Alcator C-Mod Run 980213 Information

Miniproposals

Miniproposal: 163

Date Filed: 7/18/1996

Title: Detached Divertor High q

First Author: John Goetz

Session Leader: John Goetz (shots 1-28)

Operators
Session leader(s):	John Goetz
Physics operator(s):	Ian Hutchinson
Engineering operator(s):	Unknown

Engineering Operator Run Comment
mp 163

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:18:053PM

Author: To Be Determined

Run 980213 -- MP #163 High q_parallel Dissipative Divertor

This proposal is an attempt to achieve simultaneously a good confinement
H-mode with low Zeff and a detached divertor. Run 980123 was successful
in obtaining a detached divertor H-mode with good confinement. However,
the Zeff was rather high (although the change in Zeff due to impurity
puffing was acceptable). Run 980213 was an attempt to improve the
plasma cleanliness and to diagnose well the divertor plasma.

The physics plan is to:
1a. Start with a good shot, 980123034 and lengthen the current
flattop to 1.5sec.
b. Shot with 2.5MW RF from from 0.6 to 1.5sec.
c. Shot with the impurity gas puff extended to 1.5sec to
lengthen the detached phase. (The value for PG5 in
the controller in the BOLO_FDBK wire needs to be increased
to 25 due to the change in high voltage op amp)
d. Keep shooting until the divertor detaches.
2. Optimize the feedback waveform to maximize H and minimize Zeff
with a detached divertor.
3. Diagnose the detached H-mode with the following:
a. puff deuterium through the ledge bolometer to measure
the CX contribution to power loss
b. puff some argon and/or krypton to measure impurity screening
and compression
c. measure nitrogen radiated power with McPherson
d. inject niobium to measure impurity confinement
e. measure nitrogen distribution with Chromex
f. measure scrape-off parameters with FSP
g. puff some helium in the divertor to measure flows
h. toss in some baselines for comparison purposes
4. Repeat at different q-parallels (different RF powers).

Physics Summary:
The run was successful in that all of the above points were covered.
End of run summary.

Ah, not really. Today the algorithm developed on 980123 to use the edge
bolometer signal to feedback on the impurity gas puff was used to achieve
detached divertor H-modes with varying scrape-off layer power flows. This
technique worked well in that varying degrees of detachment were achieved
by varying the requested edge bolometer waveform. The deepest detachments
achieved were up to probe 7 - the nose of the outer divertor. The amount of
nitrogen required for minimal detachment varies with q-parallel; the higher
the q-parallel, the larger the impurity puff needed to see detachment near the
strike point. Also, the nitrogen definitely sticks to some surfaces, causing a
buildup throughout the day. The Zeff began the day near 1.0 and was up to 1.3
at the end of the day (during the H-mode, before the impurity puff).
The H-factor was calculated today with the assumption that 60% of the
launched RF power was absorbed in the core plasma. This fraction was determined
by break-in-slope analysis by the RF cabal. Thus H(ITER89-P) was 1.9 or 1.8 at
the beginning of all EDA H-modes obtained today. Although shot 7 was a
baseline and shot 8 had a small impurity puff (no signs of detachment), shot 8
had the highest stored energy and the highest H-factor. This indicates that
impurity puffing can indeed be beneficial to the plasma despite all the
naysayers.
The goal of simultaneously achieving good confinement, low Zeff, and
a detached divertor was reached. On the best shot (possibly shot 015), the
H-factor was 1.8 and the Zeff was 1.1 as the H-mode developed. As nitrogen
was puffed and the divertor detached the H-factor decreased to 1.6 and the Zeff
increased to 1.4. These changes were fairly typical of those observed today.
However, those discharges with smaller q-parallel and the incorrect edge
bolometer waveform (too much edge radiation requested) exhibited larger changes
in H and Zeff.
Points 3 and 4 of the aformentioned run plan were accomplished by
running many similar discharges at three different RF power levels. Some of
the measurements of these detached H-mode plasmas follow:
i- The impurity confinement time was measured by injection of a trace
amount of niobium into the detached phase of the H-mode. This
time is ~70msec, in line with previous measurements for an EDA
H-mode.
ii- The x-ray pedestal width and location do not change upon divertor
detachment and are typical of EDA H-mode.

-> These two observations indicate that the H-mode is not becoming ELMfree when
upon detachment, the midplane Dalpha drops. The increase in core
density is due to poorer screening (better fueling) in the detached
divertor state. (Enhanced Dalpha is not necessary for EDA H-mode)

iii- Both deuterium and helium gas were puffed through the bolometer
camera located just above the outer divertor at K-port. This
gas puff should act like a 'filter' to neutral particles. In
comparing 'identical' discharges with and without puffing it is
seen that some of the power measured by these bolometers is due
to CX losses. This verifies earlier inferences by Goetz and
Terry and earlier measurements by Goetz and Pitcher in L-mode
discharges, both attached and detached. [A concern over cooling
of the bolometer foil due to the puff will be checked on 17-FEB]
iv- Measurements of the heat flux using fast thermocouples embedded in
the plates (Gangadhara and LaBombard) show that high heat fluxes
(>400 MW-m^-2) have been lowered to immeasureable levels by
detaching the divertor. The heat deposition profile is very
narrow in H-mode compared to that observed in high power L-mode.
v- During the impurity puffing on the best shot (015), the radiation in
the divertor was increased by >0.5MW to >1.5MW and the
radiation in the main plasma increased by >0.5MW to ~2MW.
Thus, these detached divertor H-mode plasmas were obtained by
reducing the power flow into the divertor and radiating the
remaining power in equal amounts.

-> In order to have these tremendous parallel heat fluxes into the divertor and
to have the high radiation in the divertor, there must be 90-100% of
the launched RF power absorbed. A working hypothesis would be that
on this run day ~60% of the RF power is absorbed in the core plasma,
30-40% in the 'edge' and SOL plasma, and 10-0% elsewhere.

vi- Helium was puffed into the divertor in order for a tangentially-
viewing spectrometer to measure flows via Doppler shifts
(Weaver). Flows were seen in the divertor and further analysis
of the data obtained is ongoing.
vii- Argon was puffed into the pre-diverted phase of the plasmas to
measure impurity screening and impurity compression (Goetz) as
the detached H-mode developed. Spatial profiles of neutral and
singly ionized nitrogen were measured (Lipschultz) in the
divertor region with the Chromex spectrometer. The nitrogen
radiation in the VUV was measured (Terry) along a bolometer
line-of-sight in the divertor allowing for direct comparison
of the measured nitrogen to total radiation. Hydrogen-like
nitrogen was measured (Terry) in the core and will be used to
calculate the core nitrogen density. Lyman spectra in divertor
were also obtained to make recombination measurements (Terry).
All of these observations (vii) are still works-in-progress.

