Alcator C-Mod Run 960117 Information

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Miniproposals
Miniproposal:117
Date Filed: 4/18/1995
Title:3He Minority Heating at 7.9T
First Author:Yuichi Takase
Session Leader:Steve Golovato (shots 1-18)

Operators
Session leader(s):Steve Golovato
Physics operator(s):Robert Granetz
Engineering operator(s):Vinny Bertolino,Frank Silva

Engineering Operator Run Comment
8 t he3 granetz

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:14:930PM
Author: To Be Determined
Run summary - 960117

SL: Golovato
PO: Granetz
EO: Silva/Bertolino

Goal - Explore D-He3 minority heating at 8 T with boronized walls.

(1) Establish 8 T operation at high rf power P > 2 MW.
(2) Scan He3 fraction.
(3) Scan density.
(4) Try PEP mode.

This run produced much better heating than had been achieved previously
in this heating regime. H-modes were readily produced, though not quite
of the quality of those achieved yesterday at 5.3 T. Heating was dependent
on He3 fraction, with best heating at an intermediate fraction (this has
not yet been calibrated but I would guess 5-10%), with no H-modes achieved
at higher fraction (shot 12) and weaker heating at lower fraction (shot 9).
Best shots were 3 and 14. A brief density scan under conditions of shot 3
was done for shots 3, 15, and 16. Dithering was seen at lower density (shot
15) and low quality h-modes at the highest density (shot 16). Shot 3 seemed
the best although the h-mode was short lived. It appeared that we were close
to the threshold power at 2-2.5 MW, with some delay between rf turnon and
h-mode onset. Antenna tuning was difficult all day, even with position
feedback, so many shots had only one antenna operating. There were
sporadic moly influxes throughout the run which did not seem to correlate
with rf or h-modes. The last shot was a fiducial which showed the moly level
to be about twice that seen in the first run with boronized walls. Shot 2
was very interesting, being at 6.5 T with no He3 puffing. Perhaps the best
h-mode of the day was achieved in a regime where the only heating would be
off-axis H minority at about R=83 cm (r=15 cm). This was varified by the
gpc Te profile. This indicates that we can do off-axis heating more
efficiently with boronized walls. Previously, heating degraded rapidily
when the resonance was moved beyond r=5 cm. Similar shots at 6.5 T had
been tried to varify that He3 was required to get heating at 6.5 T, with
little heating seen.

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 04:36:55:800PM
Author: To Be Determined
Physics Operator's summary for run 960117

MP 117 -- ICRF He3 minority heating at 7.9 tesla after last week's boronization

SL: S. Golovato
PO: R. Granetz
EO: F. Silva/V. Bertolino

Program today: check out He3 minority heating at 7.9 tesla and 1 MA following
last week's boronization of the vessel. Today's run will include a density
scan and a minority fraction scan.

Summary: The run was quite successful, in terms of getting sufficient data to
compare post-boronization He3 minority heating at 7.9 T with pre-
boronization data. The machine ran quite well, with the caveat that
cooldown times are about 25-30 minutes (same as last June). There
were some of the usual problems with nitrogen leaks due to excessive
cooling. The alternator was also having some problems staying at
its proper speed.

The RF didn't increase Te0 very much at any He3 concentration, even
with Prf up to 2.4 MW. However, stored energy increased to 120 kJ,
due to increases in density. H-modes were readily achieved, which
is definitely a noticeable improvement over the pre-boronization
run. Molybdenum level in the fiducial shot at the end of today is
about twice that of last Friday (the first run after boronization),
but still significantly better than pre-boronization. Blip reports
that boron is down by about 40% from last Friday.

Scorecard: 16 plasmas
2 fizzles
0 duds
0 tests
----------
18 total

Run setup:

NO DISCHARGE CLEANING AT ALL !

Fill A-side (actually K-side) plenum with 19-20 psi of deuterium
Fill B-top plenum with 5 psi of deuterium.
Fill B-side-lower plenum with 4-5 psi of argon.
Fill B-side-upper plenum with 19-20 psi of Helium-3. (If this plenum
already contains Helium-3, don't purge it. This stuff is expensive,
after all.). AFTER FILLING THE PLENUM, DISCONNECT THE PLC FROM THE
VALVE!!!

