Alcator C-Mod Run 951206 Information

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Miniproposals
Miniproposal:078
Date Filed: 2/8/1995
Title:ICRF Heating in H-mode Plasmas
First Author:Yuichi Takase
Session Leader:Yuichi Takase (shots 1-41)

Operators
Session leader(s):Yuichi Takase
Physics operator(s):Joseph Snipes
Engineering operator(s):Vinny Bertolino,Joe Daigle

Engineering Operator Run Comment
H-mode

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:14:430PM
Author: To Be Determined
Run Summary 951206

SL: Takase
PO: Snipes
EO: Daigle/bertolino

Run Plan for 951206:
-------------------

The objective is to optimize H-mode performance,
primarily in the H-factor (confinement enhancement
relative to L-mode) and secondarily in H-mode duration.
Considerable progress has already been made during
the 951205 run, after completing the position feedback
mini-proposal ahead of schedule. It was demonstrated
that both high starting density and active gas-puffing
during H-mode were beneficial. The position feedback
was not able to maintain constant loading, but appeared
to help prevent RF trip-outs to some degree.

The plan is to start from 951205039 and continue
exploratory investigation. Possibilities include:

X-point (or more precisely strike point) scan
Outer gap scan (using position feedback offset)
I_p scan
Use of pellet fuelling

Results:
-------

The "D-port" transmitter plate voltage was reduced last night to avoid
crowbars which have been occurring on practically all high power rf pulses.
This has solved the problem of crowbars, but it means we will not get
as high a power from this transmitter. Frequent "overloads" were still
observed causing transmitter trips, but these faults are less damaging
to the transmitter. The plan is to disassemble and inspect the final
cavity over the weekend (through Monday). The plasma position feedback
worked fairly well, but as noted yesterday plasma excursion away from
the antenna must be limited. This limit will be incorporated before
next week.

We started the run by reproducing a quasi-steady-state ELMy discharge (shots
29 and 39 from yesterday, for example). This was accomplished early in the
run (shots 5 and 6, for example), and was used as the baseline for further
optimization. We have confirmed again that "grassy ELM"-type discharges
can be reproduced reliably with high initial density and active gas-puffing
during the RF pulse. The first attempt at the fiducial shot was a fizzle.
RF ran well (1MW each from D and E) on the fiducial shot (shot 11), but
no H-mode was observed with 2MW of RF power (usually we get H-mode with
only 1MW of RF power).

The strike point was moved by programming RXL and ZXL. Initial indications
are that moving the X-point up and out (which does raise the strike point)
and moving the X-point down and out (which did not really lower the strike
point, rather the separatrix below the X-point got stretched apart, and
the strike point was about half way up the outer vertical plate) did not
improve the H-mode performance. An attempt was made to use STRKPSI control
to really get the strike point lower was unsuccessful, and was abandoned
for today we (really Steve Wolfe) didn't understand why it didn't work.
Both lower and higher currents (0.6 and 1.0MA instead of the 0.8MW baseline)
plasmas were produced, but there were no obvious improvements in the H-factor.
The outer gap was varied somewhat by programming a higher target value for
loading on position feedback (main reason was to avoid pushing the plasma
away from the antenna when the loading got too high). No systematic study
could be carried out, but no indication of improvement was observed.
Finally, we tried to inject Li pellet (D2 pellet was not available today)
prior to RF. Some encouraging signs were observed, but a clean shot
could not be taken. This was partly because we had to turn off the
radial position feedback for combined pellet-RF shots.

Although some important information was obtained during this run, it would
be desirable to repeat the "low outer strike-point" shot with STRKPSI control.
Combination of pellet (either Li or D2) clearly needs some more work.