The detailed shot log follows:

Shot Result
---- ------
001 plasma - disrupts @ 1.03 - density programming for an H-mode - MARFE
002 fizzle
003 plasma - bad H-mode - still early MARFE - 55% absorbed RF power
gives H=1.4 and Psol=1.3MW
004 plasma - better H-mode but RF troubles - MARFE gone - H=1.5 - Psol=1.5MW
005 plasma - disrupts @ 0.3? - no data due to DAQA
006 plasma - disrupts early again
007 plasma - this is the baseline - good EDA - Psol=1.5 and H=1.6 and
Zeff=1 with Prf=55%
008 plasma - enable J-Bottom for nitrogen puffing - 0.8V waveform -
H=1.9, Psol=1.0, Zeff=1.2 with Prf=55%
009 plasma - 1.0V waveform - puff through bolo box - H=1.9->1.6 - Zeff=1.3
Psol=1.3; detaches to probe 6
010 plasma - 0.9V waveform - detachment not as deep, but eventually to pr 6
- H=1.9->1.7 - Zeff=1.3 - Psol=1.3->0.9
011 plasma - H=1.8 - Psol=1.3 - Zeff=1.25 with Prf=60% - no signs of
detachment - N2 bolo waveform 0.8->0.9V
012 plasma - N2 bolo waveform = 0.9V - slight detachment - helium through
floor tiles and bolo box - H=1.8->1.55; Zeff=1.3; Psol=1.2-0.75
013 plasma - N2 bolo waveform 0.9->0.95V - H=1.7->1.6; Zeff=1.3; Psol=1.0
detachment thru probe 5
014 plasma - N2 bolo waveform 1.0V - H=1.9->1.7; Psol=1.4->0.9; Zeff=1.4
detach to pr6 - helium seen by Weaves
015 plasma - N2 bolo waveform 1.0->1.05V - GOOD shot - detachment to probe
6 begin @ 0.85 and steady - H=1.8->1.6 - Psol=1.2->1.0 -
Zeff=1.4+
016 plasma - not a good EDA - RF takes a while ramping up - super L-mode
H=1.65; Zeff=1.4; Psol=0.9MW; detaches @ 0.84 thru probe 6
017 plasma - 12ms of Ar - ELMfree H-modes; H=1.6->1.4; Zeff=1.45;
Psol=1.0->0.8; evidence of CX seen on ledge bolometers
018 fizzle
019 plasma - baseline with no impurities - super L-mode->H-mode; injections
020 plasma - more RF power (3.2MW) - baseline - Psol=2.0MW after EDA starts
021 plasma - nitrogen waveform 1.0->1.05V - detachment @ 0.84 - H=1.7
Zeff=1.3->1.6; Psol=1.2->0.7
022 plasma - nitrogen waveform 1.0->1.05V - detachment @ 0.81 with a
reattachment - H=1.7; Psol=1.4->0.8MW; Zeff=1.3->1.7
023 plasma - 10msec 0f Ar plus nitrogen; H=1.7; Psol=1.3->0.9; Zeff=1.4->1.7
detachment @ 0.81 to probe 6 (no reattachment)
024 plasma - baseline with Prf=2.1MW; H=1.6; Zeff=1.2; Psol=1.5MW
025 plasma - 1.0->1.05V waveform - H=1.5; Psol=1.0-0.7; Zeff=1.2->1.4
detaches to probe 7 by 1.25sec
026 plasma - 0.9->0.95V waveform - H=1.6->1.4; Psol=1.0->0.8; Zeff=1.2->1.5
detachment not as deep, only to probe 6
027 plasma - 0.8->0.85V waveform - H=1.9->1.5; Psol=1.0->0.9;
Zeff=1.3->1.45; detachment eventually reaches pr7 by 1.25sec
028 plasma - 0.7->0.75V waveform - H=1.8->1.5; Psol=0.9; Zeff=1.2->1.5
even less detachment on this one; takes a long time

Physics Operator Summaries

Entered: Jul 7 2004 04:36:59:503PM

Author: To Be Determined

Physop Summary 980213

MP 163 High q-parallel Dissipative Divertor.

Summary
_______

Pretty boring from the Physop viewpoint because things went so well.
Nicely controlled detachments at high power were obtained.

In addition a shot with the chopper on during the initiation was
attempted. Although the Br and Bz were fine, the null was not because the
Br was compensated not by EF2s but by the OH2s, leading to a big quadrupole
error. This needs to be investigated more before being ready for prime
time.

A couple of EF1L faults occurred but seemed to go away when instrumentation
was installed. Shot 5 the data was lost.

Scorecard
_________

Shot,Duration(s),Ipmax(MA) Shot,Duration(s),Ipmax
1 1.043 1.051 2 0.000 0.037
3 1.683 1.024 4 1.678 1.019
No Ip 5 6 0.259 0.564
7 1.830 1.029 8 1.800 1.019
9 1.740 1.024 10 1.796 1.029
11 1.776 1.030 12 1.796 1.030
13 1.769 1.035 14 1.754 1.030
15 1.750 1.030 16 1.752 1.035
17 1.763 1.041 18 0.000 0.027
19 1.786 1.030 20 1.810 1.041
21 1.765 1.041 22 1.746 1.041
23 1.746 1.038 24 1.840 1.030
25 1.750 1.030 26 1.755 1.028
27 1.762 1.030 28 1.742 1.030
Finished summary for 980213 Total of 28 shots.
28 shots. 25 plasmas. 2 fizzles. 1 no data.

Logbook Details
_______________

--------------------------------------------------------------------------------
980213xxx HUTCH PHYSICS_OPERATOR 13-FEB-1998 08:40:29.94
. . . . . . . . . . . . . . . . . . . .
MP 163 High q-parallel Dissipative Divertor.

Cold Start.
Load from 980123034.
Extend everything to 1.5s.
Fiddle with Bolo-fdbk.
Load.
--------------------------------------------------------------------------------
980213001 HUTCH PHYSICS_OPERATOR 13-FEB-1998 08:58:18.38
. . . . . . . . . . . . . . . . . . . .
Plasma. Disrupts at 1s.
L-mode (no RF) with rather high density.

Br offset to .005 from .004 to fix breakdown.
nl04 to 1.3 from 1.4.
Bt to 150 kA from 155.
--------------------------------------------------------------------------------
980213002 HUTCH PHYSICS_OPERATOR 13-FEB-1998 09:09:39.72
. . . . . . . . . . . . . . . . . . . .
Fizzle. Fast current rise to 45kA.

EF4 to -1335 from -1345,
Copy TF trace from seg2 to seg1.
--------------------------------------------------------------------------------
980213003 HUTCH PHYSICS_OPERATOR 13-FEB-1998 09:24:46.60
. . . . . . . . . . . . . . . . . . . .
Plasma. Burns through the marfe.
Disrupts in ramp down because of PS inversion.

Extend ps inversion to 2s.
Disable the argon.
Lower the nl04 to 1.2 and lower earlier.
Br offset to .0045, it has crept up.
--------------------------------------------------------------------------------
980213004 HUTCH PHYSICS_OPERATOR 13-FEB-1998 09:44:07.90
. . . . . . . . . . . . . . . . . . . .
Plasma. Still disrupts at 1.7s, RF trips at 1s and a lot of gas is puffed
to keep up nl04.

