Alcator C-Mod Run 1010627 Information

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Miniproposals
Miniproposal:215
Date Filed: 1/5/1999
Title:J-port RF System Commissioning
First Author:Steve Wukitch
Session Leader:Rejean Boivin (shots 1-22)

Operators
Session leader(s):Rejean Boivin
Physics operator(s):Ron Parker
Engineering operator(s): Unknown

Engineering Operator Run Comment
rt J-Port Conditioning MP215

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:26:600PM
Author: To Be Determined
This run will be in support of J-Port Conditioning MP215

Engineering setup:


ECDC in D2 at 2.e-4 Torr overnight prior to run.

XMTR 2,3 and 4 in run-on by 8:00 AM
XMTR 1 main power on ONLY

15 minutes of additional ECDC before the first shot

May start with some EFC tests in the morning

Power systems as on 1010621018

Gas setup:

fill B-top with 6 psi of D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi of Ar Hybrid enabled (PG1)
fill B-side upper with 30 psi of D2 Hybrid DISABLED (PG2)
fill C-side with 30 psi of D2 Hybrid enabled (PG3)
fill J-bottom with 30 psi of He Hybrid DISABLED (PG5)

Enable the following gate valves: ECE, DNB, VUV

Run starts at 09:00 and ends at 17:00.

Objectives:

1. Investigate J-port power handling.

2. Investigate antenna operation compatibility.

3. Begin characterizing the J-port antenna.
a. density scan
b. current scan

001 no EF4

002

BT = 5.3T, Ip~ 1 MA, nl_04 1~x10^20 m^-2

Request:

D: 1.0 MW [1.05,1.5] sec
E: 1.0 MW [1.29,1.5] sec
J: 2.0 MW [0.55,1.0] sec

Result: Plasma

D: Ran with only one trip
E: Ran fine
J: Ran with 4-5 trips

there is significant increased D-alpha with J-port which was not
observed yesterday - is this an effect resulting from overnight ECDC

Action: Notch up J-port power to 3.0 MW (next shot)

003

BT = 5.3T, Ip~ 1 MA, nl_04 ~1x10^20 m^-2

Request:

D: 1.0 MW [1.05,1.5] sec
E: 1.0 MW [1.29,1.5] sec
J: 3.0 MW [0.55,1.0] sec

Result: Plasma with disruption at 1.41 sec

D: Ran ran great
E: Ran but had trouble turning on
J: Ran with multiple trips - first trip occurs at initial H-mode transition
Note: Examine DV2 voltage on D-port

Action: Retune J, E, and D
Remove notch in J-port power (longer flat-top)


004 shot cycle

005

BT = 5.3T, Ip~ 1 MA, nl_04 1~1x10^20 m^-2

Request:

D: 1.0 MW [1.05,1.5] sec
E: 1.0 MW [1.29,1.5] sec
J: 3.0 MW [0.55,1.0] sec

Result: Plasma

D: Ran with several trips
E: Ran fine
J: Ran with multiple trips but got to 3.0 MW for 30 msec at 0.735 sec


Action:

006

BT = 5.3T, Ip~ 1 MA, nl_04 1~1x10^20 m^-2

Request:

D: 1.25 MW [1.05,1.5] sec
E: 1.25 MW [1.29,1.5] sec
J: 3.0 MW [0.55,1.0] sec

Result: Plasma

D: Ran with several trips
E: Ran fine
J: Multiple trips

Action: Go to inner-limited plasma (avoid H-mode)

007

BT = 5.3T, Ip~ 1 MA, nl_04 1~1x10^20 m^-2
inner gap was ~0.5 cm

Request:

D: 1.25 MW [1.05,1.5] sec
E: 1.25 MW [1.29,1.5] sec
J: 3.0 MW [0.55,1.0] sec

Result: Plasma

D: Ran with several trips
E: Ran fine
J: Multiple trips

Action: again inner-limited plasma (avoid H-mode)

009

BT = 5.3T, Ip~ 1 MA, nl_04 1~1x10^20 m^-2
Inner limited plasma

Request:

D: 1.25 MW [1.05,1.5] sec
E: 1.25 MW [1.29,1.5] sec
J: 3.0 MW [0.55,1.0] sec

Result: Plasma in L-mode;

D: Clean up to 1.3 MW, then trips;
E: Trips above 1.2 MW; OK on top of D port from 0.81 to 0.87 sec, then trips;
J: Trips above 1.5 MW this time
Action: Repeat shot and leave RF as is;

