled

Disable NINJA

Enable the following gate valves: ECE, VUV, DNB

Necessary diagnostics: ECE set for 6.3 T

*** No RF required ***



A. Run Plan for continuation of MP 361:
------------------------------------

q95=3.2 (I=1.3MA, B=6.3T, "JET shape")

With(+Btop-Dbot-Gtop+Jbot) get LM data at low density:

4. Repeat 1040413013 (nl04~7e19) but with an A-coil=2kA square wave
from 0.3 to 1.28s.

5.a Repeat 1040413010 (nl04~8.5e19) with no A-coil

5.b Repeat 1040413010 (nl04~8.5e19) but with A-coil starting at 0.1s
before intrinsic time from item5a to 1kA and then at 0.2s after
instrinsic time ramp to 3kA and back to zero at 1.28s. Tweak the
timing of second ramp so we can reach full 3.5kA without a locked
mode. (the aim of this shot is to always achieve sufficient
intrinsic error field compensation to make no locked mode).

5c. When we get success we 5b. turn off the density so it falls from
1s and we find critical density for a locked mode with near full
A-coil current.

B. MP#386 - locked mode thresholds at 1MA (C-Mod shape) These shots
will be at 5.4T, 1MA. Since the GPC2 is going to still be set for
high field, we'll be using the FRCECE for our core ECE signals.

Change A-coil configuration to (-Dtop +Dbot +Jtop -Jbot),
i.e. reversed from our "normal" connection.

1. Load 1040317025 and raise nl04 to 1.4e20. Set A-coil current to
1200A (program 1700A). This is point {3} on Ian's graph.

2. Raise or lower A-coil current setting to bracket threshold.

3. Load seg 2 from 1030715027 aiming for nl04~2.5e19, A-coil turned
off. It will probably take a few shots to get the density
down. The trick is going to be to prevent the shot from locking
early; starting with a higher density and letting it drop seems
better than having it low throughout (as we did on
1040414033). Also probably want to have significant pg3 puff in
seg1. We expect a locked mode after .6sec with no A-coil current.

4a.If we don't get an intrinsic locked mode at step 3, turn on the
A-coil (still in the "adverse" direction and raise the current
until we do. Ideally we want to find the current that gives a
locked mode at the time when oh1 is close to 18kA.

4b.If we did get an intrinsic locked mode in step 3, reverse the
A-coil connection (just reverse the supply leads) to (+Dtop -Dbot
-Jtop +Jbot). Set A-coil current to 1000A (program 1500A). This
is Ian's point {1}. We expect this to lock. If it doesn't,
decrease the A-coil current until it does; if it does lock,
increase acoil current to 2000A, which should be unlocked
(confirming the open green point on the graph).

5. Raise A-coil current to 3500A (program 4000A). This is Ian's point
{2}. This should again be locked. If it isn't, we're done; if it
is, reduce current to refine the upper bound of the stable region.

C. Resumption of MP#361 (JET shape) with alternative A-coil set

6. If time permits: Change A-coil configuration to

(+Dtop +Dbot -Jtop -Jbot)

and obtain threshold current with as many as possible of
nl04=.7e20, .85e20, 1e20, 1.4e20.

7. If there is still time left (highly unlikely) reverse the A-coil
current and repeat step 6.
Apr 30 2004 09:17:58:643AM1040430001Jim IrbyLoaded shot 1040413013 into segment #2

Loaded wire 14 from seg 3 into wire 14 in seg 2 ( replaced z-meter feedback with nl_04)

NL_04 request to 0.7e20 /m^2

Loaded 2500 A square pulse into the A-coils from 0.3 to 1.28 s

Have seg #1 from last shot yesterday --- gas prefill at 16 ms

Plasma into rampdown (disrupt at 900 kA)

Density higher than programming --- 0.89 vs 0.7 e20 /m^2
About 100 A more in A-coils than asked for

Apr 30 2004 09:39:37:493AM1040430002Jim IrbyDropped seg #2 preprogrammed gas from 40 to 7 volts (get rid of it)

Early disruption --- .725 s


Apr 30 2004 10:01:11:050AM1040430003Jim IrbyNL_04 request to 0.9e20 /m^2

Changed A-coil to add a ramp up to 4000A starting at .9 sec --- rampdown starting at 1.28 s

plasma
Apr 30 2004 10:13:22:433AM1040430004Jim IrbyDensity request 1e20 /m^2

Plasma made it barely into rampdown

Apr 30 2004 10:25:15:570AM1040430005Jim IrbyDensity ramped down from 1.e20/m^2 to negative values starting at 0.9 s

Preprogrammed gas moved negative starting at .9 s

second ramp in A-coils moved from 0.9 to 0.8 s

plasma for 1.195 s
Apr 30 2004 10:41:15:610AM1040430006Jim IrbyA-coils off
Density back to shot 4 programming

Got it.
Apr 30 2004 11:05:56:897AM1040430007Jim IrbyWolfe in for Irby for this shot
load seg2 from 1040317025, raise nl04 to 1.4e20
raise pg3 maint level to 30
raise acoil program to 1700