Lower nl04 after 1s.
Tweak EF4 program later.
Extend zcur gains past 1.7 s where they were turning off, to 2s.
--------------------------------------------------------------------------------
980213005 HUTCH PHYSICS_OPERATOR 13-FEB-1998 10:03:14.64
. . . . . . . . . . . . . . . . . . . .
Plasma. Disrupts at .33s.
DAQA reboots, so no interesting data.
--------------------------------------------------------------------------------
980213006 HUTCH PHYSICS_OPERATOR 13-FEB-1998 10:12:34.59
. . . . . . . . . . . . . . . . . . . .
Plasma. Chokes at .25s.
Seems to be hit by a bricklet at 1.4s.
--------------------------------------------------------------------------------
980213007 HUTCH PHYSICS_OPERATOR 13-FEB-1998 10:34:17.38
. . . . . . . . . . . . . . . . . . . .
Plasma till 1.8s

EF2by EF4 program was ramping down too early. Extended to 2s.
Enable the j-bottom valve. (30 psi N2).
--------------------------------------------------------------------------------
980213008 HUTCH PHYSICS_OPERATOR 13-FEB-1998 10:51:43.61
. . . . . . . . . . . . . . . . . . . .
Plasma. Same as previous. Forgot to load. Twice as much 2pi radiation.
More stored energy, despite the increased radiation.

Bolo_Feedback to 1. from ~.8
--------------------------------------------------------------------------------
980213009 HUTCH PHYSICS_OPERATOR 13-FEB-1998 11:06:36.76
. . . . . . . . . . . . . . . . . . . .
Plasma till 1.7s. Signs of detachment. 3e20 density.
Stored energy drops to 110kJ. Prad bolo 1.5MW.
Traq1 data currupted. EFIT rerun.

TF current to 158kA.
Bolo-feedback to .9
EF4 current program kept on till 2s.
--------------------------------------------------------------------------------
980213010 HUTCH PHYSICS_OPERATOR 13-FEB-1998 11:25:50.01
. . . . . . . . . . . . . . . . . . . .
Plasma till 1.8s. Field did not respond. Probably a finger problem.

TF field tweak again.
bolo_feedback to .8 at .9s.
EF4 current gain to 4 at 1.5s.
--------------------------------------------------------------------------------
980213011 HUTCH PHYSICS_OPERATOR 13-FEB-1998 11:41:40.76
. . . . . . . . . . . . . . . . . . . .
Plasma.

EF4 gain step removed. Program its ramp down at 1.5s-1.8s.
Bolo_fdbk back to .9.
--------------------------------------------------------------------------------
980213012 HUTCH PHYSICS_OPERATOR 13-FEB-1998 12:11:31.91
. . . . . . . . . . . . . . . . . . . .
Plasma till 1.79s. EF2 did not zero out.
Seems as if the disruption is a vertical motion problem induced by
switching off the x-point controller gains.

Kept x-point gains on till 2s.
Increase bolo_fdbk to .95 at 1.5s.
Set voltage demand on N2 to 30V till 1.5s.
Power supply control problem on EF1_L.
--------------------------------------------------------------------------------
980213013 HUTCH PHYSICS_OPERATOR 13-FEB-1998 12:53:08.12
. . . . . . . . . . . . . . . . . . . .
Plasma till 1.76 s (no longer than the previous shot).

Next shot: draw BOLO_FDBK to 1.0 (i.e. puff more nitrogen)
--------------------------------------------------------------------------------
980213014 HUTCH PHYSICS_OPERATOR 13-FEB-1998 13:50:22.59
. . . . . . . . . . . . . . . . . . . .
Plasma till 1.75s.

bolo_fdbk to 1.05 at 1.5s.
--------------------------------------------------------------------------------
980213016 HUTCH PHYSICS_OPERATOR 13-FEB-1998 14:21:02.06
. . . . . . . . . . . . . . . . . . . .
Plasma.

Argon puff enabled with 13ms, pulse.
Add chopper to Br controller with M=10000. This has no effect prior to turn on
but is to check out the feasibility.
--------------------------------------------------------------------------------
980213017 HUTCH PHYSICS_OPERATOR 13-FEB-1998 14:38:23.05
. . . . . . . . . . . . . . . . . . . .
Plasma. ELM-free, apparently but rather steady-state.

Initiate chopper at -.2s. Move chopper V to ramp vrom -.18 to -.1s.
Switch off j-sice and b-side lower. No impurity injections.
--------------------------------------------------------------------------------
980213018 HUTCH PHYSICS_OPERATOR 13-FEB-1998 14:48:44.25
. . . . . . . . . . . . . . . . . . . .
Fizzle. Late breakdown. But not completely obvious why.
OH2 currents change to balance chopper. EF2s do not.
Change of Br to about -1mT from 0 just prior to commutation.

Reload shot 17.
--------------------------------------------------------------------------------
980213019 HUTCH PHYSICS_OPERATOR 13-FEB-1998 15:06:31.75
. . . . . . . . . . . . . . . . . . . .
Plasma.. EDA.

--------------------------------------------------------------------------------
980213020 HUTCH PHYSICS_OPERATOR 13-FEB-1998 15:18:34.52
. . . . . . . . . . . . . . . . . . . .
Plasma. 3.2 MW.

Enable J-bottom valve.
--------------------------------------------------------------------------------
980213021 HUTCH PHYSICS_OPERATOR 13-FEB-1998 15:37:36.27
. . . . . . . . . . . . . . . . . . . .
Plasma.
--------------------------------------------------------------------------------
980213022 HUTCH PHYSICS_OPERATOR 13-FEB-1998 16:01:21.34
. . . . . . . . . . . . . . . . . . . .
Plasma.

Enable Ar. 10 ms puff.
--------------------------------------------------------------------------------
980213024 HUTCH PHYSICS_OPERATOR 13-FEB-1998 16:13:03.41
. . . . . . . . . . . . . . . . . . . .
Plasma. No impurity injections. 2.1MW RF

Enable N2 (j-bottom).
--------------------------------------------------------------------------------
980213025 HUTCH PHYSICS_OPERATOR 13-FEB-1998 16:23:39.15
. . . . . . . . . . . . . . . . . . . .
Plasma. 2MW RF. Well detached.

bolo_fdbk to .9-.95 (i.e.-.1 from previous).
--------------------------------------------------------------------------------
980213026 HUTCH PHYSICS_OPERATOR 13-FEB-1998 16:39:38.12
. . . . . . . . . . . . . . . . . . . .
Plasma.

Enable Argon.
Slow the clearin ramp at 1.8s.
Reduce bolo_fdbk to .85-.9
--------------------------------------------------------------------------------
980213027 HUTCH PHYSICS_OPERATOR 13-FEB-1998 16:56:19.35
. . . . . . . . . . . . . . . . . . . .
Plasma. Still strongly detached.

Increase clearin ramp rate at 1.75s.
bolo_fdbk to .75-.8.
--------------------------------------------------------------------------------
980213028 HUTCH PHYSICS_OPERATOR 13-FEB-1998 16:58:29.96
. . . . . . . . . . . . . . . . . . . .
Plasma. No improvement to the end.

Low D-alpha like the others.

