Alcator C-Mod Run 950330 Information

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Miniproposals
Miniproposal:
Date Filed:
Title:
First Author:
Session Leader:Jay Kesner (shots 1-31)

Operators
Session leader(s):Jay Kesner
Physics operator(s):Steve Wolfe
Engineering operator(s):Frank Silva,Vinny Bertolino

Engineering Operator Run Comment
Silva/Bertolino

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:12:867PM
Author: To Be Determined
SESSION LEADER SUMMARY

Jay Kesner

950330 - High Poloidal beta plasmas with current ramp-downs.

This was an Exploratory run using an 800->400 KA current ramp-down. The
challenge was to maximize ramp rate while maintaining ICRF coupling and
avoiding disruption. We expected that if stored energy stayed up during the
ramp-down that we would obtain high poloidal betas. We were limited to the use
of 1 ICRF source (1.5 MW).

We completed the run plan and the technical goals were accomplished. We
succeeded in maintaining RF coupling during the rapid current ramps and we
succeeded in ramping plasma current from 800 to 400 KA in 100 ms and on one
(disruptive) shot we did the ramp in 70 ms (see Steve Wolfes Physics operators
report). We reached a poloidal beta of beta_p~0.8 and for Ip=400 KA this
corresponds to a normalized beta (beta_N=beta a B /I) of beta_N~0.8.


Past experience in TFTR indicated that the current ramp-down can lead to both
enhanced energy confinement and Troyon beta limits. We were not at a
sufficiently high beta_N to approach the Troyon limit.

In the best non-disruptive ramp-down discharges we observed that the stored
energy peaked at the end of the high current (800 KA) phase at t=600 ms, with
an H-factor consistent with L-mode, i.e. H~1. (H was monitored by J. Snipes).
The poloidal beta peaked at the end of the ramp-down phase in the range of 0.7
to 0.8. This represented an increase in beta_p of >2 for a ramp ratio of 2.
This result is again consistent with L-mode.

Other important observations were that RF power typically dropped from 1.5 to 1
MW during the ramp-down and recovered afterwards. The ellipticity was typically
initially 1.6 and sometimes decreased to 1.5 during ramp-down. The drop in
stored energy during the ramp-down was seen to be a combination of a ~20% drop
in peak Te and a a ~25% drop in gaussian with of Te and a small drop in
density.

The persistence of L-mode through the ramp-down may indicate that we were not
sucessful in "freezing in" the core current profile. We can extrapolate this
result to the high performance case with pre-ramp current of 1.2 MA and ICRF
power of 3 MW.The pre-ramp poloidal beta was ~0.35 and with higher power and
current would remain about 0.35 (beta_p ~ P_Rf*tau_E ~ sqrt(P_RF)/I). A
ramp-down ratio of 3 would then give beta_P>~1.

However if higher power enables us to maintain an altered current profile (with
strong edge shear) we may obtain a regime where the confinement time does not
fall as the current falls (as is typical of L-mode), which could lead to
substantially higher poloidal betas.

--------------------------------------------------------------------------
The shot-by-shot list from the log book appears below:

RUN: 950330 SHOT: 950330001 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 08:32:06.80

Begin with 400 shot from 950315019.

1: Fizzle.

RUN: 950330 SHOT: 950330002 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 08:44:01.92
TEXT: 2. Fizzle

RUN: 950330 SHOT: 950330002 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 08:45:08.55
TEXT: 2. Fizzle.

RUN: 950330 SHOT: 950330003 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 09:06:40.41
TEXT: 3. 400 KA shot. Density jump at 0.41 s. Disrupts at 0.74 s.

RUN: 950330 SHOT: 950330004 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 09:25:58.91
TEXT: 4.Disrupts at 0.67 s.

RUN: 950330 SHOT: 950330005 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 09:56:58.75
TEXT: 5. Disrupts at 320 ms.

RUN: 950330 SHOT: 950330006 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 10:01:02.44
TEXT: 6. Continue 400 KA. Disruption at t=350 ms.

RUN: 950330 SHOT: 950330007 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 10:07:55.21
TEXT: 7. 400 KA try. Disruption at t=350 ms.

RUN: 950330 SHOT: 950330007 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 10:20:28.55
TEXT: 8. Go back to 950329037 (800 KA). Runs fine.

RUN: 950330 SHOT: 950330009 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 10:43:16.29
TEXT: 9. Attempt 800->400 KA at t=600 ms.
Vertical disrupted during rampdown: Ip= 660 at t=.720 ms. Reduce
elongation and try again.

