Alcator C-Mod Run 960301 Information

Miniproposals

Miniproposal:

Date Filed:

Title:

First Author:

Session Leader: Ian Hutchinson (shots 1-35)

Session Leader: Ian Hutchinson (shots 1-35)

Miniproposal: 124

Date Filed: 11/17/1995

Title: ICRF Heated Dimensionless Scaling (C-MOD / ASDEX-UG)

First Author: Yuichi Takase

Session Leader: Ian Hutchinson (shots 36-55)

Operators
Session leader(s):	Ian Hutchinson,Ian Hutchinson,Ian Hutchinson
Physics operator(s):	Robert Granetz
Engineering operator(s):	Vinny Bertolino,Joe Daigle

Engineering Operator Run Comment
cross field drifts etc.

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:15:820PM

Author: To Be Determined

Run summary 960301 part B (last run of the campaign)
MP124 ASDEX U dimen. sim.
5.6T, 1.0MA, low triangularity plasma

The run started at 5:00pm. We tried to produce a low triangularity plasma,
but it was clear that getting lower than deltau=0.25 and deltal=0.5 was
difficult (ideally we wanted deltau=0.1 and deltal=0.3). A density rise
was observed when RF power was injected. On some shots H-mode was observed
(which we didn't want). We tried to avoid the H-mode by lowering the RF
power and increasing the Ar puff. The Ti profile was measured by scanning
HIREX at nel=1.5 (during high power pulse). A more limited scan was
performed at nel=1.2. The run ended early (around 8:30pm) due to an EF4
problem.

*36 pla good RF, deltau=0.25, deltal=0.52, kappa=1.64, nl_04=1.0 (target)
*37 pla good RF, deltau=0.25, deltal=0.51, kappa=1.67, plasma all the way down
*38 pla one RF trip (H-mode), deltau=0.25, deltal=0.48, kappa=1.72
*39 pla Mo brick, deltau=0.35, deltal=0.49, kappa=1.72
40 pla undo RXU change, Mo brick earlier (before high power RF)
*41 pla load shot 037, deltau=0.25, deltal=0.51, kappa=1.67, H-mode, then inj
*42 pla lower power, weak H-mode
*43 pla bigger H-mode
*44 pla increase Ar puff (25->25ms), no H-mode, 1.5, 2.9, 3.8MW
*45 pla no H-mode, 100kJ @ 3.8MW, nl_04=1.1 (target)
*46 pla lower density nl_04=1.0 (target), disrupt
47 pla nl_04=0.7 (target), earlier disruption
*48 pla nl_04=0.9 (target), good shot
*49 pla repeat, good shot, but Mo injections
50 pla repeat, disrupt (Mo inj)
51 pla repeat, disrupt
52 EF4 test
53 EF4 test

Entered: Jul 7 2004 03:49:15:837PM

Author: To Be Determined

Session Leader's Summary 960301 Part 1.
MP145 Positive Field Drifts. MP140A Density Scan and Collisionality.
_______________________________________________________________________
Two density scans were performed with inner gap 1.4cm and equilibrium
essentially as 960125025. Data was tolerable but almost all shots disrupted
at the end of the shot. The following table summarizes the scans.
Most shots were probed during OH, between the two steps, and at the end.

OH 1.5MW 3MW ICRF
Shot nl04 nl04 nl04 (e20)
Ip=0.8MA,
7 0.9 1.1 1.3
9 0.64 0.79 0.84
11 0.43 0.58 0.74
12 0.4 0.5 0.6
13 0.67 0.82
16 0.74 0.93 1.0
17 1.4 1.2 1.6
18 1.49 1.56 1.2
19 1.7 1.7
Ip=1.1MA
21 1.0 1.2
22 1.0 1.2
23 0.85 1.0
24 0.8 0.95
28 0.38
29 1.1 1.25
30 1.2 1.3
31 1.2 1.4 1.4
32 1.4 1.52 1.7
33 1.7 1.8
34 0.85 1.05 1.25

Brief H-modes were observed on shots 7 and 27: our first with positive
Bt. Shot 27 is suspected of showing giant ELMS (if so, for the first
time with any field direction).

Radiation was rather high in all the shots that disrupted. Minor tweaks
on strike-points etc. did not seem to help.
________________________________________________________________________
Blow by Blow:
1 Fid Good shot. Prad fairly high, .6MW during OH. X-point rather far
in at 1s.

2 PSdud No TF

3 Dis at 1.15s. Many Mo injections. Clearin a bit lower than the reference.
Current rise way too fast. Loop voltage was moved in wrong direction.

4 Dis at 1.13s. Current rise more sensible.

5 Fiz Vertical position lost in ramp.

6 Dis at 1.13s. Otherwise quite good

7 Dis at 1.13s. Probed by FSP. nl04=.9,1.1,1.3 (OH,1.5MW,3MW)
Looks like an H-mode at RF turn off (1s)

8 Fiz Same as before

9 Dis 1.14s. nl04=.64,.79,.84. No H-mode. Mo level goes very high during RF.

10 PSdud

11 Dis 1.2s nl04=.43,.58,.74.

12 Dis .95s nl04=.4,.5,.6 Mo injection at .4s, influx at .8s.

13 PSdud

14 Dis 1.16s. nl04=.67,.82,.78. Hot spot observed on TV, reported as inner
nose.

15 Fiz

16 Dis 1.s. nl04=.74,.93,1. Mo injection at .53s.

17 Dis 1.02s. Big marfe during OH phase, absorbed by RF at .7s. nl04=1.4.

18 Dis at 1.03s. nl04=1.49,1.56,1.2 marfe absorbed by RF at .8s.

19 Dis at .85s nl04=1.7,1.7,0

20 Dis at 0.76s. 1.1MA. Limits on outboard limiter at 0.44s Possibly caused
by Mo injection at .4s, or EF3 current limit.

