Alcator C-Mod Run 960116 Information

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Miniproposals
Miniproposal:132
Date Filed:12/20/1995
Title:ICRF H Mode Confinement With Boronized Walls
First Author:Steve Golovato
Session Leader:Steve Golovato (shots 1-39)

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

Engineering Operator Run Comment
icrf, h-mode

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:14:930PM
Author: To Be Determined

Run summary - 960116

SL: Golovato
PO: Hutchinson
EO: Bertolino/Daigle

Run 951205 - H-modes with bornized walls.

Goals - (1) get position feedback working.
(2) explore H-mode quality at high rf power P > 2 MW.
(3) density scan, particularly down in density.
(4) PEP-mode plus high power rf using lithium pellets.

This run was very successful, achieving record stored energy (213 kJ),
record energy confinement (80ms), and record H-factor (2.2), with shot
25 the best example. The factor relative to ITER94 elm-free global
energy confinement scaling was as high as 1.5 .

We got the position feedback going early on fiducial
shots, with a hybrid gain of -2000 and target loading bira level of 3
volts,giving the best results. We moved on to H-mode studies, scanning the
density down and getting the best H-modes we've seen. The H-modes exhibited
strange H-alpha behavior (first observed last friday) with H-alpha at first
dropping as in normal H-mode and then rising up again to near the L-mode
level while other H-mode indicators such as loading, edge profiles, and
improved confinement continuing. However, when this H-alpha effect does
not occur, the confinement is best, as evidenced on shots 18, 24, 25, and 27
(shot 18 was at 800 kA, the others at 1 MA).

We found a low density limit for getting H-mode of nl04 > 0.5e20. The best
results were with initial nl04 = 0.7-0.9e20, with nl04 rising to about
1.5e20 during H-mode. We also got good quality H-modes at initial density
of nl04=1.2e20 (see shot 27). In the lower density high quality H-modes,
the radiated power fraction increased indicating impurity buildup, but
record values of stroed energy and confinement time were nevertheless
achieved.

We had D-port coupling problems at high density (31 and 32).
We tried gas puffing after RF turn-on (33) but D-port didn't stay on,
and we didn't even get H-mode.
Li pellet injection was tried on shots 34-39 (except 37 which was a
fiducial). Initially we had coupling problems (E-port was way off tune),
but 38 and 39 had acceptable RF. No good looking PEP mode, but we did
observe H-modes.

For information on engineering problems and shot statistics, see the physics
operator summary. For shot-to-shot comments, see the logbook under the
session_leader topic.


Physics Operator Summaries
Entered: Jul 7 2004 04:36:55:770PM
Author: To Be Determined
Physop 960116
MP 132 ICRF H-mode Confinement with Boronized walls.

SL Golovato
PO Hutch
EO Bertolino

NO ECDC this weekend (3 days) since the Friday run with boronized walls.

Summary
_______

Excellent plasmas! Got several records. Over 200kJ stored energy. H-factor
over 2.

This seems to show that if the impurity buildup during (especially) ELM-free
H-modes is controlled, then very good confinement is possible. Boronization
appears to be capable of this control, at least for a while.
Also demonstrated again the hard low-density limit of H-modes but with
2.5MW this time.
Fiducial shots: Several early but without Mo monitor; also 26, 37.
0.8MA till shot 21 then 1MA except for fiducials.
Density scans were obtained at both currents. These show best H-modes at
the lowest density for wich they occur (and are not swamped by radiation).
The reason for confinement deterioration at higher density appears to be the
effect of Halpha rise, as if ELMS but incoherent, accompanying particle
confinement degradation. This helps keep the plasma clean.
There were signs by the end that the Mo radiation was starting to come back
after several serious disruptions. However still much improved relative to
pre-boronization.
Fizzle problem was controllable by a combination of field tweaks and p0
adjustments. The boronized machine is less forgiving. If running high density,
the fill puff should be lowered to about 11ms (1.2e-5). The magnetics startup
was not changed after shot 28.
Good current rampdowns were obtained by using the RCUR offset switch at 1.1s.

