Alcator C-Mod Run 971218 Information

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Miniproposals
Miniproposal:191
Date Filed:10/2/1997
Title:Langmuir Probe E-radial Measurements During RF
First Author:John Reardon
Session Leader:John Reardon (shots 1-29)

Operators
Session leader(s):John Reardon
Physics operator(s):Robert Granetz,Ian Hutchinson
Engineering operator(s):Frank Silva

Engineering Operator Run Comment
Hutch/Reardon/Silva

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:17:507PM
Author: To Be Determined
This run supported MP191, Langmuir Probe E-radial Measurements During RF.

Two objectives were pursued simultaneously. The first objective was to check
out a diagnostic technique new to tokamaks, the use of quarter-wave stub
tuners on swept Langmuir probes to suppress the rectification of RF sheath
voltage. Does this technique allow Langmuir probe measurements to be made with
accuracy during RF heating in tokamaks?

The second objective was to acquire profiles of swept Langmuir probe traces
and RF floating potential fluctuations in the edges of RF-heated H-mode
plasmas, in order to contribute to the understanding of the H-mode confine-
ment barrier.


Both objectives were accomplished.

The probe was scanned on every shot except shots 1 (fizzle) and 2.

The largest RF floating potential fluctuations were found in the nl_04 = 8 10^19
shots (eg 15 and 22), being roughly 15 V RMS, attained on the inward scan
about 1 mm from furthest insertion. This is enough to distort probe
characteristics, and allow evaluation of the effectiveness of the stubs
(analysis in progress).

Trophy shots are 15 and 28, when the probe went in during L-mode and came
out during H-mode. For 9 shots the L-H transition happened within 20 ms
of the full insertion. Probe scanned into EDH mode for another 4 shots.
Some of the low-denisty EDH modes had really good RF heating. 2 shots of
RF L-mode and 1 of Ohmic L-mode. Calculation of profiles in progress.

Run summary:

Establish a good fiducial and keep moving the probe in until it generates
impurity bursts: shots 2-10

Move probe out and switch antennas: shots 11-13

Density scan: shots 14-21 low density: nl_04 = 8.0 10^19 (shot 15)
high density: nl_04 = 1.5 10^20 (shot 21)

Low density gives highest RF fields, thus best chance for evaluation of
stub tuners. Return there and turn down the gas puff to see if the
density will go still lower as the walls pump out.

Wall pump-out: shots 22-26 nl_04 decreases from 7.7 10^19 to 5.7 10^19

RF fields not so big as before. Good RF heating. Return to nl_04 = 8.0 10^19
where the RF fields are big and push the probe in further.

To boldly go...: shots 27-29 No moly injections, no damage to probe.

The machine operated superbly. RF was consistent and reliable: "RF likes
EDH mode"--SJ Wukitch. Excellent heating at the low densities. See
physop_summary for details.

Shot # Description

1 Fizzle
2 5.4T 800kA 1 10^20 EDA H-mode w/1 MW D-port. Most of the
fiducial EDA H-modes today seem to pass through "suppressed
D-Alpha H-mode" on their way to and from L-mode.
3 Similar. Enable scanning probe. Probe scan in EDH mode at 1.0
sec. No sign of probe related moly.
4 Remove extra D-port ramp. Probe scan in EDH mode @ 1.0 sec.
No sign of probe-related moly.
5 Move probe in .093 Scan into EDH mode @ 1.0
No sign of Moly
6 Move probe in .07 Scan into EDH mode @ 1.0
No sign of Moly
7 Move probe in .093 Scan into EDH mode @ 1.0
No sign of Moly
increasing flakiness on pot trace
so far the rf floating potential fluctuation level has
been independent of position during the probe scan

8 Move probe in .093 Scan into EDH mode @1.0.
No sign of moly
9 Move probe in .093 Scan into EDH mode @ 1.0
No sign of Moly.

1 hour delay to find and fix loose wire in pot driver circuit.