21 Dis at 1.04s. nl04=1.0,1.2,1.2. Second RF step only 1.3MW.

22 Dis at 1.03s nl04=1.0,1.2,1.2. Second RF step only 1.3MW. Magnetics
data corrupted.

23 Dis at .98s. nl04=.85,1.0,.9, no second RF pulse.

24 Dis at 1.03s nl04=.8,.95 . Second RF pulse only 1.5MW

25 Dis at .75s. Central cooling/disruption problem.

26 Dis at 1.17s Ip=.8MA, fiducial-like.

27 OK repeat. Ip=.8MA ramps down. H-mode at .91s. Giant ELMS.

28 Dis at .73s. Ip=1.1MA nl04=.38, Central cooling problem.

29 Dis at 1.0 s. nl04=1.1,1.25, second RF only 1.4MW

30 Dis at 1.0s Changes to x-point. nl04=1.2,1.3.

31 Dis at 1.0s. Old equilibrium. nl04=1.2,1.4,1.4.

32 OK Ramp-down! 2pi bolo is way down. nl04=1.4,1.52,1.7 Minor disruptions
at .25s are survived better. They look like current-rise disruptions.
No obvious proper sawteeth beforehand.

33 Dis at 1.22s nl04=1.7,1.8

34 Dis at 1.04s nl04=.85,1.05,1.25. Has sawteeth from very early. Didn't help.

35 Dis at 0.35s.

End of Density scan MPs.

Physics Operator Summaries

Entered: Jul 7 2004 04:36:56:333PM

Author: To Be Determined

Physics operator's summary for run 960301A:

MP #145, Cross-field drift studies with reversed field, and
MP #140A, Density scan to get L-mode confinement data (piggyback)

SL: Hutchinson
PO: Granetz
EO: Bertolino/Daigle

Today's primary run will study edge flows with reversed field and boronized
walls, for comparison to the normal field case. The piggyback run is to get
L-mode confinement data, which is best done in this reversed field
configuration, so as to avoid H-modes. The plan is to run +0.8 MA plasmas at
+5.3 tesla for the first half of the run, and +1.1 MA plasmas for the latter
half. Density will be scanned from 0.5 < nebar < 2.5e20 m-3 (or as wide a
range as we can get). We want as much RF power as can be RELIABLY (i.e.
repeatibly) obtained. We will also being doing small field ramps, in order to
get better spatial resolution of edge Te profiles.

Summary: Succeeded in doing density scans at both 0.8 and 1.1 MA, but
nearly all shots disrupted. The 0.8 MA shots tended to disrupt during
the rampdown. The 1.1 MA shots tended to disrupt during the flattop, or
right at the end of flattop. The exceptions were shots 032 and 033,
which were at much higher density. Shot 032 is our trophy shot for 1.1 MA
in reversed field. Because the only difference between these shots
and most of the other 1.1 MA shots was the excessive gas puffing
(including 2 NINJA capillaries), it may be that the disruptions were not
caused by equilibrium problems, but rather by impurities introduced
during minor current rise disruptions. No good plasmas at the lowest
desired densities were obtained at 1.1 MA. Despite the frequent
disruptions, plasma startup was very reliable after a Br tweak was made
on shot 015. Shot 001 was a good fiducial, and shot 027 was similar,
with a slightly slowed-down current rise. The RF worked well today,
with most shots having 3 MW. We even had some short H-modes on shot 007
shot 027. I haven't seen much concerning flows in the SOL (which was
the point of this run). Brian did mention that the flow reversal that
is sometimes seen near the separatrix in normal fields was not seen in
this reversed field run.

Scorecard: 29 plasmas
3 fizzles
0 tests
3 duds (all due to power supply problems
----------
35 total

Run plan:

Load a fiducial from yesterday's reversed field run (960229031).
After that, load in a shot based on 960125025, except with all necessary
signals flipped, and Ip reduced to +0.8 MA. Do a density scan with high
RF power. Hopefully we will stay in L-mode.
Next, increase the plasma current to +1.1 MA and repeat the density scan
with high RF power.
In order to improve the spatial resolution of edge profile measurements, we
may "tweak" the Btor a little from shot-to-shot. This will be done under
hybrid control.

Engineering setup for Friday 01 Mar 1996:

No discharge cleaning was done, due to a problem with the PEI supply.

A-side (actually K-side) plenum: 20 psi of deuterium
B-top plenum: 5 psi of deuterium.
B-side-lower plenum: 4 psi of argon.
B-side-upper plenum: don't touch.
NINJA plenum: make sure this is pumped out.
Enable hybrid control of A-side, B-top, and B-side-lower valves for start
of run.
Enable the ECE, VUV, Moly monitor, PCX, and TCX valves, assuming status of
each is okay.

Start with engineering settings from shot 960229031 for the fiducial.

Detailed shot log:

Shot 01 -- Setup from yesterday's fiducial (960229031), except reduce OH1 early
voltage by 100 volts, and the OH2's by 20 volts. Also increase
early gas puffing. Note: no discharge cleaning was done due to a
problem with the PEI.

Good shot. Good RF. No H-modes.

Shot 02 -- Load in segment 2 from 960125025. Change RCUR offset to -2000 (same
as segment 2 from yesterday). Add in a 5 kA decreasing ramp on the
TF from t=0.8 to 1.0 s. Also further reduce early OH1 and OH2
voltages by another 100 & 20 volts respectively, in order to further
reduce the (high) rate of current rise. (Hybrid now has control of
the TF.)

Dud. No TF.

Shot 03 -- Plasma. Disrupted in rampdown at 1.15 s. Current rise was way too
fast. Oops, I should have been increasing the OH1 and OH2 voltages.
Bt field ramp was 2.4% from 0.8 to 1.0 s.

Next shot: Set OH1 and OH2 early voltages +100 and +20 volts
respectively compared to yesterday's fiducial.) Also, increase
CLEARIN by 5 mm.

Shot 04 -- Plasma. Better current rise. Still disrupts in rampdown.

Next shot: raise ZCUR by 2 mm. Also rampdown the Ip and CLEARIN
faster. Also move RXL out by 3 mm.

Shot 05 -- Fizzle.

Shot 06 -- Plasma. Still disrupts in rampdown.

Next shot: repeat for scanning probe. Start Ip rampdown at 1.1 s,
rather than 1.2 s. Also increase CLEARIN another 3 mm.

Shot 07 -- Plasma. Disrupts in rampdown at 1.14 s. There might have been
an H-mode just as the RF is turning off.

Next shot: Reduce density to nl_04=0.5e20 m-2. Also tweak RXL after
1.0 s, and start Ip rampdown at 1.05 s.

Shot 08 -- Fizzle. 50 kA plasma went upwards at about 20 ms...same as on
previous fizzle.

Next shot: add in a -1 mT blip in BR_0 from t=0.010 to 0.030 s.
Also tweak CLEARIN up 1.5 mm.