Scorecard.
_________
Shot,Duration(s),Ipmax(MA) Shot,Duration(s),Ipmax
1 0.000 0.013 2 1.531 0.825
3 1.524 0.825 4 0.000 0.018
5 1.518 0.825 6 0.000 0.021
7 1.521 0.828 8 1.507 0.838
9 0.000 0.021 10 1.524 0.838
11 1.526 0.843 12 1.526 0.838
13 1.536 0.848 14 0.000 0.042
15 1.537 0.848 16 1.532 0.843
17 1.538 0.848 18 1.537 0.846
19 1.533 0.840 20 1.528 0.833
21 1.535 1.039 22 1.095 1.045
23 0.000 0.024 24 1.538 1.042
25 1.535 1.042 26 1.524 0.825
27 1.520 1.029 28 0.000 0.024
29 1.456 1.029 30 0.000 0.024
31 1.399 1.021 32 1.298 1.019
33 1.234 1.008 34 1.084 1.011
35 0.595 0.988 36 1.064 1.034
37 1.518 0.825 38 1.502 1.027
39 1.507 1.029
Finished summary for 960116 Total of 39 shots.
39 shots. 31 plasmas. 7 fizzles. 1 duds.
Fizzle = gt 17 lt 50kA.

Details
_______
Load 960112037, a fiducial shot. But there is a lot of field gradient at
startup.

Gas PG4 B-top 5.1 PG3 A-side 20.psi D2

1 OHtest

No Mo monitor of McP because opressures are too high.
2 Pla To 1.56s. 0.8MW ICRF. H-modes drop at RF trip. Some small injections.
Initial CII .01 (vs .003 on 12th) Slow current rise. Good fiducial
but no McP or Mo Mon.

Repeat.
3 Pla Early CII drops to .004. Cleaner H-mode. nl04 1.1

Add new R-controller at 1.2s with offset 4000 (from 8000)
4 Fiz Oh1 -15781 OH2l -21321, OH2u -22392. Seem to have slightly excessive
curvature at bdown. OH1 is not reaching full regulation.

OH1V to -50V from -42 in segment 1.
5 Pla OH1 -15880. Got 2MW RF but tripped. PRAD to 1.2MW.

ICEF4 to -1180 (from -1150)
Add RF feedback to the RCUR controller in segment 2 at -2000.
6 Fiz Vacuum fields quite good. Br slightly high. Oh1 -15826

Repeat
7 Pla 2.25MW sustained. H alpha saturates even though we seem to be in H-mode
PRAD only 0.6MW. 111kJ.

RF feedback to -2500, RCUR offset to 2000 at 1.1s.
8 Pla RF on earlier, .65s, Apparent pi injection at .73s. PRAD to 2.5MW!
But then pumps. out.

Argon puff .28 to .30s, 2psi.
RF feedback back to -2000.
nl04 to 0.9 from 1.
9 Fiz

Add RCUR glitch at end to compensate the offset switch at 1.1s.
Br offset to 6.4 from 6.9mT
10 Pla 2.8MW sustained. No injection. 140kJ. Te peak at nearly 4keV.
Prad=.8MW. Hfactor very high ~1.7.

nl04 to .8. Open Mo Monitor.
11 Pla 3MW sustained. Radiative injection at .95s. 155kJ.
Right gap is pulled down to .7cm.

OH1V to 200V .005-.010s. RF feedback target altered.
Mo monitor High voltage increased.
12 Pla 3MW, radiation rising but no obvious injection. 153kJ
Not much position change. Very similar to previous shot.
No Mo lines on hirex spectrum. (Or Mo mon).

nl04 to .7 Mo Mon Hi voltage increased again.
13 Pla RF trips. Mo monitor now has a sensible-looking signal. 1e15.

McPherson gate vale opened.
14 Fiz Crashed on the outside at 17ms, 40kA.