10 Move probe in .093 Scan into EDH mode @ 1.0.
Big (probe) injection of Moly.
11 Change long pulse from D-port to E-port.
Move probe out .094 Scan into EDH mode @1.0
Not-so-big probe injection of Moly at 1.0

12 Move probe out .07, change scan time to .77 (look for L-H)
Tiny moly injection. L-H happens at .81 (thanks to E-port)

13 Change to long pulse on D-port. Leave probe the same.
L-H at .778. RF floating potential fluctuation level
still nearly independent of position.

14 Lower density to 8.5 10 19. Leave probe the same
More power in RF floating potential fluctuations than before,
position dependent.
L-H at .786

15 Change scan time to .785. Lower density to 8.0 10 19
L-H transition happens with probe full in (.783 seconds)
Power in V_RF^floating still larger than before; much larger
during L-mode (inward scan) than H-mode (outward scan).

16 Raise density to 1.15 10 20. Probe scan the same
L-H at .795. Power in V_RF^floating decreases.

17 Raise density to 1.25 10 20. Probe scan .795
RF overload at .79. No H-mode

18 Repeat. Nice clean RF! H-mode .81

19 Raise density Probe scan .84
Magnet resistance fault.

20 Repeat. Disrupted at .84. Probe scan screwed up (my fault,
gas timing error): full in at .74 and again at .81 and .86
(slightly less far each time)

21 Tweak and repeat. Good shot! nl_04 reaches 1.5 10^20 before
H-mode transition at .92 Probe scan @.84 into RF L-mode.
V_RF^floating the smallest it's been all day.

22 Go to low density nl_04 = 7.7 10^19 Probe scan @.785,
H-mode at .793. V_RF^floating big again.

23 Repeat shot. nl_04= 6.8 10^19. Probe scan @.785, ELM-free
H-mode from .81 - .91 (followed by EDH). V_RF^floating
considerably diminished, though rising abruptly at L-H transition.

24 Turn off Argon and repeat. Does ELM-free H-mode disappear?
Repeat shot. nl_04= 6.3 10^19. ELM-free phase starting at .86.
"H=2" --G. Probe scan at .81.

25 Enable Argon and repeat. ELM-free H-mode at .84. Probe scan
at .81. This is as close as the probe gets to ELM-free H-mode.

26 Change probe scan to .86 and repeat. L-H transition delayed
until .94, well after 2nd antenna turns on. nl_04 = 5.7 10^19
@ probe scan (with 1 MW RF). V_RF^floating follows scanning
probe position, being very large at full insertion (cf shot 7).

27 Raise target density to 8 10^19. Dithering in Ohmic phase,
followed by L-EDH transition at .78, with Type III elms appearing
late. Probe scan at .86 into EDH.

28 Repeat. Move probe in by .07" and scan at .78.
L-EDH transition at .785

29 Repeat. Move probe in by .07" and scan at .79.
L-EDH at .78

Physics Operator Summaries
Entered: Jul 7 2004 04:36:58:253PM
Author: To Be Determined
Physop Summary. 971218 Langmuir probe E_r measurements. MP191
_____________________________________________________________

SL Reardon
PO Hutch (Granetz)

Summary
_______

An excellent day of plasmas at 0.8MA. Target Density scan from about
.6 to 1.6e20. RF powers up to 2.8MW. EDA modes at target densities
about .7 or above, radiated power well controlled. ELM free at lowest
density with accumulation, but still good confinement. Probe
experiments were done. RF antenna interaction seems to be being
conditioned; the TV shows increasingly benign behavior. H-factors in
the region of 2 were obtained near the lower densities towards the end
of the run.

What we learned.
________________

The tweaks on OH2 and on the rcur offset seem to have been helpful in getting
no fizzles after shot 1. This segment 1 is definitely a keeper.

2.5 hours of D2 ECDC once again disproves the significance of He ECDC
for getting EDA.

Main chamber neutral pressure is consistently higher than the 1996 campaign
for the same plasma density.

One psi of Argon and a pulse width of 22ms is just at the level where the
radiation is detectable, and just at the level where one can keep Rice
quiet (if not necessarily happy.) The highest stored energy had the argon
off.

