Alcator C-Mod Run 980121 Information

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Miniproposals
Miniproposal:177
Date Filed: 5/2/1997
Title:Exploration of the Prototype Cryopump on Impurity Transport
First Author:Bruce Lipschultz
Session Leader:Bruce Lipschultz (shots 1-22)
Session Leader:John Goetz (shots 1-22)

Operators
Session leader(s):Bruce Lipschultz,John Goetz
Physics operator(s):Robert Granetz
Engineering operator(s):Vinny Bertolino

Engineering Operator Run Comment
mp 177

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:17:880PM
Author: To Be Determined
Run 980121

session leader: John Goetz/Bruce Lipschultz
physop: RSG
engineering op: V. Bertolino

Mini-proposal 177: "Exploration of the Effect of the Prototype Cryopump
on Impurity Transport'

The purpose of this MP was to explore whether the impurity transport
characteristics are affected by the protoype cryopump. Ohmic plasmas with
density ramps to divertor detachment and EDA H-mode plasmas were investigated.
Argon or neon gas was puffed into these types of plasmas with the cryopump on
or off. The core impurity ion densities were monitored with x-ray and VUV
spectrometers and the divertor impurity neutral densities with an RGA.
In Ohmic plasmas, the core argon and the edge neon were "pumping out",
i.e., the time history of the signal was decaying away. Comparing the core
argon density with and without the cryopump operational indicates that the
pump had no effect on the decay rate. This indicates that something else is
doing the pumping. This is more than likely the walls. Neon line brightnesses
from charge states in the edge plasma (temperature < 150eV) do show a decrease
in the equilibrium value with the cryopump operational. However, the initial
"pumpout" is nearly identical with and without the cryopump, also indicating a
strong wall sink. The density in these Ohmic plasmas was ramped to divertor
detachment. After divertor detachment, the cryopump is observed to make a
difference in core argon density. The penetration factor for puffed argon
entering the core is lower after detachment with the cryopump on than it is
after detachment with the cryopump off. This can be seen by comparing shots
007 and 021 after 0.75sec. Shot 021 (pump off) shows an increase in the core
argon density while 007 (pump on) does not. Measurements of the neutral
particle density in the divertor indicate that the density is lower by
approximately 20% with the pump operational.
In EDA H-modes, the "pump out" effect is still evident on the core
argon density and there is no difference between plasmas with and without the
cryopump operational. Core neon brightness measurements show no "pump out"
behavior, although the SNR is small (because the neon was puffed early and
not directly into the EDA H-mode, e.g. 980109027). There is also no
discernible difference in the core neon behavior with and without the cryopump.
However, there is a slight decrease, <20%, in both the divertor neutral neon
and argon with the cryopump operational.
These results are in contrast to those obtained with the non-recycling
impurity gas nitrogen on 970617. During that run, the edge nitrogen brightness
was reduced by a factor of two with the cryopump operational. Further analysis
of these data continues.

The following is a list of the pumping speeds determined by Jim Irby
from pumpout rates from t=4 to t=8 seconds:

980121001 F Side Ratio Pumping Speed: 1485 l/s
980121001 B-bot MKS Pumping Speed: 1500 l/s

980121002 F Side Ratio Pumping Speed: 1791 l/s
980121002 B-bot MKS Pumping Speed: 2513 l/s

980121003 B-bot MKS Pumping Speed: 1205 l/s

980121004 F Side Ratio Pumping Speed: 1760 l/s
980121004 B-bot MKS Pumping Speed: 1264 l/s

980121005 B-bot MKS Pumping Speed: 1365 l/s

980121006 B-bot MKS Pumping Speed: 1135 l/s

980121007 B-bot MKS Pumping Speed: 1199 l/s

980121008 B-bot MKS Pumping Speed: 1223 l/s

980121009 F Side Ratio Pumping Speed: 1382 l/s
980121009 B-bot MKS Pumping Speed: 1744 l/s

980121010 B-bot MKS Pumping Speed: 1453 l/s

980121011 F Side Ratio Pumping Speed: 1790 l/s
980121011 B-bot MKS Pumping Speed: 2279 l/s

980121012 F Side Ratio Pumping Speed: 1387 l/s
980121012 B-bot MKS Pumping Speed: 1348 l/s

980121013 F Side Ratio Pumping Speed: 1320 l/s
980121013 B-bot MKS Pumping Speed: 1351 l/s

980121014 F Side Ratio Pumping Speed: 1005 l/s pump warming up
980121014 B-bot MKS Pumping Speed: 1025 l/s

980121015 F Side Ratio Pumping Speed: -18 l/s test shot/no puff
980121015 B-bot MKS Pumping Speed: **** l/s

980121016 F Side Ratio Pumping Speed: 253 l/s
980121016 B-bot MKS Pumping Speed: 208 l/s

980121017 B-bot MKS Pumping Speed: 152 l/s

980121018 B-bot MKS Pumping Speed: 306 l/s

980121019 B-bot MKS Pumping Speed: 298 l/s

980121020 B-bot MKS Pumping Speed: 199 l/s

980121021 B-bot MKS Pumping Speed: 200 l/s

980121022 B-bot MKS Pumping Speed: 240 l/s

The shot specifics follow:

Shot #1: Cryopump on. No impurity puff. nl04=1.7e20 reached. The plasma is
ohmic only and attached. Got background mesaurements with RGA for masses 4,
22 and 40.

shot #2: fizzle

shot #3: 60 ms Ne (4. PSI) from J-bottom, 35 ms Ar (1.95 PSI) from B-side lower.
no VUV data. No detachment. Ar pumping out..

shot #4: fizzle

shot #5: disrupt

shot #6: 800 kA. nl04=1.7e20. Detached at .75 -.8 seconds. Just the Ne
puff. No Ar. shot fine.

shot #7: Ar on. Ne off. Still detaching at the same time.

shot #8: disruption at .44 sec. Huge Mo injection at .29 + both Ne and Ar
injected at 0.3.

shot #9: Ar on. RF on at 2. MW. EDA mode. Ar levels in the core
go way up for the same amount puffed. Divertor levels stay constant.

shot #10: RF on. No gas puffed - baseline. Disrupted at 0.8 seconds due
to probe injection.

shot #11: Fizzle

shot #12: Ne and RF on. EDA mode but after the second Ne puff (.65 seconds)
the H-alpha rises quite a bit? Not a MARFE. No Ne data from McPherson.

shot #13: Less Ne in the second puff. VUV still not enough signal. More
constant EDA than 13.

shot #14: Same shot

shot #15: pass due to coming out of init

shot #16: cryopump off. Ne puff at 40 ms.

shot #17: disruption - too much Ne at 100 ms.

shot #18: Ar puffed. EDA mode. Level of Ar in the divertor and plasma
not very different from pumped case in initial level at least.

shot #19: Ne puffed for Jim to look at Li-like Ne.

shot #20: Back to ohmic. Ne puff (40 ms). Ne levels similar to ohmic
shot earlier with pump.

shot #21: Ar with ohmic shot.

shot #22: RF back on and EDA mode. Ne puff for Li-like Ne measurement.

Physics Operator Summaries
Entered: Jul 7 2004 04:36:58:863PM
Author: To Be Determined
Physics operator summary for run 980121.

MP 177 -- Cryopump and Impurities

SL: Lipschultz/Goetz
PO: Granetz

Summary: Despite losing several hours to cooling problems with the cryopump,
and to a VIP tour, we still managed to fill in a matrix of two
impurity gases (neon and argon), cryopump on and off, and RF on and
off. The plasma breakdown was back to normal (i.e. same as last
week), and machine reliability was also very good. Not accomplished
today: He-3 and krypton. See the session leader's report for the
science we learned today about the cryopump.

