Alcator C-Mod Run 951208 Information

Miniproposals

Miniproposal: 129a

Date Filed: 12/4/1995

Title: Impurity screening in limiter discharges

First Author: Gary McCracken

Session Leader: Gary McCracken (shots 1-41)

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

Engineering Operator Run Comment
Goetz/McCracken

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:14:617PM

Author: To Be Determined

Run Summary 951208 (Friday).
MiniProposal #129, Impurity screening in limiter discharges

SL G M McCracken
PO J Goetz/R Granetz
EO F Silva/J Daigle
Purpose:(1) To measure screening of recycling(Ar)and non-recycling (N2)
impurities in limiter geometry as a function of nebar and poloidal injection
position.
(2) To study SOL parameters, ne, Te and flow profiles in limited plasmas.

There was an initial problem with the limited discharge which
resulted in not getting a satisfactory background shot,nl04= 1.1e20/m2, until
#010. (We also had alternator problems.) We then started puffing argon and
in the shots up to #021 we varied the argon puffing position from the inner
wall to the divertor and the outer wall using the NINJA capillary system.
Best puffing conditions were: Plenum pressure 26 torr ;. Trigger time - 0.4 s
for 0.3 s. Because of the low plenum pressure the Ar did not get in until
about 0.7 s
The Hirex results were good and there appears to be factor of 2 better
screening when puffing on the outside and at the bottom compared with puffing
on the inside wall. When we changed to the diverted discharges, shots #022
-026, the central Hirex signals and calculated Ar densites were a factor of
typically 8 lower than the limiter discharges. We went back to a limiter
discharge (#027) after the the divertor discharges and it reproduced the
earlier ones well. Due to the delays we decided to study only one density
and concentrate on the comparison of different poloidal positions.
We started the nitrogen injection at shot #028 injecting with NINJA
into a limiter discharge at the inner midplane B16-001. The plenum pressure
was 285 torr which was the same value as used in divertor discharges on run
951205. We had a big disruption about 100 ms after the N went in. It then took
4 fizzles before we recovered. Shot #034 was good but without any N injection.
We put N in from the outer midplane later in the shot. It again disrupted
about 100 ms after the N injection. It is clear that the limiter discharges
will not take the N puff rates which we have needed in earlier divertor runs
just to get a measurable signal. We therfore reduced the plenum pressure to
143 torr for the rest of the run and concentrated on the limited shots. We got
a set of discharges with injection from the outer midplane (#037), from the
divertor (# 040) and from the inner wall (#041) as well as 2 background
shots(#033 and 039). Good McPherson data was obtained which showed the same
poloidal dependence of screening as argon. N densities have still to be
calculted using MIST.
There is Chromex data for both the N and the Ar at the midplane and in
the divertor. The signals are fairly small. There seems to be a delay between
the Chromex signals and both the Hirex and the McPherson data.
We had a succesful day with the scanning probe getting good n_e and T_e
profiles in the SOL. There was an interesting contrast between the limiter and
divertor profiles. T_e was ~30 eV in limiter discharges, compared to ~50eV in
diverted discharges. n_e was also lower in limited discharges. These
differences would account, at least in part, for the lower screening in limiter
discharges.

Summary: A succesful day in that good comparisons of Ar screening were made as
a function of poloidal injection position for both limited and diverted
discharges. Ar screening was about 8 times better in diverted than in limiter
discharges.
Nitrogen screening as a function of poloidal position was made in
limited discharges only. Because of a variety of difficulties the results were
only obtained for one value of density, nl04 = 1.1e20 m^-2. It would be nice
to have another run to complete the program.

Detailed shot sequence plan

1. Fizzle
2. No Ar puff. nl04=1.1e20, Zeff about 2
3. No Ar puff, Zeff still high
4. Fizzle
5. Fizzle
6. Plasma, but disrupted at 0.7 s. Too much argon.
7. Alternator problem
8. Fizzle
9. Plasma, no Ar, but a lot of X-rays at the start.
10. Good background shot. No Ar. nl04 = 1.1e20
11. First shot with Ar; puff B-side lower, 4.5 psi; Trigger at .3 s for 20 ms
12 NINJA puff, Inner wall B16-001, Plenum 56 torr; trigger at 0.1 s for 0.1 s
too much argon
13. NINJA puff Inner wall B16-001, Plenum 26 torr; trigger at 0.1 s for 0.1 s
14. Alternator problem
15. Fizzle
16. EF4 problem
17 Good shot, NINJA Ar puff at inner wall, plenum pressure 26 torr,
trigger at 0.1s for 0.3 s
18. Good shot, NINJA Ar puff at inner wall, 26 torr,
trigger at - 0.3 s for 0.3 s
19. Good shot, Ar puff, at outer divertor B31-038, 26 torr,
trigger at - 0.3s for 0.3 s
20. Good shot,No Ar: background
21. Good shot, Ar puff, outer wall, B33-001, trigger as #019
22. First diverted shot; no Ar puff
23. Diverted, Ar puff at inner wall, 26 torr, trigger at - 0.3 s for 0.3 s
24. Diverted, Ar puff at outer wall, as #023
25. Diverted, Ar puff at outer divertor,B31-036,as #023
26. Diverted; no Ar puff
27. Limiter shot, Ar puff, outer wall; good repeat of #021
28. Limiter shot, N2 puff, inside wall, Plenum 284 torr.
Trigger at 0.1 s for 0.3 s; disruption ~0.1 s after
N goes in. Too much.
29. Fizzle
30. Fizzle
31. Fizzle
32. Fizzle
33. Limiter shot, no N, good background shot.
34. Limiter shot, N2 puff, outside wall, Plenum 285 torr.
Trigger at 0.5 s for 0.3 s
disruption ~0.1 s after N goes in. Still too much.
35. Fizzle
36. Fizzle
37. Good limiter shot, N2 puff, outside wall, Plenum 143 torr.
Trigger at 0.5 s for 0.3 s.
38. Fizzle.
39. Limiter shot; no N, good background shot
40. Good limiter shot, N2 puff, outside divertor, Plenum 148 torr.
Trigger at 0.5 s for 0.3 s.
41. Good limiter shot, N2 puff,inside wall, Plenum 148 torr.
Trigger at 0.5 s for 0.3 s.

Physics Operator Summaries

Entered: Jul 7 2004 04:36:55:550PM

Author: To Be Determined

Physics Operator's summary for run 951208

MP #129 Impurity screening in limiter discharges

SL: G. McCracken
PO: R. Granetz (initial setup by John Goetz)
EO: V. Bertolino

Today's run plan: Start from 950526038, which was a limited plasma from the
last time we did a limiter screening run. Puff in both argon and
nitrogen via NINJA and B-side valve. We will also do some diverted
discharges for comparison.

Summary: We had intended to do screening measurements with argon and nitrogen,
from several different NINJA capillary locations, at several different
densities, comparing between limiter and divertor configurations.
Because of numerous problems early on, we scrapped the density scans,
and got only limiter nitrogen data (due to disruptions), but
completed the rest of the parameter scan for argon. Surprisingly,
the ratio of screening between similar divertor and limiter plasmas
is about a factor of 8-10 for argon (recycling impurity), which is
quite a bit better than the factor of 2 obtained from previous runs.
These numbers are for puffing from both the outboard midplane and the
private flux zone. The ratio is even higher (above 15) when puffing
from the inboard midplane, presumably because the limiter plasma has
no SOL there. One possible reason for the difference between today's
results and last year's results, as suggested by John Goetz, might be
the modification done this past summer to plug up the leak paths
around the divertor.

Phys Op stuff: most of the difficulties today were with recovery from limiter
disruptions. The disruptions were apparently caused by too much
impurity puffing. The problem was that it would take 2, 3, or even
4 fizzles before plasma was recovered. Carbon levels were high
following disruptions. Other than this, the only other problems were
several faults with the alternator, and a single EF4 fault.

Scorecard: 26 plasmas
13 fizzles
2 duds (both due to alternator problems)
----------
41 total

Run setup:

Start with shot 950526038, except load in segment 1 from yesterday's
fiducial shot 951207025. (We didn't actually load in the new segment 1
until after shot 1, due to a bug in the copy_segment routine.
John Goetz did the necessary changes to the EF2 and EF4 controllers
to account for the new power supplies.
Discharge clean as usual in deuterium before the run
Fill B-side plenum with 4 psi of argon

Detailed shot log:

Shot 01 -- Fizzle.

Next shot: load segment 1 from yesterday's fiducial shot 951207025.

Shot 02 -- Plasma, limited. Some hard x-rays. nl_04=1.15e20, which is
slightly higher than requested, but the valve closes all the way.
3 cm outer gap, scanning probe can't quite make it.

Next shot: add 20 ms to the pre-shot gas pulse. Increase RCUR by
5 mm.