Shot 09 -- Plasma. Disrupts in rampdown at 1.15 s. Density was lower, but
not quite as low as we want.

Next shot: decrease density to nl_04=0.4e20 m-2, and decrease valve
voltages in both segment 1 and 2, starting from about t=0.070 s.
Also, start CLEARIN rampdown at 1.05 s.

Shot 10 -- Dud. No TF nor PF supplies, except for EF2's and EFC. Magnet
resistance fault.

Shot 11 -- Plasma. Got nl_04=0.5e20 m-2. No H-modes. Disrupted at 1.20 s.

Next shot: repeat, except tweak CLEARIN to rampdown even faster.

Shot 12 -- Plasma. Hard disruption at t=0.96 s. Not the same as the rampdown
disruptions that we have had on every other shot. TF crowbarred.

Next shot: raise density to nl_04=0.7e20 m-2.

Shot 13 -- Dud. Most of the PF supplies didn't fire.

Shot 14 -- Plasma. Got nl_04=0.65-0.75e20 m-2. Disrupted at 1.17 s.

Next shot: increase density to nl_04=0.85e20 m-2.

Shot 15 -- Fizzle. Br looks a bit negative.

Next shot: increase Br offset by 0.6 mT

Shot 16 -- Plasma. Lots of molybdenum. Disrupted at 0.996 s. Jim Terry
reports a bright spot on the inner divertor nose.

Next shot: raise nl_04 to 1.4e20 m-2, and increase gas valve
voltage in both segments 1 and 2. Also tweak ZXL by -1 mm from
0.75-1.2 s.

Shot 17 -- Plasma. Big marfe on inboard wall until 0.7 s, when it moves down
to the divertor. Disrupted at 1.02 s.

Next shot: a little more gas valve voltage around 0.1 s in both
segments 1 and 2.

Shot 18 -- Plasma. Got the density we wanted until 0.8 s, when the marfe
movement changes the interferometer signal. Still disrupts at 1.03 s

Next shot: increase nl_04 to 1.6e20 m-2. In order to help get to
this density, we'll turn on NINJA puffing from the outboard
midplane. NINJA plenum will be filled to 20 psi (960 torr) of
deuterium.

Shot 19 -- Plasma. Lots of gas puffing. Disrupts at 0.85 s. Maybe due to
some kind of radiative event.

Next shot: raise Ip to 1.1 MA. Lower density back to
nl_04=1.0e20 m-2. Turn off NINJA puff.

Shot 20 -- Plasma. Disrupts at 0.76 s.

Next shot: increase EF3 PLC limits from 12 to 15 kA. Also tweak
RCUR programming around 0.1 s.

Shot 21 -- Plasma. Disrupts at 1.05 s. RF high power pulse wasn't as good
as previous shots.

Next shot: repeat w/slight downwards tweak on ZXL around 0.6 s, at
Brian's request.

Shot 22 -- Plasma. Disrupts at 1.03 s. Very similar to previous shot.
Magnetics traq_1 data corrupted.

Next shot: decrease nl_04 to 0.8e20 m-2. Also, remove the second
RF pulse (3 MW, ending at 1.0 s) to see if that affects the
disruptions that we have been getting.

Shot 23 -- Plasma. Still disrupted, at 0.99 s, so it has nothing to do with
the RF.

Next shot: get rid of small TF ramp. We're really grasping at
straws with this one. Turn the second RF pulse back on. Also
tweak ZXL a bit again for Brian's probe.

Shot 24 -- Plasma. Disrupted at 1.03 s. TF ramp didn't go away. I must not
have OK'd it. Second RF pulse didn't go.

Next shot: lower density to nl_04=0.6e20 m-2. Also, this time I
definitely got rid of the TF ramp. Also disable the argon valve.

Shot 25 -- Plasma, but disrupted at 0.74 s.

Next shot: run a fiducial to check and see if it disrupts. Load
segment 2 from shot 001 today.

Shot 26 -- Fiducial-like plasma. Disrupts at 1.17 s, just like all the other
0.8 MA shots today, except for the initial fiducial shot. Lots
of moly injections.

Shot 27 -- Repeat of previous fiducial-like plasma. Good shot, ramped all
the way down. Short little H-modes with giant ELM's.

Next shot: go back to 1.1 MA, with nl_04=0.4e20 m-2. Decrease
gas valve voltages in segment 1 and 2 also. Put TF ramp back in.

Shot 28 -- Plasma. 1.1 MA, nl_04 gets down to 0.4e20 m-2, but starts to rise
at the RF pulse.

Next shot: raise nl_04 to 1.2e20 m-2. Return the gas valve
voltage to the normal higher levels in both segments 1 and 2.

Shot 29 -- Plasma. Disrupts at 1.01 s. Didn't get high RF power.

Next shot: repeat, except move x-point 5 mm down and 5 mm in (to
better match the fiducial-like shot).

Shot 30 -- Plasma. Still disrupts at 1.01 s. Moving the x-point to be more
like the fiducial didn't help.

Next shot: increase nl_04 to 1.5e20 m-2. Return the x-point to the
position it had prior to this shot.

Shot 31 -- Plasma. nl_04=1.2-1.4e20 m-2. Disrupted at 1.01 s. Got 3 MW of
RF for part of the second pulse.

Next shot: try for nl_04=1.6e20 m-2. Turn on NINJA outboard
valve to help get the density up.

Shot 32 -- Good plasma! Ramped all the way down! nl_04=1.5-1.6e20 m-2.
Trophy shot.

Next shot: higher density. Try for nl_04=2.0e20 m-2. Increase
gas valve voltage in both segments 1 and 2. Turn on a second
NINJA valve (near the outer strike point).

Shot 33 -- Plasma. Makes it about halfway down the current ramp. Density
reached nl_04=1.8e20 m-2. Didn't get high power RF

Next shot: Try for very low density. nl_04=0.4e20 m-2. Reduce
gas valve voltage in both segment 1 and 2. Turn off NINJA.

Shot 34 -- Plasma. Disrupts at 1.05 s. nl_04=0.9e20 m-2.

Next shot: try for lower density again. Reduce gas valve voltage
programming some more in both segments.

Shot 35 -- Plasma, but disrupted at only t=0.35 s. Density was very low.

End of this MP. The run will continue for a 2nd shift on another MP.