Physop things learned today: Was 2 hours of ECDC in D2 (after the
recent boronization) responsible for getting the machine back into
its normal groove? Also learned today: it ain't loaded 'til it's
loaded (into the PCS model, that is).

Scorecard: 18 plasmas
3 fizzles
0 duds
1 tests/dummy shot cycles
----------
22 total

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

Engineering Setup and Run Plan for 980121 (written by John Goetz)
MP #177 Cryopump and Impurities

Engineering setup:
ECDC in D2 for a few hours in the morning
begin as on 980116025, a slow density ramp to detachment
TF under hybrid control
Gas setup - fill K-side with 30 PSI of D2, hybrid enabled
fill B-top with 6 PSI of D2, hybrid enabled
fill B-side-lower with 2 PSI of Ar, hybrid enabled
fill J-bottom with 4 PSI of Ne hybrid enabled

ECE gate valve enabled; others if diagnosticians are ready.

Physics to be done:
Investigate impurity transport in discharges with cryopumping.
Setup discharges with divertor detachment and EDA H-modes with
the cryopump cold and puff in neon, argon, krypton, and
helium-3 (depending on number of shots of course).
Measure impurity screening, compression, and enrichment.
Toss in enough baselines to ensure that it can be
determined that the cryopump is 'doing something'
Repeat the measurements with the pump off.
Begin with the cryopump cold and try to reproduce 980116025,
which is a plasma with a slow density ramp to divertor
detachment. Begin by puffing neon and argon at 0.3sec.
[move on to the other gases and baselines]
Use 980116025 and add 2MW of RF from 0.5 to 1.2sec to get EDA
H-modes and repeat.
Guesses for the various gases to be used:
40msec of 4PSI Ne thru J-Bottom
35msec of 2PSI Ar thru B-Side-Lower
20msec of 4PSI Kr thru B-Side-Lower
60msec of 4PSI He-3 thru B-Side-Upper

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

Detailed shot log:

Note: 2 hours of ECDC in deuterium was done prior to today's run.

Hybrid coldstart done; no errors found
($set default cmod$models:[hybrid.tcl]
$@hybinit_dispatch
$@show_bitbus_log
Use editor search to verify no occurrences of "error" nor
"not respond")
Reload plasma shot 980116025 (1 MA, 5.7 T, high density ramp)
RF not needed for first part of run (could be on late in the shot)
RF feedback on RCUR is turned off (RF_LOAD_E = 0.0)

Cryopump will be cold for the beginning of the run.
No impurity puffing for first shot.

Shot 01 -- Plasma. Good shot. Cryopump was cold. No impurity puffing.
Density ramps up to nl04=1.7e20 m-2 at t=1.00 s, and then ramps
down noticeably, allowing the shot to go full length without
disrupting during rampdown. This is undoubtedly due to the
cryopump. (We wanted nl04 to reach 2e20 m-2 at t=1 s.)

Next shot: turn on argon puff (35 ms) and neon puff (60 ms) at
t=0.3 s. Turn STRKPSI feedback on earlier (0.4 s instead of 0.6 s).
Program higher density demand around 0.5 s, and open up the B-top
valve (6 psi D2) with 100 volts of pre-programmed voltage from
t=0.5 to 1.0 s.

Shot 02 -- Fizzle. Looks like Br needs a tweak.

Next shot: reduce Br from .0055 to .005 T

Shot 03 -- Plasma. Good shot. Density gets to nl04=1.85e20 m-2. Almost
didn't go. Vertical instability terminates shot a little earlier
than the previous one. Argon and neon are being puffed.

Next shot: increase density demand. Soften the turnoff of STRKPSI
control at 1.25 s (the sudden turnoff may be giving rise to the
vertical instability).

Shot 04 -- Fizzle.

Next shot: reduce Br a little more (.005 to .0045)

Shot 05 -- Plasma. Disrupted at 0.48 s.