Shot
01 dud (PS)
02 pla early disruption @ .65sec (too much gas)
03 pla load 951205039, reduce gas, 800kA, nel=1.2->2.3, 2.7MW, 110kJ
04 pla similar to 951205029, RF cutting off @ 0.9sec
05 pla RF still cutting off @ .9sec
06 pla extended RF gate
07 pla D-port tripped early, disrupt @ .92sec
08 pla loading target value increased, early disruption @ .25s (PS), lost TCI
09 pla fiducial (didn't load fiducial shot)
10 fiz retake fiducial (loaded 951205025)
11 pla fiducial shot (no H-mode with 2MW RF!)
12 pla early disruption
13 pla reload 951206005, D-port a little short
14 pla RXL 1cm out, ZXL 1cm up, D-port interrupts
15 pla good shot, 2.8MW, 105kJ, strike points just below the nose
high divertor D_alpha level
16 pla RXL back in 1cm, ZXL down 2cm, not very good (similar to 15)
17 pla RXL 0.5cm out, ZXL 0.5cm down, much worse, only 85kJ
outer strike point is half way up the vertical plate
18 pla reload 951206013, disrupt @ .53sec
19 pla loaded 950131011 STRKPSI control, early disruption @ .22sec
trying to get slot divertor (i.e., very low strike point)
20 pla disrupt @ .51sec (right after STRKPSI control turns on)
21 pla reload 951206018, good shot, some E-port trip-outs
22 pla 600kA, nel=0.8->1.6, 28->87kJ
23 pla higher dens., nel=1.0->1.9, 28->86kJ
24 pla still higher dens., short D-port
25 pla 1MA, E-port tripped early, nel=1.0->2.1, 100kJ/2.5MW=40msec
26 pla higher dens. lost TCI (get lower dens), DAQ1 errors, short E-port
27 pla higher dens. nel=1.1->2.6, 131kJ
28 pla more gas, nel=1.2->2.7, 130kJ
29 pla add D2 puff from B-side-upper (didn't load into model?)
nel=1.1->2.6, 134kJ
30 pla repeat, add D2 puff from B-side-upper (didn't get higher dens)
short D-port pulse
31 pla got linear dens rise to nel=2.4, but no RF
32 fiz remove extra gas, Li pellet @.58sec
33 pla Li pellet @ .57sec, disrupt @ .72sec, H-mode, no PEP
34 pla Li pellet @ .57sec, disrupt @ .68sec, PEP (5e13 neuts/sec), no H-mode
35 pla turned off position feedback
no pellet, got H-mode, short D-port
36 pla got pellet, D-port tripped early, PEP, no H-mode
37 pla disruption @ .22sec, runaway shot
38 pla over-gassed, disrupt @ .46sec
39 pla disrupt @.41sec
40 pla reload 951206036
41 fiz remove extra gas after RF turn-on

Physics Operator Summaries
Entered: Jul 7 2004 04:36:55:503PM
Author: To Be Determined
ICRF H-mode Run 951206
Engineer in Charge: Vince Bertolino
Physicist in Charge: Joseph Snipes
Session Leader: Yuichi Takase

Goal: To improve the ICRF H-mode with high ICRF power (3 MW). We will
attempt to improve the H-mode by moving the lower X point up and down and
vary the gas feed and density programming. We succeeded in getting a
number of ELMy H-modes today with up to 3 MW of ICRF power. However, the H
factors have not improved with values of about 1.4 today. Nonetheless,
some long ELMy H-modes were obtained with 300 msec durations. Higher gas
puffing, allowed increased length of the H-modes because the RF coupling
resistance remained constant with the radial feedback. But, the H-modes
were ELMy. Raising or lowering the position of the X point seemed to make
the H-modes worse. This may be a conditioning issue in the new location.
Another thing worth trying is to have strike point control. It was
attempted for a few shots, but they led to disruptions as soon as the STRKPSI
control was turned on. Several nice 1 MA H-modes were obtained. However,
disruptions were rampant. Almost all discharges disrupted with significant
current. Some work still needs to be done to ramp down a high density
discharge without disrupting. Several lithium pellets were also injected
prior to RF and some short PEP/H-modes were obtained. However, they
disrupted violently apparently due to an interaction between the RF radial
position feedback and the pellet. There was one magnet resistance fault on
shot 1 and an OH2 fault on shot 8, but otherwise, the engineering systems
worked well. There were, however, several, unexplained early disruptions
and a couple of runaway shots. Overall, the run was reasonably successful,
though H-modes were not improved.