Shot 03 -- Plasma, limited. nl_04=1.15e20 m-2. RCUR increased by 5 mm, but
scanning probe still can't hit it. That's probably because we
have FSP control turned on (inherited from last May's shot).

Next shot: change FSP location by -7.5 mm (on advice from Brian).

Shot 04 -- Fizzle. No obvious reason why.

Next shot: no changes

Shot 05 -- Fizzle.

Next shot: tweak Br by -0.0005 T and decrease pre-pulse gas by
1 ms.

Shot 06 -- Plasma, but disrupted at 0.7 s due to large amount of argon coming
in at 0.6 s. This is not what was programmed for the argon valve.
John Goetz has just realized that I had segment 4 turned on rather
than segment 2. I don't know how that happened. Segment 4 had a
very large puff enabled for the argon valve, so that explains it.

Next shot: enable segment 2 and turn off segment 4. Disable argon
valve. Reduce RCUR by 5 mm to get it back to the original value,
but keep FSP at the new reduced value.

Shot 07 -- Dud. Alternator problem. We've just realized that John made a
mistake when he started off with shot 1. He thought that segment
2 was a limited plasma, when actually it was for a lower x-pt
diverted plasma, and segment 4 was for a limited plasma.

Next shot: switch back to segment 4, copy FSP from seg 2 to seg 4,
and copy pulse gas 1 programming from seg 2 to seg 4.

Shot 08 -- Fizzle. Steve Wolfe reports high carbon levels.

Next shot: no changes

Shot 09 -- Plasma, good limited shot. Some hard x-rays. Brian reports that
the scanning probe will be able to reach the plasma.

Next shot: increase pre-pulse gas duration by 1 ms and repeat (still
with no argon)

Shot 10 -- Plasma, good shot. No hard x-rays. Brian fired the probe on this
shot.

Next shot: enable 20 ms argon puff at t=0.300 s.

Shot 11 -- Plasma, good shot, with argon puff from B-side-lower valve.

Next shot: turn off B-side argon puff and enable NINJA argon puff
from inboard midplane. NINJA Plenum pressure is 0.5 psi.

Shot 12 -- Plasma. Disrupted at 1.18 s. Soft x-rays were greatly increased
by the NINJA argon puff.

Next shot: reduce NINJA plenum pressure from 0.5 to about 0.25 psi,
and also tweak FSP control by a few mm.

Shot 13 -- Fizzle.

Next shot: repeat with no changes.

Shot 14 -- Dud. Alternator failure.

Next shot: try again with no changes.

Shot 15 -- Fizzle. Null looks acceptable.

Next shot: reduce pre-pulse gas puff by 1 ms and retry.

Shot 16 -- Plasma, but terminated at 0.522 s due to EF4 fault at 0.33 s.

Next shot: try again.

Shot 17 -- Plasma, good shot, with NINJA inboard midplane argon puff. The
argon showed up at about t=0.8 s, which is later than we want.

Next shot: move NINJA puff earlier by 0.3 s and repeat.

Shot 18 -- Plasma, good shot, with NINJA inboard midplane argon puff.
nl_04=1.15e20 m-2.

Next shot: Use NINJA argon puff from the capillary in the private
flux zone.

Shot 19 -- Plasma, good shot, with NINJA argon puff from private flux zone at
a density of nl_04=1.15e20 m-2. Limited (as all previous shots
today have been)

Gary reports that only half as much argon gets into the plasma
compared to puffing at the inboard midplane. This is presumably
due to the effect of the SOL.

Next shot: same shot, but without any argon puffing.

Shot 20 -- Plasma, good shot. No argon puff.

Next shot: same plasma, but puff argon with NINJA from an outboard
midplane capillary.

Shot 21 -- Plasma, good shot. Limiter plasma, NINJA argon puff from outboard
midplane.

Next shot: load in the "fiducial" shot (951207025). This is a
lower x-point diverted plasma at nl_04=1.0e20 m-2 and Ip=0.8 MA.
No argon puffing.

Shot 22 -- Plasma, good fiducial shot. Diverted, nl_04=0.95e20 m-2. No
argon.

Next shot: same diverted shot, with NINJA argon puffing from
inboard midplane capillary.

Shot 23 -- Plasma, good diverted shot at nl_04=0.95e20 m-2 and with NINJA
argon puffing from the inboard midplane.

Next shot: same, except NINJA argon puff from outboard midplane.

Shot 24 -- Plasma, good diverted shot at nl_04=0.95e20 m-2, with NINJA
argon puffing from the outboard midplane.

Next shot: same, except NINJA argon puff from the private flux
zone capillary.

Shot 25 -- Plasma, good diverted shot at nl_04=0.95e20 m-2, with NINJA
argon puffing from the private flux zone.

Next shot: same, except no Ar puffing (i.e. another fiducial shot)

Shot 26 -- Plasma, good diverted shot, nl_04=0.95e20 m-2, no NINJA argon
puff. The argon signals are clearly lower than they were on the
preceding diverted shots.

Next shot: return to limiter configuration (re-load 951208021), with
NINJA argon puffing from outboard midplane.

Shot 27 -- Plasma, good limiter shot, nl_04=1.2e20 m-2, argon puff from NINJA
outboard midplane. Argon signals are back up to the levels seen
in the earlier limiter shots today.

The screening ratio is coming out to be about a factor of 8! (and
even more when puffing directly into the inboard midplane. John
Goetz has suggested that this high ratio, compared to last spring's
measurements, may be due to the closing off of the divertor leaks
and the subsequent higher compression ratio.

Next shot: change from argon to nitrogen, from the NINJA inboard
midplane location.

Shot 28 -- Plasma, limited, disrupted at t=0.48 s, with nitrogen puffing
from the NINJA inboard midplane. The radiation signals were
rising, but I don't know if they were high enough to cause this
disruption.

Next shot: puff nitrogen from the NINJA outboard wall, and delay
the puff by 0.2 s (It's hitting now around t=0.4 s.)

Shot 29 -- Fizzle. Probably due to the preceding disruption.

Next shot: try again

Shot 30 -- Fizzle. Null looks acceptable.

Next shot: decrease pre-pulse puff duration by 1 ms and try again.
Also, no nitrogen puff on the next shot.

Shot 31 -- Fizzle.

Next shot: reduce Br by 0.005 T

Shot 32 -- Fizzle.

Next shot: decrease pre-pulse puff duration by another 1 ms and
try again.

Shot 33 -- Plasma, limited, nl_04=1.1e20 m-2. No nitrogen puff. There were some
hard x-rays.

Next shot: increase pre-pulse puff duration by 1 ms and turn on
nitrogen puff from NINJA outboard midplane.

Shot 34 -- Plasma, disrupted at 0.79 s. Limited, nl_04=1.2e20 m-2, nitrogen
puff from outboard midplane. Radiation levels do not rise before
the disruption, so I don't think the nitrogen caused this
disruption.

Next shot: switch back to the fiducial diverted plasma (951207025).
Keep the NINJA nitrogen puff turned on (outer midplane).

Shot 35 -- Fizzle. No surprise.

Next shot: return to limiter configuration (re-load 951208034).
Reduce NINJA plenum pressure from 5 to 2.5 psi, and keep the
outboard midplane puff enabled.

Shot 36 -- Fizzle.

Next shot: try again, no changes

Shot 37 -- Plasma, limited, nl_04=1.2e20, nitrogen puffing from NINJA outboard
midplane. Some hard x-rays.

Next shot: same, except puff nitrogen from the NINJA private flux
zone capillary.

Shot 38 -- Fizzle. Null looks acceptable.

Next shot: try again, but turn off nitrogen puffing to get a
background.

Shot 39 -- Plasma, limited, nl_04=1.2e20 m-2, no nitrogen puffing.

Next shot: same, except enable NINJA puff from private flux zone.

Shot 40 -- Plasma, limited, nl_04=1.2e20 m-2, nitrogen puff from private flux
zone.

Next shot: same, except enable NINJA puff from inboard midplane.

Shot 41 -- Plasma, limited, nl_04=1.2e20 m-2, nitrogen puff from inboard
midplane, plasma survived this puff.

End of run

Session Leader Comments

Dec 8 1995 08:20:49:790AM Gary McCracken Impurity Screening in limiter Discharges

MP 129
Objectives: To measure screening of Ar and N impurities injected
into limiter discharges. To measure SOL parameters in limiter
discharges

Dec 10 1995 12:54:10:390PM Gary McCracken Summary: Despite the difficulties and the small number of shots , it
was an interesting and useful run. The principal result is that there
is a much bigger difference between divertor and limiter screening of Ar
now than we have seen before. For the Hirex data there was about a
factor 8 more Ar atoms in the plasma in limiter than in divertor
discharges. For Ar into limiter discharges there was also better
screening when puffing at the outside or the bottom than when puffing at
the inner wall (by about a factor 2).
We only managed to do limiter discharges with N2 puffing. Here
again the screening was about a factor of 2-3 better for outside or
divertor puffing than inner wall. Comparison with previous divertor
shots indicates that N screeing is much poorer with the limiter
Overall I think the work justifies another run to see the density
dependence of limiter screening

Dec 8 1995 08:57:04:790AM 951208001 Gary McCracken Plan to have a limiter shot with nl04=1e20. No argon injection, but
look at background spectra. Fizzle

Dec 8 1995 09:22:27:310AM 951208002 Gary McCracken Quite good limiter shot with nl04=1.15e20. No argon injection.
LCFS too far from the scanning probe. Will move it closer next shot
Zeff high due to not enough prefill.

