Alcator C-Mod Run 1060728 Information

Back to runs

Miniproposals
Miniproposal:418
Date Filed: 3/4/2005
Title:LH system commisioning
First Author:Stefano Bernabei
Session Leader:Ron Parker (shots 1-28)

Operators
Session leader(s):Ron Parker
Physics operator(s):Earl Marmar
Engineering operator(s):Andy Pfeiffer,Sam Pierson,Gary Dekow

Engineering Operator Run Comment
MP#418 LH System Conditioning (Cont'd) SL: Wilson/Parker PO: Marmar

Session Leader Plans
Entered: Jul 27 2006 04:27:43:047PM
Author: Ron Parker
Session leader plan for Friday 28 July 2006

MP#418 LH System Conditioning (Cont'd)
SL: Wilson/Parker
PO: Marmar


Objectives:

Increase power to 1 MW and obtain full CD, lowering current if necessary.

Explore ICRF interactions and conpatibility with LH.


Physics Operators Plans
Entered: Jul 27 2006 04:26:14:170PM
Author: Ron Parker
Physop Plan and Engineering Setup Friday, July 28, 2006

MP#418 LH System Conditioning (Cont'd)
SL: Wilson/Parker
PO: Marmar

ECDC from 6:00 - 8:00 AM in D2 at 2.e-4 Torr

Power systems as on 1060720
A-coil configuration: normal [+Dtop -Dbot -Jtop +Jbot] and enabled.
C-coil Start=0.3sec, Invert=2.0sec

ICRF will be required for the last third of the run. All transmitters should be ready.

Gas Setup:
----------
fill B-top 6psi D2 Hybrid enabled (PG4)
fill B-side lower 1 psi Argon Hybrid Disabled (PG1)
fill B-side Upper as is, Hybrid Disabled (PG2)
fill B-main 40psi D2 Hybrid Enabled (PG3)


Enable ECE, VUV, Z-bolo shutter assuming no vacuum problems

Run Plan: Setup nominal diverted L-Mode discharge. BT = 5.4 T
IP = 700 kA, nl_04 ~ 0.4e20 m-2.

Objectives:

Increase power to 1 MW and obtain full CD, lowering current if necessary.

Explore ICRF interactions and conpatibility with LH.


Entered: Jul 28 2006 08:53:13:303AM
Author: Earl Marmar
last run day of the FY06 campaign

continuing where we left off from yesterday

LH current drive: increase power and aim for 100% non-inductive;

add ICRF to LHCD: investigate synergy

Session Leader Summaries
Entered: Jul 28 2006 04:37:37:013PM
Author: Ron Parker
An interesting if incomplete run, the last of the campaign. The maximum coupled LH power was increased to 900 kW absorbed, and the loop voltage was caused to go positive, if only transiently. One reason that this could not be sustained was a density rise, probably caused by the RF itself. The other reason has to do with lack of steady-state as the E-field relaxes. One sees the voltage hover near 0 as the LH power ramps, due to the transformer action in trying to keep constant current, followed by a slow decrease as the LH power plateaus at its programmed level. Interestingly, higher current resulted in better LH coupling as the reflected power decreased somewhat with increased current. Also interesting was the MHD phenomena showing up on the ECE, often fairly coherent oscillations, but sometimes quiescent. The latter case seemed to correspond to the best performance. The run was cut short by plasma disruptions and fizzles, the latter probably due to a leak that got worse during the day, the former due to failure in the chopper/TMX supply. At least the intermittency associated with this supply is gone, and this should allow the problem to be definitely identified and remedied. Disappointing was that we did not get to explore the interaction with the ICRF. We did get one ~0.6 MW shot from J-port, during which the RF faulted but then recovered. This antagonism will be a key issue in moving forward with both systems in the next campaign.

Physics Operator Summaries
Entered: Jul 28 2006 04:58:16:537PM
Author: Earl Marmar
The machine ran fairly well today, and we got some interesting LHCD results, including substantial current drive in shots with Ip between 0.5MA and 1MA (see session leader summary for details).

There were a number of operational problems:

There was a leak, which got fairly large in the middle of the day.

Shot 5 was no-power because of a PLC acknowledgement failure.

EF1 upper was not following its demand, starting from shot 1, which was probably affecting the startup; this was fixed for shot 21.

Following a 1 MA disruption (shot 16), we had 4 fizzles. Then we ran deuterium ECDC for 15 minutes, and fixed the EF1 power supply problem. Shot 21 also fizzled, but that may have been due to an increase in Bz that resulted from fixing EF1.
Shots 25 and 26 disrupted in current rise (chopper was not working). The EFC supply could not be repaired in time to continue the run.