Scorecard: 41 shots, 37 plasmas, 3 fizzles, 1 magnet resistance fault

Shot 1 : Start with shot 951205043 with Br offset set to 7.5 mT. No TF.
Magnet resistance fault.
Shot 2 : Added 1 ms to the pre-puff. Got plasma, but too much gas.
Disrupted at 0.62 sec.
Shot 3 : Copied shot 951205039, but reduced the gas early and throughout
the pulse. Set the pre-RF density to 1.4 x 10^20 m^-3. Br offset
set to 7.5 mT. Ip set to 0.8 MA. Short H-mode. Disrupted at 1.2 sec.
Shot 4 : Increased ramp of RCUR and CLEARIN during rampdown to bring the
plasma against the inner wall to pump out the density. Still
disrupted at 1.14 sec. H-mode 0.6 - 0.9 sec.
Shot 5 : Increased ramp of RCUR and CLEARIN during rampdown to bring the
plasma against the inner wall to pump out the density. H-mode from
0.6 - 0.9 sec. Disrupted at 1.26 sec.
Shot 6 : Increased ramp of RCUR and CLEARIN during rampdown to bring the
plasma against the inner wall to pump out the density. H-mode from
0.66 - 0.87 sec. Disrupted at 1.15 sec.
Shot 7 : Set RXL gain to 18 from 1 to 1.4 sec to try to keep the strike
point from crawling up the inner nose during rampdown. Disrupted
violently at 0.92 sec apparently due to the RF radial position
feedback causing a vertical instability. It disrupted up.
Shot 8 : Golovato reduced the feedback loading resistance. Plasma
disrupted at 0.25 sec. OH2L fault. Interferometer died as well.
Shot 9 : Repeat. Disrupted at 0.96 sec.
Shot 10: Copied shot 951205025. Fiducial. Fizzle!
Shot 11: Fiducial. Changed pre-puff to 13 ms flattop and Br offset to 7.5
mT. Good fiducial. Wall conditions look pretty bad. No H-mode.
Disrupted at 1.2 sec.
Shot 12: Loaded shot 951206005. Hard x rays from 0.03 sec. Disrupted at
0.23 sec.
Shot 13: Increased early gas a bit between 0.01 and 0.1 sec. Good shot.
H-mode from 0.66 - 0.76 sec.
Shot 14: Changed RXL and ZXL programming to move the X point up and out by
1 cm in each direction from 0.6 to 1 sec. Large density
oscillations. Gas feedback unstable. Disrupted at 1.28 sec.
Shot 15: Lowered nl04 request to 1.2 x 10^20 m^-2. H-mode from 0.64 - 1.01
sec. with high recycling in the divertor.
Shot 16: Moved RXL back to -0.005 m and ZXL down 2 cm. ELMy H-mode from
0.68 - 0.82 sec. RF tripped at 0.82 sec to half the peak power.
Shot 17: Moved RXL to 0 and ZXL down another 0.5 cm ramping from -3.2 to
-3.5 cm. Some signs of H-mode from 0.62 - 0.84 sec in the
divertor, but not much of a density rise.
Shot 18: Increased Ar puff duration by 2 msec. Reloaded shot 951206013
Disrupted violently at 0.52 sec. Appears to be a moly UFO.
Shot 19: Copied STRKPSI controllers from shot 950131011 as well as RXL and
ZXL. Disrupted at 0.22 sec. STRKPSI control killed the plasma.
Shot 20: Changed start time of STRKPSI controller to 0.47 sec. Disrupted
at 0.5 sec. Clearly the STRKPSI controller is not working.
Shot 21: Loaded shot 951206018. Good shot. H-modes from 0.65 - 0.79 sec.
Shot 22: Ip set to 0.6 MA. Reduced Ar by 2 msec. Reduced density to
1 x 10^20 m^-2 with a step up to 1.5 x 10^20 m^-2. Good shot.
H-modes from 0.66 - 0.98 sec.
Shot 23: Increased density from 0.6 to 1 sec from 1.5 to 1.8 x 10^20 m^-2.
Added gas pre-programming on A side valve. Good shot. H-mode from
0.68 - 0.96 sec.
Shot 24: Raised nl04 to 1.2 x 10^20 m^-2 before the RF and then increased
to 2.2 x 10^20 m^-2 during the RF. Good shot. RF tripped. Short
H-mode from 0.67 to 0.7 sec.
Shot 25: Raised Ip to 1 MA. Good shot. ELMy H-mode from 0.65 - 0.98 sec.
Shot 26: Increased Ar puff to 22 msec duration. Increased density to 1.5
x 10^20 m^-2 before RF and up to 3 x 10^20 m^-2 during RF.
Increased pre-programmed gas on A side throughout the discharge.
Good shot. nl04 and density feedback failed.
Shot 27: Repeat with nl04. Good shot. ELMy H-modes from 0.62 - 1.06 sec.
Shot 28: Raised nl04 from 0.8 to 1 sec to 3 x 10^20 m^-2. Increased gas
puffing on A side. ELMy H-mode from 0.63 - 0.9 sec.
Shot 29: Turned on B side upper gas valve with deuterium at 50 V during the
flattop. Good shot. H-mode from 0.64 - 0.88 sec.
Shot 30: Only 1.5 MW of RF. No H-mode.
Shot 31: B side upper gas set to 100 V from 0.3 to 0.45 sec, then 90 V from
0.45 to 1 sec. Good shot. Density ramps up to 2.4 x 10^20 m^-2
without RF. No H-mode.
Shot 32: B side upper turned off. A side pre-programmed gas turned down to
60 V. Lithium pellet at 0.58 sec. Fizzle!
Shot 33: Lithium pellet at 0.58 sec. Disrupted at 0.72 sec. Large
oscillation in RCUR. Short PEP H-mode from 0.62 - 0.67 sec.
Shot 34: RF radial feedback gain changed from -2750 to -2000. Li pellet at
0.58 sec. Disrupted at 0.675 sec. Short PEP mode.
Shot 35: RF radial feedback turned off by Golovato. Li pellet requested at
0.58 sec. No pellet. RF tripped at 0.67 s. H-modes between 0.65
and 0.79 sec.
Shot 36: One more time. Li pellet at 0.58 sec. Low RF. No H-mode. No PEP
mode.
Shot 37: Runaway discharge from 0.03 sec. Disrupted at 0.215 sec.
Shot 38: Increased early gas puff. Still hard x rays from 0.03 sec.
Disrupted at 0.46 sec.
Shot 39: Increased early gas puff some more and increased pre-puff by 2
msec.
Shot 40: Loaded segment 1 from shot 36. Increased pre-puff to 15 msec
duration. O.K. shot. Li pellet at 0.58 sec. Disrupted at 0.835
sec.
Shot 41: Fizzle!