RUN: 950330 SHOT: 950330010 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 10:50:30.76
TEXT: 10. Disrupts at t=550 s, Ip=770 KA. Possible Mo injection.

RUN: 950330 SHOT: 950330011 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 11:14:13.98
TEXT: 11. ** Made-it. Ramp down in 250 ms. Mo injection early in ramp.
0.5 MW RF.

RUN: 950330 SHOT: 950330012 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 11:34:02.28
TEXT: 12.* Control x-point rather than strike point to keep discharge off nose.
Lost it at 0.91 s, just after ramp-down.

RUN: 950330 SHOT: 950330013 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 12:10:22.00
TEXT: 13. Redo wi increased x-point gains.Disrupt at 1 s. 1.4 MW RF at end of
rampdown. During ramp stored energy drops. After stored energy rises
during rf.

RUN: 950330 SHOT: 950330014 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 12:49:38.42
TEXT: 14. ** did not disrupt. Rf off. Data lost

RUN: 950330 SHOT: 950330015 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 12:53:29.90
TEXT: 15. ** Repeat of 14 to regain data. beta_p rises from .28 to .39;
W_plas falls from 55KJ to 15KJ.

RUN: 950330 SHOT: 950330016 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 13:12:05.19
TEXT: 16. Speed up ramp-down. 600-700 ms. Ip drops to 521. sec; 700-800 Ip
drops to 400 KA. beta_p peaks at ~700 ms at ~0.5.

RUN: 950330 SHOT: 950330017 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 13:33:23.79
TEXT: 17. Adjust controls and move rf to 800. Disrupts at 840.

RUN: 950330 SHOT: 950330018 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 13:59:01.94
TEXT: 18. Disrupted again at 0.84. beta_p~0.56. W_plas drops slowly during
rampdown.

RUN: 950330 SHOT: 950330019 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 14:11:45.34
TEXT: 19. ** RF at 700 ms. beta_p rises to 0.71 at 750 ms.

RUN: 950330 SHOT: 950330020 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 14:26:13.53
TEXT: 20. ** Redo. Get similar result. RF at 700 ms. beta_p rises to 0.71
at 730 ms. (seeing ramp effect for 30 ms).

RUN: 950330 SHOT: 950330021 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 14:30:31.84
TEXT: 21. ** Redo with change in control. Get similar result. RF at 700 ms.
beta_p rises to 0.67 at 730 ms. (seeing ramp effect for 30 ms).

RUN: 950330 SHOT: 950330022 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 15:07:08.83
TEXT: 22. Heat earlier at t=550 (50 ms before ramp-down). Disrupted at 740 ms
at beta_p=0.8.

RUN: 950330 SHOT: 950330023 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 15:24:47.45
TEXT: 23. Redo with control corrections. Screen current transmitter
trip due to plasma hitting antenna. beta_P(max)=0.8. Also beta_N~0.8.

RUN: 950330 SHOT: 950330024 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 15:28:32.85
TEXT: 24. Fizzle.

RUN: 950330 SHOT: 950330025 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 15:41:24.97
TEXT: 25. Redo 24. RF on at 550 ms and screen trip at 800 ms. Stays off
antenna. beta_p~beta_N flattens at 0.8.

RUN: 950330 SHOT: 950330026 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 15:59:06.01
TEXT: 26.*** Rf on time moved up to 500 ms to extend preheat time: stays on.
Energy confinement H>1 throughout shot.

RUN: 950330 SHOT: 950330027 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 16:10:21.01
TEXT: 27. Similar to previous shot. Max beta_N~beta_p~.75.

RUN: 950330 SHOT: 950330028 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 16:23:54.46
TEXT: 28. Similar conditions. Reprogram Controls to improve outer gap. Similar
max beta_p~0.75.

RUN: 950330 SHOT: 950330029 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 16:39:50.89
TEXT: 29. Disruption at 670 ms.

RUN: 950330 SHOT: 950330030 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 16:51:55.23
TEXT: 30. tweek control. Disrupts again.

RUN: 950330 SHOT: 950330031 TOPIC: SESSION_LEADER USERNAME: KESNER
ENTERED: 30-MAR-1995 17:24:59.95
TEXT: 31. Ramp down in 50 ms. Rf at 500 ms. Vertical disruption at t=680.
li=2.3, beta_p~beta_N~0.85 are records for the day. As with previous shots stored energies peak
at end of high current flat-top (t=600 ms) and falls as the plasma
current falls. beta_p and l_i peaks at end of ramp-down.