Enable hybrid control of A-side and B-top for start of run

Start with the engineering setup from shot 960116037, for an initial
fiducial shot. After a successful fiducial, we will switch to the
engineering setup for 950609005 (an 8 tesla, 1 MA shot) for most of
the rest of the run.
Make sure that TF inversion is set at 1.1 s.

RF ready to go on first shot.
LPI will be used later in the run.
Enable the ECE, VUV, Moly monitor, PCX, and TCX valves, assuming status of
each is okay.

Detailed shot log:

Shot 01 -- Fiducial plasma. Good shot. H-modes. Low molybdenum.
Prf=0.7 MW.

Next shot: Load in 8 T, 1 MA shot from 950609005, but Frank Silva
wants to limit field to 6.5 T for this first time (to verify new
EF4 supplies, etc). Other changes: put feedback gain of -2000 on
RF loading to RCUR, turn off FSP control, put in pre-puff pulse
for breakdown (last June had pre-fill instead). No He3 yet.

Shot 02 -- Plasma, good 6.5 T shot at 1 MA. ELMy-to-ELMfree-to_ELMy H-mode.
Density nearly doubles during RF. ECE polychromator was set for
7.9 T, so it does not have correct central Te.

Next shot: enable He3 pulse gas, and increase field to 8 T.

Shot 03 -- Plasma, good 8 T shot at 1 MA. Prf=1 MW then 2 MW. Some kind
of really big impurity influx (probably molybdenum) at 1.04 s.
Toroidal field just barely made it to 8 T at t=1 s. ECE shows
some heating. There were also some H-modes.

Next shot: repeat. RF need tuning. Part of the problem could be
that the toroidal field is ramping throughout the shot.

Shot 04 -- Plasma. Good 8 T, 1 MA shot. TF flattopped from t=0.8 to 1.1 s.
Prf=1.1 MW for 0.3 s. ECE polychromater shows Te0=5.0-5.3 keV,
but Michelson only shows 2.5 keV. Amanda confirms that GPC was
not properly calibrated. Minor molybdenum injection at 0.8 s.
L-H dithering, but didn't make it into H-mode.

Next shot: repeat, hopefully with more Prf. Also increase argon
pulse duration from 25 to 30 ms.

Shot 05 -- Plasma. Good 8 T, 1 MA shot. Dithering, and even a 40 ms ELM-free
H-mode. Prf=2 MW for 0.11 s. OH1 and EF1 crowbarred at 1.46 s.

Next shot: repeat

Shot 06 -- Plasma. Good 8 T, 1 MA shot. Prf=1.1 MW only. Moly injection
at 0.73 s. Brian fired the scanning probe for the first time on
this shot (@t=0.6 s). No H-modes.

Next shot: repeat...still trying to raise RF power. Also, lower
the TF PLC current limit by 3 kA (227 down to 224 kA) so that
Bt=7.9 rather than 8.0 T.

Long delay while problems with the alternator are checked out.

Shot 07 -- Plasma. Good 7.9 T, 1 MA shot. Molybdenum injection at 0.87 s.
Prf=2.0 MW. Unimpressive electron heating.

Next shot: start scanning the He3 concentration. Decrease initial
He3 pulse width from 50 to 15 ms. Also, extend RF pulse from
t=1.0 to t=1.1 s, since Bt and Ip are flattopped until then.

Shot 08 -- Plasma. Good 7.9 T, 1 MA shot. No moly injections. Lots of
dithering, but no H-modes. Prf=1.1 MW only.

Next shot: repeat with more RF power. Also extend RCUR flattop
to 1.1 s.

Shot 09 -- Plasma. Disrupted at 1.15 s (Ihalo_upper=64 kA only.) Prf=2.2 MW.
No observable Te increase at this low He3 concentration. Lots of
molybdenum too.

Next shot: increase He3 concentration by increasing initial He3
pulse width from 15 to 100 ms.

Shot 10 -- Plasma. Disrupted at 1.14 s. Almost no halo currents. E-port
antenna arc'ed out early. No heating observed.

