Alcator C-Mod Run 1051118 Information

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Miniproposals
Miniproposal:438
Date Filed:11/17/2005
Title:J Antenna Evaluation: Operation without Faraday screen
First Author:Steve Wukitch
Session Leader:Steve Wukitch (shots 1-23)

Operators
Session leader(s):Steve Wukitch
Physics operator(s):Jim Irby
Engineering operator(s):Gary Dekow,Ed Fitzgerald

Engineering Operator Run Comment
MP 438 J Antenna Evaluation: Operation without Faraday Screen; SL:Wukitc

Session Leader Plans
Entered: Nov 17 2005 05:03:26:587PM
Author: Steve Wukitch
Engineering setup for Friday 18-Nov-2005

MP 438 J Antenna Evaluation: Operation without Faraday Screen

Session leader: Wukitch
Physics operator: Irby

Overnight ECDC in D2, and bake at 60 C.

Run begins at 09:00 and ends at 17:00

Power systems as on 1051117031 (1.0 MA fiducial, 5.4 T, lower single null)

A-coil configuration: normal [+Dtop -Dbot -Jtop +Jbot] and enabled.

Gas Setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar Hybrid DISABLED (PG1)
leave B-side upper as is Hybrid DISABLED (PG2)
fill B-main (C-side) with 40 psi D2 Hybrid enabled (PG3)
leave NINJA as is DISABLED

Enable the following gate valves and shutters: ECE, VUV, Z-bolo shutters

Torvac setup: Gate valves open

ICRF Setup:

All transmitters to run-on by 8:30 am.

Important Diagnostics: magnetics, standard impurity spectroscopy,
video monitors for antennas

Plan:

1. continue with H-mode threshold
2. switch to USN to do L-mode comparison (1050729014 with BT=5.2 T,
Ip=1 MA, nl_04~0.9)
3. density scan in USN

Plan is subject to change depending on course of events.

Physics Operators Plans

Session Leader Summaries
Entered: Nov 18 2005 04:24:06:653PM
Author: Steve Wukitch
Run Summary:

In USN, J antenna has lower heating effectiveness than D and E
antennas at 2, 2.5, 2.7 and 3 MW level. The 2 pi foil consistently
shows 25-30% more radiated power with J antenna. The sawtooth period
is 18 msec for D and E antenna pulse and 12 msec for J antenna at 5.2
T. Difference in heating effectiveness is much more apparant in USN
than LSN and at high power. Cu tracks strongly with J antenna and an
interaction is clearly observed between the upper and lower strap. We
also confirmed the neutral pressure limit is ~0.4 mTorr and unchanged
from last campaign for J antenna. Finally we also identified D
antenna as the stronger Mo source compared to E (J is similar to E in
terms of Mo). Power scans from 0.001-1.5 MW were performed and there
is little difference between D, E and J antenna. Furthermore, there
does not appear to be a 1/P dependence observed in other experiments
suggesting sheath dissipation is negligible (for unknown reasons at
this point. If one quickly considers the last few experiments
(DIII-D, ASDEX-U, TEXTOR, and Phaedrus-T) where Faraday screen-less
operation has attempted, one notes that those with simple straps
succeeded whereas those with convoluted straps did not. The Faraday
screen-less operational problems may be antenna engineering rather
than sheath effects.

Physics Operator Summaries
Entered: Nov 18 2005 04:53:43:577PM
Author: Jim Irby
I believe this day was very useful for the rf group. We were able to
easily startup the machine from shot 1051117031, make two lower null
discharges, and then go to upper null on shot 05. Steve Wolfe had
programmed segment 3 for an upper null discharge, and it worked
extremely well. Much was learned about relative j-port and d- and
e-port operation, impurity generation, power limits etc. We were
able to couple in 6 MW of rf power on shot 22 producing h-modes in an
upper null configuration (120 kJ).

A problem associated with the OH supplies caused us to stop the run 45
minutes early. The currents from the OH2L and OH2U supplies had large
errors from the time they turned on. OH2U almost recovered before
t=0, but OH2L did not. Shots 21 and 23 had this problem, but shot 22
was a good shot. Shot 16 disrupted because of on OH2L supply problem.
We will need to check the supplies out carefully before Monday's run.