Physics Operator Summaries
Entered: Jul 7 2004 04:36:53:690PM
Author: To Be Determined
Physics Operator Summary for 950330

MP#089 High Betap with current rampdown
SL: Kesner
PO: Wolfe
EO: Silva/Bertolino

Run Plan:
---------
Start with engineering setup from 950315019. A-side plenum filled to 19psi D2.


1. Begin with 400kA shot based on 950315019, but with density flattopped at
NL_04=0.9e20. Get baseline heating shots at 400kA. See how much RF power we're
likely to get. Up to 5 shots.

2. Change to 800kA shot, engineering setup from 950328014. Program current
rampdown from 800 -> 400kA beginning at 0.6sec; density flat at level of
earlier shots. Tune up RF heating following rampdown. Determine fastest
rampdown compatible with no disruptions. May need to compromise on density. Up

3. Get to maximum available RF power under these conditions, firing immediately
after rampdown. (up to 5 shots)

4. Same equilibrium, begin heating in 800kA phase. (2-5 shots)

5. Same equilibrium, vary amount of pre-heating in 800kA phase, max heating in
post-rampdown. (Time remaining, if any)

Results:
--------
This was a difficult run, but we did manage to get a sizeable portion of the
planned data. We had to abandon step 1 (baseline heating at 400kA) when we
were unable to reproduce the 400kA shots that had run easily on 950315. A
number of rampdowns from 800kA to 400kA were successfully run, with up to
1.5MW injected into the post-rampdown phase and beginning in the pre-rampdown
800kA plasma and continuing through the ramp and the low-current phase.
Rampdowns as fast as 100msec were run without disruption, and on the last shot
an attempt at a 50msec ramp just made it to the lower plateau in 70msec before
disrupting (VDE). The shots were all very close to vertical instability,
with N/Ncrit going above 1.35 during the ramp.

There were brief H-modes during the rampdowns, but they were not very good and
didn't last. Some H-alpha drops accompanied by density and Moly rises and
strong MHD occured when the RF was injected late in the low current phase. If
these were in fact h-modes, they were not a good thing, since they tended to
cause disruptions.

For details of the physics results, see the Session Leader Summary. Briefly,
while betap's went up in the rampdown, the stored energy did not stay up, as
expected based on the TFTR result. There may have been some increase in tauE
relative to L-mode, but it decayed fairly quickly. Nevertheless, record betap
values for C-MOD were obtained with only 1.5 MW of RF.

Shot summary:
-------------
Shot 1 Fill at 1.8e-5 fizzled.
shot 2 adjusted EF4 15A more positive (-1085), Fizzle
lower fill to 1.6
Shot 3 delay pulse gas by 3msec Ran to .7sec, Density went high
Seemed to be a MARFE or Fin
effect?
Shot 4-7 various tweaks Disrupted early, similar
symptoms
Shot 8 Reloaded 950329037 in Seg 2 Ran into rampdown. No supply
problems
Shot 9 Attempted 800->400 ramp in Seg 3 Disrupted at 660Ka, vertical
instab.
Shot 10 Tweaks to CLEARIN, ZXL Gain Moly inj. disruption at .5sec
Shot 11 Retry Ran, but ended up limiting on
nose
Shot 12 Turn off FSP,STRKPSI, use xpoint Lost it around .9 sec, during
RF.
Shot 13 Increase RXL,ZXL gain Disrupts at .99. We're losing
control (EF1 voltage) during
RF.
Shot 14 Speed up rampdown (200msec) Ran to 1.25 sec. Data system
Increase ZXL gain to 45/s hung; Electron data bad.
Turn off RF
control
Shot 15 Re-run of 14 Ran fine *
Shot 16 Ramp down in 100ms (.60:.70) Made it all the way.
RF at 0.9 betap up to .5 in rampdown
Shot 17 RF to .8sec Disrupted at .84. EF2's at 0.
Shot 18 Ramp EF4 further down Similar disruption, EF2's ok.
MHD (very ELMy H-mode?) during
RF.
Shot 19-20 Change Ip controller, reduced OH2 Ran ok, outer gap is smaller *
RF to .7sec after ramp. No MHD during RF.
Shot 21 Change Ip controller back to normal Similar *
Shot 22 Move RF to .55sec, before ramp Disrupted around .7sec (VDE)
Shot 23 Increase CLEARIN I-gain and ZXU P-gain RF drops out at .78 (screen
current trip; too much
loading!). Disrupts at 1.07
after big density increase.
(Marfe? Fin?)
Shot 24 Move RCUR in 3mm to increase gap Fizzle
Increase RCUR gain from 60/s to 90/s
Shot 25 retry Disrupted at 1.04 after nl
increase, similar to 23
RF faulted again, around 800
Shot 26 RF power dropped to avoid trip, moved Ran through ok.
to .5 sec betap~betan~.75 *
Shot 27 Try to make gap smaller before ramp, Ran through, similar to 26 *
but actually went the wrong way
Shot 28 Actually make outer gap smaller Good shot, similar to 26,27 *
Almost lost it vertically at
.7sec.
Shot 29 Noticed that RCUR predictor was the Disrupts vertically at .7
old one with no offset. Fix it, as
usual.
Shot 30 Adjust initial gap (smaller) Disrupts vertically at .7
Shot 31 Reload 28, adjust gap in that Disrupts vertically at .7
Program 50msec rampdown Gets to betap>.8