Session Leader Comments
Dec 6 1995 08:36:40:080AMYuichi TakaseRun Plan for 951206

The objective is to optimize H-mode performance,
primarily in the H-factor (confinement enhancement
relative to L-mode) and secondarily in H-mode duration.
Considerable progress has already been made during
the 951205 run, after completing the position feedback
mini-proposal ahead of schedule. It was demonstrated
that both high starting density and active gas-puffing
during H-mode were beneficial. The position feedback
was not able to maintain constant loading, but appeared
to help prevent RF trip-outs to some degree.

The plan is to start from 951205039 and continue
exploratory investigation. Possibilities include:

X-point (or more precisely strike point) scan
Outer gap scan (using position feedback offset)
I_p scan
Use of pellet fuelling

Other suggestions will also be considered.

Engineering setup as in 951205039.
Fiducial will be taken mid-day if diagnostics are not
ready on shot 1.

Dec 6 1995 08:58:18:920AM951206001Yuichi TakaseShot 1 dud (PS)

Dec 6 1995 09:08:06:050AM951206002Yuichi TakaseShot 2 plasma
Early disruption @ .65sec (too much gas)

Dec 6 1995 10:19:27:840AM951206003Yuichi TakaseShot 3 plasma
load 951205039, reduce gas, 800kA
nel=1.2->2.3, 2.7MW, 110kJ

Dec 6 1995 10:19:46:640AM951206004Yuichi TakaseShot 4 plasma
similar to 951205029, RF cutting off @ 0.9sec

Dec 6 1995 10:20:11:170AM951206005Yuichi TakaseShot 5 plasma
RF still cutting off @ .9sec

Dec 6 1995 10:20:44:790AM951206006Yuichi TakaseShot 6 plasma
extended RF gate to 1.5sec (was .9sec)

Dec 6 1995 10:21:03:990AM951206007Yuichi TakaseShot 7 plasma
D-port tripped early, disrupt @ .92sec

Dec 6 1995 10:33:14:000AM951206009Yuichi TakaseShot 9 plasma
fiducial (didn't load fiducial shot)
loaded 951205025 for the next shot

Dec 6 1995 10:34:22:440AM951206010Yuichi TakaseShot 10 fizzle
retake fiducial (loaded 951205025)
try again for the next shot

Dec 6 1995 11:03:19:160AM951206011Yuichi TakaseShot 11 plasma
fiducial shot (no H-mode with 2MW RF!)