Next shot: repeat. Also, change RCUR flattop to end at 1.06 s
rather than 1.10 s. (Maybe the change made to RCUR between shots
08 and 09 had something to do with these late disruption.)

Shot 11 -- Fizzle (70 kA). Null looks similar to previous shots.

Next shot: decrease Br by 0.5 mT and increase pre-pulse gas
puff duration by 1 ms.

Shot 12 -- Plasma. Good 7.9 T, 1 MA plasma. Ian noticed that there was a
glitch in the RCUR wire at 1.08 s which likely caused the
disruptions on shots 09 and 10. It was also there on this shot.
It turned out that it was due to the RF feedback. This was not
seen prior to shot 09 because the E-port antenna was not working
then.

Next shot: reduce He3 pulse duration from 100 to 30 ms. Change
RF feedback gate to get rid of spike in RCUR error. Also extend
RCUR flattop to 1.10 s.

Shot 13 -- Fizzle (100 kA!!). Jim Irby claims that it was due to nitrogen from
a leak that just recently opened up.

Next shot: repeat with no changes

Long delay while N2 pump is shut off to get rid of leak.

Shot 14 -- Plasma. Good 7.9 T, 1 MA plasma. Big moly injection at 1.05 s, but
RF stays on. Prf=2.4 MW. Not much increase in Te0. Glitch in
RCUR at 1.1 s is gone. Dithering and H-modes during RF.

Next shot: start density scan at fixed He3 valve programming. Set
nl_04 to 0.8e20 (from 1.0e20). Set He3 initial pulse duration
to 40 ms (comparable to 50 ms for nl_04=1.0e20)

Shot 15 -- Plasma. Good 7.9T, 1 MA plasma. Big moly injection at 1.12 s.
Prf = 2.4MW (after 0.95 s). Dithering H-mode with an increase
in Te0 only at the high power RF.

John Goetz takes over temporarily as physics operator.

Next shot: Draw nl_04 to 1.25e20 and set width of He3 pulse
to 62.5 ms.

Shot 16 -- Plasma. Good 7.9T, 1 MA plasma. No moly injections on this
one. Prf = 2.4MW for 0.37 s. Density (nl_04) = 1.26e20 before
transition into high power RF. Approx. 0.4keV delta Te0

Next shot: Load 960117001 for a fiducial. Argon disabled.

Shot 17 -- Plasma, but terminated at 0.28 s due to OH1 fault.

Granetz returns as physics operator.

Next shot: repeat, because we need a fiducial.

Shot 18 -- Plasma, good fiducial shot. Molybdenum continues to be low,
although it's about a factor of 2 higher than last Friday's
fiducial. I guess the boron has not been completely worn off yet.

End of run.

Session Leader Comments
Jan 17 1996 05:05:51:600PMSteve Golovatorun 960117 - 8 T D-He3 heating with boronized walls.

goal - look at He3 minority heating in D majority plasma at 8 T,
see if boronized walls improve heating efficiency, which was poor
with unboronized walls.

(1) establish plasma and high rf power at 8 T.
(2) He3 fraction scan
(3) density scan
(4) pep-mode wit lithium pellet

Jan 17 1996 09:26:28:420AM960117001Steve Golovatoshot 960117001 - fiducial shot.

plasma. e-port crowbarred.

Jan 17 1996 09:26:58:660AM960117001Steve Golovatoshot 960117002 - 6.5 T, intermediate field.

plasma.

Jan 17 1996 10:39:28:090AM960117002Steve Golovatoshot 960117002 - strong heating at 6.5 T, good h-mode, stays in even
when power drops to 1 MW. h-factor = 1.7, tau_e=70ms.

Jan 17 1996 09:35:31:110AM960117003Steve Golovatoshot 960117003 - 8 T, gets there at 1 sec.

plasma, rf ran, e-port strted late, h-mode after e-port on, 2 MW,
120kj. moly event after rf during rampdown.

Jan 17 1996 10:21:41:960AM960117004Steve Golovatoshot 960117004 - tuned e-port.

plasma. no h-mode, e-port mistuned.

Jan 17 1996 10:29:33:200AM960117005Steve Golovatoshot 960117005 - tuned e-port.

plasma. h-mode when e-port comes on late, lose it when e-port trips off
early.