Dec 8 1995 09:34:19:950AM 951208003 Gary McCracken Limiter shot with nl04=1.15e20. Still no argon injection.
LCFS still out of range for FSP. Zeff still high, 1.8

Dec 8 1995 09:39:50:310AM 951208004 Gary McCracken Supposed to be first shot with argon injection
B-side lower 4 psi, trigger at 0.3 s for 20 ms
Fizzle

Dec 8 1995 09:48:59:260AM 951208005 Gary McCracken Fizzle

Dec 8 1995 10:03:40:020AM 951208006 Gary McCracken Plasma,but disrupted at 0.7 s
Argon was incorrectly injected at 0.6 s for 0.2 s
Curiously the Hirex signal was high at the beginning of the shot before
the Ar went in.

Dec 8 1995 10:15:10:200AM 951208007 Gary McCracken No plasma, alternator problem.

Dec 8 1995 10:15:32:780AM 951208008 Gary McCracken Fizzle

Dec 8 1995 10:41:03:040AM 951208009 Gary McCracken Better shot, but hard Xrays. No Hirex data because of Xrays
No argon injected. Chromex ok

Dec 8 1995 10:50:44:830AM 951208010 Gary McCracken Better shot, X-rays lower. Hirex still has Xray background but no clear
Ar peak on the Chromex. We will take this as our background shot
nl04=1.1e20

Dec 8 1995 10:57:37:030AM 951208011 Gary McCracken Good shot nl04=1.1e20.
Ar injection from B-side lower , 4psi, trigger at 0.3 s for 20 ms
some Ar on chromex but not till after o.7 s

Dec 8 1995 11:10:19:180AM 951208012 Gary McCracken Good shot nl04=1.1e20.
Ar injection from NINJA inner wall B16-001 , 56 torr, trigger at
0.2 s for 100 ms
Ar clear on HIREX coming in at about 0.7 s and climbing to 600 counts/s
Chromex showed ARII line at 442.6 nm. It started to climb at 0.75s
and reached ~4000 c/s
Shot disrupted on current ramp down. Need to reduce Ar input for next
shot. We will lower the plenum pressure

Dec 8 1995 11:32:02:150AM 951208013 Gary McCracken Reduce Ar plenum pressure to 26 torr
Ar injection from NINJA inner wall B16-001, trigger at
-0.1 s for 100 ms to get Ar in earlier
Fizzle. Due to disruption on previous shot?

Dec 8 1995 11:48:37:850AM 951208014 Gary McCracken Ar injection from NINJA inner wall B16-001, pressure trigger at
-0.1 s for 100 ms to get Ar in earlier
No plasma. Alernator problem

Dec 8 1995 11:59:05:570AM 951208015 Gary McCracken Ar injection from NINJA inner wall B16-001, pressure 26 torr trigger at
-0.1 s for 100 ms
Fizzle.

Dec 8 1995 12:19:20:470PM 951208016 Gary McCracken Ar injection from NINJA inner wall B16-001, pressure 26 torr trigger at
-0.1 s for 100 ms
Disruption at 0.5 s. EF4 PS problem

Dec 8 1995 12:37:04:680PM 951208017 Gary McCracken Ar injection from NINJA inner wall B16-001, pressure 26 torr trigger at
-0.1 s for 100 ms
Good shot with Ar but it doesn't come in until about 0.8 s. Seen on
HIrex bu not on Chromex
Bring Ar trigger forward on next shot

Dec 8 1995 12:44:15:250PM 951208018 Gary McCracken Ar injection from NINJA inner wall B16-001, pressure 26 torr trigger at
-0.3 s for 100 ms
Good shot with Ar in at about 0.6 s. Seen on Hirex
Seen on Chromex staring at 0.8 s
Change Ar injection position to divertor next shot

Dec 8 1995 12:57:26:140PM 951208019 Gary McCracken Ar injection from NINJA divertor B31-038, pressure 26 torr trigger at
-0.3 s for 100 ms
Good shot with Ar in at about 0.6 s. Seen on Hirex ;slightely lower
than inner wall injection
No Ar for next shot

Dec 8 1995 01:07:00:840PM 951208020 Gary McCracken Still limiter shot, but no N injection to get background
Good background signal of about 20 counts/s on Hirex.
Background very small on Chromex

Dec 8 1995 01:18:27:170PM 951208021 Gary McCracken Ar injection from NINJA outer wall, B33-001` on AB limiter
Trigger at -0.4 s for 0.1 s. Pressure still 26 torr
Godd Hirex signal. Similar to divertor injection position
and lower than the inner wall injection position

Dec 8 1995 01:25:53:750PM 951208022 Gary McCracken First divertor shot. Standard fiducial shot
No argon injection. Background ~ 5 counts/s , much lower
than limiter shot.

Dec 8 1995 01:40:52:200PM 951208023 Gary McCracken Second divertor shot. Standard fiducial shot except for Ar injection
Argon injection at inner wall midplane B16-001 .
Trigger -0.4 s for 0.1 s Pressure =26 torr
Hirex rises to 20 counts/s at 1.0 s. Much lower than limited shots

Dec 8 1995 01:54:06:430PM 951208024 Gary McCracken Third divertor shot. Standard fiducial shot except for Ar injection
Argon injection at outer wall midplane B33-001 .
Trigger -0.4 s for 0.1 s Pressure =26 torr
Hirex signal confusing. No clear Ar rise during shot

Dec 8 1995 02:02:49:380PM 951208025 Gary McCracken Fourth divertor shot. Standard fiducial shot except for Ar injection
Argon injection at divertor B31-038 .
Trigger -0.4 s for 0.1 s Pressure =26 torr
Very smal rise in Ar on Hirex. close to the noise level

Dec 8 1995 02:14:21:230PM 951208026 Gary McCracken Fifth divertor shot. Standard fiducial shot
No Ar injection
Hirex signal low, about 3 counts/s, so the argon does seem to have
been getting in in the diverted shots
We will go back to the limited shot with Ar injection just to make sure

Dec 8 1995 02:32:07:500PM 951208027 Gary McCracken Limited shot with Ar injection from NINJA outer limiter B33-001
Trigger -0.4 for 0.1 s . Pressure 26 torr
Hirex rise to just over 100 counts/s. Very good reproducibilty
with previous limited shot #021. So there is very striking difference
the screening of the limited and diverted shots

Dec 8 1995 02:51:21:830PM 951208028 Gary McCracken Change to Nitrogen injection. Plenum pressure at 284 torr
Limited shot with N injection from NINJA inner limiter B16-001
Trigger at 0.1 for 0.3 s. Goes in at 0.3 s from CCD NII filter
looking at inner wall.
Disruption at 0.47 s. Not clear whetther it was due to the N or to
a tile problem

Dec 8 1995 03:02:05:760PM 951208029 Gary McCracken Nitrogen injection. Plenum pressure at 284 torr
Limited shot with N injection from NINJA outer limiter B33-001
Trigger at 0.5 for 0.3 s.
Fizzle

Dec 8 1995 03:05:38:270PM 951208030 Gary McCracken Nitrogen injection. Plenum pressure at 284 torr
Limited shot with N injection from NINJA outer limiter B33-001
Trigger at 0.5 for 0.3 s.
Fizzle again!

Dec 8 1995 03:18:51:330PM 951208031 Gary McCracken Stopped N injection for this shot
Limited .
Fizzle again

Dec 8 1995 03:39:56:610PM 951208032 Gary McCracken Stopped N injection for this shot
Limited .
Fizzle again

Dec 8 1995 03:40:48:040PM 951208033 Gary McCracken Stopped N injection for this shot
Limited .
Good shot. Background
We will turn the N on again for the nest shot

Dec 8 1995 04:05:10:170PM 951208034 Gary McCracken N injection at outer midplane B33-001. Plenum pressure 284 torr
Trigger 0.5 s for 0.3 s
Limited . Discharge disrupted at 0.8 s ie about 150 ms after the N started to go
in. It looks as if the limited discharges will simply not take this
much N even though tthe diverted ones will. cf run 951205.