Session Leader Comments

Feb 13 1998 08:03:56:150AM John Goetz MP #163 High q_parallel Dissipative Divertor

This proposal is an attempt to achieve simultaneously a good confinement
H-mode with low Zeff and a detached divertor. Run 980123 was successful
in obtaining a detached divertor H-mode with good confinement. However,
the Zeff was rather high (although the change in Zeff due to impurity
puffing was acceptable). Run 980213 will be an attempt to improve the
plasma cleanliness and to diagnose well the divertor plasma.

The physics plan is to:
1a. Start with a good shot, 980123034 and lengthen the current
flattop to 1.5sec.
b. Shot with 2.5MW RF from from 0.6 to 1.5sec.
c. Shot with the impurity gas puff extended to 1.5sec to
lengthen the detached phase. (The value for PG5 in
the controller in the BOLO_FDBK wire needs to be increased
to 25 due to the change in high voltage op amp)
d. Keep shooting until the divertor detaches.
2. Optimize the feedback waveform to maximize H and minimize Zeff
with a detached divertor.
3. Diagnose the detached H-mode with the following:
a. puff deuterium through the ledge bolometer to measure
the CX contribution to power loss
b. puff some argon and/or krypton to measure impurity screening
and compression
c. measure nitrogen radiated power with McPherson
d. inject niobium to measure impuri

Feb 13 1998 08:04:38:530AM John Goetz d. inject niobium to measure impurity confinement
e. measure nitrogen distribution with Chromex
f. measure scrape-off parameter with FSP
g. puff some helium in the divertor to measure flows
h. toss in some baselines for comparison purposes
4. Repeat at different q-parallels (different RF powers).

Feb 13 1998 09:06:19:250AM 980213001 John Goetz Plasma
disrupts @ 1.03
density programming was for an H-mode, but no RF requested by the SL
large MARFE from 0.5sec onward

Feb 13 1998 09:06:29:180AM 980213002 John Goetz Fizzle

Feb 13 1998 09:23:15:240AM 980213003 John Goetz Plasma
early MARFE drives up the density
not a very good H-mode; H=1.4 with Prf absorbed = 55%
rather high radiation - 1.3MW into SOL
no Zeff

Feb 13 1998 09:37:05:210AM 980213004 John Goetz Plasma
early MARFE is over by 0.3 leading to a better H-mode
H=1.5 with Prf absorbed = 55%
lower radiation - 1.5MW into SOL
no Zeff

Feb 13 1998 10:07:23:560AM 980213005 John Goetz Plasma
disrupts very early
DAQA troubles give this shot no data

Feb 13 1998 10:11:41:750AM 980213006 John Goetz Plasma
disrupts @ 0.25
injection @ 0.13

Feb 13 1998 10:27:07:320AM 980213007 John Goetz Plasma
nice flattop
good EDA; H=1.6 with Prf = 55%
Psol = 1.5MW with Prf = 55%
Zeff = 1 and flat through the whole pulse
this is the baseline

Feb 13 1998 10:47:27:940AM 980213008 John Goetz Plasma
turned on impurity puff - nitrogen throught J-Bottom - drawn trapezoidal waveform of 0.8V
good EDA; H=1.9 with Prf = 55%
Psol = 1.0MW with Prf = 55%
Zeff = 1 and rises to 1.2 during impurity puff

Feb 13 1998 11:08:09:060AM 980213009 John Goetz Plasma
turned on impurity puff - nitrogen throught J-Bottom - drawn trapezoidal waveform of 1.0V
good EDA; H=1.9->1.55 with Prf = 55%
Psol = 1.3MW with Prf = 55%
Zeff = 1 and rises to 1.3 during impurity puff
definite detachment through probe 6 on the outer divertor - iner divertor only detached
near the strike point?

Feb 13 1998 11:32:48:150AM 980213010 John Goetz Plasma
turned on impurity puff - nitrogen throught J-Bottom - drawn trapezoidal waveform of 0.9V
good EDA; H=1.9->1.7 with Prf = 60%
Psol = 1.3->0.6MW with Prf = 60%
Zeff = 1 and rises to 1.3 during impurity puff
definite detachment through probe 6 on the outer divertor - iner divertor only detached
near the strike point?

Feb 13 1998 11:37:42:150AM 980213011 John Goetz Plasma
turned on impurity puff - nitrogen throught J-Bottom - lower the
initial point to 0.8 then rise to 0.9
good EDA; H=1.8 with Prf = 60%
Psol = 1.3->0.6MW with Prf = 60%
Zeff = 1 and rises to 1.3 during impurity puff
no detachment - what happened?

Feb 13 1998 12:02:35:340PM 980213012 John Goetz Plasma
nitrogen through J-Bottom - trapezoidal 0.9V waveform
good EDA; H=1.8->1.55 with Prf = 60%
Psol = 1.2->0.75MW with Prf = 60%
Zeff = 1 and rises to 1.3 during impurity puff
slight detachment to probe 6

Feb 13 1998 12:55:22:380PM 980213013 John Goetz Plasma
nitrogen through J-Bottom - trapezoidal 0.9V->0.95V waveform
extend preprogrammed voltage on PG5 to 1.5sec
good EDA; H=1.7->1.6 with Prf = 60%
Psol = 1.0MW with Prf = 60%
Zeff = 1 and rises to 1.3 during impurity puff
detachment to probe 5
niobium injection @ 1.04sec; Tau = 55-75msec

Feb 13 1998 01:18:10:700PM 980213014 John Goetz Plasma
nitrogen through J-Bottom - trapezoidal 1.0V waveform
good EDA; second density flattop begins after 0.85sec
H=1.9->1.7 with Prf = 60% after 0.83sec
Psol = 1.4->0.9MW with Prf = 60%
Zeff = 1 and rises to 1.4 during impurity puff
detachment to probe 6
some helium seen tangentially in the divertor for flow measurements

Feb 13 1998 01:39:58:140PM 980213015 John Goetz Plasma
nitrogen through J-Bottom - trapezoidal 1.0->1.05V waveform
good EDA; second density flattop begins after 0.85sec
H=1.9->1.7 with Prf = 60% after 0.83sec
Psol = 1.2->1.0MW with Prf = 60%
Zeff = 1 and rises to 1.4+ during impurity puff
detachment to probe 6 beginning @ 0.85sec
some helium seen tangentially in the divertor for flow measurements

Feb 13 1998 02:05:00:760PM 980213016 John Goetz Plasma
nitrogen through J-Bottom - trapezoidal 1.0->1.05V waveform
RF turnon at 0.5 sec, but ramp up until 0.6 -> not a good EDA (super L-mode)
so H=1.65 with Prf = 60% after 0.83sec
Psol = 1.2->1.0MW with Prf = 60%
Zeff = 1 and rises to 1.4 during impurity puff
detachment to probe 6 beginning @ 0.85sec
some helium seen tangentially in the divertor for flow measurements

Feb 13 1998 02:39:43:630PM 980213017 John Goetz Plasma
nitrogen through J-Bottom - trapezoidal 1.0->1.05V waveform
RF turnon at 0.5 sec - EDA then ELMfree then EDA then detached
12msec argon puff through B-side-lower may be the cause
so H=1.6->1.4 with Prf = 60% after 0.89sec
Psol = 1.0->0.8MW with Prf = 60%
Zeff = 1 and rises to 1.4 during impurity puff
detachment to probe 6 beginning @ 0.89sec
some helium seen flowing tangentially in the divertor
evidence of CX seen with gas screening on ledge divertor bolometers