Problems:
--------
Low current operation in the absence of RF (both flattop and post-rampdown)
was subject to sudden density increases (Gas puff shuts off, NL and Z-meter
soar anyway); these may have been detachments (fins) or a MARFE effect.
Whatever, they tended to lead to disruptions, probably density limit.

Shot 14 had a data system hang, corrupted ELECTRON tree data. EFIT and other
Batch Analysis did not run. May be recoverable.

There is a PCS bug that does not correctly get the FACTOR values for each time
in Segment 3 copied shots. It gets the actual factor, but the limits for each
time are missing until you calculate them.

There is a trivial PCS bug that the Segment name which appears as the title of
the ALL-P screen does not change when the Segment title is changed.

Scorecard: 31 shots. 28 plasmas. 3 fizzles. 0 duds.

Session Leader Comments
Mar 30 1995 08:26:35:820AMJay KesnerHigh Poloidal beta plasmas with ramp-downs. Initial run. Use 800->400 KA
current ramp-down. Maximize ramp rate while maintaining ICRF coupling.
Eventually will try 1200->400 KA rampdown. Goal : high beta_N and high
eps beta_p to explore high bootstrap fraction regime.

Begin with 400 shot from 950315019.

Mar 30 1995 08:27:20:430AM950330001Jay KesnerHigh Poloidal beta plasmas with ramp-downs. Initial run. Use 800->400 KA
current ramp-down. Maximize ramp rate while maintaining ICRF coupling.
Eventually will try 1200->400 KA rampdown. Goal : high beta_N and high
eps beta_p to explore high bootstrap fraction regime.

Begin with 400 shot from 950315019.

Mar 30 1995 08:32:06:800AM950330001Jay KesnerHigh Poloidal beta plasmas with ramp-downs. Initial run. Use 800->400 KA
current ramp-down. Maximize ramp rate while maintaining ICRF coupling.
Eventually will try 1200->400 KA rampdown. Goal : high beta_N and high
eps beta_p to explore high bootstrap fraction regime.

Begin with 400 shot from 950315019.

1: Fizzle.

Mar 30 1995 08:44:01:920AM950330002Jay Kesner2. Fizzle

Mar 30 1995 08:45:08:550AM950330002Jay Kesner2. Fizzle.

Mar 30 1995 09:06:40:410AM950330003Jay Kesner3. 400 KA shot. Density jump at 0.41 s. Disrupts at 0.74 s.

Mar 30 1995 09:25:58:910AM950330004Jay Kesner 4.Disrupts at 0.67 s.

Mar 30 1995 09:56:58:750AM950330005Jay Kesner5. Disrupts at 320 ms.

Mar 30 1995 10:01:02:440AM950330006Jay Kesner6. Continue 400 KA. Disruption at t=350 ms.

Mar 30 1995 10:07:55:210AM950330007Jay Kesner7. 400 KA try. Disruption at t=350 ms.

Mar 30 1995 10:20:28:550AM950330007Jay Kesner8. Go back to 950329037 (800 KA). Runs fine.

Mar 30 1995 10:43:16:290AM950330009Jay Kesner9. Attempt 800->400 KA at t=600 ms.
Verticle disrupted during rampdown: Ip= 660 at t=.720 ms. Reduce
elongation and try again.