Dec 8 1995 04:05:57:290PM 951208035 Gary McCracken N injection at outer midplane B33-001. Plenum pressure 284 torr
Trigger 0.5 s for 0.3 s
Fiducial diverted shot.
Fizzle

Dec 8 1995 04:28:54:850PM 951208036 Gary McCracken Reduce plenum pressure to 143 torr in order to try and get some
screening measurements for limited discharges.
N injection at outer midplane B33-001. Trigger 0.5 s for 0.3 s
Limited shot.
Fizzle

Dec 8 1995 04:35:48:550PM 951208037 Gary McCracken Plenum pressure 143 torr
N injection at outer midplane B33-001. Trigger 0.5 s for 0.3 s
Limited shot. Good shot and got a reasonable signal on the McPherson,
a rise of about 1e14 units.

Dec 8 1995 04:37:35:520PM 951208038 Gary McCracken Plenum pressure 143 torr
N injection at divertor B31-038. Trigger 0.5 s for 0.3 s
Limited shot.
Fizzle

Dec 8 1995 04:47:30:380PM 951208039 Gary McCracken No N injection for a backgroundshot
Limited. Good shot

Dec 8 1995 05:03:25:530PM 951208040 Gary McCracken N injection at divertor B31-086 (divertor)
Trigger at 0.5 s for 0.3 s. Plenum pressure 143 torr
Limited.
Good shot. McPherson data good. Clear increase of the signal
above the background level of the previous shot

Dec 10 1995 12:36:55:310PM 951208041 Gary McCracken Limited shot: N puff at inner wall B16-001, plenum pressure=143 torr,
Trigger at 0.5 s for 0.3s
Good shot. Good McPherson data

Physics Operator Comments

Dec 8 1995 08:41:48:530AM John Goetz Run 951208 is in support of Mini-Proposal #129 - Impurity Screening
in Limiter Discharges

Purpose:
(1) Measure screening of recycling and non-recycling impurities
in limiter geometry as a function of density and
poloidal injection position
(2) Study SOL parameters in limited plasmas

Setup:
Load 950526038
FACTOR EF2, EF4, and EF2_BY_EF4
100V from [-.515,-.499] on PULSE_GAS_4 (K_SIDE)
100V x 0.02sec @ 0.3sec on PULSE_GAS_1 (B_SIDE_LOWER)
points at (0,100) and (.01,25) on PULSE_GAS_3 (B_TOP)
keep 951207025 in reserve for the divertor comparison shots

Dec 8 1995 09:54:00:700AM 951208001 Robert Granetz Physics Operator's summary for run 951208

MP #129 Impurity screening in limiter discharges

SL: G. McCracken
PO: R. Granetz (initial setup by John Goetz)
EO: V. Bertolino

Today's run plan: Start from 950526038, which was a limited plasma from the
last time we did a limiter screening run. Puff in both argon and
nitrogen via NINJA and B-side valve. We will also do some diverted
discharges for comparison.

Run setup:

Start with shot 950526038, except load in segment 1 from yesterday's
fiducial shot 951207025. (We didn't actually load in the new segment 1
until after shot 1, due to a bug in the copy_segment routine.
John Goetz did the necessary changes to the EF2 and EF4 controllers
to account for the new power supplies.
Discharge clean as usual in deuterium before the run
Fill B-side plenum with 4 psi of argon

Dec 8 1995 09:54:40:760AM 951208001 Robert Granetz Shot 01 -- Fizzle.

Next shot: load segment 1 from yesterday's fiducial shot 951207025.

Dec 8 1995 09:55:05:660AM 951208002 Robert Granetz Shot 02 -- Plasma, limited. Some hard x-rays. nl_04=1.15e20, which is
slightly higher than requested, but the valve closes all the way.
3 cm outer gap, scanning probe can't quite make it.

Next shot: add 20 ms to the pre-shot gas pulse. Increase RCUR by
5 mm.

Dec 8 1995 09:55:28:680AM 951208003 Robert Granetz Shot 03 -- Plasma, limited. nl_04=1.15e20 m-2. RCUR increased by 5 mm, but
scanning probe still can't hit it. That's probably because we
have FSP control turned on (inherited from last May's shot).

Next shot: change FSP location by -7.5 mm (on advice from Brian).

Dec 8 1995 09:55:39:500AM 951208004 Robert Granetz Shot 04 -- Fizzle. No obvious reason why.

Next shot: no changes

Dec 8 1995 09:55:53:070AM 951208005 Robert Granetz Shot 05 -- Fizzle.

Next shot: tweak Br by -0.0005 T and decrease pre-pulse gas by
1 ms.

Dec 8 1995 10:05:52:070AM 951208006 Robert Granetz Shot 06 -- Plasma, but disrupted at 0.7 s due to large amount of argon coming
in at 0.6 s. This is not what was programmed for the argon valve.
John Goetz has just realized that I had segment 4 turned on rather
than segment 2. I don't know how that happened. Segment 4 had a
very large puff enabled for the argon valve, so that explains it.

Next shot: enable segment 2 and turn off segment 4. Disable argon
valve. Reduce RCUR by 5 mm to get it back to the original value,
but keep FSP at the new reduced value.

Dec 8 1995 10:20:19:650AM 951208007 Robert Granetz Shot 07 -- Dud. Alternator problem. We've just realized that John made a
mistake when he started off with shot 1. He thought that segment
2 was a limited plasma, when actually it was for a lower x-pt
diverted plasma, and segment 4 was for a limited plasma.

Next shot: switch back to segment 4, copy FSP from seg 2 to seg 4,
and copy pulse gas 1 programming from seg 2 to seg 4.

Dec 8 1995 10:18:41:840AM 951208008 Robert Granetz Shot 08 -- Fizzle. Steve Wolfe reports high carbon levels.

Next shot: no changes

Dec 8 1995 10:35:24:760AM 951208009 Robert Granetz Shot 09 -- Plasma, good limited shot. Some hard x-rays. Brian reports that
the scanning probe will be able to reach the plasma.

Next shot: increase pre-pulse gas duration by 1 ms and repeat (still
with no argon)

Dec 8 1995 10:45:50:260AM 951208010 Robert Granetz Shot 10 -- Plasma, good shot. No hard x-rays. Brian fired the probe on this
shot.

Next shot: enable 20 ms argon puff at t=0.300 s.

Dec 8 1995 10:51:31:490AM 951208011 Robert Granetz Shot 11 -- Plasma, good shot, with argon puff from B-side-lower valve.

Next shot: turn off B-side argon puff and enable NINJA argon puff
from inboard midplane. NINJA Plenum pressure is 0.5 psi.

Oct 16 1996 09:17:06:490AM 951208011 Robert Granetz It is now 10 months after this run. Detailed analysis by Francesca and
myself of the argon levels on this shot with the B-side-lower valve compared
to the argon levels on later shots today using the NINJA system have led us to
believe that the B-side valve did not actually open on this shot (maybe it
opened a tiny bit, but certainly nowhere near fully open). This was the first
use of the valve during this day's run, and it is now known that the valve
sometimes `sticks' after not being used for a day.

Dec 8 1995 11:06:11:250AM 951208012 Robert Granetz Shot 12 -- Plasma. Disrupted at 1.18 s. Soft x-rays were greatly increased
by the NINJA argon puff.

Next shot: reduce NINJA plenum pressure from 0.5 to about 0.25 psi,
and also tweak FSP control by a few mm.

Dec 8 1995 11:44:08:760AM 951208013 Robert Granetz Shot 13 -- Fizzle.

Next shot: repeat with no changes.

Dec 8 1995 11:44:23:950AM 951208014 Robert Granetz Shot 14 -- Dud. Alternator failure.

Next shot: try again with no changes.

Dec 8 1995 12:04:51:160PM 951208015 Robert Granetz Shot 15 -- Fizzle. Null looks acceptable.

Next shot: reduce pre-pulse gas puff by 1 ms and retry.

Dec 8 1995 12:12:11:490PM 951208016 Robert Granetz Shot 16 -- Plasma, but terminated at 0.522 s due to EF4 fault at 0.33 s.

Next shot: try again.

Dec 8 1995 12:33:38:200PM 951208017 Robert Granetz Shot 17 -- Plasma, good shot, with NINJA inboard midplane argon puff. The
argon showed up at about t=0.8 s, which is later than we want.

Next shot: move NINJA puff earlier by 0.3 s and repeat.

Dec 8 1995 12:38:59:210PM 951208018 Robert Granetz Shot 18 -- Plasma, good shot, with NINJA inboard midplane argon puff.
nl_04=1.15e20 m-2.

Next shot: Use NINJA argon puff from the capillary in the private
flux zone.

Dec 8 1995 12:56:10:050PM 951208019 Robert Granetz Shot 19 -- Plasma, good shot, with NINJA argon puff from private flux zone at
a density of nl_04=1.15e20 m-2. Limited (as all previous shots
today have been)

Next shot: same shot, but without any argon puffing.