Feb 13 1998 02:59:18:700PM 980213018 John Goetz Fzzle

Feb 13 1998 02:59:02:760PM 980213019 John Goetz Plasma
no impurities puffed
super L-mode - H-mode - then a few injections
this is a baseline

Feb 13 1998 03:14:58:790PM 980213020 John Goetz Plasma
no impurities puffed
Prf = 3.2MW
Psol = 2.0MW after the H-mode settles into a nice EDA
this is a baseline

Feb 13 1998 03:33:51:970PM 980213021 John Goetz Plasma
N2 puff back on - 1.0->1.05V waveform
detachment @ 0.84 to probe 6 (but maybe a reattachment)
H=1.7 with 60% absorption
Zeff = 1.3->1.6
Psol = 1.2->0.7 with 60% absorption

Feb 13 1998 03:43:15:960PM 980213022 John Goetz Plasma
N2 puff back on - 1.0->1.05V waveform
detachment @ 0.81 to probe 5 (and maybe a reattachment)
H=1.7 with 60% absorption
Zeff = 1.3->1.7
Psol = 1.4->0.8 with 60% absorption

Feb 13 1998 03:58:06:910PM 980213023 John Goetz Plasma
N2 puff back on - 1.0->1.05V waveform
detachment @ 0.81 to probe 6 (no reattachment?)
H=1.7 with 60% absorption
Zeff = 1.4->1.7
Psol = 1.3->0.9 with 60% absorption

Feb 13 1998 04:10:05:450PM 980213024 John Goetz Plasma
no impurities
baseline with Prf=2.1MW
super L-mode then H-mode transition @ 0.65sec
H=1.6; Psol=1.5MW; Zeff=1.2

Feb 13 1998 04:27:04:660PM 980213025 John Goetz Plasma
1.0->1.05V nitrogen waveform
detaches through probe 6 @ 0.84; up to probe 7 by 1.25sec
H=1.5 with 60% absorption
Psol=1.0->0.7Mw with 60% absorption
Zeff= 1.2->1.4

Feb 13 1998 04:38:15:150PM 980213026 John Goetz Plasma
0.9->0.95V nitrogen waveform
detachment not as deep as 025
H=1.6->1.4 after detachment -> 1.3 as it progresses (with 60% absorption)
Psol=1.0->0.8MW (with 60% absorption)
Zeff= 1.2->1.5

Feb 13 1998 04:50:04:430PM 980213027 John Goetz Plasma
0.8->0.85V nitrogen waveform
detachment to probe 6-7 by 1.25sec
H=1.9->1.5 (with 60% absorption)
Psol=1.0->0.9MW (with 60% absorption)
Zeff= 1.3->1.45

Feb 13 1998 05:05:10:190PM 980213028 John Goetz Plasma
0.7->0.75V nitrogen waveform
detachment eventually to probe 6 by 1.25sec
H=1.8->1.5 (with 60% absorption)
Psol=0.9MW (with 60% absorption)
Zeff= 1.2->1.5

Physics Operator Comments

Feb 13 1998 08:40:29:940AM Ian Hutchinson MP 163 High q-parallel Dissipative Divertor.

Cold Start.
Load from 980123034.
Extend everything to 1.5s.
Fiddle with Bolo-fdbk.
Load.

Feb 13 1998 08:58:18:380AM 980213001 Ian Hutchinson Plasma. Disrupts at 1s.
L-mode (no RF) with rather high density.

Br offset to .005 from .004 to fix breakdown.
nl04 to 1.3 from 1.4.
Bt to 150 kA from 155.

Feb 13 1998 09:09:39:720AM 980213002 Ian Hutchinson Fizzle. Fast current rise to 45kA.

EF4 to -1335 from -1345,
Copy TF trace from seg2 to seg1.

Feb 13 1998 09:24:46:600AM 980213003 Ian Hutchinson Plasma. Burns through the marfe.
Disrupts in ramp down because of PS inversion.

Extend ps inversion to 2s.
Disable the argon.
Lower the nl04 to 1.2 and lower earlier.
Br offset to .0045, it has crept up.

Feb 13 1998 09:44:07:900AM 980213004 Ian Hutchinson Plasma. Still disrupts at 1.7s, RF trips at 1s and a lot of gas is puffed
to keep up nl04.

Lower nl04 after 1s.
Tweak EF4 program later.
Extend zcur gains past 1.7 s where they were turning off, to 2s.

Feb 13 1998 10:03:14:640AM 980213005 Ian Hutchinson Plasma. Disrupts at .33s.
DAQA reboots, so no interesting data.

Feb 13 1998 10:12:34:590AM 980213006 Ian Hutchinson Plasma. Chokes at .25s.
Seems to be hit by a bricklet at 1.4s.

Feb 13 1998 10:34:17:380AM 980213007 Ian Hutchinson Plasma till 1.8s

EF2by EF4 program was ramping down too early. Extended to 2s.
Enable the j-bottom valve. (30 psi N2).

Feb 13 1998 10:51:43:610AM 980213008 Ian Hutchinson Plasma. Same as previous. Forgot to load. Twice as much 2pi radiation.
More stored energy, despite the increased radiation.

Bolo_Feedback to 1. from ~.8

Feb 13 1998 11:06:36:760AM 980213009 Ian Hutchinson Plasma till 1.7s. Signs of detachment. 3e20 density.
Stored energy drops to 110kJ. Prad bolo 1.5MW.
Traq1 data currupted. EFIT rerun.

TF current to 158kA.
Bolo-feedback to .9
EF4 current program kept on till 2s.

Feb 13 1998 11:25:50:010AM 980213010 Ian Hutchinson Plasma till 1.8s. Field did not respond. Probably a finger problem.

TF field tweak again.
bolo_feedback to .8 at .9s.
EF4 current gain to 4 at 1.5s.

Feb 13 1998 11:41:40:760AM 980213011 Ian Hutchinson Plasma.

EF4 gain step removed. Program its ramp down at 1.5s-1.8s.
Bolo_fdbk back to .9.

Feb 13 1998 12:11:31:910PM 980213012 Ian Hutchinson Plasma till 1.79s. EF2 did not zero out.
Seems as if the disruption is a vertical motion problem induced by
switching off the x-point controller gains.

Kept x-point gains on till 2s.
Increase bolo_fdbk to .95 at 1.5s.
Set voltage demand on N2 to 30V till 1.5s.
Power supply control problem on EF1_L.

Feb 13 1998 12:53:08:120PM 980213013 Ian Hutchinson Plasma till 1.76 s (no longer than the previous shot).

Next shot: draw BOLO_FDBK to 1.0 (i.e. puff more nitrogen)

Feb 13 1998 01:50:22:590PM 980213014 Ian Hutchinson Plasma till 1.75s.

bolo_fdbk to 1.05 at 1.5s.

Feb 13 1998 02:21:02:060PM 980213016 Ian Hutchinson Plasma.