OH1V to 170V, 5-10ms.
15 Pla Slight initial bump on outside.
Rf Tripped to 1MW, but H-mode sustained. Mo 2e15.

RCUR feedback on at 6ms (from 8ms).
16 Pla 2.6MW sustained. 140MJ Mo 1.2e15.

nl04 to .6
17 Pla 2.6Mw trips to 1MW. Strong Mo radiation rise to 5e15. 156MJ.

Repeat
18 Pla Rf sustained 2.4MW. Substantial Radiation, but rolls over as the Halpha
secondary rise occurs. 164kJ but also rolls over. H-factor over 2.
Prad is lower than 2pi. (?Argon)

19 Pla 2.5MW sustained. Radiation controlled. 100kJ of energy.
Density about 1.e20.

nl04 to .45
20 Pla L-mode. 2.5MW sustained. .65 nl04. PRAD.4MW. PSOL 3MW. Mo 1e15.

nl04 to .6. Load Ip from 951206028, 1MA shot.
21 Pla ELM-free H-mode. RF trips to 1.3 MW in .8s. Mo integrates to 8e15.
185 kJ.

Repeat
22 Pla Mostly L-mode. Disruption at .8MA in ramp down. Seems to be caused by
a radiative event at 1.08, disrupting at 1.09s.

Raise nl04 to .8
23 Fiz Close. CII .006.

24 Pla Ramped down. 2.3MW sustained. ELM-free throughout. Big radiation.
210 kJ. Mo 8e15. H-factor reaches 2.5 but radiation rolls it over.

nl04 to .7.
25 Pla Very similar shot. Mo rises slightly slower.

Load segment 2 from shot 3. Fiducial.
26 Pla Fine Fiducial. Mo still rising at the end to 1.4e15..

Reload seg 2 from 25.
Disable Ar. nl04=1.
27 Pla 2.7MW sustained. H-mode nl04 to 2.3. Secondary Halpah rise.
Mo 2e15. 202kJ.

Enable Ar. nl04 to 1.2.
28 Fiz CII .004, 27kA.

OH1V to 200 @5ms (only).
29 Pla 2.9MW 186kJ. Strong secondary Halpa rise. Mo 2e15. H-factor still
nearly 2.

nl04 to 1.5, add gas puff on PG4 100 from .2to .25s.
Reduce fill puff to 17ms from 19.
30 Fiz p0 barely reduced. About 1.7e-5 ratiomatic.

Fill puff to 15ms.
31 Pla RF tripped to 1.2MW. H-mode dithers/ELMS. Got p0=1.36e-5.
Startup looks good. Mo 1.5e15. PRAD 1.2MW.

Decrease nl04 ramp rate.
32 Pla RF trips to 1.2MW. PRAD 1.2MW, Mo 1.5e15.

Progam nl04 with H-mode shape to 2.3e20, to keep gas on.
33 Pla RF trips again to 1.0MW. H-mode not obtained. Mo injection at .2s.
Disrupts during ramp-down at 450kA. Wolfe says we won't get a plasma.

Lower fill-puff to 12ms.
Set nl04 to 1.e20. Call for pellets at .5 and .8s.
34 Pla Wolfe was wrong. But disrupted in ramp down at .9MA.
Got the pellets. RF only at the 1.4MW level.No PEP. p0=1.2e-5.

35 Pla Disrupts at 1MA .55s Looks as if the pellet did it. It was huge.
Plasma went vertically, it appears to be yanked by the RF feedback.

Remove RF RCUR feedback. Fill puff to 11ms.
36 Pla Got 2 RF pulses but only the first pellet.
Disruption at 1.08s, Halo warning. No H-mode, no obvious reason.
Mo now 3e15 during RF with not H-mode.

Import seg 2 from shot 26. Fiducial
37 Pla Fine fiducial. Mo =1.5e15 in H-Mode.

Reload 36.
38 Pla Ramps down. Mo injection at .63s. First pellet gives H-Mode.