Mar 30 1995 10:50:30:760AM950330010Jay Kesner10. Disrupts at t=550 s, Ip=770 KA. Possible Mo injection.

Mar 30 1995 11:14:13:980AM950330011Jay Kesner11. ** Made-it. Ramp down in 250 ms. Mo injection early in ramp.
0.5 MW RF.

Mar 30 1995 11:34:02:280AM950330012Jay Kesner12.* Control x-point rather than strike point to keep discharge off nose.
Lost it at 0.91 s, just after ramp-down.

Mar 30 1995 12:10:22:000PM950330013Jay Kesner13. Redo wi increased x-point gains.Disrunp at 1 s. 1.4 MW RF at end of
rampdown. During ramp stored energy drops. After stored energy rises
during rf.

Mar 30 1995 12:49:38:420PM950330014Jay Kesner14. ** did not disrupt. Rf off. Data lost

Mar 30 1995 12:53:29:900PM950330015Jay Kesner15. ** Repeat of 14 to regain data. beta_p rises from .28 to .39;
W_plas falls from 55KJ to 15KJ.

Mar 30 1995 01:12:05:190PM950330016Jay Kesner16. Speed up ramp-down. 600-700 ms. Ip drops to 521. sec; 700-800 Ip
drops to 400 KA. beta_p peaks at ~700 ms at ~0.5.

Mar 30 1995 01:33:23:790PM950330017Jay Kesner17. Tweek up ramp and move rf to 800. Disrupts at 840.

Mar 30 1995 01:59:01:940PM950330018Jay Kesner18. Disrupted again at 0.84. beta_p~0.56. W_plas drops slowly during
rampdown.

Mar 30 1995 02:11:45:340PM950330019Jay Kesner19. ** RF at 700 ms. beta_p rises to 0.71 at 750 ms.

Mar 30 1995 02:26:13:530PM950330020Jay Kesner20. ** Redo. Get similar result. RF at 700 ms. beta_p rises to 0.71
at 730 ms. (seeing ramp effect for 30 ms).

Mar 30 1995 02:30:31:840PM950330021Jay Kesner21. ** Redo with change in control. Get similar result. RF at 700 ms.
beta_p rises to 0.67 at 730 ms. (seeing ramp effect for 30 ms).

Mar 30 1995 03:07:08:830PM950330022Jay Kesner22. Heat earlier at t=550 (50 ms before ramp-down). Disrupted at 740 ms
at beta_p=0.8.

Mar 30 1995 03:24:47:450PM950330023Jay Kesner23. Redo with control corrections. Screen current transmitter
trip due to plasma hitting antenna. beta_P(max)=0.8. Also beta_N~0.8.

Mar 30 1995 03:28:32:850PM950330024Jay Kesner24. Fizzle.

Mar 30 1995 03:41:24:970PM950330025Jay Kesner25. Redo 24. RF on at 550 ms and screen trip at 800 ms. Stays off
antenns. beta_p~beta_N flattens at 0.8.

Mar 30 1995 03:59:06:010PM950330026Jay Kesner26.*** Rf on time moved up to 500 ms to extend preheat time: stays on.
Energy confinement H>1 throughout shot.

Mar 30 1995 04:10:21:010PM950330027Jay Kesner27. Similar to previous shot. Max beta_N~beta_p~.75.

Mar 30 1995 04:23:54:460PM950330028Jay Kesner28. Similar conditions. Reprogram Rcurrent to improve outer gap. Similar
max beta_p~0.75.

Mar 30 1995 04:39:50:890PM950330029Jay Kesner29. Disruption at 670 ms.

Mar 30 1995 04:51:55:230PM950330030Jay Kesner30. tweek control. Disrupts again.

Mar 30 1995 05:24:59:950PM950330031Jay Kesner31. Ramp down in 50 ms. Rf at 500 ms. Vertical disruption at t=680.
li=2.3, beta_p~beta_N~0.85 are records for the day. As with previous shots stored energies peak
at end of high current flat-top (t=600 ms) and falls as the plasma
current falls. beta_p and l_i peaks at end of ramp-down.

Physics Operator Comments
Mar 30 1995 07:05:15:260AMSteve WolfeRun plan for 950330

MP 089 High beta-p with current rampdown
SL: Kesner
PO: Wolfe
EO: Bertolino
Start with engineering setup from 950315019. A-side plenum filled to 19psi D2.