As always, early marfe, or at least cold edge, obtained by gas influx,
is good for keeping the radiation low. The transition between shot 21
and the suceeding ones is a good example of the time to unload the
walls: two or three shots today.

Clear synchronism was observed on several occasions between impurity
injections, RF trips, and TV antenna explosions. The conclusion is that we
still have some antenna conditioning to do. We should also wonder how
to avoid the antenna picture-frame edge heating.

Scorecard:
__________
Shot,Duration(s),Ipmax(MA) Shot,Duration(s),Ipmax
1 0.000 0.037 2 1.674 0.833
3 1.672 0.833 4 1.671 0.833
5 1.673 0.833 6 1.672 0.833
7 1.682 0.833 8 1.672 0.833
9 1.673 0.833 10 1.678 0.833
11 1.670 0.833 12 1.673 0.833
13 1.672 0.838 14 1.697 0.838
15 1.689 0.843 16 1.661 0.833
17 1.648 0.828 18 1.636 0.830
19 0.000 0.005 20 0.865 0.830
21 1.610 0.833 22 1.691 0.841
23 1.692 0.843 24 1.269 0.849
25 1.696 0.843 26 1.699 0.851
27 1.692 0.843 28 1.693 0.843
29 1.695 0.843
Finished summary for 971218 Total of 29 shots.
29 shots. 27 plasmas. 1 fizzle. 1 (power-supply)dud.

Details:
________
971218xxx HUTCH PHYSICS_OPERATOR 18-DEC-1997 07:28:36.62
. . . . . . . . . . . . . . . . . . . .
Reardon's Miniproposal: Langmuir Probe E_r Measurements. 191.

Leak on F-port was found, cuased by freezing. Purged now with Argon.
Sparker visual inspecyion shows nothing unpleasant.
About 2.5 hrs ECDC in deuterium.
Did coldstart.

Load the segment 4 fiducial. 7:30 am start.
--------------------------------------------------------------------------------
971218001 HUTCH PHYSICS_OPERATOR 18-DEC-1997 07:42:58.84

44 kA fizzle.

Lower OH2 Voltages to 0V at 7ms, from about 18V. Try to fix the index.
--------------------------------------------------------------------------------
971218002 HUTCH PHYSICS_OPERATOR 18-DEC-1997 08:02:45.42

Plasma. Got two pulses of 1MW Rf. EDA mode on both.
Some Hards at 0.1s.

Lower rcur offset in seg 1 to 6300 from 6500.
Import Seg 4 to seg 2. Choose seg 2.
--------------------------------------------------------------------------------
971218003 HUTCH PHYSICS_OPERATOR 18-DEC-1997 08:30:04.55

Plasma. Got 1MW and a 2MW blip. Some injections early. Good ramp-down.
Early density is rising quite quickly. EDA.
Report that the leak is apparantly not gone.

Enable Ar at 1.15psi, 12ms pulse.
--------------------------------------------------------------------------------
971218004 HUTCH PHYSICS_OPERATOR 18-DEC-1997 08:38:16.98

Plasma. Argon does not seem to give us a problem. Still some injections.
--------------------------------------------------------------------------------
971218005 HUTCH PHYSICS_OPERATOR 18-DEC-1997 08:51:25.37

Plasma. Takes longer to develop EDA. Power a little lower.

Disable Argon.
--------------------------------------------------------------------------------
971218006 HUTCH PHYSICS_OPERATOR 18-DEC-1997 09:16:06.98

Plasma. Boring! RF power up a bit. EDA earlier.
--------------------------------------------------------------------------------
971218007 HUTCH PHYSICS_OPERATOR 18-DEC-1997 09:31:09.12

Plasma

Enable Argon. Rice reports no signal before so put pulse to 15ms.
--------------------------------------------------------------------------------
971218008 HUTCH PHYSICS_OPERATOR 18-DEC-1997 09:44:59.50

Plasma. Rice reports he cannot confirm or deny the presence of Argon.

Ar puff to 17 ms.
--------------------------------------------------------------------------------
971218009 HUTCH PHYSICS_OPERATOR 18-DEC-1997 10:35:07.31

Plasma. Seems to have some argon this time but not a lot, and still retains EDA.