Dec 6 1995 11:05:08:400AM951206012Yuichi TakaseShot 12 plasma
early disruption @ .23sec

Dec 6 1995 01:11:51:050PM951206013Yuichi TakaseShot 13 plasma
reload 951206005, D-port a little short

Dec 6 1995 01:13:04:600PM951206014Yuichi TakaseShot 14 plasma
RXL 1cm out, ZXL 1cm up, D-port interrupts

Dec 6 1995 01:13:23:670PM951206015Yuichi TakaseShot 15 plasma
good shot, 2.8MW, 105kJ, strike points just below the nose
high divertor D_alpha level

Dec 6 1995 01:13:40:100PM951206016Yuichi TakaseShot 16 plasma
RXL back in 1cm, ZXL down 2cm, not very good (similar to 15)

Dec 6 1995 01:13:59:900PM951206017Yuichi TakaseShot 17 plasma
RXL 0.5cm out, ZXL 0.5cm down, much worse, only 85kJ
outer strike point is half way up the vertical plate

Dec 6 1995 01:14:17:520PM951206018Yuichi TakaseShot 18 plasma
reload 951206013, disrupt @ .53sec

Dec 6 1995 01:15:04:870PM951206019Yuichi TakaseShot 19 plasma
loaded 950131011 STRKPSI control, early disruption @ .22sec
trying to get slot divertor (i.e., very low strike point)

Dec 6 1995 01:15:33:040PM951206020Yuichi TakaseShot 20 plasma
disrupt @ .51sec (right after STRKPSI control turns on)

Dec 6 1995 01:53:25:180PM951206021Yuichi TakaseShot 21 plasma
reload 951206018, good shot, some E-port trip-outs

Dec 6 1995 01:53:41:640PM951206022Yuichi TakaseShot 22 plasma
600kA, nel=0.8->1.6, 28->87kJ

Dec 6 1995 01:54:10:670PM951206023Yuichi TakaseShot 23 plasma
600kA, higher dens., nel=1.0->1.9, 28->86kJ

Dec 6 1995 01:54:29:850PM951206024Yuichi TakaseShot 24 plasma
still higher dens., short D-port

Dec 6 1995 04:40:57:270PM951206025Yuichi TakaseShot 25 plasma
1MA, E-port tripped early, nel=1.0->2.1, 100kJ/2.5MW=40msec

Dec 6 1995 04:41:13:200PM951206026Yuichi TakaseShot 26 plasma
higher dens. lost TCI (get lower dens), DAQ1 errors, short E-port

Dec 6 1995 04:41:30:630PM951206027Yuichi TakaseShot 27 plasma
higher dens. nel=1.1->2.6, 131kJ

Dec 6 1995 04:41:47:320PM951206028Yuichi TakaseShot 28 plasma
more gas, nel=1.2->2.7, 130kJ

Dec 6 1995 04:42:09:840PM951206029Yuichi TakaseShot 29 plasma
add D2 puff from B-side-upper (didn't load into model?)
nel=1.1->2.6, 134kJ

Dec 6 1995 04:42:32:010PM951206030Yuichi TakaseShot 30 plasma
repeat, add D2 puff from B-side-upper (didn't get higher dens)
short D-port pulse

Dec 6 1995 04:42:46:720PM951206031Yuichi TakaseShot 31 plasma
got linear dens rise to nel=2.4, but no RF

Dec 6 1995 04:43:10:950PM951206032Yuichi TakaseShot 32 fizzle
remove extra gas, Li pellet @.58sec

Dec 6 1995 04:43:30:070PM951206033Yuichi TakaseShot 33 plasma
Li pellet @ .57sec, disrupt @ .72sec, H-mode, no PEP

Dec 6 1995 04:43:46:200PM951206034Yuichi TakaseShot 34 plasma
Li pellet @ .57sec, disrupt @ .68sec, PEP (5e13 neuts/sec), no H-mode