Jan 17 1996 10:56:24:360AM960117006Steve Golovatoshot 960117006 - tuned e-port again. rasied feedback target density.

plasma. big moly injection at rf turnon. e-port tripped throughout.

Jan 17 1996 11:54:50:450AM960117007Steve Golovatoshot 960117007 - tuned e-port again. lowered bt to 7.9 from 8.05, should
get there by .7 sec.

plasma. both transmitters ran. h-mode late in shot, moly injection
at 870ms.

Jan 17 1996 12:26:23:750PM960117008Steve Golovatoshot 960117008 - lowered he3, initial puff to 15ms from 50ms.
lengthened rf pulse to 1.1sec, end of ip and bt flattop.

plasma, no h-mode. no e-port rf. dithering, no moly injection at
1.1MW.

Jan 17 1996 01:12:05:910PM960117009Steve Golovatoshot 960117009 - raised d-port power, started e-port before d-port.

plasma, good h-mode, 2.2MW.

Jan 17 1996 01:24:10:780PM960117010Steve Golovatoshot 960117010 - increased he3 to 100ms puff.

plasma, no h-mode. d-port tripped out.

Jan 17 1996 01:35:20:730PM960117011Steve Golovatoshot 960117011 - lowered d-port power.

fizzle. last shot had full current disruption at end.

Jan 17 1996 02:00:05:480PM960117012Steve Golovatoshot 960117012 - plasma, no h-mode at 2.3MW at high he3.

Jan 17 1996 02:28:57:010PM960117013Steve Golovatoshot 960117013 - lower he3 to 30ms initial pulse.

fizzle.

Jan 17 1996 03:16:16:660PM960117014Steve Golovatoshot 960117014 - h-mode, h-factor abotu 1.3, 120 kj, 2.5MW.

Jan 17 1996 03:45:19:250PM960117015Steve Golovatoshot 960117015 - start density scan. best he3 concentration appears
to be 50ms initial pulse, shot 3 had h-factor of about 1.7.

lower nl04 from 1.e20 to .8e20, lower pufff to 40ms to keep he3 conc
about the same.

plasma, no h-mode, dithering at 2.5 MW.

Jan 17 1996 04:58:43:700PM960117016Steve Golovatoshot 960117016 - raise nl04 to 1.25e20, he3 puff to 62.5ms.

plasma, h-mode, lose h-mode early. 2.5MW.

Jan 17 1996 04:59:06:770PM960117017Steve Golovatoshot 960117017 - fiducial.

oh1 fault, no plasma.

Jan 17 1996 04:59:31:130PM960117018Steve Golovatoshot 960117018 - fiducial,again.

plasma, good h-mode.

Jan 17 1996 04:59:38:660PM960117018Steve Golovatoshot 960117018 - fiducial,again.

plasma, good h-mode.

Physics Operator Comments
Jan 16 1996 06:16:43:900PMRobert GranetzPhysics Operator's summary for run 960117

MP 117 -- ICRF He3 minority heating at 7.9 tesla after last week's boronization

SL: S. Golovato
PO: R. Granetz
EO: V. Bertolino

Program today: check out He3 minority heating at 7.9 tesla and 1 MA following
last week's boronization of the vessel. Today's run will include a density
scan and a minority fraction scan.

Jan 16 1996 06:17:41:380PMRobert GranetzRun setup:

NO DISCHARGE CLEANING AT ALL !

Fill A-side (actually K-side) plenum with 19-20 psi of deuterium
Fill B-top plenum with 5 psi of deuterium.
Fill B-side-lower plenum with 4-5 psi of argon.
Fill B-side-upper plenum with 19-20 psi of Helium-3. (If this plenum
already contains Helium-3, don't purge it. This stuff is expensive,
after all.). AFTER FILLING THE PLENUM, DISCONNECT THE PLC FROM THE
VALVE!!!

Enable hybrid control of A-side and B-top for start of run

Start with the engineering setup from shot 960116037, for an initial
fiducial shot. After a successful fiducial, we will switch to the
engineering setup for 950609005 (an 8 tesla, 1 MA shot) for most of
the rest of the run.
Make sure that TF inversion is set at 1.1 s.