Long pause for cell access.
--------------------------------------------------------------------------------
971218010 HUTCH PHYSICS_OPERATOR 18-DEC-1997 10:51:24.35

Plasma. Big radiation rise at 1 sec. Reardon's probe goes in at that time.

Ar puff to 20ms.
--------------------------------------------------------------------------------
971218011 HUTCH PHYSICS_OPERATOR 18-DEC-1997 11:05:20.81

Plasma. EDA mode might be slightly delayed cf earlier shots.
Impurity injection at .98s. Not as severe as last shot.

Zenith crashes. Let's hope the data system survives.
--------------------------------------------------------------------------------
971218012 HUTCH PHYSICS_OPERATOR 18-DEC-1997 11:18:34.68

Plasma. Probe in at .77s. The impurity burst is gone.

Ar to 22ms.
Can't remember if I loaded this. Last store was at 11.09.
--------------------------------------------------------------------------------
971218013 HUTCH PHYSICS_OPERATOR 18-DEC-1997 11:26:42.85

Plasma

Lower nl04 to .8e20. Lower puff V to about 36V at .2s, to help.
Keep RF on till 1.2s.
--------------------------------------------------------------------------------
971218014 HUTCH PHYSICS_OPERATOR 18-DEC-1997 11:48:14.33 . . . .

Plasma. Got .87e20 density. Nice ramp-down of radiation during the
extended H-mode. Ratiomatic drops from .25mtorr, previous shot to .12
this shot.

Lower puff V some more, to 20 then 15V.
--------------------------------------------------------------------------------
971218015 HUTCH PHYSICS_OPERATOR 18-DEC-1997 12:03:06.72 . . . .

Plasma. Got 0.8e20 density. 0.09 mtorr ratiomatic. Slightly higer
radiation, but otherwise similar to 14. A couple of shots ago I
lowered the early zcyr3 feedback ot 6 proportional.

Go up to nl04 demand of 1.25e20. Raise puff to 50V at .2s.
--------------------------------------------------------------------------------
971218016 HUTCH PHYSICS_OPERATOR 18-DEC-1997 12:15:26.94

Plasma. Got 1.15 nl04 at RF turn-on. 0.4 mtorr ratiomatic.

Increase puff at .15s, and to 25 V later. nl04 to 1.35e20
--------------------------------------------------------------------------------
971218017 HUTCH PHYSICS_OPERATOR 18-DEC-1997 12:32:06.56

Plasma. RF trips. No prolonged H-mode. Big early marfe. nl04=1.24e20. Incipient 60Hz zcur
instability at 1.1s.

Lower zcur P to 4 at .24s. .35 at .778s.
--------------------------------------------------------------------------------
971218018 HUTCH PHYSICS_OPERATOR 18-DEC-1997 12:44:37.60

Plasma. 1.25e20 at .74s.Ratiomatic .56mtorr. Inital current rise has slowed significantly.

nl04 to 1.6, increased V.
--------------------------------------------------------------------------------
971218019 HUTCH PHYSICS_OPERATOR 18-DEC-1997 12:48:27.63

Magnet resistance fault. No power supplies.
--------------------------------------------------------------------------------
971218020 HUTCH PHYSICS_OPERATOR 18-DEC-1997 13:07:37.51

Plasma. Disrupts at .8s. growing vertical instability.
Got nl06=1.64. Probe went in at .74s. Ratiomatic 1mtorr.
Outer gap seems to be slightly larger than before.

zcur3 back to 4. gain.
--------------------------------------------------------------------------------
971218021 HUTCH PHYSICS_OPERATOR 18-DEC-1997 13:23:21.32

Plasma. Sustained the marfe to .5s. This seems to be causing or
enhancing the vertical problem. Then when marfe disappears, nl04 drops
and gets back up to 1.5 at rf-turn-on. H-mode transition at the step
up to level 2 RF.