Next shot: reduce Ip to 0.8 MA, reduce density demand to
nl04=1.7e20 m-2 at t=1.0 s. Turn off argon, but leave neon on.

Shot 06 -- Plasma. Good shot. Ip=0.8 MA. nl04=1.7e20 m-2 at 1.0 s, as
requested. Neon was on, argon was off.

Next shot: turn off neon and turn on argon. Purge neon (because
JT is seeing nitrogen with the neon). Also tweak STRKPSI to try and
satisfy Brian.

Shot 07 -- Plasma. Good shot. Argon was on, neon off. Some hard x-rays
early in the shot.

Next shot: tweak early gas puffing. More tweaks to STRKPSI, since
Brian's target didn't improve. Turn on both argon and neon. Add
a second (20 ms) puff to both gases at t=0.65 s. Reduce initial
neon puff from 60 to 40 ms.

Shot 08 -- Plasma. Disrupted at 0.45 s. It looks like we can't have both the
neon and argon on at the same time! There was also a large (moly?)
injection at 0.3 s, which may also be to blame.

Next shot: Turn off neon, leave argon on (with two puffs).
Extend density flattop to 1.2 s.

Shot 09 -- Plasma. Good shot. 2 MW of ICRF was mistakenly turned on from
t=0.5 to 1.0+ s. EDA H-mode.

Next shot: no argon nor neon. Use STRKPSI control only after
t=0.75 s, and use ZXL up to 0.745 s. Turn on 2 MW of RF (on purpose
this time).

Shot 10 -- Plasma. Disrupted at 0.81 s, probably caused by Brian's probe going
in too far.

Next shot: turn on neon, leave argon off.

There's a break for JT to get cell access to fix a problem with the McPherson.

Shot 11 -- Fizzle. Null is okay. Chalk it up to disruption recovery.

Next shot: no changes

Shot 12 -- Plasma. Good shot. Prf=2 MW from t=0.5 to 1.2 s, no faults.
ELM-free followed by EDA H-mode. Edge xrays clearly see the
2nd neon puff at 0.65 s.

Next shot: Change ZXL programming from 0.5 to 0.75 s for Brian.
Turn off B-top (D2) valve programming in segment 2. Reduce 2nd
neon puff from 20 to 12 ms.

Shot 13 -- Plasma. Good shot. Similar to previous shot. Early probe
targeting is still not satisfactory...give it up for now.

Next shot: increase first neon puff from 40 to 100 ms, and remove
2nd neon puff. Change argon to krypton in B-side-lower, but leave
disabled. Shorten He-3 puff (B-side-upper) from 60 to 20 ms, at a
pressure of 16 psi, but leave disabled.

Shot 14 -- Plasma. Good shot. Oops...operator error. I forgot to load the
lengthened neon waveform. We'll have to repeat this shot.

Next shot: repeat with no changes.

There's a break here to allow cell access. The cryopump ran out of LN2. A new
dewar will be connected up. We'll have to have a dummy shot cycle, since we
had to back out of shot 15 because of the cryopump.

Shot 15 -- Dummy shot cycle to re-align the planets and the
machine's karma.

There was a very long break here to work on the cryopump. After several hours,
it was determined that it could not be cooled down. Therefore, we will
continue with the non-cryo comparison shots.

Next shot: swap out the krypton and replace it with argon. Do not
enable the argon. Turn on neon at 0.3 s, with a pulse duration
of 40 ms.

Shot 16 -- Plasma. Good shot. Neon puffed. Prf=2 MW. This shot looks very
similar to shot 14, but without the cryopumping. JT does not get
a strong enough neon signal. Very noticeable on edge xrays though.

Next shot: increase neon puff duration to 100 ms (from 40 ms).

Shot 17 -- Plasma. Disrupted at 0.43 s, quite obviously due to too much neon.