Session Leader Comments

Physics Operator Comments

Mar 1 1996 08:29:12:690AM Robert Granetz MP #145, Cross-field drift studies with reversed field, and
MP #140A, Density scan to get L-mode confinement data (piggyback)

SL: Hutchinson
PO: Granetz
EO: Bertolino

Today's primary run will study edge flows with reversed field and boronized
walls, for comparison to the normal field case. The piggyback run is to get
L-mode confinement data, which is best done in this reversed field
configuration, so as to avoid H-modes. The plan is to run +0.8 MA plasmas at
+5.3 tesla for the first half of the run, and +1.1 MA plasmas for the latter
half. Density will be scanned from 0.5 < nebar < 2.5e20 m-3 (or as wide a
range as we can get). We want as much RF power as can be RELIABLY (i.e.
repeatibly) obtained. We will also being doing small field ramps, in order to
get better spatial resolution of edge Te profiles.

Mar 1 1996 08:29:32:570AM Robert Granetz Run plan:

Load a fiducial from yesterday's reversed field run (960229031).
After that, load in a shot based on 960125025, except with all necessary
signals flipped, and Ip reduced to +0.8 MA. Do a density scan with high
RF power. Hopefully we will stay in L-mode.
Next, increase the plasma current to +1.1 MA and repeat the density scan
with high RF power.
In order to improve the spatial resolution of edge profile measurements, we
may "tweak" the Btor a little from shot-to-shot. This will be done under
hybrid control.

Mar 1 1996 08:30:49:190AM Robert Granetz Engineering setup for Tuesday 01 Mar 1996:

No discharge cleaning was done, due to a problem with the PEI supply.

A-side (actually K-side) plenum: 20 psi of deuterium
B-top plenum: 5 psi of deuterium.
B-side-lower plenum: 4 psi of argon.
B-side-upper plenum: don't touch.
NINJA plenum: make sure this is pumped out.
Enable hybrid control of A-side, B-top, and B-side-lower valves for start
of run.
Enable the ECE, VUV, Moly monitor, PCX, and TCX valves, assuming status of
each is okay.

Start with engineering settings from shot 960229031 for the fiducial.

Mar 1 1996 09:27:25:380AM 960301001 Robert Granetz Shot 01 -- Setup from yesterday's fiducial (960229031), except reduce OH1 early
voltage by 100 volts, and the OH2's by 20 volts. Also increase
early gas puffing. Note: no discharge cleaning was done due to a
problem with the PEI.

Good shot. Good RF. No H-modes.

Mar 1 1996 09:36:43:940AM 960301002 Robert Granetz Shot 02 -- Load in segment 2 from 960125025. Change RCUR offset to -2000 (same
as segment 2 from yesterday). Add in a 5 kA decreasing ramp on the
TF from t=0.8 to 1.0 s. Also further reduce early OH1 and OH2
voltages by another 100 & 20 volts respectively, in order to further
reduce the (high) rate of current rise. (Hybrid now has control of
the TF.)

Dud. No TF.

Mar 1 1996 10:01:31:310AM 960301003 Robert Granetz Shot 03 -- Plasma. Disrupted in rampdown at 1.15 s. Current rise was way too
fast. Oops, I should have been increasing the OH1 and OH2 voltages.
Bt field ramp was 2.4% from 0.8 to 1.0 s.

Next shot: Set OH1 and OH2 early voltages +100 and +20 volts
respectively compared to yesterday's fiducial.) Also, increase
CLEARIN by 5 mm.

Mar 1 1996 10:10:39:960AM 960301004 Robert Granetz Shot 04 -- Plasma. Better current rise. Still disrupts in rampdown.

Next shot: raise ZCUR by 2 mm. Also rampdown the Ip and CLEARIN
faster. Also move RXL out by 3 mm.

Mar 1 1996 10:25:30:580AM 960301005 Robert Granetz Shot 05 -- Fizzle.

Mar 1 1996 10:35:34:070AM 960301006 Robert Granetz Shot 06 -- Plasma. Still disrupts in rampdown.

Next shot: repeat for scanning probe. Start Ip rampdown at 1.1 s,
rather than 1.2 s. Also increase CLEARIN another 3 mm.

Mar 1 1996 11:27:22:390AM 960301007 Robert Granetz Shot 07 -- Plasma. Disrupts in rampdown at 1.14 s. There might have been
an H-mode just as the RF is turning off.

Next shot: Reduce density to nl_04=0.5e20 m-2. Also tweak RXL after
1.0 s, and start Ip rampdown at 1.05 s.

Mar 1 1996 11:07:03:960AM 960301008 Robert Granetz Shot 08 -- Fizzle. 50 kA plasma went upwards at about 20 ms...same as on
previous fizzle.

Next shot: add in a -1 mT blip in BR_0 from t=0.010 to 0.030 s.
Also tweak CLEARIN up 1.5 mm.

Mar 1 1996 11:19:33:650AM 960301009 Robert Granetz Shot 09 -- Plasma. Disrupts in rampdown at 1.15 s. Density was lower, but
not quite as low as we want.

Next shot: decrease density to nl_04=0.4e20 m-2, and decrease valve
voltages in both segment 1 and 2, starting from about t=0.070 s.
Also, start CLEARIN rampdown at 1.05 s.

Mar 1 1996 11:26:37:170AM 960301010 Robert Granetz Shot 10 -- Dud. No TF nor PF supplies, except for EF2's and EFC. Magnet
resistance fault.

Mar 1 1996 11:38:29:840AM 960301011 Robert Granetz Shot 11 -- Plasma. Got nl_04=0.5e20 m-2. No H-modes. Disrupted at 1.20 s.

Next shot: repeat, except tweak CLEARIN to rampdown even faster.

Mar 1 1996 11:51:06:640AM 960301012 Robert Granetz Shot 12 -- Plasma. Hard disruption at t=0.96 s. Not the same as the rampdown
disruptions that we have had on every other shot. TF crowbarred.

Next shot: raise density to nl_04=0.7e20 m-2.

Mar 1 1996 11:57:44:090AM 960301013 Robert Granetz Shot 13 -- Dud. Most of the PF supplies didn't fire.

Mar 1 1996 12:21:53:920PM 960301014 Robert Granetz Shot 14 -- Plasma. Got nl_04=0.65-0.75e20 m-2. Disrupted at 1.17 s.

Next shot: increase density to nl_04=0.85e20 m-2.