Lower nl04 to .6e20. Lower V a lot.
--------------------------------------------------------------------------------
971218022 HUTCH PHYSICS_OPERATOR 18-DEC-1997 13:36:38.36

Plasma. .74e20 density. Inkection oat time of RF trip, 1.18s. Ratiomatic .1mtorr. Gas off most of
shot. No vertical problems. 2.8 MW RF, T_e to 3.5kV.
--------------------------------------------------------------------------------
971218023 HUTCH PHYSICS_OPERATOR 18-DEC-1997 13:46:30.63

Plasma. ELM-free phase till .9s. Ratiomatic 0.05mtorr. nl04 .7e20.
150 kJ.

Disable Ar.
--------------------------------------------------------------------------------
971218024 HUTCH PHYSICS_OPERATOR 18-DEC-1997 14:04:16.97

Plasma. L-mode for 0.15 s, then a short ELM-free, then an EDA from 0.9
to 1.2 s. Disrupted at 1.25 s. Target nl04=0.6e19 m-2, goes to
1.5e20 during EDA. Hit by a brick.

Stored energy flat-topped at 150 kJ (0.8 MA), which gives H=2.

Granetz taking over now from Hutch as physop for this last hour of
today's run.

Next shot: re-enable argon puff.
--------------------------------------------------------------------------------
971218025 HUTCH PHYSICS_OPERATOR 18-DEC-1997 14:24:49.74

Plasma. Two ELM-free H-modes. Target density was same as last shot
(nl04=0.6e20 m-2). 150 kJ (momentarily). There was argon on this
shot. Z_67_Yag = 3. JT reports seeing stainless steel (Fe and Ni).

Next shot: repeat with no changes. Jim Reardon wants to scan ELM-free edges.
--------------------------------------------------------------------------------
971218026 HUTCH PHYSICS_OPERATOR 18-DEC-1997 14:25:23.65

Plasma. L-mode until 0.9 s, then ELM-free H-mode when RF steps up to 2 MW.

Next shot: raise target density to nl04=0.8e20 m-2 (from 0.6).
--------------------------------------------------------------------------------
971218027 HUTCH PHYSICS_OPERATOR 18-DEC-1997 14:38:52.20

Plasma. Dithering during much of the ohmic phase. Switches into EDA
when RF turns on, then becomes ELMy. 150 kJ. Target density
increased to nl04=0.8e20 m-2, as requested.

Next shot: no PCS changes
--------------------------------------------------------------------------------
971218028 HUTCH PHYSICS_OPERATOR 18-DEC-1997 14:53:48.20

Plasma. H-alpha characteristics look nearly identical to the previous
shot. Jim Reardon moved his probe 2 mm farther in for this shot.
Nothing evident on spectroscopy. There is, however, another sighting
of nickel (stainless steel) at t=1.11 s, and molybdenum at t=1.2 s
(that's the antenna).

Next shot: stick probe in another 2 mm further.
--------------------------------------------------------------------------------
971218029 HUTCH PHYSICS_OPERATOR 18-DEC-1997 15:01:24.77

Ian returns.
Plasma RF trips. Some rise in radiation at the end of RF.

Session Leader Comments

Physics Operator Comments
Dec 18 1997 07:28:36:620AMIan HutchinsonReardon's Miniproposal: Langmuir Probe E_r Measurements. 191.

Leak on F-port was found, cuased by freezing. Purged now with Argon.
Sparker visual inspecyion shows nothing unpleasant.
About 2.5 hrs ECDC in deuterium.
Did coldstart.

Load the segment 4 fiducial. 7:30 am start.
Dec 18 1997 07:42:58:840AM971218001Ian Hutchinson44 kA fizzle.

Lower OH2 Voltages to 0V at 7ms, from about 18V. Try to fix the index.
Dec 18 1997 08:02:45:420AM971218002Ian HutchinsonPlasma. Got two pulses of 1MW Rf. EDA mode on both.
Some Hards at 0.1s.

Lower rcur offset in seg 1 to 6300 from 6500.
Import Seg 4 to seg 2. Choose seg 2.
Dec 18 1997 08:30:04:550AM971218003Ian HutchinsonPlasma. Got 1MW and a 2MW blip. Some injections early. Good ramp-down.
Early density is rising quite quickly. EDA.
Report that the leak is apparantly not gone.