Next shot: turn off neon, turn on argon (35 ms @ 0.3 s, no 2nd puff)

Shot 18 -- Plasma. Good shot. Argon puffed. Prf=2 MW.

Next shot: turn off argon. Turn on neon (40 ms @ 0.3 s). JT will
look at a different (and hopefully stronger) neon line.

Shot 19 -- Plasma. Good shot. Neon puffed. Prf=2 MW.

Next shot: same, except no RF. To help get the desired density in
the ohmic plasma, turn back on the B-top valve from 0.5 to 1.0 s.
Keep the neon on.

Shot 20 -- Plasma. Good shot. Neon puffed. Ohmic. nl04=1.74e20 m-2.

Next shot: turn off neon, turn on argon (35 ms @ 0.3 s). No RF.

Shot 21 -- Plasma. Good shot. Argon puffed. Ohmic.

Next shot: turn off argon, turn on neon (40 ms @ 0.3 s). Turn
RF back on.

Shot 22 -- Plasma. Good shot. Neon puffed. Prf=2 MW.

End of run.

Session Leader Comments
Jan 21 1998 09:49:41:520AM980121001Bruce LipschultzShot #1: Cryopump on. No impurity puff. nl04=1.7e20 reached. The plasma is
ohmic only and attached. Got background mesaurements with RGA for masses 4,
22 and 40.
Jan 21 1998 10:26:48:910AM980121003Bruce Lipschultzshot #3: 60 ms Ne (4. PSI) from J-bottom, 35 ms Ar (1.95 PSI) from B-side lower.
no VUV data. No detachment.
Jan 21 1998 11:37:55:610AM980121003Bruce Lipschultzshot #3: 60 ms Ne (4. PSI) from J-bottom, 35 ms Ar (1.95 PSI) from B-side lower.
no VUV data. No detachment. Ar pumping out..
Jan 21 1998 11:38:14:550AM980121006Bruce Lipschultzshot #6: 800 kA. nl04=1.7e20. Detached at .75 -.8 seconds. Just the Ne
puff. No Ar. shot fine.
Jan 21 1998 11:38:33:960AM980121007Bruce Lipschultzshot #7: Ar on. Ne off. Still detaching at the same time.
Jan 21 1998 11:57:41:230AM980121009Bruce Lipschultzshot #9: Ar on. RF on at 2. MW. EDA mode. Ar levels in the core
go way up for the same amount puffed. Divertor levels stay constant.
Jan 21 1998 12:26:45:150PM980121010Bruce Lipschultzshot #10: RF on. No gas puffed - baseline. Disrupted at 0.8 seconds due
to probe injection.
Jan 21 1998 12:53:16:950PM980121012Bruce Lipschultzshot #12: Ne and RF on. EDA mode but after the second Ne puff (.65 seconds)
the H-alpha rises quite a bit? Not a MARFE. No Ne data from McPherson.
Jan 21 1998 01:12:57:210PM980121013Bruce Lipschultzshot #13: Less Ne in the second puff. VUV still not enough signal. More
constant EDA than 13.
Jan 21 1998 03:44:26:590PM980121014Bruce Lipschultzshot 14: same as 13.
Jan 21 1998 03:45:54:040PM980121016Bruce Lipschultzshot #16: cryopump off. Ne puff at 40 ms.
Jan 21 1998 03:53:27:400PM980121017Bruce Lipschultzshot #17: disruption - too much Ne at 100 ms.
Jan 21 1998 04:14:52:520PM980121018Bruce Lipschultzshot #18: Ar puffed. EDA mode. Level of Ar in the divertor and plasma
not very different from pumped case in initial level at least.
Jan 21 1998 04:29:43:970PM980121019Bruce Lipschultzshot #19: Ne puffed for Jim to look at Li-like Ne.
Jan 21 1998 04:42:30:200PM980121020Bruce Lipschultzshot #20: Back to ohmic. Ne puff (40 ms). Ne levels similar to ohmic
shot earlier with pump.
Jan 21 1998 04:55:32:030PM980121021Bruce Lipschultzshot #21: Ar with ohmic shot.
Jan 21 1998 05:10:53:630PM980121022Bruce Lipschultzshot #22: RF back on and EDA mode. Ne puff for Li-like Ne measurement.