Dec 6 1995 04:44:04:630PM951206035Yuichi TakaseShot 35 plasma
turned off position feedback
no pellet, got H-mode, short D-port

Dec 6 1995 04:44:21:940PM951206036Yuichi TakaseShot 36 plasma
got pellet, D-port tripped early, PEP, no H-mode

Dec 6 1995 04:44:39:670PM951206037Yuichi TakaseShot 37 plasma
disruption @ .22sec, runaway shot

Dec 6 1995 04:44:54:730PM951206038Yuichi TakaseShot 38 plasma
over-gassed, disrupt @ .46sec

Dec 6 1995 05:07:26:620PM951206039Yuichi TakaseShot 39 plasma
disrupt @.41sec

Dec 6 1995 05:07:47:420PM951206040Yuichi TakaseShot 40 plasma
reload 95120603

Dec 6 1995 05:08:40:000PM951206041Yuichi TakaseShot 41 fizzle
removed extra gas after RF turn-on

Physics Operator Comments
Dec 6 1995 10:22:57:690AMJoseph SnipesICRF H-mode Run 951206
Engineer in Charge: Vince Bertolino
Physicist in Charge: Joseph Snipes
Session Leader: Yuichi Takase

Goal: To improve the ICRF H-mode with high ICRF power (3 MW). We will
attempt to improve the H-mode by moving the lower X point up and down and
vary the gas feed and density programming.


Dec 6 1995 10:32:15:450AM951206001Joseph SnipesShot 1 : Start with shot 951205043 with Br offset set to 7.5 mT. No TF.
Magnet resistance fault.


Dec 6 1995 10:32:44:520AM951206002Joseph SnipesShot 2 : Added 1 ms to the pre-puff. Got plasma, but too much gas.
Disrupted at 0.62 sec.


Dec 6 1995 10:33:09:650AM951206003Joseph SnipesShot 3 : Copied shot 951205039, but reduced the gas early and throughout
the pulse. Set the pre-RF density to 1.4 x 10^20 m^-3. Br offset
set to 7.5 mT. Ip set to 0.8 MA. Short H-mode. Disrupted at 1.2 sec.


Dec 6 1995 10:33:43:530AM951206004Joseph SnipesShot 4 : Increased ramp of RCUR and CLEARIN during rampdown to bring the
plasma against the inner wall to pump out the density. Still
disrupted at 1.14 sec. H-mode 0.6 - 0.9 sec.


Dec 6 1995 10:34:03:650AM951206005Joseph SnipesShot 5 : Increased ramp of RCUR and CLEARIN during rampdown to bring the
plasma against the inner wall to pump out the density. H-mode from
0.6 - 0.9 sec. Disrupted at 1.26 sec.


Dec 6 1995 10:34:23:190AM951206006Joseph SnipesShot 6 : Increased ramp of RCUR and CLEARIN during rampdown to bring the
plasma against the inner wall to pump out the density. H-mode from
0.66 - 0.87 sec. Disrupted at 1.15 sec.


Dec 6 1995 10:34:47:850AM951206007Joseph SnipesShot 7 : Set RXL gain to 18 from 1 to 1.4 sec to try to keep the strike
point from crawling up the inner nose during rampdown. Disrupted
violently at 0.92 sec apparently due to the RF radial position
feedback causing a vertical instability. It disrupted up.


Dec 6 1995 10:35:07:130AM951206008Joseph SnipesShot 8 : Golovato reduced the feedback loading resistance. Plasma
disrupted at 0.25 sec. OH2L fault. Interferometer died as well.


Dec 6 1995 10:40:06:290AM951206009Joseph SnipesShot 9 : Repeat. Disrupted at 0.96 sec.


Dec 6 1995 10:40:32:490AM951206010Joseph SnipesShot 10: Copied shot 951205025. Fiducial. Fizzle!


Dec 6 1995 10:42:49:550AM951206011Joseph SnipesShot 11: Fiducial. Changed pre-puff to 13 ms flattop and Br offset to 7.5
mT. Good fiducial. Wall conditions look pretty bad. No H-mode.
Disrupted at 1.2 sec.

Dec 6 1995 11:07:26:740AM951206012Joseph SnipesShot 12: Loaded shot 951206005. Hard x rays from 0.03 sec. Disrupted at
0.23 sec.