Dec 8 1995 01:18:30:790PM 951208019 Robert Granetz Gary reports that only half as much argon gets into the plasma
compared to puffing at the inboard midplane. This is presumably
due to the effect of the SOL.

Dec 8 1995 12:59:12:220PM 951208020 Robert Granetz Shot 20 -- Plasma, good shot. No argon puff.

Next shot: same plasma, but puff argon with NINJA from an outboard
midplane capillary.

Dec 8 1995 01:16:19:230PM 951208021 Robert Granetz Shot 21 -- Plasma, good shot. NINJA argon puff from outboard midplane.

Next shot: load in the "fiducial" shot (951207025). This is a
lower x-point diverted plasma at nl_04=1.0e20 m-2 and Ip=0.8 MA.
No argon puffing.

Dec 8 1995 01:23:36:000PM 951208022 Robert Granetz Shot 22 -- Plasma, good fiducial shot. Diverted, nl_04=0.95e20 m-2. No
argon.

Next shot: same diverted shot, with NINJA argon puffing from
inboard midplane capillary.

Dec 8 1995 01:38:10:110PM 951208023 Robert Granetz Shot 23 -- Plasma, good diverted shot at nl_04=0.95e20 m-2 and with NINJA
argon puffing from the inboard midplane.

Next shot: same, except NINJA argon puff from outboard midplane.

Dec 8 1995 01:53:54:040PM 951208024 Robert Granetz Shot 24 -- Plasma, good diverted shot at nl_04=0.95e20 m-2, with NINJA
argon puffing from the outboard midplane.

Next shot: same, except NINJA argon puff from the private flux
zone capillary.

Dec 8 1995 02:03:18:130PM 951208025 Robert Granetz Shot 25 -- Plasma, good diverted shot at nl_04=0.95e20 m-2, with NINJA
argon puffing from the private flux zone.

Next shot: same, except no Ar puffing (i.e. another fiducial shot)

Dec 8 1995 02:13:53:270PM 951208026 Robert Granetz Shot 26 -- Plasma, good diverted shot, nl_04=0.95e20 m-2, no NINJA argon
puff. The argon signals are clearly lower than they were on the
preceding diverted shots.

Next shot: return to limiter configuration (re-load 951208021), with
NINJA argon puffing from outboard midplane.

Dec 8 1995 02:30:51:140PM 951208027 Robert Granetz Shot 27 -- Plasma, good limiter shot, nl_04=1.2e20 m-2, argon puff from NINJA
outboard midplane. Argon signals are back up to the levels seen
in the earlier limiter shots today.

The screening ratio is coming out to be about a factor of 8! (and
even more when puffing directly into the inboard midplane.

Next shot: change from argon to nitrogen, from the NINJA inboard
midplane location.

Dec 8 1995 02:54:12:680PM 951208027 Robert Granetz John Goetz has suggested that this high ratio, compared to last spring's
measurements, may be due to the closing off of the divertor leaks and the
subsequent higher compression ratio.

Dec 8 1995 02:48:45:930PM 951208028 Robert Granetz Shot 28 -- Plasma, limited, disrupted at t=0.48 s, with nitrogen puffing
from the NINJA inboard midplane. The radiation signals were
rising, but I don't know if they were high enough to cause this
disruption.

Next shot: puff nitrogen from the NINJA outboard wall, and delay
the puff by 0.2 s (It's hitting now around t=0.4 s.)

Dec 8 1995 02:57:47:710PM 951208029 Robert Granetz Shot 29 -- Fizzle. Probably due to the preceding disruption.

Next shot: try again

Dec 8 1995 03:13:48:820PM 951208030 Robert Granetz Shot 30 -- Fizzle. Null looks acceptable.

Next shot: decrease pre-pulse puff duration by 1 ms and try again.
Also, no nitrogen puff on the next shot.

Dec 8 1995 03:18:18:590PM 951208031 Robert Granetz Shot 31 -- Fizzle.

Next shot: reduce Br by 0.005 T

Dec 8 1995 03:32:01:760PM 951208032 Robert Granetz Shot 32 -- Fizzle.

Next shot: decrease pre-pulse puff duration by another 1 ms and
try again.

Feb 1 1996 05:44:35:060PM 951208033 Robert Granetz Shot 33 -- Plasma, limited, nl_04=1.1e20 m-2. No nitrogen puff. There were some
hard x-rays.

Next shot: increase pre-pulse puff duration by 1 ms and turn on
nitrogen puff from NINJA outboard midplane.

Feb 1 1996 05:46:01:360PM 951208034 Robert Granetz Shot 34 -- Plasma, disrupted at 0.79 s. Limited, nl_04=1.2e20 m-2, nitrogen
puff from outboard midplane. Radiation levels do not rise before
the disruption, so I don't think the nitrogen caused this
disruption.

Next shot: switch back to the fiducial diverted plasma (951207025).
Keep the NINJA nitrogen puff turned on (outer midplane).

Dec 8 1995 04:07:06:620PM 951208035 Robert Granetz Shot 35 -- Fizzle. No surprise.

Next shot: return to limiter configuration (re-load 951208034).
Reduce NINJA plenum pressure from 5 to 2.5 psi, and keep the
outboard midplane puff enabled.

Dec 8 1995 04:18:55:320PM 951208036 Robert Granetz Shot 36 -- Fizzle.

Next shot: try again, no changes

Feb 1 1996 05:46:57:540PM 951208037 Robert Granetz Shot 37 -- Plasma, limited, nl_04=1.2e20, nitrogen puffing from NINJA outboard
midplane. Some hard x-rays.

Next shot: same, except puff nitrogen from the NINJA private flux
zone capillary.

Dec 8 1995 04:50:22:130PM 951208038 Robert Granetz Shot 38 -- Fizzle. Null looks acceptable.

Next shot: try again, but turn off nitrogen puffing to get a
background.

Dec 8 1995 04:49:13:300PM 951208039 Robert Granetz Shot 39 -- Plasma, limited, nl_04=1.2e20 m-2, no argon puffing.

Next shot: same, except enable NINJA puff from private flux zone.

Dec 8 1995 04:56:39:430PM 951208040 Robert Granetz Shot 40 -- Plasma, limited, nl_04=1.2e20 m-2, nitrogen puff from private flux
zone.

Next shot: same, except enable NINJA puff from inboard midplane.

Dec 8 1995 05:09:47:830PM 951208041 Robert Granetz Shot 41 -- Plasma, limited, nl_04=1.2e20 m-2, nitrogen puff from inboard
midplane, plasma survived this puff.