1. Begin with 400kA shot based on 950315019, but with density flattopped at
NL_04=0.9e20. Get baseline heating shots at 400kA. See how much RF power we're
likely to get. Up to 5 shots.

2. Change to 800kA shot, engineering setup from 950328014. Program current
rampdown from 800 -> 400kA beginning at 0.6sec; density flat at level of
earlier shots. Tune up RF heating following rampdown. Determine fastest
rampdown compatible with no disruptions. May need to compromise on density. Up

3. Get to maximum available RF power under these conditions, firing immediately
after rampdown. (up to 5 shots)

4. Same equilibrium, begin heating in 800kA phase. (2-5 shots)

5. Same equilibrium, vary amount of pre-heating in 800kA phase, max heating in
post-rampdown. (Time remaining, if any)

Mar 30 1995 07:47:14:720AMSteve WolfeFor shot 950330001:

Load shot from 950315019. Startup may need tweaking, but I'll see
what it gives.
Flattop NL_04 at 9.e19, getting there at .41 sec
Note that this shot had RXL,ZXL control, with ZXL=-.016. Could change.

Into Segment 3, load Segment 2 from 950328014 (800kA shot from Tues.,
with FSP and STRKPSI control.) I'll use this as basis of rampdown shot.
Copy NL_04 from seg2 -> seg3
Zero Strkpsi sweep
Ramp Ip from -8e5 to -3.8e5 between 0.6sec and 0.85 sec
ramp EF4 from 2500 to 790 in the same time
extend FSP flattop from .92 to 1.0sec

Load into Model (segment 3 off)
Do a coldstart (HYBINIT_DISPATCH.COM)
Note minor PCS bug: The title of the segment 3 All P's screen has not
changed to "800 -> 400 rampdown" from "Diverted Rampdown"

Change fizzle detector off-time from 1.9 to 1.6 (I don't know when it
was set to 1.9?) and reload model to make sure it takes

Mar 30 1995 08:30:14:660AM950330001Steve WolfeShot 950330001:

Fill pressure 1.8e-5
Starting early: INIT at 08:23

Fizzle. CII a little high, Bz maybe a little negative
No sign of it on ECE

Mar 30 1995 08:43:16:820AM950330002Steve WolfeShot 950330002:

Drop EF4 to -1085 from -1100.
Drop fill to 1.6e-5

Fizzle again- bounce at 16msec.
Still no sign on ECE, current got a little further

Mar 30 1995 09:02:39:850AM950330003Steve WolfeShot 950330003:

Delay PG3 in Seg 1 by 3msec (from -.004 to -.001)

Got a plasma- disrupted early, around 0.7sec
Density went screaming up? Something very weird on that shot with the
density. Density started up fast at 0.4sec, A-side turned off as it
should, NL_05 reached 1.4e20.
There are big gaps on both sides, and the upper x-point is near the inner
wall.

Mar 30 1995 09:21:27:960AM950330004Steve WolfeShot 950330004:

Slow down initial density ramp (to .5 sec)
This time we railed the EF2's?
Same weird density behavior, but later (.48 sec)
Also a big thrash on OH2s at segment switch.

Mar 30 1995 09:41:59:700AM950330005Steve WolfeShot 950330005:

Reduce gain on Ip for until 300msec
Reduce NL_04 gain from 8 to 4

Lost it early. There is a big jump onb EF1U at .3 sec, gain switch on ZXU
Drop this for next shot.
There's a big jump in radiated power, but no Mo injection.

Mar 30 1995 09:56:34:260AM950330006Steve WolfeShot 950330006:

Drop gain jump on ZXU at .3 sec

Another early loss. Something is broken.
This one has a vertical instability at .3 to .35 sec.
Both gaps are big.
Maybe a power supply problem on EF4? Seems to be full on coming out
of crossover, while hybrid demand is going negative.

Mar 30 1995 10:06:39:830AM950330007Steve WolfeShot 950330007:

Move CLEARIN from +.004 to 0.
Still something wrong. Disrupting at around .32sec
Go back to an 800ka shot and see if we can get the shot.

Mar 30 1995 10:18:36:130AM950330008Steve WolfeShot 950330008:

reload segment 2 from 950329037
This should be the same as last shot from yesterday. We'll see if there
is a problem.

Ran to end of flattop - disrupted in ramp-down. No sign of trouble in the
early phase as on the 400kA shots. There was a little h-alpha bust around
300 to 325.