Physics Operator Comments
Jan 21 1998 07:53:45:510AMRobert GranetzEngineering Setup and Run Plan for 980121 (written by John Goetz)
MP #177 Cryopump and Impurities

Engineering setup:
ECDC in D2 for a few hours in the morning
begin as on 980116025, a slow density ramp to detachment
TF under hybrid control
Gas setup - fill K-side with 30 PSI of D2, hybrid enabled
fill B-top with 6 PSI of D2, hybrid enabled
fill B-side-lower with 2 PSI of Ar, hybrid enabled
fill J-bottom with 4 PSI of Ne hybrid enabled

ECE gate valve enabled; others if diagnosticians are ready.
Jan 21 1998 07:54:58:830AMRobert Granetz (con't : )
Engineering Setup and Run Plan for 980121 (written by John Goetz)
MP #177 Cryopump and Impurities

Physics to be done:
Investigate impurity transport in discharges with cryopumping.
Setup discharges with divertor detachment and EDA H-modes with
the cryopump cold and puff in neon, argon, krypton, and
helium-3 (depending on number of shots of course).
Measure impurity screening, compression, and enrichment.
Toss in enough baselines to ensure that it can be
determined that the cryopump is 'doing something'
Repeat the measurements with the pump off.
Begin with the cryopump cold and try to reproduce 980116025,
which is a plasma with a slow density ramp to divertor
detachment. Begin by puffing neon and argon at 0.3sec.
[move on to the other gases and baselines]
Use 980116025 and add 2MW of RF from 0.5 to 1.2sec to get EDA
H-modes and repeat.
Guesses for the various gases to be used:
40msec of 4PSI Ne thru J-Bottom
35msec of 2PSI Ar thru B-Side-Lower
20msec of 4PSI Kr thru B-Side-Lower
60msec of 4PSI He-3 thru B-Side-Upper
Jan 21 1998 08:40:12:650AMRobert Granetz Note: 2 hours of ECDC in deuterium was done prior to today's run.

Hybrid coldstart done; no errors found
($set default cmod$models:[hybrid.tcl]
$@hybinit_dispatch
$@show_bitbus_log
Use editor search to verify no occurrences of "error" nor
"not respond")
Reload plasma shot 980116025 (1 MA, 5.7 T, high density ramp)
RF not needed for first part of run (could be on late in the shot)
RF feedback on RCUR is turned off (RF_LOAD_E = 0.0)

Cryopump will be cold for the beginning of the run.
No impurity puffing for first shot.
Jan 21 1998 09:40:13:070AM980121001Robert GranetzShot 01 -- Plasma. Good shot. Cryopump was cold. No impurity puffing.
Density ramps up to nl04=1.7e20 m-2 at t=1.00 s, and then ramps
down noticeably, allowing the shot to go full length without
disrupting during rampdown. This is undoubtedly due to the
cryopump. (We wanted nl04 to reach 2e20 m-2 at t=1 s.)

Next shot: turn on argon puff (35 ms) and neon puff (60 ms) at
t=0.3 s. Turn STRKPSI feedback on earlier (0.4 s instead of 0.6 s).
Program higher density demand around 0.5 s, and open up the B-top
valve (6 psi D2) with 100 volts of pre-programmed voltage from
t=0.5 to 1.0 s.
Jan 21 1998 10:11:14:500AM980121002Robert GranetzShot 02 -- Fizzle. Looks like Br needs a tweak.