RF ready to go on first shot.
LPI will be used later in the run.
Enable the ECE, VUV, Moly monitor, PCX, and TCX valves, assuming status of
each is okay.

Jan 17 1996 08:58:14:570AM960117001Robert GranetzShot 01 -- Fiducial plasma. Good shot. H-modes. Low molybdenum.
Prf=0.7 MW.

Next shot: Load in 8 T, 1 MA shot from 950609005, but Frank Silva
wants to limit field to 6.5 T for this first time (to verify new
EF4 supplies, etc). Other changes: put feedback gain of -2000 on
RF loading to RCUR, turn off FSP control, put in pre-puff pulse
for breakdown (last June had pre-fill instead). No He3 yet.

Jan 17 1996 09:04:27:250AM960117002Robert GranetzShot 02 -- Plasma, good 6.5 T shot at 1 MA. ELMy-to-ELMfree-to_ELMy H-mode.
Density nearly doubles during RF. ECE polychromator was set for
7.9 T, so it does not have correct central Te.

Next shot: enable He3 pulse gas, and increase field to 8 T.

Jan 17 1996 09:27:38:150AM960117003Robert GranetzShot 03 -- Plasma, good 8 T shot at 1 MA. Prf=1 MW then 2 MW. Some kind
of really big impurity influx (probably molybdenum) at 1.04 s.
Toroidal field just barely made it to 8 T at t=1 s. ECE shows
some heating.

Next shot: repeat. RF need tuning. Part of the problem could be
that the toroidal field is ramping throughout the shot.

Jan 17 1996 10:09:30:720AM960117004Robert GranetzShot 04 -- Plasma. Good 8 T, 1 MA shot. TF flattopped from t=0.8 to 1.1 s.
Prf=1.1 MW for 0.3 s. ECE polychromater shows Te0=5.0-5.3 keV,
but Michelson only shows 2.5 keV. Amanda confirms that EPC was
not properly calibrated. Minor molybdenum injection at 0.8 s.
L-H dithering, but didn't make it into H-mode.

Next shot: repeat, hopefully with more Prf. Also increase argon
pulse duration from 25 to 30 ms.

Jan 17 1996 10:30:49:660AM960117005Robert GranetzShot 05 -- Plasma. Good 8 T, 1 MA shot. Dithering, and even a 40 ms ELM-free
H-mode. Prf=2 MW for 0.11 s. OH1 and EF1 crowbarred at 1.46 s.

Next shot: repeat

Jan 17 1996 11:04:54:150AM960117006Robert GranetzShot 06 -- Plasma. Good 8 T, 1 MA shot. Prf=1.1 MW only. Moly injection
at 0.73 s. Brian fired the scanning probe for the first time on
this shot (@t=0.6 s). No H-modes.

Next shot: repeat...still trying to raise RF power. Also, lower
the TF PLC current limit by 3 kA (227 down to 224 kA) so that
Bt=7.9 rather than 8.0 T.

Jan 17 1996 11:54:00:280AM960117007Robert GranetzShot 07 -- Plasma. Good 7.9 T, 1 MA shot. Molybdenum injection at 0.87 s.
Prf=2.0 MW. Unimpressive electron heating.

Next shot: start scanning the He3 concentration. Decrease initial
He3 pulse width from 50 to 15 ms.

Jan 17 1996 12:13:10:660PM960117008Robert GranetzShot 08 -- Plasma. Good 7.9 T, 1 MA shot. No moly injections. Lots of
dithering, but no H-modes. Prf=1.1 MW only.

Next shot: repeat with more RF power. Also extend RCUR flattop
to 1.1 s.

Jan 17 1996 12:36:29:250PM960117009Robert GranetzShot 09 -- Plasma. Disrupted at 1.15 s (Ihalo_upper=64 kA only.) Prf=2.2 MW.
No observable heating at this low He3 concentration. Lots of
molybdenum too.

Next shot: increase He3 concentration by increasing initial He3
pulse width from 15 to 100 ms.

Jan 17 1996 01:12:52:230PM960117010Robert GranetzShot 10 -- Plasma. Disrupted at 1.14 s. Almost no halo currents. E-port
antenna arc'ed out early. No heating observed.