Engineering Operator Comments

Shot Time Type Status Comment

1 08:53:53:370AM Plasma Ok

2 09:06:56:910AM Plasma Ok

3 09:22:36:820AM Plasma Ok

4 09:35:10:710AM Plasma Ok

5 09:44:31:750AM Plasma Ok

6 09:53:03:440AM Plasma Ok

7 10:04:12:080AM Plasma Bad alternator inhibit fault

8 10:13:37:570AM Plasma Ok

9 10:23:28:840AM Plasma Ok

10 10:37:20:800AM Plasma Ok

11 10:46:54:690AM Plasma Ok

12 10:56:32:030AM Plasma Ok

13 11:16:02:530AM Plasma Ok

14 11:40:40:670AM Plasma Bad alt overvolt

15 11:53:02:830AM Plasma Ok

16 12:06:08:290PM Plasma Bad ef4 blown fuse

17 12:22:54:980PM Plasma Ok

18 12:34:18:910PM Plasma Ok

19 12:43:09:620PM Plasma Ok

20 12:56:35:220PM Plasma Ok

21 01:09:17:580PM Plasma Ok

22 01:18:26:370PM Plasma Ok

23 01:30:47:930PM Plasma Ok

24 01:45:11:010PM Plasma Ok

25 01:55:29:480PM Plasma Ok

26 02:06:04:640PM Plasma Ok

27 02:18:34:380PM Plasma Ok

28 02:39:18:350PM Plasma Ok

29 02:53:53:830PM Plasma Ok

30 03:03:25:630PM Plasma Ok

31 03:14:42:940PM Plasma Ok

32 03:24:15:680PM Plasma Ok

33 03:33:18:620PM Plasma Ok

34 03:44:31:150PM Plasma Ok

35 04:01:06:050PM Plasma Ok

36 04:12:32:570PM Plasma Ok no faults

37 04:21:21:280PM Plasma Ok

38 04:31:52:860PM Plasma Ok

39 04:42:52:930PM Plasma Ok

40 04:53:31:360PM Plasma Ok

41 05:05:02:810PM Plasma Ok

Session Leader Comments
Dec 8 1995 08:20:49:790AM		Gary McCracken	Impurity Screening in limiter Discharges MP 129 Objectives: To measure screening of Ar and N impurities injected into limiter discharges. To measure SOL parameters in limiter discharges
Dec 10 1995 12:54:10:390PM		Gary McCracken	Summary: Despite the difficulties and the small number of shots , it was an interesting and useful run. The principal result is that there is a much bigger difference between divertor and limiter screening of Ar now than we have seen before. For the Hirex data there was about a factor 8 more Ar atoms in the plasma in limiter than in divertor discharges. For Ar into limiter discharges there was also better screening when puffing at the outside or the bottom than when puffing at the inner wall (by about a factor 2). We only managed to do limiter discharges with N2 puffing. Here again the screening was about a factor of 2-3 better for outside or divertor puffing than inner wall. Comparison with previous divertor shots indicates that N screeing is much poorer with the limiter Overall I think the work justifies another run to see the density dependence of limiter screening
Dec 8 1995 08:57:04:790AM	951208001	Gary McCracken	Plan to have a limiter shot with nl04=1e20. No argon injection, but look at background spectra. Fizzle
Dec 8 1995 09:22:27:310AM	951208002	Gary McCracken	Quite good limiter shot with nl04=1.15e20. No argon injection. LCFS too far from the scanning probe. Will move it closer next shot Zeff high due to not enough prefill.
Dec 8 1995 09:34:19:950AM	951208003	Gary McCracken	Limiter shot with nl04=1.15e20. Still no argon injection. LCFS still out of range for FSP. Zeff still high, 1.8
Dec 8 1995 09:39:50:310AM	951208004	Gary McCracken	Supposed to be first shot with argon injection B-side lower 4 psi, trigger at 0.3 s for 20 ms Fizzle
Dec 8 1995 09:48:59:260AM	951208005	Gary McCracken	Fizzle
Dec 8 1995 10:03:40:020AM	951208006	Gary McCracken	Plasma,but disrupted at 0.7 s Argon was incorrectly injected at 0.6 s for 0.2 s Curiously the Hirex signal was high at the beginning of the shot before the Ar went in.
Dec 8 1995 10:15:10:200AM	951208007	Gary McCracken	No plasma, alternator problem.
Dec 8 1995 10:15:32:780AM	951208008	Gary McCracken	Fizzle
Dec 8 1995 10:41:03:040AM	951208009	Gary McCracken	Better shot, but hard Xrays. No Hirex data because of Xrays No argon injected. Chromex ok
Dec 8 1995 10:50:44:830AM	951208010	Gary McCracken	Better shot, X-rays lower. Hirex still has Xray background but no clear Ar peak on the Chromex. We will take this as our background shot nl04=1.1e20
Dec 8 1995 10:57:37:030AM	951208011	Gary McCracken	Good shot nl04=1.1e20. Ar injection from B-side lower , 4psi, trigger at 0.3 s for 20 ms some Ar on chromex but not till after o.7 s
Dec 8 1995 11:10:19:180AM	951208012	Gary McCracken	Good shot nl04=1.1e20. Ar injection from NINJA inner wall B16-001 , 56 torr, trigger at 0.2 s for 100 ms Ar clear on HIREX coming in at about 0.7 s and climbing to 600 counts/s Chromex showed ARII line at 442.6 nm. It started to climb at 0.75s and reached ~4000 c/s Shot disrupted on current ramp down. Need to reduce Ar input for next shot. We will lower the plenum pressure
Dec 8 1995 11:32:02:150AM	951208013	Gary McCracken	Reduce Ar plenum pressure to 26 torr Ar injection from NINJA inner wall B16-001, trigger at -0.1 s for 100 ms to get Ar in earlier Fizzle. Due to disruption on previous shot?
Dec 8 1995 11:48:37:850AM	951208014	Gary McCracken	Ar injection from NINJA inner wall B16-001, pressure trigger at -0.1 s for 100 ms to get Ar in earlier No plasma. Alernator problem
Dec 8 1995 11:59:05:570AM	951208015	Gary McCracken	Ar injection from NINJA inner wall B16-001, pressure 26 torr trigger at -0.1 s for 100 ms Fizzle.
Dec 8 1995 12:19:20:470PM	951208016	Gary McCracken	Ar injection from NINJA inner wall B16-001, pressure 26 torr trigger at -0.1 s for 100 ms Disruption at 0.5 s. EF4 PS problem
Dec 8 1995 12:37:04:680PM	951208017	Gary McCracken	Ar injection from NINJA inner wall B16-001, pressure 26 torr trigger at -0.1 s for 100 ms Good shot with Ar but it doesn't come in until about 0.8 s. Seen on HIrex bu not on Chromex Bring Ar trigger forward on next shot
Dec 8 1995 12:44:15:250PM	951208018	Gary McCracken	Ar injection from NINJA inner wall B16-001, pressure 26 torr trigger at -0.3 s for 100 ms Good shot with Ar in at about 0.6 s. Seen on Hirex Seen on Chromex staring at 0.8 s Change Ar injection position to divertor next shot
Dec 8 1995 12:57:26:140PM	951208019	Gary McCracken	Ar injection from NINJA divertor B31-038, pressure 26 torr trigger at -0.3 s for 100 ms Good shot with Ar in at about 0.6 s. Seen on Hirex ;slightely lower than inner wall injection No Ar for next shot
Dec 8 1995 01:07:00:840PM	951208020	Gary McCracken	Still limiter shot, but no N injection to get background Good background signal of about 20 counts/s on Hirex. Background very small on Chromex
Dec 8 1995 01:18:27:170PM	951208021	Gary McCracken	Ar injection from NINJA outer wall, B33-001` on AB limiter Trigger at -0.4 s for 0.1 s. Pressure still 26 torr Godd Hirex signal. Similar to divertor injection position and lower than the inner wall injection position
Dec 8 1995 01:25:53:750PM	951208022	Gary McCracken	First divertor shot. Standard fiducial shot No argon injection. Background ~ 5 counts/s , much lower than limiter shot.
Dec 8 1995 01:40:52:200PM	951208023	Gary McCracken	Second divertor shot. Standard fiducial shot except for Ar injection Argon injection at inner wall midplane B16-001 . Trigger -0.4 s for 0.1 s Pressure =26 torr Hirex rises to 20 counts/s at 1.0 s. Much lower than limited shots
Dec 8 1995 01:54:06:430PM	951208024	Gary McCracken	Third divertor shot. Standard fiducial shot except for Ar injection Argon injection at outer wall midplane B33-001 . Trigger -0.4 s for 0.1 s Pressure =26 torr Hirex signal confusing. No clear Ar rise during shot
Dec 8 1995 02:02:49:380PM	951208025	Gary McCracken	Fourth divertor shot. Standard fiducial shot except for Ar injection Argon injection at divertor B31-038 . Trigger -0.4 s for 0.1 s Pressure =26 torr Very smal rise in Ar on Hirex. close to the noise level
Dec 8 1995 02:14:21:230PM	951208026	Gary McCracken	Fifth divertor shot. Standard fiducial shot No Ar injection Hirex signal low, about 3 counts/s, so the argon does seem to have been getting in in the diverted shots We will go back to the limited shot with Ar injection just to make sure
Dec 8 1995 02:32:07:500PM	951208027	Gary McCracken	Limited shot with Ar injection from NINJA outer limiter B33-001 Trigger -0.4 for 0.1 s . Pressure 26 torr Hirex rise to just over 100 counts/s. Very good reproducibilty with previous limited shot #021. So there is very striking difference the screening of the limited and diverted shots
Dec 8 1995 02:51:21:830PM	951208028	Gary McCracken	Change to Nitrogen injection. Plenum pressure at 284 torr Limited shot with N injection from NINJA inner limiter B16-001 Trigger at 0.1 for 0.3 s. Goes in at 0.3 s from CCD NII filter looking at inner wall. Disruption at 0.47 s. Not clear whetther it was due to the N or to a tile problem
Dec 8 1995 03:02:05:760PM	951208029	Gary McCracken	Nitrogen injection. Plenum pressure at 284 torr Limited shot with N injection from NINJA outer limiter B33-001 Trigger at 0.5 for 0.3 s. Fizzle
Dec 8 1995 03:05:38:270PM	951208030	Gary McCracken	Nitrogen injection. Plenum pressure at 284 torr Limited shot with N injection from NINJA outer limiter B33-001 Trigger at 0.5 for 0.3 s. Fizzle again!
Dec 8 1995 03:18:51:330PM	951208031	Gary McCracken	Stopped N injection for this shot Limited . Fizzle again
Dec 8 1995 03:39:56:610PM	951208032	Gary McCracken	Stopped N injection for this shot Limited . Fizzle again
Dec 8 1995 03:40:48:040PM	951208033	Gary McCracken	Stopped N injection for this shot Limited . Good shot. Background We will turn the N on again for the nest shot
Dec 8 1995 04:05:10:170PM	951208034	Gary McCracken	N injection at outer midplane B33-001. Plenum pressure 284 torr Trigger 0.5 s for 0.3 s Limited . Discharge disrupted at 0.8 s ie about 150 ms after the N started to go in. It looks as if the limited discharges will simply not take this much N even though tthe diverted ones will. cf run 951205.
Dec 8 1995 04:05:57:290PM	951208035	Gary McCracken	N injection at outer midplane B33-001. Plenum pressure 284 torr Trigger 0.5 s for 0.3 s Fiducial diverted shot. Fizzle
Dec 8 1995 04:28:54:850PM	951208036	Gary McCracken	Reduce plenum pressure to 143 torr in order to try and get some screening measurements for limited discharges. N injection at outer midplane B33-001. Trigger 0.5 s for 0.3 s Limited shot. Fizzle
Dec 8 1995 04:35:48:550PM	951208037	Gary McCracken	Plenum pressure 143 torr N injection at outer midplane B33-001. Trigger 0.5 s for 0.3 s Limited shot. Good shot and got a reasonable signal on the McPherson, a rise of about 1e14 units.
Dec 8 1995 04:37:35:520PM	951208038	Gary McCracken	Plenum pressure 143 torr N injection at divertor B31-038. Trigger 0.5 s for 0.3 s Limited shot. Fizzle
Dec 8 1995 04:47:30:380PM	951208039	Gary McCracken	No N injection for a backgroundshot Limited. Good shot
Dec 8 1995 05:03:25:530PM	951208040	Gary McCracken	N injection at divertor B31-086 (divertor) Trigger at 0.5 s for 0.3 s. Plenum pressure 143 torr Limited. Good shot. McPherson data good. Clear increase of the signal above the background level of the previous shot
Dec 10 1995 12:36:55:310PM	951208041	Gary McCracken	Limited shot: N puff at inner wall B16-001, plenum pressure=143 torr, Trigger at 0.5 s for 0.3s Good shot. Good McPherson data