Load at 30-Apr-2004 10:49:37.00
Open tree /home/irby -1
Open tree done

Plasma
Apr 30 2004 11:21:12:330AM1040430008Jim IrbyA-coil programming to 3000 A --- no timing change

Increased density ramp rate to get to 1.4e20/m^2 at 0.7 s

plasma

Lost interferometer CO2 laser power most of shot, but signal was good enough for feedback


Apr 30 2004 11:36:57:167AM1040430009Jim IrbyA-coil programming to 2400A

plasma --- large density fluctuations or injections around 1.37 s

Apr 30 2004 12:03:16:240PM1040430010Jim IrbyDelayed A-coil start from 0.6 to 0.8 s

plasma
Apr 30 2004 12:16:33:230PM1040430011Jim IrbyA-coils off
loaded shot 1030715027 --- low density

early disruption at 0.66 s

into cell to check supply
Apr 30 2004 12:31:00:830PM1040430012Jim IrbyNo changes. Assume density will come down

Still no A-coil

plasma into rampdown
Apr 30 2004 01:27:37:523PM1040430013Jim IrbyA-coil start moved back to 0.3 s ---- polarity reversed

long pause to check IOC in OH2 again ---- PLC signal gain drop

PLC signal problem seems to have fixed itself.

Will take PLC OH test --- 10 kA OH1, OH2U, OH2L
Apr 30 2004 01:47:54:547PM1040430014Jim IrbyA-coils back on

Plasma for 1.2 s

A-coil current was set too high, should have been 1500A.


Apr 30 2004 02:02:49:100PM1040430015Jim IrbyA-coil current 1500 A

plasma
Apr 30 2004 02:10:09:150PM1040430016Jim Irbyrepeat hoping for lower density

plasma into rampdown

Apr 30 2004 02:25:30:500PM1040430017Jim IrbyTurn off of programmed gas and density moved earlier by approx 100 ms to 0.5 s


Density into rampdown, but it was still too high
Apr 30 2004 02:38:02:567PM1040430018Jim IrbyDropped preprogrammed density from 36 to 20 volts, timing the same
Steve asked Steve to delay beam to end-of-shot (currently at 0.4 s)

density into rampdown, but very little change in density

Apr 30 2004 02:44:43:913PM1040430019Jim IrbyEliminated all preprogrammed gas
Dropped max nl_04 request to 3e19 from 6e19 /m^2
Raised A-coil current from 1500 to 2000A programmed

plasma into rampdown --- lower density at last

Apr 30 2004 03:02:00:527PM1040430020Jim IrbyA-coils to 3000 from 2000 A

plasma into rampdown --- lots of runaways

Apr 30 2004 03:12:17:110PM1040430021Jim IrbyA-coil current from 3000 to 3500 A
Nl_04 request peak at 3e19 then dropping to 2.5e19 /m^2 from 0.5 to 0.6 s


plasma into rampdown --- fewer hards
Apr 30 2004 03:29:16:587PM1040430022Jim IrbyA-coil back to 2500A

plasma into rampdown

Apr 30 2004 03:47:07:153PM1040430023Jim IrbyUpped density request to 3.5e19 /m^2

plasma into rampdown


Apr 30 2004 04:19:14:073PM1040430024Jim IrbySwitching back to JET run: loaded seg 2 of 1040430006 into seg 2
A-coils to 3500A, start time 0.8 s
Density request to 1.6e20/m^2

plasma
Apr 30 2004 04:32:28:093PM1040430025Jim IrbyA-coils to 4000A
Density request to 1.2e20 /m^2

lots of injected material!
Not useful

Apr 30 2004 04:41:32:223PM1040430026Jim IrbyRetry shot 25

plasma for 1.5 s
Apr 30 2004 04:54:57:133PM1040430027Jim IrbyA-coils to 2000A, start to 0.6 s

plasma
Apr 30 2004 05:08:33:967PM1040430028Jim IrbyA-coil current to 4000A
Nl04 to 1.4e20/m^2

plasma ---- DONE

Engineering Operator Comments
ShotTimeTypeStatusComment
109:05:03:477AMPlasmaOk
209:24:40:110AMPlasmaOk
309:45:50:273AMPlasmaOk
410:06:45:047AMPlasmaOk
510:21:34:447AMPlasmaOk
610:33:54:220AMPlasmaOk
711:00:52:150AMPlasmaOk
811:16:11:033AMPlasmaOk
911:30:38:623AMPlasmaOk
1011:44:26:250AMPlasmaOk
1112:04:27:570PMPlasmaOk
1212:25:11:373PMPlasmaOk
1301:23:25:927PMTestOk
1401:36:42:137PMPlasmaOk
1501:49:18:797PMPlasmaOk
1602:01:41:817PMPlasmaOk
1702:15:54:870PMPlasmaOk
1802:28:53:203PMPlasmaOk
1902:41:54:583PMPlasmaOk
2002:54:58:227PMPlasmaOk
2103:08:48:640PMPlasmaOk
2203:24:48:100PMPlasmaOk
2303:37:26:337PMPlasmaOk
2404:06:21:520PMPlasmaOk
2504:20:05:010PMPlasmaOk
2604:32:42:280PMPlasmaOk
2704:45:22:537PMPlasmaOk
2804:59:11:183PMPlasmaOk