Enable Ar at 1.15psi, 12ms pulse.
Dec 18 1997 08:38:16:980AM971218004Ian HutchinsonPlasma. Argon does not seem to give us a problem. Still some injections.
Dec 18 1997 08:51:25:370AM971218005Ian HutchinsonPlasma. Takes longer to develop EDA. Power a little lower.

Disable Argon.
Dec 18 1997 09:16:06:980AM971218006Ian HutchinsonPlasma. Boring! RF power up a bit. EDA earlier.
Dec 18 1997 09:31:09:120AM971218007Ian HutchinsonPlasma

Enable Argon. Rice reports no signal before so put pulse to 15ms.
Dec 18 1997 09:44:59:500AM971218008Ian HutchinsonPlasma. Rice reports he cannot confirm or deny the presence of Argon.

Ar puff to 17 ms.
Dec 18 1997 10:35:07:310AM971218009Ian HutchinsonPlasma. Seems to have some argon this time but not a lot, and still retains EDA.

Long pause for cell access.
Dec 18 1997 10:51:24:350AM971218010Ian HutchinsonPlasma. Big radiation rise at 1 sec. Reardon's probe goes in at that time.

Ar puff to 20ms.
Dec 18 1997 11:05:20:810AM971218011Ian HutchinsonPlasma. EDA mode might be slightly delayed cf earlier shots.
Impurity injection at .98s. Not as severe as last shot.

Zenith crashes. Let's hope the data system survives.
Dec 18 1997 11:18:34:680AM971218012Ian HutchinsonPlasma. Probe in at .77s. The 1s impurity burst is gone.

Ar to 22ms.
Can't remember if I loaded this. Last store was at 11.09.
Dec 18 1997 11:26:42:850AM971218013Ian HutchinsonPlasma

Lower nl04 to .8e20. Lower puff V to about 36V at .2s, to help.
Keep RF on till 1.2s.
Dec 18 1997 11:48:14:330AM971218014Ian HutchinsonPlasma. Got .87e20 density. Nice ramp-down of radiation during the extended H-mode.
Ratiomatic drops from .25mtorr, previous shot to .12 this shot.

Lower puff V some more, to 20 then 15V.
Dec 18 1997 12:03:06:720PM971218015Ian HutchinsonPlasma. Got 0.8e20 density. 0.09 mtorr ratiomatic. Slightly higer radiation, but otherwise
similar to 14. A couple of shots ago I lowered the early zcyr3 feedback ot 6 proportional.

Go up to nl04 demand of 1.25e20. Raise puff to 50V at .2s.
Dec 18 1997 12:15:26:940PM971218016Ian HutchinsonPlasma. Got 1.15 nl04 at RF turn-on. 0.4 mtorr ratiomatic.

Increase puff at .15s, and to 25 V later. nl04 to 1.35e20
Dec 18 1997 12:32:06:560PM971218017Ian HutchinsonPlasma. RF trips. No prolonged H-mode. Big early marfe. nl04=1.24e20. Incipient 60Hz zcur
instability at 1.1s.

Lower zcur P to 4 at .24s. .35 at .778s.
Dec 18 1997 12:44:37:600PM971218018Ian HutchinsonPlasma. 1.25e20 at .74s.Ratiomatic .56mtorr. Inital current rise has slowed significantly.

nl04 to 1.6, increased V.
Dec 18 1997 12:48:27:630PM971218019Ian HutchinsonMagnet resistance fault. No power supplies.
Dec 18 1997 01:07:37:510PM971218020Ian HutchinsonPlasma. Disrupts at .8s. growing vertical instability.
Got nl06=1.64. Probe went in at .74s. Ratiomatic 1mtorr.
Outer gap seems to be slightly larger than before.

zcur3 back to 4. gain.
Dec 18 1997 01:23:21:320PM971218021Ian HutchinsonPlasma. Sustained the marfe to .5s. This seems to be causing or enhancing the vertical
problem. Then when marfe disappears, nl04 drops and gets back up to 1.5 at rf-turn-on.
H-mode transition at the step up to level 2 RF.