Mar 1 1996 12:28:04:800PM 960301015 Robert Granetz Shot 15 -- Fizzle. Br looks a bit negative.

Next shot: increase Br offset by 0.6 mT

Mar 1 1996 12:42:43:830PM 960301016 Robert Granetz Shot 16 -- Plasma. Lots of molybdenum. Disrupted at 0.996 s. Jim Terry
reports a bright spot on the inner divertor nose.

Next shot: raise nl_04 to 1.4e20 m-2, and increase gas valve
voltage in both segments 1 and 2. Also tweak ZXL by -1 mm from
0.75-1.2 s.

Mar 1 1996 01:00:19:780PM 960301017 Robert Granetz Shot 17 -- Plasma. Big marfe on inboard wall until 0.7 s, when it moves down
to the divertor. Disrupted at 1.02 s.

Next shot: a little more gas valve voltage around 0.1 s in both
segments 1 and 2.

Mar 1 1996 01:26:41:620PM 960301018 Robert Granetz Shot 18 -- Plasma. Got the density we wanted until 0.8 s, when the marfe
movement changes the interferometer signal. Still disrupts at 1.03 s

Next shot: increase nl_04 to 1.6e20 m-2. In order to help get to
this density, we'll turn on NINJA puffing from the outboard
midplane. NINJA plenum will be filled to 20 psi (960 torr) of
deuterium.

Mar 1 1996 01:36:19:100PM 960301019 Robert Granetz Shot 19 -- Plasma. Lots of gas puffing. Disrupts at 0.85 s. Maybe due to
some kind of radiative event.

Next shot: raise Ip to 1.1 MA. Lower density back to
nl_04=1.0e20 m-2. Turn off NINJA puff.

Mar 1 1996 01:51:36:900PM 960301020 Robert Granetz Shot 20 -- Plasma. Disrupts at 0.76 s.

Next shot: increase EF3 PLC limits from 12 to 15 kA. Also tweak
RCUR programming around 0.1 s.

Mar 1 1996 02:02:50:080PM 960301021 Robert Granetz Shot 21 -- Plasma. Disrupts at 1.05 s. RF high power pulse wasn't as good
as previous shots.

Next shot: repeat w/slight downwards tweak on ZXL around 0.6 s, at
Brian's request.

Mar 1 1996 02:14:38:780PM 960301022 Robert Granetz Shot 22 -- Plasma. Disrupts at 1.03 s. Very similar to previous shot.
Magnetics traq_1 data corrupted.

Next shot: decrease nl_04 to 0.8e20 m-2. Also, remove the second
RF pulse (3 MW, ending at 1.0 s) to see if that affects the
disruptions that we have been getting.

Mar 1 1996 02:27:38:950PM 960301023 Robert Granetz Shot 23 -- Plasma. Still disrupted, at 0.99 s, so it has nothing to do with
the RF.

Next shot: get rid of small TF ramp. We're really grasping at
straws with this one. Turn the second RF pulse back on. Also
tweak ZXL a bit again for Brian's probe.

Mar 1 1996 02:36:42:190PM 960301024 Robert Granetz Shot 24 -- Plasma. Disrupted at 1.03 s. TF ramp didn't go away. I must not
have OK'd it. Second RF pulse didn't go.

Next shot: lower density to nl_04=0.6e20 m-2. Also, this time I
definitely got rid of the TF ramp. Also disable the argon valve.

Mar 1 1996 03:23:46:960PM 960301025 Robert Granetz Shot 25 -- Plasma, but disrupted at 0.74 s.

Next shot: run a fiducial to check and see if it disrupts. Load
segment 2 from shot 001 today.

Mar 1 1996 03:23:59:700PM 960301026 Robert Granetz Shot 26 -- Fiducial-like plasma. Disrupts at 1.17 s, just like all the other
0.8 MA shots today, except for the initial fiducial shot. Lots
of moly injections.

Mar 1 1996 03:24:13:160PM 960301027 Robert Granetz Shot 27 -- Repeat of previous fiducial-like plasma. Good shot, ramped all
the way down. Short little H-modes with giant ELM's.

Next shot: go back to 1.1 MA, with nl_04=0.4e20 m-2. Decrease
gas valve voltages in segment 1 and 2 also. Put TF ramp back in.

Mar 1 1996 03:24:25:270PM 960301028 Robert Granetz Shot 28 -- Plasma. 1.1 MA, nl_04 gets down to 0.4e20 m-2, but starts to rise
at the RF pulse.

Next shot: raise nl_04 to 1.2e20 m-2. Return the gas valve
voltage to the normal higher levels in both segments 1 and 2.

Mar 1 1996 03:40:56:420PM 960301029 Robert Granetz Shot 29 -- Plasma. Disrupts at 1.01 s. Didn't get high RF power.

Next shot: repeat, except move x-point 5 mm down and 5 mm in (to
better match the fiducial-like shot).

Mar 1 1996 03:58:11:350PM 960301030 Robert Granetz Shot 30 -- Plasma. Still disrupts at 1.01 s. Moving the x-point to be more
like the fiducial didn't help.

Next shot: increase nl_04 to 1.5e20 m-2. Return the x-point to the
position it had prior to this shot.

Mar 1 1996 04:13:51:080PM 960301031 Robert Granetz Shot 31 -- Plasma. nl_04=1.2-1.4e20 m-2. Disrupted at 1.01 s. Got 3 MW of
RF for part of the second pulse.

Next shot: try for nl_04=1.6e20 m-2. Turn on NINJA outboard
valve to help get the density up.

Mar 1 1996 04:28:16:780PM 960301032 Robert Granetz Shot 32 -- Good plasma! Ramped all the way down! nl_04=1.5-1.6e20 m-2.
Trophy shot.

Next shot: higher density. Try for nl_04=2.0e20 m-2. Increase
gas valve voltage in both segments 1 and 2. Turn on a second
NINJA valve (near the outer strike point).

Mar 1 1996 04:38:58:370PM 960301033 Robert Granetz Shot 33 -- Plasma. Makes it about halfway down the current ramp. Density
reached nl_04=1.8e20 m-2. Didn't get high power RF

Next shot: Try for very low density. nl_04=0.4e20 m-2. Reduce
gas valve voltage in both segment 1 and 2. Turn off NINJA.

Mar 1 1996 04:43:43:420PM 960301034 Robert Granetz Shot 34 -- Plasma. Disrupts at 1.05 s. nl_04=0.9e20 m-2.