Next shot: repeat. Also, change RCUR flattop to end at 1.06 s
rather than 1.10 s. (Maybe the change made to RCUR between shots
08 and 09 had something to do with these late disruption.)

Jan 17 1996 01:43:23:980PM960117011Robert GranetzShot 11 -- Fizzle (70 kA). Null looks similar to previous shots.

Next shot: decrease Br by 0.5 mT and increase pre-pulse gas
puff duration by 1 ms.

Jan 17 1996 02:13:21:280PM960117012Robert GranetzShot 12 -- Plasma. Good 7.9 T, 1 MA plasma. Ian noticed that there was a
glitch in the RCUR wire at 1.08 s which likely caused the
disruptions on shots 09 and 10. It was also there on this shot.
It turned out that it was due to the RF feedback. This was not
seen prior to shot 09 because the E-port antenna was not working
then.

Next shot: reduce He3 pulse duration from 100 to 30 ms. Change
RF feedback gate to get rid of spike in RCUR error. Also extend
RCUR flattop to 1.10 s.

Jan 17 1996 02:31:41:070PM960117013Robert GranetzShot 13 -- Fizzle (100 kA!!). Jim Irby claims that it was due to nitrogen from
a leak that just recently opened up.

Next shot: repeat with no changes

Jan 17 1996 03:22:47:430PM960117014Robert GranetzShot 14 -- Plasma. Good 7.9 T, 1 MA plasma. Big moly injection at 1.05 s, but
RF stays on. Prf=2.4 MW. Not much increase in Te0. Glitch in
RCUR at 1.1 s is gone. Dithering and H-modes during RF.

Next shot: start density scan at fixed He3 valve programming. Set
nl_04 to 0.8e20 (from 1.0e20). Set He3 initial pulse duration
to 40 ms (comparable to 50 ms for nl_04=1.0e20)

Jan 17 1996 04:55:54:880PM960117015Robert GranetzShot 15 -- Plasma. Good 7.9T, 1 MA plasma. Big moly injection at 1.12 s.
Prf = 2.4MW (after 0.95 s). Dithering H-mode with an increase
in Te0 only at the high power RF.

John Goetz takes over temporarily as physics operator.

Next shot: Draw nl_04 to 1.25e20 and set width of He3 pulse
to 62.5 ms.

Jan 17 1996 04:56:07:050PM960117016Robert GranetzShot 16 -- Plasma. Good 7.9T, 1 MA plasma. No moly injections on this
one. Prf = 2.4MW for 0.37 s. Density (nl_04) = 1.26e20 before
transition into high power RF. Approx. 0.4keV delta Te0

Next shot: Load 960117001 for a fiducial. Argon disabled.

Jan 17 1996 04:58:06:750PM960117017Robert GranetzShot 17 -- Plasma, but terminated at 0.28 s due to OH1 fault.

Granetz returns as physics operator.

Next shot: repeat, because we need a fiducial.

Jan 17 1996 05:11:24:510PM960117018Robert GranetzShot 18 -- Plasma, good fiducial shot. Molybdenum continues to be low,
although it's about a factor of 2 higher than last Friday's
fiducial. I guess the boron has not been completely worn off yet.

End of run.

Engineering Operator Comments
ShotTimeTypeStatusComment
108:31:17:910AMPlasmaOkfiducial ok
208:52:31:270AMPlasmaOk6.5t
309:09:04:910AMPlasmaOk8tesla
409:48:06:630AMPlasmaOk
510:17:14:490AMPlasmaOkcomm fault oh1
610:46:06:870AMPlasmaOk
711:38:15:780AMPlasmaOk
812:01:23:360PMPlasmaOk
912:25:39:500PMPlasmaOk
1001:01:28:370PMPlasmaOk
1101:33:22:270PMPlasmaOk
1201:51:41:020PMPlasmaOk
1302:26:59:240PMPlasmaOk
1402:59:50:040PMPlasmaOk
1503:35:01:150PMPlasmaOk
1604:09:31:050PMPlasmaOk
1704:45:59:870PMPlasmaOk
1804:55:33:480PMPlasmaOk