Dec 6 1995 11:31:46:800AM951206013Joseph SnipesShot 13: Increased early gas a bit between 0.01 and 0.1 sec.
Good shot. H-mode from 0.66 - 0.76 sec.

Dec 6 1995 11:32:24:760AM951206014Joseph SnipesShot 14: Changed RXL and ZXL programming to move the X point up and out by
1 cm in each direction from 0.6 to 1 sec. Large density
oscillations. Gas feedback unstable. Disrupted at 1.28 sec.


Dec 6 1995 11:45:33:430AM951206015Joseph SnipesShot 15: Lowered nl04 request to 1.2 x 10^20 m^-2. H-mode from 0.64 - 1.01
sec. with high recycling in the divertor.


Dec 6 1995 11:59:21:380AM951206016Joseph SnipesShot 16: Moved RXL back to -0.005 m and ZXL down 2 cm. ELMy H-mode from
0.68 - 0.82 sec. RF tripped at 0.82 sec to half the peak power.


Dec 6 1995 12:09:47:030PM951206017Joseph SnipesShot 17: Moved RXL to 0 and ZXL down another 0.5 cm ramping from -3.2 to
-3.5 cm. Some signs of H-mode from 0.62 - 0.84 sec in the
divertor, but not much of a density rise.


Dec 6 1995 01:12:03:250PM951206018Joseph SnipesShot 18: Increased Ar puff duration by 2 msec. Reloaded shot 951206013
Disrupted violently at 0.52 sec. Appears to be a moly UFO.


Dec 6 1995 01:12:27:560PM951206019Joseph SnipesShot 19: Copied STRKPSI controllers from shot 950131011 as well as RXL and
ZXL. Disrupted at 0.22 sec. STRKPSI control killed the plasma.


Dec 6 1995 01:12:53:640PM951206020Joseph SnipesShot 20: Changed start time of STRKPSI controller to 0.47 sec. Disrupted
at 0.5 sec. Clearly the STRKPSI controller is not working.


Dec 6 1995 01:13:17:330PM951206021Joseph SnipesShot 21: Loaded shot 951206018. Good shot. H-modes from 0.65 - 0.79 sec.


Dec 6 1995 01:30:45:060PM951206022Joseph SnipesShot 22: Reduced Ip to 0.6 MA. Reduced Ar by 2 msec. Reduced density to
1 x 10^20 m^-2 with a step up to 1.5 x 10^20 m^-2.

Dec 6 1995 01:38:57:180PM951206023Joseph SnipesShot 23: Increased density from 0.6 to 1 sec from 1.5 to 1.8 x 10^20 m^-2.
Added gas pre-programming on A side valve. Good shot. H-mode from
0.68 - 0.96 sec.


Dec 6 1995 01:53:04:800PM951206024Joseph SnipesShot 24: Raised nl04 to 1.2 x 10^20 m^-2 before the RF and then increased
to 2.2 x 10^20 m^-2 during the RF. Good shot. RF tripped. Short
H-mode from 0.67 to 0.7 sec.


Dec 6 1995 02:13:58:460PM951206025Joseph SnipesShot 25: Raised Ip to 1 MA. Good shot. ELMy H-mode from 0.65 - 0.98 sec.

Dec 6 1995 02:25:39:300PM951206026Joseph SnipesShot 26: Increased Ar puff to 22 msec duration. Increased density to 1.5
x 10^20 m^-2 before RF and up to 3 x 10^20 m^-2 during RF.
Increased pre-programmed gas on A side throughout the discharge.
Good shot. nl04 and density feedback failed.


Dec 6 1995 02:45:27:360PM951206027Joseph SnipesShot 27: Repeat with nl04. Good shot. ELMy H-modes from 0.62 - 1.06 sec.


Dec 6 1995 02:47:53:720PM951206028Joseph SnipesShot 28: Raised nl04 from 0.8 to 1 sec to 3 x 10^20 m^-2. Increased gas
puffing on A side. ELMy H-mode from 0.63 - 0.9 sec.


Dec 6 1995 03:52:01:200PM951206029Joseph SnipesShot 29: Turned on B side upper gas valve with deuterium at 50 V during the
flattop. Good shot. H-mode from 0.64 - 0.88 sec.


Dec 6 1995 03:52:35:890PM951206030Joseph SnipesShot 30: Only 1.5 MW of RF. No H-mode.