39 Pla Repeat. Fine.


Session Leader Comments
Jan 16 1996 09:25:14:310AMSteve Golovatorun 960116 -

goal: to further investigate and optimize h-modes with boronized walls.

(1) get position feedback working,
(2) raise power using both transmitters.
(3) density scan to find best conditions, particualrly at lower density
where we are well above threshold and where the boronization
will have the most effect on moly levels in the core.
(4) pep-mode with lithium pellets.

Jan 16 1996 09:26:34:800AMSteve Golovatorun 960116 - no ecdc since last run to see how boronized walls behave.

Jan 16 1996 09:15:10:300AM960116001Steve Golovatoshot 960116001 - power supply test

Jan 16 1996 09:16:53:290AM960116002Steve Golovatoshot 960116002 - fiducial shot.

plasma, h-mode, no e-port rf.
no moly monitor yet, pump shut down at power glitch
friday night and is still pumping down.

Jan 16 1996 09:19:02:530AM960116003Steve Golovatoshot 960116003 - fiducial shot.

plasma, h-mode, no e-port rf, pppl arc detector in cell gving continuous
arc indication, will be disabled ,at transmitter. this is a redundant
arc indication, there is an additional reflected power arc detector at
the transmitter.

Jan 16 1996 09:20:03:920AM960116004Steve Golovatoshot 960116004 - fiducial shot. raised d-port power, increased overlap
of d and e, to .8-1. sec.

fizzle.

Jan 16 1996 09:47:21:600AM960116005Steve Golovatoshot 960116005 - plasma, h-mode. d-port tripped early.
h-mode quality not so high so far.

Jan 16 1996 09:49:03:930AM960116006Steve Golovatoshot 960116006 - rasied e-port power. position feedback enabled with
gain of -2000 (max safe gain is -2750). will feedback for about 8 ohms
loading (-2.8 volts on bira).

Jan 16 1996 10:01:17:370AM960116006Steve Golovatoshot 960116006 - fizzle.

Jan 16 1996 10:03:47:220AM960116007Steve Golovatoshot 960116007 - plasma, h-mode, 2.3MW. getting strange h-mode with
h-alpha recovering to high level during h-mode.
positin feedback working.

Jan 16 1996 10:17:32:690AM960116008Steve Golovatoshot 960116008 - raising power, increasing fb gain to -2500.

plasma. 2.6MW. h-mode. event at .733 sec, impurity injection?

Jan 16 1996 10:21:40:470AM960116008Steve Golovatoshot 960116008 - raising power, increasing fb gain to -2500.

plasma. 2.6MW. h-mode. event at .733 sec, impurity injection?

Jan 16 1996 10:27:31:320AM960116009Steve Golovatoshot 960116009 - reduce fb gain to -2000, plasma may have been pulled
to close last shot causing impurity event, cause and effect difficult
to determine. lower nl04 to 0.9e20.

fizzle.

Jan 16 1996 10:49:58:570AM960116010Steve Golovatoshot 960116010 - plasma, h-mode, 2.8MW. nl04=1.e20 just before rf,
was 1.1e20 for previous shots. wp_efit = 140 kj, record for 800ka.

Jan 16 1996 10:50:34:540AM960116010Steve Golovatoshot 960116010 - plasma, h-mode, 2.8MW. nl04=1.e20 just before rf,
was 1.1e20 for previous shots. wp_efit = 140 kj, record for 800ka.
h-factor=1.7 steady-state.

Jan 16 1996 11:10:48:260AM960116011Steve Golovatoshot 960116011 - lower nl04 to 0.8e20.

plasma, initial nl04=0.9e20, 3MW. 155kj., had impurity event at
.911sec, plasma may be too close to antenna at the lower nl.

Jan 16 1996 11:25:29:850AM960116012Steve Golovatoshot 960116012 - lowered target loading for feedback (changed bira from
2.8 to 2.9), hopefully to not pull the plasma too close to the antennas.

plasma, h-mode, 3MW, nl04 durig h-mode =1.7e20., Te_gpc=3.3kev,
Te_ts=4kev, 155 kj, h-factor=1.6. stored energy rising contiuously
during h-mode.