Physics Operator Comments
Dec 8 1995 08:41:48:530AM		John Goetz	Run 951208 is in support of Mini-Proposal #129 - Impurity Screening in Limiter Discharges Purpose: (1) Measure screening of recycling and non-recycling impurities in limiter geometry as a function of density and poloidal injection position (2) Study SOL parameters in limited plasmas Setup: Load 950526038 FACTOR EF2, EF4, and EF2_BY_EF4 100V from [-.515,-.499] on PULSE_GAS_4 (K_SIDE) 100V x 0.02sec @ 0.3sec on PULSE_GAS_1 (B_SIDE_LOWER) points at (0,100) and (.01,25) on PULSE_GAS_3 (B_TOP) keep 951207025 in reserve for the divertor comparison shots
Dec 8 1995 09:54:00:700AM	951208001	Robert Granetz	Physics Operator's summary for run 951208 MP #129 Impurity screening in limiter discharges SL: G. McCracken PO: R. Granetz (initial setup by John Goetz) EO: V. Bertolino Today's run plan: Start from 950526038, which was a limited plasma from the last time we did a limiter screening run. Puff in both argon and nitrogen via NINJA and B-side valve. We will also do some diverted discharges for comparison. Run setup: Start with shot 950526038, except load in segment 1 from yesterday's fiducial shot 951207025. (We didn't actually load in the new segment 1 until after shot 1, due to a bug in the copy_segment routine. John Goetz did the necessary changes to the EF2 and EF4 controllers to account for the new power supplies. Discharge clean as usual in deuterium before the run Fill B-side plenum with 4 psi of argon
Dec 8 1995 09:54:40:760AM	951208001	Robert Granetz	Shot 01 -- Fizzle. Next shot: load segment 1 from yesterday's fiducial shot 951207025.
Dec 8 1995 09:55:05:660AM	951208002	Robert Granetz	Shot 02 -- Plasma, limited. Some hard x-rays. nl_04=1.15e20, which is slightly higher than requested, but the valve closes all the way. 3 cm outer gap, scanning probe can't quite make it. Next shot: add 20 ms to the pre-shot gas pulse. Increase RCUR by 5 mm.
Dec 8 1995 09:55:28:680AM	951208003	Robert Granetz	Shot 03 -- Plasma, limited. nl_04=1.15e20 m-2. RCUR increased by 5 mm, but scanning probe still can't hit it. That's probably because we have FSP control turned on (inherited from last May's shot). Next shot: change FSP location by -7.5 mm (on advice from Brian).
Dec 8 1995 09:55:39:500AM	951208004	Robert Granetz	Shot 04 -- Fizzle. No obvious reason why. Next shot: no changes
Dec 8 1995 09:55:53:070AM	951208005	Robert Granetz	Shot 05 -- Fizzle. Next shot: tweak Br by -0.0005 T and decrease pre-pulse gas by 1 ms.
Dec 8 1995 10:05:52:070AM	951208006	Robert Granetz	Shot 06 -- Plasma, but disrupted at 0.7 s due to large amount of argon coming in at 0.6 s. This is not what was programmed for the argon valve. John Goetz has just realized that I had segment 4 turned on rather than segment 2. I don't know how that happened. Segment 4 had a very large puff enabled for the argon valve, so that explains it. Next shot: enable segment 2 and turn off segment 4. Disable argon valve. Reduce RCUR by 5 mm to get it back to the original value, but keep FSP at the new reduced value.
Dec 8 1995 10:20:19:650AM	951208007	Robert Granetz	Shot 07 -- Dud. Alternator problem. We've just realized that John made a mistake when he started off with shot 1. He thought that segment 2 was a limited plasma, when actually it was for a lower x-pt diverted plasma, and segment 4 was for a limited plasma. Next shot: switch back to segment 4, copy FSP from seg 2 to seg 4, and copy pulse gas 1 programming from seg 2 to seg 4.
Dec 8 1995 10:18:41:840AM	951208008	Robert Granetz	Shot 08 -- Fizzle. Steve Wolfe reports high carbon levels. Next shot: no changes
Dec 8 1995 10:35:24:760AM	951208009	Robert Granetz	Shot 09 -- Plasma, good limited shot. Some hard x-rays. Brian reports that the scanning probe will be able to reach the plasma. Next shot: increase pre-pulse gas duration by 1 ms and repeat (still with no argon)
Dec 8 1995 10:45:50:260AM	951208010	Robert Granetz	Shot 10 -- Plasma, good shot. No hard x-rays. Brian fired the probe on this shot. Next shot: enable 20 ms argon puff at t=0.300 s.
Dec 8 1995 10:51:31:490AM	951208011	Robert Granetz	Shot 11 -- Plasma, good shot, with argon puff from B-side-lower valve. Next shot: turn off B-side argon puff and enable NINJA argon puff from inboard midplane. NINJA Plenum pressure is 0.5 psi.
Oct 16 1996 09:17:06:490AM	951208011	Robert Granetz	It is now 10 months after this run. Detailed analysis by Francesca and myself of the argon levels on this shot with the B-side-lower valve compared to the argon levels on later shots today using the NINJA system have led us to believe that the B-side valve did not actually open on this shot (maybe it opened a tiny bit, but certainly nowhere near fully open). This was the first use of the valve during this day's run, and it is now known that the valve sometimes `sticks' after not being used for a day.
Dec 8 1995 11:06:11:250AM	951208012	Robert Granetz	Shot 12 -- Plasma. Disrupted at 1.18 s. Soft x-rays were greatly increased by the NINJA argon puff. Next shot: reduce NINJA plenum pressure from 0.5 to about 0.25 psi, and also tweak FSP control by a few mm.
Dec 8 1995 11:44:08:760AM	951208013	Robert Granetz	Shot 13 -- Fizzle. Next shot: repeat with no changes.
Dec 8 1995 11:44:23:950AM	951208014	Robert Granetz	Shot 14 -- Dud. Alternator failure. Next shot: try again with no changes.
Dec 8 1995 12:04:51:160PM	951208015	Robert Granetz	Shot 15 -- Fizzle. Null looks acceptable. Next shot: reduce pre-pulse gas puff by 1 ms and retry.
Dec 8 1995 12:12:11:490PM	951208016	Robert Granetz	Shot 16 -- Plasma, but terminated at 0.522 s due to EF4 fault at 0.33 s. Next shot: try again.
Dec 8 1995 12:33:38:200PM	951208017	Robert Granetz	Shot 17 -- Plasma, good shot, with NINJA inboard midplane argon puff. The argon showed up at about t=0.8 s, which is later than we want. Next shot: move NINJA puff earlier by 0.3 s and repeat.
Dec 8 1995 12:38:59:210PM	951208018	Robert Granetz	Shot 18 -- Plasma, good shot, with NINJA inboard midplane argon puff. nl_04=1.15e20 m-2. Next shot: Use NINJA argon puff from the capillary in the private flux zone.
Dec 8 1995 12:56:10:050PM	951208019	Robert Granetz	Shot 19 -- Plasma, good shot, with NINJA argon puff from private flux zone at a density of nl_04=1.15e20 m-2. Limited (as all previous shots today have been) Next shot: same shot, but without any argon puffing.
Dec 8 1995 01:18:30:790PM	951208019	Robert Granetz	Gary reports that only half as much argon gets into the plasma compared to puffing at the inboard midplane. This is presumably due to the effect of the SOL.
Dec 8 1995 12:59:12:220PM	951208020	Robert Granetz	Shot 20 -- Plasma, good shot. No argon puff. Next shot: same plasma, but puff argon with NINJA from an outboard midplane capillary.
Dec 8 1995 01:16:19:230PM	951208021	Robert Granetz	Shot 21 -- Plasma, good shot. NINJA argon puff from outboard midplane. Next shot: load in the "fiducial" shot (951207025). This is a lower x-point diverted plasma at nl_04=1.0e20 m-2 and Ip=0.8 MA. No argon puffing.
Dec 8 1995 01:23:36:000PM	951208022	Robert Granetz	Shot 22 -- Plasma, good fiducial shot. Diverted, nl_04=0.95e20 m-2. No argon. Next shot: same diverted shot, with NINJA argon puffing from inboard midplane capillary.
Dec 8 1995 01:38:10:110PM	951208023	Robert Granetz	Shot 23 -- Plasma, good diverted shot at nl_04=0.95e20 m-2 and with NINJA argon puffing from the inboard midplane. Next shot: same, except NINJA argon puff from outboard midplane.
Dec 8 1995 01:53:54:040PM	951208024	Robert Granetz	Shot 24 -- Plasma, good diverted shot at nl_04=0.95e20 m-2, with NINJA argon puffing from the outboard midplane. Next shot: same, except NINJA argon puff from the private flux zone capillary.
Dec 8 1995 02:03:18:130PM	951208025	Robert Granetz	Shot 25 -- Plasma, good diverted shot at nl_04=0.95e20 m-2, with NINJA argon puffing from the private flux zone. Next shot: same, except no Ar puffing (i.e. another fiducial shot)
Dec 8 1995 02:13:53:270PM	951208026	Robert Granetz	Shot 26 -- Plasma, good diverted shot, nl_04=0.95e20 m-2, no NINJA argon puff. The argon signals are clearly lower than they were on the preceding diverted shots. Next shot: return to limiter configuration (re-load 951208021), with NINJA argon puffing from outboard midplane.
Dec 8 1995 02:30:51:140PM	951208027	Robert Granetz	Shot 27 -- Plasma, good limiter shot, nl_04=1.2e20 m-2, argon puff from NINJA outboard midplane. Argon signals are back up to the levels seen in the earlier limiter shots today. The screening ratio is coming out to be about a factor of 8! (and even more when puffing directly into the inboard midplane. Next shot: change from argon to nitrogen, from the NINJA inboard midplane location.
Dec 8 1995 02:54:12:680PM	951208027	Robert Granetz	John Goetz has suggested that this high ratio, compared to last spring's measurements, may be due to the closing off of the divertor leaks and the subsequent higher compression ratio.
Dec 8 1995 02:48:45:930PM	951208028	Robert Granetz	Shot 28 -- Plasma, limited, disrupted at t=0.48 s, with nitrogen puffing from the NINJA inboard midplane. The radiation signals were rising, but I don't know if they were high enough to cause this disruption. Next shot: puff nitrogen from the NINJA outboard wall, and delay the puff by 0.2 s (It's hitting now around t=0.4 s.)
Dec 8 1995 02:57:47:710PM	951208029	Robert Granetz	Shot 29 -- Fizzle. Probably due to the preceding disruption. Next shot: try again
Dec 8 1995 03:13:48:820PM	951208030	Robert Granetz	Shot 30 -- Fizzle. Null looks acceptable. Next shot: decrease pre-pulse puff duration by 1 ms and try again. Also, no nitrogen puff on the next shot.
Dec 8 1995 03:18:18:590PM	951208031	Robert Granetz	Shot 31 -- Fizzle. Next shot: reduce Br by 0.005 T
Dec 8 1995 03:32:01:760PM	951208032	Robert Granetz	Shot 32 -- Fizzle. Next shot: decrease pre-pulse puff duration by another 1 ms and try again.
Feb 1 1996 05:44:35:060PM	951208033	Robert Granetz	Shot 33 -- Plasma, limited, nl_04=1.1e20 m-2. No nitrogen puff. There were some hard x-rays. Next shot: increase pre-pulse puff duration by 1 ms and turn on nitrogen puff from NINJA outboard midplane.
Feb 1 1996 05:46:01:360PM	951208034	Robert Granetz	Shot 34 -- Plasma, disrupted at 0.79 s. Limited, nl_04=1.2e20 m-2, nitrogen puff from outboard midplane. Radiation levels do not rise before the disruption, so I don't think the nitrogen caused this disruption. Next shot: switch back to the fiducial diverted plasma (951207025). Keep the NINJA nitrogen puff turned on (outer midplane).
Dec 8 1995 04:07:06:620PM	951208035	Robert Granetz	Shot 35 -- Fizzle. No surprise. Next shot: return to limiter configuration (re-load 951208034). Reduce NINJA plenum pressure from 5 to 2.5 psi, and keep the outboard midplane puff enabled.
Dec 8 1995 04:18:55:320PM	951208036	Robert Granetz	Shot 36 -- Fizzle. Next shot: try again, no changes
Feb 1 1996 05:46:57:540PM	951208037	Robert Granetz	Shot 37 -- Plasma, limited, nl_04=1.2e20, nitrogen puffing from NINJA outboard midplane. Some hard x-rays. Next shot: same, except puff nitrogen from the NINJA private flux zone capillary.
Dec 8 1995 04:50:22:130PM	951208038	Robert Granetz	Shot 38 -- Fizzle. Null looks acceptable. Next shot: try again, but turn off nitrogen puffing to get a background.
Dec 8 1995 04:49:13:300PM	951208039	Robert Granetz	Shot 39 -- Plasma, limited, nl_04=1.2e20 m-2, no argon puffing. Next shot: same, except enable NINJA puff from private flux zone.
Dec 8 1995 04:56:39:430PM	951208040	Robert Granetz	Shot 40 -- Plasma, limited, nl_04=1.2e20 m-2, nitrogen puff from private flux zone. Next shot: same, except enable NINJA puff from inboard midplane.
Dec 8 1995 05:09:47:830PM	951208041	Robert Granetz	Shot 41 -- Plasma, limited, nl_04=1.2e20 m-2, nitrogen puff from inboard midplane, plasma survived this puff.