Next shot: reduce Br from .0055 to .005 T
Jan 21 1998 10:29:18:790AM980121003Robert GranetzShot 03 -- Plasma. Good shot. Density gets to nl04=1.85e20 m-2. Almost
didn't go. Vertical instability terminates shot a little earlier
than the previous one. Argon and neon are being puffed.

Next shot: increase density demand. Soften the turnoff of STRKPSI
control at 1.25 s (the sudden turnoff may be giving rise to the
vertical instability).
Jan 21 1998 11:10:42:570AM980121004Robert GranetzShot 04 -- Fizzle.

Next shot: reduce Br a little more (.005 to .0045)
Jan 21 1998 10:51:50:900AM980121005Robert GranetzShot 05 -- Plasma. Disrupted at 0.48 s.

Next shot: reduce Ip to 0.8 MA, reduce density demand to
nl04=1.7e20 m-2 at t=1.0 s. Turn off argon, but leave neon on.
Jan 21 1998 11:10:08:400AM980121006Robert GranetzShot 06 -- Plasma. Good shot. Ip=0.8 MA. nl04=1.7e20 m-2 at 1.0 s, as
requested. Neon was on, argon was off.

Next shot: turn off neon and turn on argon. Purge neon (because
JT is seeing nitrogen with the neon). Also tweak STRKPSI to try and
satisfy Brian.
Jan 21 1998 11:25:12:000AM980121007Robert GranetzShot 07 -- Plasma. Good shot. Argon was on, neon off. Some hard x-rays
early in the shot.

Next shot: tweak early gas puffing. More tweaks to STRKPSI, since
Brian's target didn't improve. Turn on both argon and neon. Add
a second (20 ms) puff to both gases at t=0.65 s. Reduce initial
neon puff from 60 to 40 ms.
Jan 21 1998 11:37:38:590AM980121008Robert GranetzShot 08 -- Plasma. Disrupted at 0.45 s. It looks like we can't have both the
neon and argon on at the same! There was also a large (moly?)
injection at 0.3 s, which may also be to blame.

Next shot: Turn off neon, leave argon on (with two puffs).
Extend density flattop to 1.2 s.
Jan 21 1998 11:55:09:370AM980121009Robert GranetzShot 09 -- Plasma. Good shot. 2 MW of ICRF was mistakenly turned on from
t=0.5 to 1.0+ s. EDA H-mode.

Next shot: no argon nor neon. Use STRKPSI control only after
t=0.75 s, and use ZXL up to 0.745 s. Turn on 2 MW of RF (on purpose
this time).
Jan 21 1998 12:21:40:220PM980121010Robert GranetzShot 10 -- Plasma. Disrupted at 0.81 s, probably caused by Brian's probe going
in too far.

Next shot: turn on neon, leave argon off.

There's a break for JT to get cell access to fix a problem with the McPherson.
Jan 21 1998 12:33:25:260PM980121011Robert GranetzShot 11 -- Fizzle. Null is okay. Chalk it up to disruption recovery.

Next shot: no changes
Jan 21 1998 12:49:31:970PM980121012Robert GranetzShot 12 -- Plasma. Good shot. Prf=2 MW from t=0.5 to 1.2 s, no faults.
ELM-free followed by EDA H-mode. Edge xrays clearly see the
2nd neon puff at 0.65 s.

Next shot: Change ZXL programming from 0.5 to 0.75 s for Brian.
Turn off B-top (D2) valve programming in segment 2. Reduce 2nd
neon puff from 20 to 12 ms.
Jan 21 1998 01:15:06:960PM980121013Robert GranetzShot 13 -- Plasma. Good shot. Similar to previous shot. Early probe
targeting is still not satisfactory...give it up for now.

Next shot: increase first neon puff from 40 to 100 ms, and remove
2nd neon puff. Change argon to krypton in B-side-lower, but leave
disabled. Shorten He-3 puff (B-side-upper) from 60 to 20 ms, at a
pressure of 16 psi, but leave disabled.
Jan 21 1998 01:38:03:760PM980121014Robert GranetzShot 14 -- Plasma. Good shot. Oops...operator error. I forgot to load the
lengthened neon waveform. We'll have to repeat this shot.