Jan 16 1996 11:39:19:720AM960116013Steve Golovatoshot 960116013 - lower initial nl04 to 0.7e20, lower target loading
again.

plasma, h-mode, e-port overloaded at .723sec. moly monitor back on,
level similar to last run but rf power much higher.

Jan 16 1996 11:42:24:110AM960116014Steve Golovatoshot 960116014 - fizzle.

Jan 16 1996 11:57:54:690AM960116015Steve Golovatoshot 960116015 - tuned e-port, adjusted inital e-port power to
avoid overload during short l-mode at beginning.

plasma, h-mode, Te_ts=4.6kec just before e-port crowbarred.

Jan 16 1996 12:12:34:010PM960116016Steve Golovatoshot 960116016 - lower e-port power, try again.

plasma, h-mode, 2.7MW, 140kj, h-factor=1.7

Jan 16 1996 12:26:51:010PM960116017Steve Golovatoshot 960116017 - lower initial nl04 to .6e20

plasma, h-mode, e-port crowbarred at 0.8sec. moly up to 5, was 1-2.
2.6MW, 160kj.

Jan 16 1996 12:35:37:030PM960116018Steve Golovatoshot 960116018 - lowered e-port power.

plasma, h-mode, 2.5MW, 164kj just before h-alpha blob starts,
Te_gpc=4kev, Te_ts=4.5kev, h-factor>2 just before blob.

Jan 16 1996 12:50:23:900PM960116019Steve Golovatoshot 960116018 - lowered initial nk04 to .5e20.

plasma, h-mode, but small density rise, Te_gpc=3kev, 2.5MW, 104kj.
h-mode quality down.

Jan 16 1996 12:58:38:710PM960116020Steve Golovatoshot 960116020 - lowered initial nk04 to .45e20.

plasma, no h-mode. 2.7MW. this is apparently the low density
limit for h_mode, about nl04=.5-.6e20.

Jan 16 1996 01:17:34:780PM960116021Steve Golovatoshot 960116021 - going back to best shot, 960116018, and raising
Ip to 1 MA.

plasma, h-mode, 185kj, 2.4mw, d-port tripped.

Jan 16 1996 01:26:50:390PM960116022Steve Golovatoshot 960116022 - tuned d-port a little, try again.

plasma, lose h-mode early, may need more initial density at this Ip.
disrupted during rampdown 850ka.

Jan 16 1996 01:34:32:570PM960116023Steve Golovatoshot 960116023 - raise density to .8e20 to recover from disruption.

fizzle.

Jan 16 1996 01:54:35:240PM960116024Steve Golovatoshot 960116024 - try again.

plasma, h-mode. 2.4 MW, continuous nl rise during rf. Te_gpc=4.5kev,
Te_ts at sawtooth peak=6.5kev. no h-alpha blob during h-mode. moly
level high. wp_efit=211kj. neutron rate 9.5e13. h-factor > 2.

Jan 16 1996 02:12:11:200PM960116025Steve Golovatoshot 960116025 - lower initial nl lowered to .7e20.

plasma. much like last shot, moly lower, not saturated.
2.4MW, 213KJ, neutrons 1.06E14. h-factor=2.2. best shot!!!!

Jan 16 1996 02:34:03:660PM960116026Steve Golovatoshot 960116026 - fiducial.

Jan 16 1996 02:41:39:530PM960116027Steve Golovatoshot 960116027 - back to 1 MA
nel_04 = 1.2 (before RF)
200 kJ, H = 2 (nice steady state)

Jan 16 1996 02:45:35:640PM960116028Steve Golovatoshot 960116028 - fizzle

Jan 16 1996 03:05:35:560PM960116029Steve Golovatoshot 960116029 - Stored energy of 186 kJ with a nice steady
state. H-factor of 1.70 (approx).

Jan 16 1996 03:09:03:650PM960116029Steve Golovatoshot 960116029 - Addendum to previous entry. The density
was nel_04=1.25 for this shot.