Lower nl04 to .6e20. Lower V a lot.
Dec 18 1997 01:36:38:360PM971218022Ian HutchinsonPlasma. .74e20 density. Inkection oat time of RF trip, 1.18s. Ratiomatic .1mtorr. Gas off most of
shot. No vertical problems. 2.8 MW RF, T_e to 3.5kV.
Dec 18 1997 01:46:30:630PM971218023Ian HutchinsonPlasma. ELM-free phase till .9s. Ratiomatic 0.05mtorr. nl04 .7e20.
150 kJ.

Disable Ar.
Dec 18 1997 02:04:16:970PM971218024Ian HutchinsonPlasma. L-mode for 0.15 s, then a short ELM-free, then an EDA from 0.9 to 1.2 s. Disrupted at
1.25 s. Target nl04=0.6e19 m-2, goes to 1.5e20 during EDA.

Stored energy flattopped at 150 kJ (0.8 MA), which gives H=2.

Granetz taking over now from Hutch as physop for this last hour of today's run.

Next shot: re-enable argon puff.
Dec 18 1997 02:24:49:740PM971218025Ian HutchinsonPlasma. Two ELM-free H-modes. Target density was same as last shot (nl04=0.6e20 m-2).
150 kJ (momentarily). There was argon on this shot. Z_67_Yag = 3. JT reports seeing stainless
steel (Fe and Ni).

Next shot: repeat with no changes. Jim Reardon wants to scan ELM-free edges.
Dec 18 1997 02:25:23:650PM971218026Ian HutchinsonPlasma. L-mode until 0.9 s, then ELM-free H-mode when RF steps up to 2 MW.

Next shot: raise target density to nl04=0.8e20 m-2 (from 0.6).
Dec 18 1997 02:38:52:200PM971218027Ian HutchinsonPlasma. Dithering during much of the ohmic phase. Switches into EDA when RF turns on,
then becomes ELMy. 150 kJ. Target density increased to nl04=0.8e20 m-2, as requested.

Next shot: no PCS changes
Dec 18 1997 02:53:48:200PM971218028Ian HutchinsonPlasma. H-alpha characteristics look nearly identical to the previous shot. Jim Reardon moved
his probe 2 mm farther in for this shot. Nothing evident on spectroscopy. There is, however,
another sighting of nickel (stainless steel) at t=1.11 s, and molybdenum at t=1.2 s (that's the
antenna).

Next shot: stick probe in another 2 mm further.
Dec 18 1997 03:01:24:770PM971218029Ian HutchinsonIan returns.
Plasma RF trips. Some rise in radiation at the end of RF.

Engineering Operator Comments
ShotTimeTypeStatusComment
107:33:51:210AMPlasmaOkno faults
207:45:23:330AMPlasmaOkno faults
308:01:22:350AMPlasmaOkno faults
408:19:25:060AMPlasmaOk
508:34:36:770AMPlasmaOk
608:49:40:810AMPlasmaOk
709:08:27:950AMPlasmaOk
809:20:41:270AMPlasmaOk
909:36:07:840AMPlasmaOk
1010:35:58:300AMPlasmaOk
1110:48:53:120AMPlasmaOk
1211:00:52:270AMPlasmaOk
1311:17:21:390AMPlasmaOk
1411:31:51:010AMPlasmaOk
1511:46:55:380AMPlasmaOk
1612:01:12:850PMPlasmaOk
1712:16:03:030PMPlasmaOk
1812:29:41:060PMPlasmaOk
1912:43:07:160PMPlasmaBadmag resist fault
2012:51:37:150PMPlasmaOk
2101:05:44:260PMPlasmaOk
2201:21:55:890PMPlasmaOk
2301:34:25:010PMPlasmaOk
2401:47:37:530PMPlasmaOk
2502:01:06:570PMPlasmaOk
2602:16:15:670PMPlasmaOk
2702:29:28:040PMPlasmaOk
2802:42:19:280PMPlasmaOk
2902:56:36:270PMPlasmaOk