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	08:53:53:370AM	Plasma	Ok
2	09:06:56:910AM	Plasma	Ok
3	09:22:36:820AM	Plasma	Ok
4	09:35:10:710AM	Plasma	Ok
5	09:44:31:750AM	Plasma	Ok
6	09:53:03:440AM	Plasma	Ok
7	10:04:12:080AM	Plasma	Bad	alternator inhibit fault
8	10:13:37:570AM	Plasma	Ok
9	10:23:28:840AM	Plasma	Ok
10	10:37:20:800AM	Plasma	Ok
11	10:46:54:690AM	Plasma	Ok
12	10:56:32:030AM	Plasma	Ok
13	11:16:02:530AM	Plasma	Ok
14	11:40:40:670AM	Plasma	Bad	alt overvolt
15	11:53:02:830AM	Plasma	Ok
16	12:06:08:290PM	Plasma	Bad	ef4 blown fuse
17	12:22:54:980PM	Plasma	Ok
18	12:34:18:910PM	Plasma	Ok
19	12:43:09:620PM	Plasma	Ok
20	12:56:35:220PM	Plasma	Ok
21	01:09:17:580PM	Plasma	Ok
22	01:18:26:370PM	Plasma	Ok
23	01:30:47:930PM	Plasma	Ok
24	01:45:11:010PM	Plasma	Ok
25	01:55:29:480PM	Plasma	Ok
26	02:06:04:640PM	Plasma	Ok
27	02:18:34:380PM	Plasma	Ok
28	02:39:18:350PM	Plasma	Ok
29	02:53:53:830PM	Plasma	Ok
30	03:03:25:630PM	Plasma	Ok
31	03:14:42:940PM	Plasma	Ok
32	03:24:15:680PM	Plasma	Ok
33	03:33:18:620PM	Plasma	Ok
34	03:44:31:150PM	Plasma	Ok
35	04:01:06:050PM	Plasma	Ok
36	04:12:32:570PM	Plasma	Ok	no faults
37	04:21:21:280PM	Plasma	Ok
38	04:31:52:860PM	Plasma	Ok
39	04:42:52:930PM	Plasma	Ok
40	04:53:31:360PM	Plasma	Ok
41	05:05:02:810PM	Plasma	Ok