Jan 16 1996 03:09:46:540PM960116030Steve Golovatoshot 960116030 - Shot was a fizzle

Jan 16 1996 03:28:43:780PM960116031Steve Golovatoshot 960116031 - Achieved nl_04=1.40, but D-port power shut down.
H-factor was 1.4, a "positve" function of the rf power.

Jan 16 1996 03:41:40:880PM960116032Steve Golovatoshot 960116032 - Achieved nl_04=1.38, but D-port shut dowm again.
Got W_efit=128 kJ.

Jan 16 1996 03:49:59:440PM960116033Steve Golovatoshot 960116033 - Tried to gas puff immediately after rf injection.
Experienced D-port shut down again. Decided to go to PEP mode.

Jan 16 1996 04:15:11:840PM960116034Steve Golovatoshot 960116034 - Two Li-pellets injected. RF power in D- port OK (had
only one trip), but E-port had problems staying on..

Jan 16 1996 04:22:46:300PM960116035Steve Golovatoshot 960116035 - Two Li-pellets again. We retuned D- and E-ports
after shot #34. Got a disruption caused by rf - feedback. Feedback was
not set up right and will be turned off for the next shot.

Jan 16 1996 04:39:32:190PM960116036Steve Golovatoshot 960116036 - One Li- pellet at 0.5 sec. D-port had a trip
but recovered and E-port coupled well. No H-mode with about 2.6-2.7
MW of ICRf power.

Jan 16 1996 04:53:54:270PM960116037Steve Golovatoshot 960116037 - A Fiducial Shot. D- and E- ports coupled power
properly - feedback control was still shut off. Got H-mode with
about 83 kJ of stored energy.

Jan 16 1996 05:02:54:230PM960116038Steve Golovatoshot 960116038 - One pellet injected. Got H-mode with 138 kJ of
stored energy. D- and E-port power coupled properly.

Jan 16 1996 05:14:00:150PM960116039Steve Golovatoshot 960116039 - Injected one Li-pellet. Got H-mode with 148 kJ
of stored energy. RF power coupled Ok through D- and E- port.

Physics Operator Comments

Engineering Operator Comments
ShotTimeTypeStatusComment
108:34:31:100AMTestOk
208:52:05:480AMPlasmaOk
309:04:38:840AMPlasmaOk
409:15:07:320AMPlasmaOk
509:28:06:010AMPlasmaOk
609:44:41:760AMPlasmaOk
709:53:36:650AMPlasmaOk
810:11:00:370AMPlasmaOk
910:25:48:980AMPlasmaOk
1010:38:51:860AMPlasmaOk
1111:00:14:780AMPlasmaOk
1211:13:31:420AMPlasmaOk
1311:28:24:190AMPlasmaOk
1411:40:45:770AMPlasmaOk
1511:49:42:040AMPlasmaOk
1612:01:09:160PMPlasmaOk
1712:14:56:660PMPlasmaOk
1812:24:54:160PMPlasmaOk
1912:39:53:220PMPlasmaOk
2012:51:52:250PMPlasmaOk
2101:03:52:680PMPlasmaOk
2201:17:49:160PMPlasmaOk
2301:32:55:810PMPlasmaOk
2401:44:14:760PMPlasmaOk
2501:59:08:650PMPlasmaOk
2602:12:23:560PMPlasmaOk
2702:23:25:900PMPlasmaOk
2802:41:50:110PMPlasmaOk
2902:50:30:690PMPlasmaOk
3003:05:25:090PMPlasmaOk
3103:14:51:250PMPlasmaOk
3203:28:11:640PMPlasmaOk
3303:39:48:860PMPlasmaOk
3403:58:24:360PMPlasmaOk
3504:11:36:490PMPlasmaOk
3604:27:14:960PMPlasmaOk
3704:39:35:460PMPlasmaOk
3804:53:02:010PMPlasmaOk
3905:01:37:190PMPlasmaOk