Problems:

Had data system problem on shot 01 and we opted to do a no power test.
Had disruption on shot 16 following OH2L power supply problem.
Had fizzle on shot 21 because of OH supply problem.
Had fizzle on shot 23 because of OH supply problem.
Had red light on alternator drive but nothing indicated at alternator

Reverse bridge/TF test on shot 17 and 18.

tests 01,17,18
duds
fizzles 02,11,15,21,23
plasmas 03,04,05,06,07,08,09,10,12,13
14,16,19,20,22

Session Leader Comments
Nov 18 2005 09:39:02:957AM1051118001Steve Wukitchno power
Nov 18 2005 09:38:52:317AM1051118002Steve Wukitchfizzle
Nov 18 2005 09:42:18:380AM1051118003Steve Wukitch003 BT~5.2 T, Ip~1 MA, nl_04~0.9
D: ramp to 0.8 MW [0.6,1] sec
E: ramp to 1.2 MW [0.6,1] sec
J: ramp to 2 MW [1.1,1.5] sec
result: plasma
D: ran
E: ran
J: ran 2 faults
good comparison - repeat with order swapped
Nov 18 2005 09:58:52:130AM1051118004Steve Wukitch004 BT~5.2 T, Ip~1 MA, nl_04~0.9
D: ramp to 0.8 MW [0.6,1] sec
E: ramp to 1.2 MW [0.6,1] sec
J: ramp to 2 MW [1.1,1.5] sec
result: plasma
D: ran
E: ran
J: ran 2 faults
good comparison - move to USN on next shot
Nov 18 2005 10:34:45:613AM1051118005Steve Wukitch005 BT~5.2 T, Ip~1 MA, nl_04~0.9, USN
D: ramp to 0.8 MW [1.1,1.5] sec
E: ramp to 1.2 MW [1.1,1.5] sec
J: ramp to 2 MW [0.6,1] sec
result: plasma
D: ran
E: ran
J: ran
good comparison - swap order
D+E has better response with respect to impurities

Nov 18 2005 10:33:19:567AM1051118006Steve Wukitch006 BT~5.2 T, Ip~1 MA, nl_04~0.9, USN
D: ramp to 0.8 MW [0.6,1] sec
E: ramp to 1.2 MW [0.6,1] sec
J: ramp to 2 MW [1.1,1.5] sec
result: plasma
D: ran
E: ran
J: ran
good comparison
Nov 18 2005 10:44:36:503AM1051118007Steve Wukitch007 BT~5.2 T, Ip~1 MA, nl_04~0.9, USN
D: 0.8 MW [1.1,1.5] sec
E: 1.2 MW [1.1,1.5] sec
J: 2 MW [0.6,1] sec
result: plasma
D: ran
E: ran
J: ran - 1 fault
good comparison
swap order

Nov 18 2005 11:22:08:707AM1051118008Steve Wukitch008 BT~5.2 T, Ip~1 MA, nl_04~0.9, USN
D: 0.8 MW [0.6,1] sec
E: 1.2 MW [0.6,1] sec
J: 2 MW [1.1,1.5] sec
result: plasma
D: ran
E: ran
J: ran
good comparison
swap order

Nov 18 2005 11:22:23:270AM1051118009Steve Wukitch009 BT~5.2 T, Ip~1 MA, nl_04~0.9, USN
D: 1 MW [0.6,.9] sec
E: 1.3 MW [0.6,.9] sec
J: 2.5 MW [1,1.3] sec
result: plasma
D: ran
E: ran
J: ran
good comparison

Nov 18 2005 11:33:47:943AM1051118010Steve Wukitch010 BT~5.2 T, Ip~1 MA, nl_04~0.9, USN
D: 1 MW [1,1.3] sec
E: 1.3 MW [1,1.3] sec
J: 2.5 MW [0.6,.9] sec
result: plasma
D: ran 1 fault
E: ran
J: ran
good comparison
raise power some more

Nov 18 2005 11:58:45:160AM1051118011Steve Wukitchfizzle
Nov 18 2005 11:58:33:660AM1051118012Steve Wukitch012 BT~5.2 T, Ip~1 MA, nl_04~0.9, USN
D: 1 MW [1,1.3] sec
E: 1.3 MW [1,1.3] sec
J: 2.7 MW [0.6,.9] sec
result: plasma
D: ran
E: ran
J: ran
good comparison
raise power some more