Argon puff enabled with 13ms, pulse.
Add chopper to Br controller with M=10000. This has no effect prior to turn on
but is to check out the feasibility.

Feb 13 1998 02:38:23:050PM 980213017 Ian Hutchinson Plasma. ELM-free, apparently but rather steady-state.

Initiate chopper at -.2s. Move chopper V to ramp vrom -.18 to -.1s.
Switch off j-sice and b-side lower. No impurity injections.

Feb 13 1998 02:48:44:250PM 980213018 Ian Hutchinson Fizzle. Late breakdown. But not completely obvious why.
OH2 currents change to balance chopper. EF2s do not.
Change of Br to about -1mT from 0 just prior to commutation.

Reload shot 17.

Feb 13 1998 03:06:31:750PM 980213019 Ian Hutchinson Plasma.. EDA.

Feb 13 1998 03:18:34:520PM 980213020 Ian Hutchinson Plasma. 3.2 MW.

Enable J-bottom valve.

Feb 13 1998 03:37:36:270PM 980213021 Ian Hutchinson Plasma.

Feb 13 1998 04:01:21:340PM 980213022 Ian Hutchinson Plasma.

Enable Ar. 10 ms puff.

Feb 13 1998 04:13:03:410PM 980213024 Ian Hutchinson Plasma. No impurity injections. 2.1MW RF

Enable N2 (j-bottom).

Feb 13 1998 04:23:39:150PM 980213025 Ian Hutchinson Plasma. 2MW RF. Well detached.

bolo_fdbk to .9-.95 (i.e.-.1 from previous).

Feb 13 1998 04:39:38:120PM 980213026 Ian Hutchinson Plasma.

Enable Argon.
Slow the clearin ramp at 1.8s.
Reduce bolo_fdbk to .85-.9

Feb 13 1998 04:56:19:350PM 980213027 Ian Hutchinson Plasma. Still strongly detached.

Increase clearin ramp rate at 1.75s.
bolo_fdbk to .75-.8.

Feb 13 1998 04:58:29:960PM 980213028 Ian Hutchinson Plasma. No improvement to the end.

Low D-alpha like the others.

Engineering Operator Comments

Shot Time Type Status Comment

1 08:42:22:200AM Plasma Ok

2 08:56:43:800AM Plasma Ok

3 09:08:22:680AM Plasma Ok

4 09:23:20:790AM Plasma Bad ef1l ioc

5 09:42:08:220AM Plasma Ok

6 10:03:23:670AM Plasma Ok

7 10:15:09:300AM Plasma Ok

8 10:32:16:060AM Plasma Ok

9 10:46:23:620AM Plasma Ok

10 11:04:11:970AM Plasma Ok

11 11:21:28:900AM Plasma Ok

12 11:38:38:640AM Plasma Ok ef1l ioc after fizzle

13 12:35:44:250PM Plasma Ok

14 01:01:07:050PM Plasma Ok

15 01:18:33:250PM Plasma Ok

16 01:38:15:950PM Plasma Bad ef1 lower flt.