Next shot: try for lower density again. Reduce gas valve voltage
programming some more in both segments.

Mar 1 1996 04:54:34:750PM 960301035 Robert Granetz Shot 35 -- Plasma, but disrupted at only t=0.35 s. Density was very low.

End of this MP. The run will continue for a 2nd shift on another MP.

Engineering Operator Comments

Shot Time Type Status Comment

1 09:12:57:120AM Plasma Ok

2 09:31:12:810AM Plasma Bad no tf

3 09:42:29:110AM Plasma Ok

4 09:57:49:120AM Plasma Ok

5 10:16:15:510AM Plasma Ok

6 10:26:04:240AM Plasma Ok

7 10:37:09:450AM Plasma Ok

8 10:49:36:910AM Plasma Ok

9 11:07:01:970AM Plasma Ok

10 11:19:43:120AM Plasma Bad mag resist fault in pulse

11 11:27:13:510AM Plasma Ok

12 11:37:41:220AM Plasma Ok

13 11:55:04:690AM Plasma Bad ef4 ioc

14 12:10:23:020PM Plasma Ok

15 12:21:00:430PM Plasma Ok

16 12:29:23:430PM Plasma Ok

17 12:48:23:430PM Plasma Ok

18 01:10:45:720PM Plasma Ok

19 01:26:13:270PM Plasma Ok

20 01:38:01:530PM Plasma Ok

21 01:51:09:340PM Plasma Ok

22 02:04:27:760PM Plasma Ok

23 02:14:44:670PM Plasma Ok Comm Fault Bypass OH2u

24 02:26:34:460PM Plasma Ok

25 02:36:38:880PM Plasma Ok

26 02:47:41:760PM Plasma Ok

27 02:57:03:090PM Plasma Ok

28 03:08:54:740PM Plasma Ok

29 03:30:40:850PM Plasma Ok

30 03:43:56:050PM Plasma Ok

31 04:04:18:770PM Plasma Ok

32 04:16:56:600PM Plasma Ok

33 04:29:49:980PM Plasma Ok

34 04:38:26:550PM Plasma Ok

35 04:49:20:980PM Plasma Ok

36 04:58:15:070PM Plasma Ok

37 05:16:49:520PM Plasma Ok

38 05:32:28:120PM Plasma Ok

39 05:46:36:160PM Plasma Ok

40 05:57:51:960PM Plasma Ok

41 06:06:49:660PM Plasma Ok

42 06:20:40:940PM Plasma Ok

43 06:37:41:280PM Plasma Ok

44 06:50:58:360PM Plasma Ok

45 06:59:58:060PM Plasma Ok

46 07:09:18:800PM Plasma Ok

47 07:22:06:350PM Plasma Ok

48 07:32:39:500PM Plasma Ok

49 07:41:15:110PM Plasma Ok

50 07:50:07:880PM Plasma Ok

51 07:58:46:100PM Plasma Ok TF self powered fired OH2U comm Fault Bypass.

52 08:28:57:580PM Plasma Ok

53 08:35:34:620PM Test Bad TF did not go.