Scorecard:

Duds: 1
fizzles: 5
nopower shots: 1
PLC tests: 2
Plasmas: 19

Total cycles: 28

Session Leader Comments
Jul 28 2006 09:25:50:643AM1060728001Ron ParkerFirst shot was to warm up the machine. We are having computer problems this morning and unable to run LH control program.
Jul 28 2006 09:39:38:743AM1060728002Ron ParkerShot 2 was to keep machine warm while computer group works on LH control problem. Thanks to Tom's efforts, LH ready to go at 9:40.
Jul 28 2006 09:55:12:500AM1060728003Ron ParkerGood LH shot, low power ~450 kW net. Loop voltage ~ 0.6 V.
Next: Raise power to 550 kW.
Jul 28 2006 10:08:27:287AM1060728004Ron ParkerShot 4 was good, LH power up to 600 kW net. Loop voltage ~ 0.5 V.

Next: Continue to higher power -- ~ 700 kW.
Jul 28 2006 10:11:31:833AM1060728004Ron ParkerShot 5 did not go.
Jul 28 2006 10:50:08:660AM1060728007Ron ParkerInteresting shot, near zero loop volts. Low density.
Jul 28 2006 11:02:16:260AM1060728008Ron ParkerAnother good shot for LH, loop voltage almost 0 for a while, but climbs during pulse. Peak LH power just shy of 800 kW.
Jul 28 2006 11:27:35:490AM1060728010Ron ParkerShot OK, loop voltage still slightly positive. Try lowering current again.
Jul 28 2006 11:41:05:273AM1060728011Ron ParkerShot 11 was OK, LH pulse uninterrupted until 1.25 s. 750 kW,
loop voltage still 0.2 V, 500 kA shot.
Jul 28 2006 12:02:23:800PM1060728012Ron ParkerShot 12 was the best yet in terms of loop voltage, even positive for short time. Density is low, reflection coefficient lower at higher current.
Jul 28 2006 12:08:54:677PM1060728013Ron ParkerPretty much the same as shot 12.
Jul 28 2006 12:50:43:067PM1060728015Ron ParkerNot as good as previous shots, but LH power touches 900 kW.
Jul 28 2006 02:51:13:457PM1060728022Ron ParkerAfter delay due to plasma problems, shot 22 ran. loop voltage not very low, ~0.3 V.
Jul 28 2006 03:12:27:920PM1060728023Ron ParkerShot 23 had both ICRF and LH for the first time. LH tripped but came back.

Physics Operator Comments
Jul 28 2006 09:23:35:630AM1060728001Earl Marmarstarting where we left off from yesterday

LH current drive: increase power and aim for 100% non-inductive

load from 1060727020 (Ron Parker already did this)

no LH yet; having trouble with the LH control algorithm causing linux systems to crash

plasma; startup looks ok
Jul 28 2006 09:39:09:057AM1060728002Earl Marmarwhile waiting for the LH control to be fixed, running some shots for Kelly Smith to look at polarimetry

plasma
Jul 28 2006 10:04:13:067AM1060728003Earl MarmarLH has declared they are ready

plasma

LH power 450 KW net

Jul 28 2006 10:05:12:597AM1060728004Earl Marmarnl_04 target to 3e19 (from 3.5e19)

plasma

some impurity influx around 0.8 seconds, then it calms down

P_LH ~ 600 kW net

Jul 28 2006 10:12:55:617AM1060728005Earl Marmarno pcs changes

ICRF to start tuning (after LH is off)

no power shot (ack. failure entering pulse)
Jul 28 2006 10:31:06:780AM1060728006Earl Marmartry again

no pcs changes

ICRF to start tuning (after LH is off)

dud (fields, gas and sparker look ok)
a vacuum leak has been opening up over the last 30 minutes or so (28, 14, 40 on the RGA)

Jul 28 2006 10:46:18:380AM1060728007Earl Marmaradd 1 msec to prefill puff (now 21 msec)

plasma
late breakdown
lower density
Vloop pretty close to 0 during LH

disrupt ~1.1 second (impurity influx)



Jul 28 2006 11:04:53:637AM1060728008Earl Marmarreduce prefill puff by 1 msec (now 20 msec)

tweak nl_04 target to 3.5e19 at .35 sec, then decreasing to 3.0e19

plasma
earlier breakdown

Vloop below 0.2


Jul 28 2006 11:05:47:403AM1060728009Earl Marmarnl_04 to 3e19 straight across

plasma



Jul 28 2006 11:25:41:237AM1060728010Earl Marmarno pcs changes

plasma
some early hards (bouncy startup)