Mar 30 1995 06:26:01:200PM950330008Steve WolfeOn shot 8, we also reloaded the engineering timing from 950329037,
getting back the .120 sec crowbar times we normally run with.

Mar 30 1995 10:34:46:710AM950330009Steve WolfeShot 950330009:

Switch to segment 3, the ramp-down program.
From now on I need to remember to make changes in Segment 3!!!

Didn't make it past the rampdown
No supplies railed, Oh2's went to zero real fast.
Current went down to 660kA
Looks like mainly a vertical problem.
EF1U&L are also getting jerked pretty hard.

Mar 30 1995 10:52:11:290AM950330010Steve WolfeShot 950330010:

Reduce CLEARIN by 4mm (from +.002 to -.002)
Reduce gain on ZXL from 3 to 1 between .6 and .85 - OOPs I made that change
in Segment 2. Try again.

Early disruption, around 500msec - before the rampdown.
Looks like a big moly injection.

Mar 30 1995 11:06:42:140AM950330011Steve WolfeShot 950330011:

No further changes, I think it was just a moly injection.
Changes on last shot were:
Reduce CLEARIN by 4mm (from +.002 to -.002)
Reduce gain on ZXL from 3 to 1 between .6 and .85

Looks like it made it!
Need to go to x-point control, we end up on the nose at the end of
flattop, and touch on the upper EF1 plate at beginning of rampdown.

Mar 30 1995 11:28:19:400AM950330012Steve WolfeShot 950330012:

Increase RXL gain to 20/sec
ZXL to 12/sec
FSP gain to 0.0
STRKPSI gain to zero

Looks like we lost that one after .9sec
EF2L goes to zero at 0.9sec
Elongation drops a lot at the end.
ZXL control is poor. RXL gets lost as EF2 goes to zero.

Mar 30 1995 11:57:30:800AM950330013Steve WolfeShot 950330013:

Increase RXL gain to 30/sec after .55sec
ZXL to 30/sec after 0.5s

Another late disruption right at 1.0 sec, EF2's stayed on this time.
It actually starts to lose it at .99, whcih seems to be where RXU gain
switches off. Extend that for next pulse.
We start to lose control at .9 sec, when the RF comes on.
It pushes everything around, and raile the EF1 voltages. The betap
increase is doing us in?

Mar 30 1995 12:25:21:500PM950330014Steve WolfeShot 950330014:

Re-call the ZXL predictor, the factor window had 100. for all the limits
INcrease ZXL factor from 3e-5 to 5e-5; increase time constant on ZXL to 7
Get Physics PID up to 45.
INcrease rampdown speed to get to 400kA at 0.8sec
Leave RF off for this shot.

Ran through till 1.25
Looks ok, There is a data system hang.
RXL could stand more gain.
There may be a problem related to EF4 getting to a second flattop

Mar 30 1995 12:46:01:260PM950330015Steve WolfeShot 950330015:

Repeat to try to get data this time. The electrons tree for shot 14 is
corrupt and inaccessible.

Repeat ran fine.
betap rises during rampdown, falls in second flattop.

Mar 30 1995 01:04:41:280PM950330016Steve WolfeShot 950330016:

Ramp down in 100msec (600 to 700.)
EF4 ramp over same time.
Raise gain on RXL to 50 after .5 sec
RF at .9sec

Made it.
betap reaches .5 during rampdown.
Ramp is to 500ka in .1 sec, then dribbles down to 400 in another .1s

Mar 30 1995 01:43:38:740PM950330018Steve WolfeShot 950330018:

Ramp EF4 down to 263 at 680msec

Disruption at .84sec
Very similar, except Ef2's didn't floor until after the disruption.

Mar 30 1995 02:11:16:860PM950330019Steve WolfeShot 950330019:

Try decreasing the OH2 component of the Ip controller
as in rampdown phase
Move RF up to 0.7sec

That one ran through. Rcur notched in during the ramp.
Looked like it rode the limiter, but outer gap on EFIT claims to be ok
(if 1.3cm is ok)

Mar 30 1995 02:29:07:010PM950330021Steve WolfeShot 950330021:

Remove change in OH2 gains in Ip controller
Otherwise no change

Very similar, still notches in and moves out. It may not have done
anything

Mar 30 1995 02:54:25:530PM950330022Steve WolfeShot 950330022:

Move RF to 550msec
No other changes, although we ought to see about getting the gap up.