54 08:49:38:510PM Test Ok

55 08:55:58:110PM Test Ok

Physics Operator Comments
Mar 1 1996 08:29:12:690AM		Robert Granetz	MP #145, Cross-field drift studies with reversed field, and MP #140A, Density scan to get L-mode confinement data (piggyback) SL: Hutchinson PO: Granetz EO: Bertolino Today's primary run will study edge flows with reversed field and boronized walls, for comparison to the normal field case. The piggyback run is to get L-mode confinement data, which is best done in this reversed field configuration, so as to avoid H-modes. The plan is to run +0.8 MA plasmas at +5.3 tesla for the first half of the run, and +1.1 MA plasmas for the latter half. Density will be scanned from 0.5 < nebar < 2.5e20 m-3 (or as wide a range as we can get). We want as much RF power as can be RELIABLY (i.e. repeatibly) obtained. We will also being doing small field ramps, in order to get better spatial resolution of edge Te profiles.
Mar 1 1996 08:29:32:570AM		Robert Granetz	Run plan: Load a fiducial from yesterday's reversed field run (960229031). After that, load in a shot based on 960125025, except with all necessary signals flipped, and Ip reduced to +0.8 MA. Do a density scan with high RF power. Hopefully we will stay in L-mode. Next, increase the plasma current to +1.1 MA and repeat the density scan with high RF power. In order to improve the spatial resolution of edge profile measurements, we may "tweak" the Btor a little from shot-to-shot. This will be done under hybrid control.
Mar 1 1996 08:30:49:190AM		Robert Granetz	Engineering setup for Tuesday 01 Mar 1996: No discharge cleaning was done, due to a problem with the PEI supply. A-side (actually K-side) plenum: 20 psi of deuterium B-top plenum: 5 psi of deuterium. B-side-lower plenum: 4 psi of argon. B-side-upper plenum: don't touch. NINJA plenum: make sure this is pumped out. Enable hybrid control of A-side, B-top, and B-side-lower valves for start of run. Enable the ECE, VUV, Moly monitor, PCX, and TCX valves, assuming status of each is okay. Start with engineering settings from shot 960229031 for the fiducial.
Mar 1 1996 09:27:25:380AM	960301001	Robert Granetz	Shot 01 -- Setup from yesterday's fiducial (960229031), except reduce OH1 early voltage by 100 volts, and the OH2's by 20 volts. Also increase early gas puffing. Note: no discharge cleaning was done due to a problem with the PEI. Good shot. Good RF. No H-modes.
Mar 1 1996 09:36:43:940AM	960301002	Robert Granetz	Shot 02 -- Load in segment 2 from 960125025. Change RCUR offset to -2000 (same as segment 2 from yesterday). Add in a 5 kA decreasing ramp on the TF from t=0.8 to 1.0 s. Also further reduce early OH1 and OH2 voltages by another 100 & 20 volts respectively, in order to further reduce the (high) rate of current rise. (Hybrid now has control of the TF.) Dud. No TF.
Mar 1 1996 10:01:31:310AM	960301003	Robert Granetz	Shot 03 -- Plasma. Disrupted in rampdown at 1.15 s. Current rise was way too fast. Oops, I should have been increasing the OH1 and OH2 voltages. Bt field ramp was 2.4% from 0.8 to 1.0 s. Next shot: Set OH1 and OH2 early voltages +100 and +20 volts respectively compared to yesterday's fiducial.) Also, increase CLEARIN by 5 mm.
Mar 1 1996 10:10:39:960AM	960301004	Robert Granetz	Shot 04 -- Plasma. Better current rise. Still disrupts in rampdown. Next shot: raise ZCUR by 2 mm. Also rampdown the Ip and CLEARIN faster. Also move RXL out by 3 mm.
Mar 1 1996 10:25:30:580AM	960301005	Robert Granetz	Shot 05 -- Fizzle.
Mar 1 1996 10:35:34:070AM	960301006	Robert Granetz	Shot 06 -- Plasma. Still disrupts in rampdown. Next shot: repeat for scanning probe. Start Ip rampdown at 1.1 s, rather than 1.2 s. Also increase CLEARIN another 3 mm.
Mar 1 1996 11:27:22:390AM	960301007	Robert Granetz	Shot 07 -- Plasma. Disrupts in rampdown at 1.14 s. There might have been an H-mode just as the RF is turning off. Next shot: Reduce density to nl_04=0.5e20 m-2. Also tweak RXL after 1.0 s, and start Ip rampdown at 1.05 s.
Mar 1 1996 11:07:03:960AM	960301008	Robert Granetz	Shot 08 -- Fizzle. 50 kA plasma went upwards at about 20 ms...same as on previous fizzle. Next shot: add in a -1 mT blip in BR_0 from t=0.010 to 0.030 s. Also tweak CLEARIN up 1.5 mm.
Mar 1 1996 11:19:33:650AM	960301009	Robert Granetz	Shot 09 -- Plasma. Disrupts in rampdown at 1.15 s. Density was lower, but not quite as low as we want. Next shot: decrease density to nl_04=0.4e20 m-2, and decrease valve voltages in both segment 1 and 2, starting from about t=0.070 s. Also, start CLEARIN rampdown at 1.05 s.
Mar 1 1996 11:26:37:170AM	960301010	Robert Granetz	Shot 10 -- Dud. No TF nor PF supplies, except for EF2's and EFC. Magnet resistance fault.
Mar 1 1996 11:38:29:840AM	960301011	Robert Granetz	Shot 11 -- Plasma. Got nl_04=0.5e20 m-2. No H-modes. Disrupted at 1.20 s. Next shot: repeat, except tweak CLEARIN to rampdown even faster.
Mar 1 1996 11:51:06:640AM	960301012	Robert Granetz	Shot 12 -- Plasma. Hard disruption at t=0.96 s. Not the same as the rampdown disruptions that we have had on every other shot. TF crowbarred. Next shot: raise density to nl_04=0.7e20 m-2.
Mar 1 1996 11:57:44:090AM	960301013	Robert Granetz	Shot 13 -- Dud. Most of the PF supplies didn't fire.
Mar 1 1996 12:21:53:920PM	960301014	Robert Granetz	Shot 14 -- Plasma. Got nl_04=0.65-0.75e20 m-2. Disrupted at 1.17 s. Next shot: increase density to nl_04=0.85e20 m-2.
Mar 1 1996 12:28:04:800PM	960301015	Robert Granetz	Shot 15 -- Fizzle. Br looks a bit negative. Next shot: increase Br offset by 0.6 mT
Mar 1 1996 12:42:43:830PM	960301016	Robert Granetz	Shot 16 -- Plasma. Lots of molybdenum. Disrupted at 0.996 s. Jim Terry reports a bright spot on the inner divertor nose. Next shot: raise nl_04 to 1.4e20 m-2, and increase gas valve voltage in both segments 1 and 2. Also tweak ZXL by -1 mm from 0.75-1.2 s.
Mar 1 1996 01:00:19:780PM	960301017	Robert Granetz	Shot 17 -- Plasma. Big marfe on inboard wall until 0.7 s, when it moves down to the divertor. Disrupted at 1.02 s. Next shot: a little more gas valve voltage around 0.1 s in both segments 1 and 2.
Mar 1 1996 01:26:41:620PM	960301018	Robert Granetz	Shot 18 -- Plasma. Got the density we wanted until 0.8 s, when the marfe movement changes the interferometer signal. Still disrupts at 1.03 s Next shot: increase nl_04 to 1.6e20 m-2. In order to help get to this density, we'll turn on NINJA puffing from the outboard midplane. NINJA plenum will be filled to 20 psi (960 torr) of deuterium.
Mar 1 1996 01:36:19:100PM	960301019	Robert Granetz	Shot 19 -- Plasma. Lots of gas puffing. Disrupts at 0.85 s. Maybe due to some kind of radiative event. Next shot: raise Ip to 1.1 MA. Lower density back to nl_04=1.0e20 m-2. Turn off NINJA puff.
Mar 1 1996 01:51:36:900PM	960301020	Robert Granetz	Shot 20 -- Plasma. Disrupts at 0.76 s. Next shot: increase EF3 PLC limits from 12 to 15 kA. Also tweak RCUR programming around 0.1 s.
Mar 1 1996 02:02:50:080PM	960301021	Robert Granetz	Shot 21 -- Plasma. Disrupts at 1.05 s. RF high power pulse wasn't as good as previous shots. Next shot: repeat w/slight downwards tweak on ZXL around 0.6 s, at Brian's request.
Mar 1 1996 02:14:38:780PM	960301022	Robert Granetz	Shot 22 -- Plasma. Disrupts at 1.03 s. Very similar to previous shot. Magnetics traq_1 data corrupted. Next shot: decrease nl_04 to 0.8e20 m-2. Also, remove the second RF pulse (3 MW, ending at 1.0 s) to see if that affects the disruptions that we have been getting.
Mar 1 1996 02:27:38:950PM	960301023	Robert Granetz	Shot 23 -- Plasma. Still disrupted, at 0.99 s, so it has nothing to do with the RF. Next shot: get rid of small TF ramp. We're really grasping at straws with this one. Turn the second RF pulse back on. Also tweak ZXL a bit again for Brian's probe.
Mar 1 1996 02:36:42:190PM	960301024	Robert Granetz	Shot 24 -- Plasma. Disrupted at 1.03 s. TF ramp didn't go away. I must not have OK'd it. Second RF pulse didn't go. Next shot: lower density to nl_04=0.6e20 m-2. Also, this time I definitely got rid of the TF ramp. Also disable the argon valve.
Mar 1 1996 03:23:46:960PM	960301025	Robert Granetz	Shot 25 -- Plasma, but disrupted at 0.74 s. Next shot: run a fiducial to check and see if it disrupts. Load segment 2 from shot 001 today.
Mar 1 1996 03:23:59:700PM	960301026	Robert Granetz	Shot 26 -- Fiducial-like plasma. Disrupts at 1.17 s, just like all the other 0.8 MA shots today, except for the initial fiducial shot. Lots of moly injections.
Mar 1 1996 03:24:13:160PM	960301027	Robert Granetz	Shot 27 -- Repeat of previous fiducial-like plasma. Good shot, ramped all the way down. Short little H-modes with giant ELM's. Next shot: go back to 1.1 MA, with nl_04=0.4e20 m-2. Decrease gas valve voltages in segment 1 and 2 also. Put TF ramp back in.
Mar 1 1996 03:24:25:270PM	960301028	Robert Granetz	Shot 28 -- Plasma. 1.1 MA, nl_04 gets down to 0.4e20 m-2, but starts to rise at the RF pulse. Next shot: raise nl_04 to 1.2e20 m-2. Return the gas valve voltage to the normal higher levels in both segments 1 and 2.
Mar 1 1996 03:40:56:420PM	960301029	Robert Granetz	Shot 29 -- Plasma. Disrupts at 1.01 s. Didn't get high RF power. Next shot: repeat, except move x-point 5 mm down and 5 mm in (to better match the fiducial-like shot).
Mar 1 1996 03:58:11:350PM	960301030	Robert Granetz	Shot 30 -- Plasma. Still disrupts at 1.01 s. Moving the x-point to be more like the fiducial didn't help. Next shot: increase nl_04 to 1.5e20 m-2. Return the x-point to the position it had prior to this shot.
Mar 1 1996 04:13:51:080PM	960301031	Robert Granetz	Shot 31 -- Plasma. nl_04=1.2-1.4e20 m-2. Disrupted at 1.01 s. Got 3 MW of RF for part of the second pulse. Next shot: try for nl_04=1.6e20 m-2. Turn on NINJA outboard valve to help get the density up.
Mar 1 1996 04:28:16:780PM	960301032	Robert Granetz	Shot 32 -- Good plasma! Ramped all the way down! nl_04=1.5-1.6e20 m-2. Trophy shot. Next shot: higher density. Try for nl_04=2.0e20 m-2. Increase gas valve voltage in both segments 1 and 2. Turn on a second NINJA valve (near the outer strike point).
Mar 1 1996 04:38:58:370PM	960301033	Robert Granetz	Shot 33 -- Plasma. Makes it about halfway down the current ramp. Density reached nl_04=1.8e20 m-2. Didn't get high power RF Next shot: Try for very low density. nl_04=0.4e20 m-2. Reduce gas valve voltage in both segment 1 and 2. Turn off NINJA.
Mar 1 1996 04:43:43:420PM	960301034	Robert Granetz	Shot 34 -- Plasma. Disrupts at 1.05 s. nl_04=0.9e20 m-2. Next shot: try for lower density again. Reduce gas valve voltage programming some more in both segments.
Mar 1 1996 04:54:34:750PM	960301035	Robert Granetz	Shot 35 -- Plasma, but disrupted at only t=0.35 s. Density was very low. End of this MP. The run will continue for a 2nd shift on another MP.