17 02:19:05:840PM Plasma Ok

18 02:35:59:100PM Plasma Ok

19 02:46:44:430PM Plasma Ok

20 03:02:11:910PM Plasma Ok

21 03:16:12:310PM Plasma Ok

22 03:31:49:090PM Plasma Ok

23 03:46:27:130PM Plasma Ok no faults/plasma

24 03:59:35:750PM Plasma Ok no faults/plasma

25 04:12:26:600PM Plasma Ok no faults/plasma

26 04:26:26:340PM Plasma Ok no faults/plasma

27 04:41:09:100PM Plasma Ok no faults/plasma

28 04:54:53:420PM Plasma Ok no faults/plasma

Session Leader Comments
Feb 13 1998 08:03:56:150AM		John Goetz	MP #163 High q_parallel Dissipative Divertor This proposal is an attempt to achieve simultaneously a good confinement H-mode with low Zeff and a detached divertor. Run 980123 was successful in obtaining a detached divertor H-mode with good confinement. However, the Zeff was rather high (although the change in Zeff due to impurity puffing was acceptable). Run 980213 will be an attempt to improve the plasma cleanliness and to diagnose well the divertor plasma. The physics plan is to: 1a. Start with a good shot, 980123034 and lengthen the current flattop to 1.5sec. b. Shot with 2.5MW RF from from 0.6 to 1.5sec. c. Shot with the impurity gas puff extended to 1.5sec to lengthen the detached phase. (The value for PG5 in the controller in the BOLO_FDBK wire needs to be increased to 25 due to the change in high voltage op amp) d. Keep shooting until the divertor detaches. 2. Optimize the feedback waveform to maximize H and minimize Zeff with a detached divertor. 3. Diagnose the detached H-mode with the following: a. puff deuterium through the ledge bolometer to measure the CX contribution to power loss b. puff some argon and/or krypton to measure impurity screening and compression c. measure nitrogen radiated power with McPherson d. inject niobium to measure impuri
Feb 13 1998 08:04:38:530AM		John Goetz	d. inject niobium to measure impurity confinement e. measure nitrogen distribution with Chromex f. measure scrape-off parameter with FSP g. puff some helium in the divertor to measure flows h. toss in some baselines for comparison purposes 4. Repeat at different q-parallels (different RF powers).
Feb 13 1998 09:06:19:250AM	980213001	John Goetz	Plasma disrupts @ 1.03 density programming was for an H-mode, but no RF requested by the SL large MARFE from 0.5sec onward
Feb 13 1998 09:06:29:180AM	980213002	John Goetz	Fizzle
Feb 13 1998 09:23:15:240AM	980213003	John Goetz	Plasma early MARFE drives up the density not a very good H-mode; H=1.4 with Prf absorbed = 55% rather high radiation - 1.3MW into SOL no Zeff
Feb 13 1998 09:37:05:210AM	980213004	John Goetz	Plasma early MARFE is over by 0.3 leading to a better H-mode H=1.5 with Prf absorbed = 55% lower radiation - 1.5MW into SOL no Zeff
Feb 13 1998 10:07:23:560AM	980213005	John Goetz	Plasma disrupts very early DAQA troubles give this shot no data
Feb 13 1998 10:11:41:750AM	980213006	John Goetz	Plasma disrupts @ 0.25 injection @ 0.13
Feb 13 1998 10:27:07:320AM	980213007	John Goetz	Plasma nice flattop good EDA; H=1.6 with Prf = 55% Psol = 1.5MW with Prf = 55% Zeff = 1 and flat through the whole pulse this is the baseline
Feb 13 1998 10:47:27:940AM	980213008	John Goetz	Plasma turned on impurity puff - nitrogen throught J-Bottom - drawn trapezoidal waveform of 0.8V good EDA; H=1.9 with Prf = 55% Psol = 1.0MW with Prf = 55% Zeff = 1 and rises to 1.2 during impurity puff
Feb 13 1998 11:08:09:060AM	980213009	John Goetz	Plasma turned on impurity puff - nitrogen throught J-Bottom - drawn trapezoidal waveform of 1.0V good EDA; H=1.9->1.55 with Prf = 55% Psol = 1.3MW with Prf = 55% Zeff = 1 and rises to 1.3 during impurity puff definite detachment through probe 6 on the outer divertor - iner divertor only detached near the strike point?
Feb 13 1998 11:32:48:150AM	980213010	John Goetz	Plasma turned on impurity puff - nitrogen throught J-Bottom - drawn trapezoidal waveform of 0.9V good EDA; H=1.9->1.7 with Prf = 60% Psol = 1.3->0.6MW with Prf = 60% Zeff = 1 and rises to 1.3 during impurity puff definite detachment through probe 6 on the outer divertor - iner divertor only detached near the strike point?
Feb 13 1998 11:37:42:150AM	980213011	John Goetz	Plasma turned on impurity puff - nitrogen throught J-Bottom - lower the initial point to 0.8 then rise to 0.9 good EDA; H=1.8 with Prf = 60% Psol = 1.3->0.6MW with Prf = 60% Zeff = 1 and rises to 1.3 during impurity puff no detachment - what happened?
Feb 13 1998 12:02:35:340PM	980213012	John Goetz	Plasma nitrogen through J-Bottom - trapezoidal 0.9V waveform good EDA; H=1.8->1.55 with Prf = 60% Psol = 1.2->0.75MW with Prf = 60% Zeff = 1 and rises to 1.3 during impurity puff slight detachment to probe 6
Feb 13 1998 12:55:22:380PM	980213013	John Goetz	Plasma nitrogen through J-Bottom - trapezoidal 0.9V->0.95V waveform extend preprogrammed voltage on PG5 to 1.5sec good EDA; H=1.7->1.6 with Prf = 60% Psol = 1.0MW with Prf = 60% Zeff = 1 and rises to 1.3 during impurity puff detachment to probe 5 niobium injection @ 1.04sec; Tau = 55-75msec
Feb 13 1998 01:18:10:700PM	980213014	John Goetz	Plasma nitrogen through J-Bottom - trapezoidal 1.0V waveform good EDA; second density flattop begins after 0.85sec H=1.9->1.7 with Prf = 60% after 0.83sec Psol = 1.4->0.9MW with Prf = 60% Zeff = 1 and rises to 1.4 during impurity puff detachment to probe 6 some helium seen tangentially in the divertor for flow measurements
Feb 13 1998 01:39:58:140PM	980213015	John Goetz	Plasma nitrogen through J-Bottom - trapezoidal 1.0->1.05V waveform good EDA; second density flattop begins after 0.85sec H=1.9->1.7 with Prf = 60% after 0.83sec Psol = 1.2->1.0MW with Prf = 60% Zeff = 1 and rises to 1.4+ during impurity puff detachment to probe 6 beginning @ 0.85sec some helium seen tangentially in the divertor for flow measurements
Feb 13 1998 02:05:00:760PM	980213016	John Goetz	Plasma nitrogen through J-Bottom - trapezoidal 1.0->1.05V waveform RF turnon at 0.5 sec, but ramp up until 0.6 -> not a good EDA (super L-mode) so H=1.65 with Prf = 60% after 0.83sec Psol = 1.2->1.0MW with Prf = 60% Zeff = 1 and rises to 1.4 during impurity puff detachment to probe 6 beginning @ 0.85sec some helium seen tangentially in the divertor for flow measurements
Feb 13 1998 02:39:43:630PM	980213017	John Goetz	Plasma nitrogen through J-Bottom - trapezoidal 1.0->1.05V waveform RF turnon at 0.5 sec - EDA then ELMfree then EDA then detached 12msec argon puff through B-side-lower may be the cause so H=1.6->1.4 with Prf = 60% after 0.89sec Psol = 1.0->0.8MW with Prf = 60% Zeff = 1 and rises to 1.4 during impurity puff detachment to probe 6 beginning @ 0.89sec some helium seen flowing tangentially in the divertor evidence of CX seen with gas screening on ledge divertor bolometers
Feb 13 1998 02:59:18:700PM	980213018	John Goetz	Fzzle
Feb 13 1998 02:59:02:760PM	980213019	John Goetz	Plasma no impurities puffed super L-mode - H-mode - then a few injections this is a baseline
Feb 13 1998 03:14:58:790PM	980213020	John Goetz	Plasma no impurities puffed Prf = 3.2MW Psol = 2.0MW after the H-mode settles into a nice EDA this is a baseline
Feb 13 1998 03:33:51:970PM	980213021	John Goetz	Plasma N2 puff back on - 1.0->1.05V waveform detachment @ 0.84 to probe 6 (but maybe a reattachment) H=1.7 with 60% absorption Zeff = 1.3->1.6 Psol = 1.2->0.7 with 60% absorption
Feb 13 1998 03:43:15:960PM	980213022	John Goetz	Plasma N2 puff back on - 1.0->1.05V waveform detachment @ 0.81 to probe 5 (and maybe a reattachment) H=1.7 with 60% absorption Zeff = 1.3->1.7 Psol = 1.4->0.8 with 60% absorption
Feb 13 1998 03:58:06:910PM	980213023	John Goetz	Plasma N2 puff back on - 1.0->1.05V waveform detachment @ 0.81 to probe 6 (no reattachment?) H=1.7 with 60% absorption Zeff = 1.4->1.7 Psol = 1.3->0.9 with 60% absorption
Feb 13 1998 04:10:05:450PM	980213024	John Goetz	Plasma no impurities baseline with Prf=2.1MW super L-mode then H-mode transition @ 0.65sec H=1.6; Psol=1.5MW; Zeff=1.2
Feb 13 1998 04:27:04:660PM	980213025	John Goetz	Plasma 1.0->1.05V nitrogen waveform detaches through probe 6 @ 0.84; up to probe 7 by 1.25sec H=1.5 with 60% absorption Psol=1.0->0.7Mw with 60% absorption Zeff= 1.2->1.4
Feb 13 1998 04:38:15:150PM	980213026	John Goetz	Plasma 0.9->0.95V nitrogen waveform detachment not as deep as 025 H=1.6->1.4 after detachment -> 1.3 as it progresses (with 60% absorption) Psol=1.0->0.8MW (with 60% absorption) Zeff= 1.2->1.5
Feb 13 1998 04:50:04:430PM	980213027	John Goetz	Plasma 0.8->0.85V nitrogen waveform detachment to probe 6-7 by 1.25sec H=1.9->1.5 (with 60% absorption) Psol=1.0->0.9MW (with 60% absorption) Zeff= 1.3->1.45
Feb 13 1998 05:05:10:190PM	980213028	John Goetz	Plasma 0.7->0.75V nitrogen waveform detachment eventually to probe 6 by 1.25sec H=1.8->1.5 (with 60% absorption) Psol=0.9MW (with 60% absorption) Zeff= 1.2->1.5