Nov 18 2005 12:07:55:457PM1051118013Steve Wukitch013 BT~5.2 T, Ip~1 MA, nl_04~0.9, USN
D: 1.3 MW [1,1.3] sec
E: 1.55 MW [1,1.3] sec
J: 3 MW [0.6,.9] sec
result: plasma
D: ran
E: ran
J: ran
good comparison
swap order

Nov 18 2005 12:24:17:240PM1051118014Steve Wukitch014 BT~5.2 T, Ip~1 MA, nl_04~0.9, USN
D: 1.3 MW [0.6,.9] sec
E: 1.55 MW [0.6,.9] sec
J: 3 MW [1,1.3] sec
result: plasma
D: ran
E: ran
J: ran faults at 0.4 mtorr
good comparison
note interaction on strap 1 between upper and lower strap

Nov 18 2005 12:40:03:770PM1051118015Steve Wukitchfizzle
Nov 18 2005 02:32:11:130PM1051118016Steve Wukitch016 early disruption
Nov 18 2005 02:32:50:647PM1051118017Steve Wukitch017 reverse bridge test to lower OH resistance
Nov 18 2005 02:33:49:600PM1051118018Steve Wukitchreverse bridge test to lower OH resistance
Nov 18 2005 02:34:08:223PM1051118019Steve Wukitch019 BT~5.2 T, Ip~1 MA, nl_04~0.9, USN
D: 1.3 MW [0.6,.9] sec
E: 1.55 MW [0.6,.9] sec
J: 3 MW [1,1.3] sec
result: plasma
D: ran
E: ran
J: ran faults near neutral pressure limit

Nov 18 2005 02:34:32:083PM1051118020Steve Wukitch020 BT~5.2 T, Ip~1 MA, nl_04~0.9, USN
D: 1.3 MW [0.6,.8] sec
E: 1.3 MW [0.9,1.1] sec
J: 3 MW [1.2,1.4] sec
result: plasma
D: ran
E: ran
J: ran faults near neutral pressure limit

Nov 18 2005 02:34:45:100PM1051118021Steve Wukitchfizzle
Nov 18 2005 04:23:09:013PM1051118022Steve Wukitch022 BT~5.2 T, Ip~1 MA, nl_04~0.9, USN
D: 1.3 MW [0.9,1.2] sec
E: 1.55 MW [0.9,1.2] sec
J: 3 MW [0.9,1.2] sec
result: plasma
D: ran 3 faults
E: ran
J: ran faults
some time with Prf=6 MW

Nov 18 2005 04:23:17:700PM1051118023Steve Wukitchfizzle

Physics Operator Comments
Nov 18 2005 09:19:42:520AM1051118001Jim IrbyHad ECDC in D2 overnight once TMP1 was repaired
TMP1 currently under bake and valved off from machine (3e-7 Torr, mostly mass 18)

Will start from 1051117031/32
pg4 at 30 ms (as required on 1051117031)
TCI looks okay

Loaded 1051117031 to be sure

had network slowdown --- decided to take no power shot
data system was okay though

Nov 18 2005 09:31:57:817AM1051118002Jim Irbyfizzle at 15 ms

pressure is low compared to 1051117031 (0.072 vs 0.056 today)

fields look okay


Nov 18 2005 09:49:53:473AM1051118003Jim Irbypg4 to 32 ms from 30
ef4 from -1345 to -1325 A

plasma into rampdown --- some h-modes --- good start with RF

pressure still low compared to yesterday, but breakdown fine
Bzo a little too high
injection/hesitation at 0.018 s

BORON camera sees first light through IR filter --- Jim T will adjust exposure

coax warning, but value very low at end of shot


Nov 18 2005 10:08:56:410AM1051118004Jim Irbyef4 from -1325 to -1335 A

plasma into rampdown
Nov 18 2005 10:28:37:300AM1051118005Jim Irbyswitched from seg 2 to seg 3: 1 MA USN
Bt to 5.2 T at 0.1 s

plasma into rampdown --- nice upper null plasma --- no h-modes

h/(h+d) 9% at 1 s (up from LSN case)




Nov 18 2005 10:42:46:960AM1051118006Jim Irbyno changes

plasma into rampdown

h/(h+d) now 3% at 1 s??


Nov 18 2005 10:50:13:740AM1051118007Jim Irbyno changes

plasma into rampdown --- rf from ramps to square pulses

h/(h+d) at 23%??