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	09:12:57:120AM	Plasma	Ok
2	09:31:12:810AM	Plasma	Bad	no tf
3	09:42:29:110AM	Plasma	Ok
4	09:57:49:120AM	Plasma	Ok
5	10:16:15:510AM	Plasma	Ok
6	10:26:04:240AM	Plasma	Ok
7	10:37:09:450AM	Plasma	Ok
8	10:49:36:910AM	Plasma	Ok
9	11:07:01:970AM	Plasma	Ok
10	11:19:43:120AM	Plasma	Bad	mag resist fault in pulse
11	11:27:13:510AM	Plasma	Ok
12	11:37:41:220AM	Plasma	Ok
13	11:55:04:690AM	Plasma	Bad	ef4 ioc
14	12:10:23:020PM	Plasma	Ok
15	12:21:00:430PM	Plasma	Ok
16	12:29:23:430PM	Plasma	Ok
17	12:48:23:430PM	Plasma	Ok
18	01:10:45:720PM	Plasma	Ok
19	01:26:13:270PM	Plasma	Ok
20	01:38:01:530PM	Plasma	Ok
21	01:51:09:340PM	Plasma	Ok
22	02:04:27:760PM	Plasma	Ok
23	02:14:44:670PM	Plasma	Ok	Comm Fault Bypass OH2u
24	02:26:34:460PM	Plasma	Ok
25	02:36:38:880PM	Plasma	Ok
26	02:47:41:760PM	Plasma	Ok
27	02:57:03:090PM	Plasma	Ok
28	03:08:54:740PM	Plasma	Ok
29	03:30:40:850PM	Plasma	Ok
30	03:43:56:050PM	Plasma	Ok
31	04:04:18:770PM	Plasma	Ok
32	04:16:56:600PM	Plasma	Ok
33	04:29:49:980PM	Plasma	Ok
34	04:38:26:550PM	Plasma	Ok
35	04:49:20:980PM	Plasma	Ok
36	04:58:15:070PM	Plasma	Ok
37	05:16:49:520PM	Plasma	Ok
38	05:32:28:120PM	Plasma	Ok
39	05:46:36:160PM	Plasma	Ok
40	05:57:51:960PM	Plasma	Ok
41	06:06:49:660PM	Plasma	Ok
42	06:20:40:940PM	Plasma	Ok
43	06:37:41:280PM	Plasma	Ok
44	06:50:58:360PM	Plasma	Ok
45	06:59:58:060PM	Plasma	Ok
46	07:09:18:800PM	Plasma	Ok
47	07:22:06:350PM	Plasma	Ok
48	07:32:39:500PM	Plasma	Ok
49	07:41:15:110PM	Plasma	Ok
50	07:50:07:880PM	Plasma	Ok
51	07:58:46:100PM	Plasma	Ok	TF self powered fired OH2U comm Fault Bypass.
52	08:28:57:580PM	Plasma	Ok
53	08:35:34:620PM	Test	Bad	TF did not go.
54	08:49:38:510PM	Test	Ok
55	08:55:58:110PM	Test	Ok