Physics Operator Comments
Feb 13 1998 08:40:29:940AM		Ian Hutchinson	MP 163 High q-parallel Dissipative Divertor. Cold Start. Load from 980123034. Extend everything to 1.5s. Fiddle with Bolo-fdbk. Load.
Feb 13 1998 08:58:18:380AM	980213001	Ian Hutchinson	Plasma. Disrupts at 1s. L-mode (no RF) with rather high density. Br offset to .005 from .004 to fix breakdown. nl04 to 1.3 from 1.4. Bt to 150 kA from 155.
Feb 13 1998 09:09:39:720AM	980213002	Ian Hutchinson	Fizzle. Fast current rise to 45kA. EF4 to -1335 from -1345, Copy TF trace from seg2 to seg1.
Feb 13 1998 09:24:46:600AM	980213003	Ian Hutchinson	Plasma. Burns through the marfe. Disrupts in ramp down because of PS inversion. Extend ps inversion to 2s. Disable the argon. Lower the nl04 to 1.2 and lower earlier. Br offset to .0045, it has crept up.
Feb 13 1998 09:44:07:900AM	980213004	Ian Hutchinson	Plasma. Still disrupts at 1.7s, RF trips at 1s and a lot of gas is puffed to keep up nl04. Lower nl04 after 1s. Tweak EF4 program later. Extend zcur gains past 1.7 s where they were turning off, to 2s.
Feb 13 1998 10:03:14:640AM	980213005	Ian Hutchinson	Plasma. Disrupts at .33s. DAQA reboots, so no interesting data.
Feb 13 1998 10:12:34:590AM	980213006	Ian Hutchinson	Plasma. Chokes at .25s. Seems to be hit by a bricklet at 1.4s.
Feb 13 1998 10:34:17:380AM	980213007	Ian Hutchinson	Plasma till 1.8s EF2by EF4 program was ramping down too early. Extended to 2s. Enable the j-bottom valve. (30 psi N2).
Feb 13 1998 10:51:43:610AM	980213008	Ian Hutchinson	Plasma. Same as previous. Forgot to load. Twice as much 2pi radiation. More stored energy, despite the increased radiation. Bolo_Feedback to 1. from ~.8
Feb 13 1998 11:06:36:760AM	980213009	Ian Hutchinson	Plasma till 1.7s. Signs of detachment. 3e20 density. Stored energy drops to 110kJ. Prad bolo 1.5MW. Traq1 data currupted. EFIT rerun. TF current to 158kA. Bolo-feedback to .9 EF4 current program kept on till 2s.
Feb 13 1998 11:25:50:010AM	980213010	Ian Hutchinson	Plasma till 1.8s. Field did not respond. Probably a finger problem. TF field tweak again. bolo_feedback to .8 at .9s. EF4 current gain to 4 at 1.5s.
Feb 13 1998 11:41:40:760AM	980213011	Ian Hutchinson	Plasma. EF4 gain step removed. Program its ramp down at 1.5s-1.8s. Bolo_fdbk back to .9.
Feb 13 1998 12:11:31:910PM	980213012	Ian Hutchinson	Plasma till 1.79s. EF2 did not zero out. Seems as if the disruption is a vertical motion problem induced by switching off the x-point controller gains. Kept x-point gains on till 2s. Increase bolo_fdbk to .95 at 1.5s. Set voltage demand on N2 to 30V till 1.5s. Power supply control problem on EF1_L.
Feb 13 1998 12:53:08:120PM	980213013	Ian Hutchinson	Plasma till 1.76 s (no longer than the previous shot). Next shot: draw BOLO_FDBK to 1.0 (i.e. puff more nitrogen)
Feb 13 1998 01:50:22:590PM	980213014	Ian Hutchinson	Plasma till 1.75s. bolo_fdbk to 1.05 at 1.5s.
Feb 13 1998 02:21:02:060PM	980213016	Ian Hutchinson	Plasma. Argon puff enabled with 13ms, pulse. Add chopper to Br controller with M=10000. This has no effect prior to turn on but is to check out the feasibility.
Feb 13 1998 02:38:23:050PM	980213017	Ian Hutchinson	Plasma. ELM-free, apparently but rather steady-state. Initiate chopper at -.2s. Move chopper V to ramp vrom -.18 to -.1s. Switch off j-sice and b-side lower. No impurity injections.
Feb 13 1998 02:48:44:250PM	980213018	Ian Hutchinson	Fizzle. Late breakdown. But not completely obvious why. OH2 currents change to balance chopper. EF2s do not. Change of Br to about -1mT from 0 just prior to commutation. Reload shot 17.
Feb 13 1998 03:06:31:750PM	980213019	Ian Hutchinson	Plasma.. EDA.
Feb 13 1998 03:18:34:520PM	980213020	Ian Hutchinson	Plasma. 3.2 MW. Enable J-bottom valve.
Feb 13 1998 03:37:36:270PM	980213021	Ian Hutchinson	Plasma.
Feb 13 1998 04:01:21:340PM	980213022	Ian Hutchinson	Plasma. Enable Ar. 10 ms puff.
Feb 13 1998 04:13:03:410PM	980213024	Ian Hutchinson	Plasma. No impurity injections. 2.1MW RF Enable N2 (j-bottom).
Feb 13 1998 04:23:39:150PM	980213025	Ian Hutchinson	Plasma. 2MW RF. Well detached. bolo_fdbk to .9-.95 (i.e.-.1 from previous).
Feb 13 1998 04:39:38:120PM	980213026	Ian Hutchinson	Plasma. Enable Argon. Slow the clearin ramp at 1.8s. Reduce bolo_fdbk to .85-.9
Feb 13 1998 04:56:19:350PM	980213027	Ian Hutchinson	Plasma. Still strongly detached. Increase clearin ramp rate at 1.75s. bolo_fdbk to .75-.8.
Feb 13 1998 04:58:29:960PM	980213028	Ian Hutchinson	Plasma. No improvement to the end. Low D-alpha like the others.

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	08:42:22:200AM	Plasma	Ok
2	08:56:43:800AM	Plasma	Ok
3	09:08:22:680AM	Plasma	Ok
4	09:23:20:790AM	Plasma	Bad	ef1l ioc
5	09:42:08:220AM	Plasma	Ok
6	10:03:23:670AM	Plasma	Ok
7	10:15:09:300AM	Plasma	Ok
8	10:32:16:060AM	Plasma	Ok
9	10:46:23:620AM	Plasma	Ok
10	11:04:11:970AM	Plasma	Ok
11	11:21:28:900AM	Plasma	Ok
12	11:38:38:640AM	Plasma	Ok	ef1l ioc after fizzle
13	12:35:44:250PM	Plasma	Ok
14	01:01:07:050PM	Plasma	Ok
15	01:18:33:250PM	Plasma	Ok
16	01:38:15:950PM	Plasma	Bad	ef1 lower flt.
17	02:19:05:840PM	Plasma	Ok
18	02:35:59:100PM	Plasma	Ok
19	02:46:44:430PM	Plasma	Ok
20	03:02:11:910PM	Plasma	Ok
21	03:16:12:310PM	Plasma	Ok
22	03:31:49:090PM	Plasma	Ok
23	03:46:27:130PM	Plasma	Ok	no faults/plasma
24	03:59:35:750PM	Plasma	Ok	no faults/plasma
25	04:12:26:600PM	Plasma	Ok	no faults/plasma
26	04:26:26:340PM	Plasma	Ok	no faults/plasma
27	04:41:09:100PM	Plasma	Ok	no faults/plasma
28	04:54:53:420PM	Plasma	Ok	no faults/plasma