Nov 18 2005 11:06:47:863AM1051118008Jim Irbyprefill from 32 to 31 ms
Stewart asks for 10 psi D2 in NINJA --- plans to puff late

plasma into rampdown

h/(h+d) at 9%

Nov 18 2005 11:19:09:677AM1051118009Jim Irbyargon/neon puff for 40 ms starting at 1.3 s
NINJA should be puffing after 1.3 s too

plasma into rampdown --- startup a little better

no argon/neon --- was not enabled
Nov 18 2005 11:38:04:503AM1051118010Jim Irbyno changes

plasma into rampdown but a little disruptive at the end (puffs of various sorts?)

some small early injections


Nov 18 2005 11:45:32:240AM1051118011Jim Irbyno changes

fizzle

lost it around 19 ms

Nov 18 2005 11:56:16:770AM1051118012Jim Irbyef4 to -1325 from -1335 A

plasma into rampdown --- Bz0 more positive, breakdown a little later, current rise okay

runaways need to be fixed
Nov 18 2005 12:13:28:067PM1051118013Jim Irbypg3 programmed gas increased a little and started at 0.02 s vs 0.03 s on previous shot

plasma into rampdown --- runaways down
late startup --- almost lost it
Nov 18 2005 12:29:58:897PM1051118014Jim Irbyef4 back to -1335 A

plasma for 1.75 s, 500 kA disruption


Nov 18 2005 12:33:38:973PM1051118015Jim Irbyno argon/neon or D2 puffing

fizzle --- no clear reason except for the previous disruption
Nov 18 2005 01:23:38:363PM1051118016Jim Irbyrf guys enter the power room --- found blown fuse

no changes --- still no argon/neon/d2

disruption at 0.5 s

OH2L drops out at 0.482 s

OH2L fuses are fine
Nov 18 2005 01:37:14:647PM1051118017Jim Irbysetup for OH reverse bridge/TF test

resistance at t=0 down to 2.54 uohm


Nov 18 2005 01:55:10:020PM1051118018Jim Irbyrepeat reverse bridge test

resistance up to 3.2 uohm


Nov 18 2005 02:12:45:880PM1051118019Jim Irbywill try for plasma --- resistance was going down during last test

plasma into rampdown --- ran 1.94 s

resistance 1.96 uohm
Nov 18 2005 02:25:23:723PM1051118020Jim Irbyno DPCS changes

plasma into rampdown --- pressure back up to previous levels


Nov 18 2005 03:10:18:443PM1051118021Jim Irbyprefill from 31 to 30 ms

fizzle --- trouble with OH2L --- fields wrong well before t=0


Nov 18 2005 04:01:14:120PM1051118022Jim Irbyzeroed Br0 (was -0.0003 T)
put back prefill gas to 31 ms

no problems found with the supplies

plasma into rampdown --- nearly 6 MW of rf --- 120 kJ upper null h-modes


Nov 18 2005 04:12:59:370PM1051118023Jim Irbyno DPCS changes

fizzle --- Br0 way off --- big error in OH2L,U currents again
OH2U current back on track by -0.8 s, but OH2L does not recover

got 50 kA Ip


Engineering Operator Comments
ShotTimeTypeStatusComment
109:06:42:753AMPlasmaBadIgor failed init no power shot
209:20:09:960AMPlasmaOk
309:36:42:740AMPlasmaOk
409:51:18:147AMPlasmaOk
510:12:56:100AMPlasmaOk
610:26:17:067AMPlasmaOk
710:40:01:363AMPlasmaOk
810:54:43:710AMPlasmaOk
911:08:58:287AMPlasmaOk
1011:22:14:427AMPlasmaOk
1111:35:30:253AMPlasmaOk
1211:48:45:380AMPlasmaOk
1312:01:48:940PMPlasmaOk
1412:15:04:583PMPlasmaOk
1512:28:33:600PMPlasmaOk
1601:05:38:660PMPlasmaBadOH2L Fault
1701:28:17:927PMPlasmaOk
1801:41:32:410PMTestOkTF-OH Reverse Bridge shot
1901:57:44:270PMPlasmaOk
2002:12:59:893PMPlasmaOk
2102:27:00:393PMPlasmaOk
2203:45:35:660PMPlasmaOk
2303:58:52:410PMPlasmaOk