Disrupted early, around .7sec
Lost it down, outer gap gets small.

Mar 30 1995 03:15:01:000PM950330023Steve WolfeShot 950330023:

Recalculate CLEARIN Predictor and check factor
Actually needed to go down from 2.7 to 2.3e-5
INcrease time constant from 3. to 3.6 (near limit)
This gives P=32.4/s, I = 144/s^2
Increase I to 250/s^2
ZXU increase factor from 2e-5 to 4e-5,
increase time constant from 3.5->7/sec

Ran through to 1.07sec
Lost the RF at 0.785
Density goes through the roof again????
Plasma runs way out, outer gap goes nearly to zero.

Mar 30 1995 03:26:26:310PM950330024Steve WolfeShot 950330024:

Move RCUR in from .653 to .650
Increase RCUR gain from 60 to 90/s at .5sec

Fizzle. Late breakdown, high CII (.004)

Mar 30 1995 03:38:20:020PM950330025Steve WolfeShot 950330025:

retry
Move RCUR in from .653 to .650
Increase RCUR gain from 60 to 90/s at .5sec

Disrupts at 1.04 sec, similar to 23
Rf faults at .8sec
Betap=betaN=0.8 during RF

Mar 30 1995 04:07:22:620PM950330027Steve WolfeShot 950330027:

Program outer gap smaller by 8mm before the ramp (<.600) then swing out

It ran through. OOPs I actually moved RCUR in instead of out.
RF was lower in 800kA phase.

Mar 30 1995 04:08:17:920PM950330027Steve WolfeShot 950330027:

Program outer gap smaller by 8mm before the ramp (<.600) then swing out

It ran through. OOPs I actually moved RCUR in instead of out.
RF was lower in 800kA phase.

Mar 30 1995 04:19:02:770PM950330028Steve WolfeShot 950330028:

Program outer gap smaller by 8mm before the ramp (<.600) then swing out
Do it right this time (.650->.654)
Damn! I've been runnng all day with an old Predictor with no offset!!!
No wonder its screwing up!

It ran through, but I want to fix the RCUR.

Mar 30 1995 04:34:48:650PM950330029Steve WolfeShot 950330029:

Recalculate RCUR predictor, hold constant at .662

Disruption at 0.74sec, lost it vertically
Gap was 2cm before ramp

Mar 30 1995 04:47:03:650PM950330030Steve WolfeShot 950330030:

Move RCUR to .6645 (5mm smaller gap)
Same disruption. Goes vertically.

Mar 30 1995 04:56:25:220PM950330031Steve WolfeShot 950330031:

Reload 28, and move late RCUR in 2mm (.648)
Ramp down in 50msec

Disrupted at .7

Engineering Operator Comments
ShotTimeTypeStatusComment
108:24:40:100AMPlasmaOkno faults
208:33:24:200AMPlasmaOkno faults
308:46:10:130AMPlasmaOkno faults
409:09:38:180AMPlasmaOkno faults
509:27:08:050AMPlasmaOkno faults
609:44:35:520AMPlasmaOkno faults
710:04:11:170AMPlasmaOkno faults
810:13:47:140AMPlasmaOkno faults
910:25:38:770AMPlasmaOkno faults
1010:41:19:080AMPlasmaOkno faults
1110:53:43:990AMPlasmaOkno faults
1211:14:19:810AMPlasmaOkno faults
1311:34:06:790AMPlasmaOkno faults
1412:07:37:640PMPlasmaOkno faults
1512:37:34:750PMPlasmaOkno faults
1612:52:57:390PMPlasmaOkno faults
1701:12:58:160PMPlasmaOkno faults
1801:34:19:650PMPlasmaOkno faults
1901:54:08:420PMPlasmaOkno faults
2002:12:12:150PMPlasmaOkno faults
2102:24:02:140PMPlasmaOkno faults
2202:35:38:870PMPlasmaOkno faults
2303:05:26:920PMPlasmaOkno faults
2403:20:51:520PMPlasmaOkno faults
2503:28:51:640PMPlasmaOkno faults
2603:42:53:500PMPlasmaOkno faults
2704:00:14:910PMPlasmaOkno faults
2804:11:51:880PMPlasmaOkno faults
2904:22:44:690PMPlasmaOkno faults
3004:38:03:040PMPlasmaOkno faults
3104:52:21:340PMPlasmaOkno faults