Jul 28 2006 11:40:24:370AM1060728011Earl MarmarIp to 500 kA

plasma
lots of early hards

Jul 28 2006 12:00:20:140PM1060728012Earl Marmarincrease prefill puff 2 msec
Ip to 800 kA

plasma
early hards gone
disrupt in rampdown (Li pellet)



Jul 28 2006 12:43:25:517PM1060728013Earl Marmarno pcs changes

plasma


Jul 28 2006 12:42:54:640PM1060728014Earl MarmarIp to 1 MA

plasma


Jul 28 2006 12:42:40:440PM1060728015Earl Marmarno pcs changes

plasma


Jul 28 2006 12:55:58:897PM1060728016Earl Marmarno pcs changes

plasma

a lot of early hards; slightly late breakdown, but no obvious bounce

Disrupt at .72 s


Jul 28 2006 01:03:04:917PM1060728017Earl Marmaradd 2 msec to prefill puff (now 26 msec)

tweak early nl_04 to 3.5e19 early

fizzle


Jul 28 2006 04:39:32:230PM1060728018Earl Marmarreduce prefill puff by 1 msec (now 22 msec)
EF4 10 amp more negative for t le 0

fizzle
Jul 28 2006 01:40:42:197PM1060728019Earl Marmarreduce prefill puff by 2 msec (now 20 msec)

leak has been getting progressively worse
mass 28 now ~4e-8 (right RGA)

fizzle
Jul 28 2006 01:46:43:777PM1060728020Earl Marmarreduce prefill puff by 1 msec (now 19 msec)
EF4 15 amp more negative (now -1360A)
fizzle


Jul 28 2006 03:14:12:607PM1060728021Earl MarmarECDC in D2 (P-gauge = 2e-4) for 15 minutes prior to this shot.

Ip to 800 kA

fizzle

breakdown is earlier
Bz is now too negative
Jul 28 2006 03:13:59:857PM1060728022Earl MarmarEF4 25 amp less negative before t=0 (now -1335A)

plasma

nice startup
Jul 28 2006 03:13:31:607PM1060728023Earl Marmarno pcs changes
move the ICRF to overlap with LH

plasma
Jul 28 2006 03:13:11:903PM1060728024Earl Marmarno pcs changes
plasma

early hards
disrupt at 0.47 s
Jul 28 2006 03:28:19:830PM1060728025Earl Marmaradd 1 msec to prefill puff

plasma

hards gone

chopper supply malfunctioned, lost it vertically at .21 second
Jul 28 2006 03:50:22:140PM1060728026Earl Marmarno pcs changes

hards are back early

same efc problem as on shot 25: early disruption
Jul 28 2006 04:00:21:580PM1060728027Earl MarmarEFC only PLC test
Jul 28 2006 04:33:48:027PM1060728028Earl Marmaranother EFC PLC test
still not working

That's the end of the run and the end of the FY06 campaign.

Engineering Operator Comments
ShotTimeTypeStatusComment
109:04:46:823AMPlasmaOk
209:28:08:067AMPlasmaOk
309:41:05:633AMPlasmaOk
409:54:58:670AMPlasmaOk
510:08:44:567AMPlasmaBadack failed Igor in pulse
610:20:50:633AMPlasmaOk
710:35:46:530AMPlasmaOk
810:51:22:020AMPlasmaOk
911:03:50:167AMPlasmaOk
1011:16:53:170AMPlasmaOk
1111:31:18:460AMPlasmaOk
1211:49:14:217AMPlasmaOk
1312:03:37:533PMPlasmaOk
1412:16:35:227PMPlasmaOk
1512:32:45:280PMPlasmaOk
1612:46:24:533PMPlasmaOk
1701:01:17:150PMPlasmaOk
1801:14:31:217PMPlasmaOk
1901:29:58:957PMPlasmaOk
2001:44:42:243PMPlasmaOk
2102:29:38:997PMPlasmaOk
2202:42:48:670PMPlasmaOk
2302:56:36:913PMPlasmaOk
2403:09:00:247PMPlasmaOkPF breaker pulled after the disruption
2503:22:03:047PMPlasmaBadEFC Problem
2603:42:38:337PMPlasmaBadEFC Voltage Problem Again
2704:04:08:173PMTestBadEFC Test
2804:25:30:960PMTestBadEFC still broken