Dec 6 1995 03:53:24:100PM951206031Joseph SnipesShot 31: B side upper gas set to 100 V from 0.3 to 0.45 sec, then 90 V from
0.45 to 1 sec. Good shot. Density ramps up to 2.4 x 10^20 m^-2
without RF. No H-mode.


Dec 6 1995 03:53:51:580PM951206032Joseph SnipesShot 32: B side upper turned off. A side pre-programmed gas turned down to
60 V. Lithium pellet at 0.58 sec. Fizzle!


Dec 6 1995 03:54:16:840PM951206033Joseph SnipesShot 33: Lithium pellet at 0.58 sec. Disrupted at 0.72 sec. Large
oscillation in RCUR. Short PEP H-mode from 0.62 - 0.67 sec.


Dec 6 1995 04:01:49:820PM951206034Joseph SnipesShot 34: RF radial feedback gain changed from -2750 to -2000. Li pellet at
0.58 sec. Disrupted at 0.675 sec.

Dec 6 1995 04:18:54:900PM951206035Joseph SnipesShot 35: RF radial feedback turned off by Golovato. Li pellet requested at
0.58 sec. No pellet. RF tripped at 0.67 s. H-modes between 0.65
and 0.79 sec.


Dec 6 1995 04:20:42:440PM951206036Joseph SnipesShot 36: One more time. Li pellet at 0.58 sec. Low RF. No H-mode. No PEP
mode.


Dec 6 1995 04:33:24:350PM951206037Joseph SnipesShot 37: Runaway discharge from 0.03 sec. Disrupted at 0.215 sec.


Dec 6 1995 04:54:51:560PM951206038Joseph SnipesShot 38: Increased early gas puff. Still hard x rays from 0.03 sec.
Disrupted at 0.46 sec.


Dec 6 1995 04:55:11:130PM951206039Joseph SnipesShot 39: Increased early gas puff some more and increased pre-puff by 2
msec.


Dec 6 1995 05:08:07:170PM951206040Joseph SnipesShot 40: Loaded segment 1 from shot 36. Increased pre-puff to 15 msec
duration. O.K. shot. Li pellet at 0.58 sec. Disrupted at 0.835 sec.



Dec 6 1995 05:08:38:180PM951206041Joseph SnipesShot 41: Fizzle!



Engineering Operator Comments
ShotTimeTypeStatusComment
108:43:49:650AMPlasmaBadmag res fault
208:50:30:220AMPlasmaOk
309:07:06:930AMPlasmaOk
409:18:12:950AMPlasmaOk
509:29:10:040AMPlasmaOk
609:39:28:550AMPlasmaOk
709:54:27:770AMPlasmaOk
810:08:10:330AMPlasmaBadoh2l comm fault
910:22:07:890AMPlasmaOk
1010:30:15:160AMPlasmaOk
1110:38:58:220AMPlasmaOk
1210:54:08:640AMPlasmaOk
1311:04:29:910AMPlasmaOk
1411:20:31:030AMPlasmaOk
1511:31:16:240AMPlasmaOk
1611:44:36:110AMPlasmaOk
1711:59:13:960AMPlasmaOk
1812:17:57:830PMPlasmaOk
1912:32:27:210PMPlasmaOk
2012:50:53:720PMPlasmaOk
2112:58:34:060PMPlasmaOk
2201:13:16:650PMPlasmaOk
2301:29:38:720PMPlasmaOk
2401:39:47:150PMPlasmaOk
2501:54:40:320PMPlasmaOk
2602:13:11:580PMPlasmaOk
2702:24:33:470PMPlasmaOk
2802:38:02:420PMPlasmaOk
2902:48:12:490PMPlasmaOk
3002:56:35:410PMPlasmaOk
3103:06:01:790PMPlasmaOk
3203:22:47:210PMPlasmaOk
3303:31:55:970PMPlasmaOk
3403:50:42:430PMPlasmaOk
3504:01:36:520PMPlasmaOk
3604:12:44:240PMPlasmaOk
3704:25:42:570PMPlasmaOk
3804:34:57:650PMPlasmaOk
3904:45:18:830PMPlasmaOk
4004:54:01:840PMPlasmaOk
4105:05:31:000PMPlasmaOk