Next shot: repeat with no changes.
Jan 21 1998 01:39:28:990PM980121015Robert GranetzThere's a break here to allow cell access. The cryopump ran out of LN2. A new
dewar will be connected up. We'll have to have a dummy shot cycle, since we
had to back out of shot 15 because of the cryopump.

Shot 15 -- Dummy shot cycle to re-align the planets and the
machine's karma.
Jan 21 1998 03:24:29:480PM980121015Robert GranetzThere was a very long break here to work on the cryopump. After several hours,
it was determined that it could not be cooled down. Therefore, we will
continue with the non-cryo comparison shots.

Next shot: swap out the krypton and replace it with argon. Do not
enable the argon. Turn on neon at 0.3 s, with a pulse duration
of 40 ms.
Jan 21 1998 03:45:00:500PM980121016Robert GranetzShot 16 -- Plasma. Good shot. Neon puffed. Prf=2 MW. This shot looks very
similar to shot 14, but without the cryopumping. JT does not get
a strong enough neon signal. Very noticeable on edge xrays though.

Next shot: increase neon puff duration to 100 ms (from 40 ms).
Jan 21 1998 03:55:14:510PM980121017Robert GranetzShot 17 -- Plasma. Disrupted at 0.43 s, quite obviously due to too much neon.

Next shot: turn off neon, turn on argon (35 ms @ 0.3 s, no 2nd puff)
Jan 21 1998 04:07:10:460PM980121018Robert GranetzShot 18 -- Plasma. Good shot. Argon puffed. Prf=2 MW.

Next shot: turn off argon. Turn on neon (40 ms @ 0.3 s). JT will
look at a different (and hopefully stronger) neon line.
Jan 21 1998 04:22:02:400PM980121019Robert GranetzShot 19 -- Plasma. Good shot. Neon puffed. Prf=2 MW.

Next shot: same, except no RF. To help get the desired density in
the ohmic plasma, turn back on the B-top valve from 0.5 to 1.0 s.
Keep the neon on.
Jan 21 1998 04:34:31:250PM980121020Robert GranetzShot 20 -- Plasma. Good shot. Neon puffed. Ohmic. nl04=1.74e20 m-2.

Next shot: turn off neon, turn on argon (35 ms @ 0.3 s). No RF.
Jan 21 1998 04:57:02:970PM980121021Robert GranetzShot 21 -- Plasma. Good shot. Argon puffed. Ohmic.

Next shot: turn off argon, turn on neon (40 ms @ 0.3 s). Turn
RF back on.
Jan 21 1998 04:59:39:080PM980121022Robert GranetzShot 22 -- Plasma. Good shot. Neon puffed. Prf=2 MW.

End of run.

Engineering Operator Comments
ShotTimeTypeStatusComment
108:59:30:500AMPlasmaOk
210:05:04:990AMPlasmaOk
310:13:26:780AMPlasmaOk
410:30:27:300AMPlasmaOk
510:40:43:730AMPlasmaOk
610:53:08:810AMPlasmaOk
711:11:12:830AMPlasmaOk
811:26:51:060AMPlasmaOk
911:41:52:400AMPlasmaOk
1011:57:37:160AMPlasmaOk
1112:26:08:150PMPlasmaOk
1212:35:32:750PMPlasmaOk
1312:53:23:280PMPlasmaOk
1401:17:02:380PMTestOk
1501:30:11:380PMTestOkno power test shot
1603:34:45:100PMTestOk
1703:48:36:310PMTestOk
1804:00:35:970PMPlasmaOk
1904:15:12:760PMPlasmaOk
2004:28:45:300PMPlasmaOk
2104:41:40:020PMPlasmaOk
2204:54:55:890PMPlasmaOk