010

BT = 5.3T, Ip~ 1 MA, nl_04 1~1x10^20 m^-2
Inner limited plasma

Request:

D: 1.25 MW [1.05,1.5] sec
E: 1.25 MW [1.29,1.5] sec
J: 3.0 MW [0.55,1.0] sec

Result: Plasma in L-mode;

D: OK up to 1.3 MW;
E: OK up to 1.1 MW on top of D port ;
J: Deteriorating and drops out above 1.2 MW with multiple arcs;

activity on the J-port screen

Action: Lower power request to 2.0 MW on J-port and further slow ramp
rate

011 dud
012 dud

013

BT = 5.3T, Ip~ 1 MA, nl_04 1~1x10^20 m^-2
Inner limited plasma

Request:

D: 1.25 MW [1.05,1.5] sec
E: 1.25 MW [1.29,1.5] sec
J: 2.0 MW [0.55,1.0] sec

Result: L -mode plasma, disrupted at 1.0 sec

D: 1.25 MW, only two trips
E: 1.25 MW, good, no trips, on top of D port power;
J: No target plasma during J-port injection

no edge interaction on the septum!

Action: ECDC on
open

014 dud

015 dud

016

BT = 5.3T, Ip~ 1 MA, nl_04 1~1x10^20 m^-2


Request:

D: 1.15 MW [0.65,1.0] sec
E: 1.25 MW [0.80,1.0] sec
J: 2.0 MW [1.05,1.5] sec

Result: Plasma with a few H-mode periods
D: 1.25 MW Ok
E: 1.25 MW Ok, H-mode with D+E up to 2.5 MW
J: OK up to 1.6 MW, then a two trips on the way to 2.0 MW ; brief
H-Mode periods

Action: Retune


017

BT = 5.3T, Ip~ 1 MA, nl_04 1~1x10^20 m^-2

Request:

D: 1.15 MW [0.65,1.0] sec
E: 1.25 MW [0.80,1.0] sec
J: 2.0 MW [1.05,1.5] sec

Result: Plasma with two H-modes
D: 1.25 MW Ok
E: 1.25 MW Ok, H-mode with D+E up to 2.5 MW
J: OK up to 1.6 MW, then tripped on the way to 2.0 MW ; with a brief
H-Mode period

Action: Lower current to 0.8 MA
-

018 Fizzle

019

BT = 5.3T, Ip~ 0.8 MA, nl_04 1~1x10^20 m^-2

Request:

D: 1.15 MW [0.64,1.0] sec
E: 1.25 MW [0.64,1.0] sec
J: 2.0 MW [1.05,1.5] sec

Result: Plasma with two EDA H-modes

D: Ran with trips at start and end of rf pulse
E: Ran fine
J: Ran up to 1.5 MW and then had multiple trips.

Action: Go to 1.2 MA next shot


020

BT = 5.3T, Ip~ 1.2 MA, nl_04 1~1x10^20 m^-2

Request:

D: 1.15 MW [0.64,1.0] sec
E: 1.25 MW [0.64,1.0] sec
J: 2.0 MW [1.05,1.5] sec

Result: Plasma

D: Ran with trips
E: Ran with trips
J: Better ! Ran with one trip and then continued on to 2.0 MW

Action:
-

021

BT = 5.3T, Ip~ 1.2 MA, nl_04 1~1x10^20 m^-2

Request:

D: 1.0 MW [0.64,0.78] sec
E: 1.0 MW [0.64,0.78] sec
J: 2.2 MW [1.05,1.5] sec & 3.2 MW from [0.86,0.91] sec

Result: Plasma - got two H-modes and a disruption

D: Ran with one trip
E: Ran fine
J: Ran fine through short (50 msec) pulse
Multiple trips on longer pulse
Note: Xmtr4 - screen current overload



Action: Reduce current to 1.0 MA and J-port short pulse power to 3.0 MW

022

BT = 5.3T, Ip~ 1.0 MA, nl_04 1~.9x10^20 m^-2

Request:

D: 1.0 MW [0.64,0.78] sec
E: 1.0 MW [0.64,0.78] sec
J: 2.2 MW [1.05,1.5] sec & 3.0 MW from [0.86,0.91] sec

Result: Plasma - got four H-modes

D: Ran fine
E: Ran with one trip
J: Ran fine through 50 msec pulse
Ran with only one trip on second longer pulse
Note:

Action: End of run


Run Summary:

The J-port antenna was tested to 3.0 MW into plasma (1010627022). It
heated well and reached ~26 kV briefly. The antenna had numerous
faults when the voltage reached ~20 kV and degraded over a series of
discharges. The fast data suggests that some arcs are surviving for
30-50 usec. We suspect arcing in the antenna strap is responsible for
these arcs because no signal corresponding to the arcs in the optical
monitor signals is observed and the antenna paper clip geometry could
allow an arc on one antenna strap half without resulting in a phase
balance or reflected power fault in the transmission line. We often
observe an interaction at the antenna midplane near the septum and
side limiters at about the location of the short. This interaction
was worse when running inner wall limited (an attempt to stay in
L-mode) and is weakly dependent on plasma current (019,016,021). To
finish the antenna characterization, we need to a gap, phase, and BT
scan.

Physics Operator Summaries
Entered: Jul 7 2004 04:37:13:520PM
Author: To Be Determined
This run will be in support of RF conditioning of J-Port Antenna, MP215

-
ENGINEERING SETUP:

ECDC in D2 overnight at 2.e-4 Torr

We may require ECDC between shots

Power systems as on 1010626012

RF: XMTR 1 thru 4 in run-on by 8:00 AM

Gas setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar Hybrid enabled (PG1)
fill B-side upper with 30 psi D2 Hybrid DISABLED (PG2)
fill C-side with 30 psi D2 Hybrid enabled (PG3)
fill J-Bottom with 30 psi He Hybrid DISABLED(PG5)

Enable the following gate valves: ECE, DNB, VUV

Run starts at 9:00 and ends at 17:00

RUN SUMMARY

The run was devoted to bringing up RF power in the J-Port antenna. Discharges
began by reproducing shot 1010626012. The first shot was a dud due to the
failure of EF4 to turn on. The problem was resolved by cycling the EF4 control
system, and shot 2 went off as planned. Shot 3 was a repeat of shot 2, although
it disrupted at 1.4 s. Shot 4 was a no power shot caused by a false I^2t fault
indication. Shot 5 went off as programmed as did shot 6, again reproducing
shot 1010626012. The Physics Leader then requested an inner wall limited shot
and shot 1010621021 was loaded. This turned out to be still diverted since the
PO moved the gap 5mm in the wrong direction in an attempt to make the discharge
more strongly inner-wall limited.This was corrected in shot 8, and shots 8-10
were indeed strongly inner-wall limited. Shots 11 and 12 were duds. In shot
11 the NBI valve had been opened, so this was suspected to cause the dud.
However, shot 12 was also a dud and the valve was not opened; therefore, field
errors were the more likely culprit. EF4 current was decreased from -1280 to
-1290 Amps, and shots 13 and 14 went off as programmed. These and all subsequent
shots were diverted. After shot 12, ECDC was applied between shots for the rest
of the run. In shot 14, the density was reduced from 1e-20 to 0.9e-20. Shot 15
had a very late breakdown and fizzled. The BR offset was suspected to be too
high (-.1 mT) and it was decreased by 0.5 mT. Shot 16 then started up well and
ran as programmed, as did shot 17 although it terminated in a severe disruption
at 1.38 s. Next, the plasma current was reduced from 1 MA to 0.8 MA, but shot
18 fizzled. This was likely due to impurities generated by the disruption in
shot 17. Shot 19 was a repeat of the shot set up for shot 18, and it ran as
programmed. The current was raised to 1.2 MA for the next 2 shots, 20 and 21,
and they ran as programmed but both terminated in severe disruptions. The
current was then lowered to 1.0 MA and shot 22, the last shot of the day,
started up well and ran as programmed.

Overall, a fair day for the machine -- 16 shots starting up and running as
programmed, 2 duds, 2 fizzles and 2 no-shots due to engineering problems (1 power
supply, one computer). There were several disruptions, presumably caused by
RF conditioning or perhaps due to the RF heating.

Session Leader Comments

Physics Operator Comments
Jun 27 2001 09:31:31:983AM1010627001Ron ParkerShot 1 will begin with the settings from 1010626012.

The shot was a dud. EF4 did not turn on. No apparent problem was found, so we'll try again.
Jun 27 2001 09:41:00:060AM1010627002Ron ParkerShot 2 ran well, no changes were made to power supplies except to cycle through the EF4
control.
Next shot:repeat.

Jun 27 2001 10:02:23:717AM1010627003Ron ParkerShot 3 started up as programmed, but disrupted at 1.4 s.

The startup was a bit sluggish and the fill pressure will be reduced (2 ms on pulse
gas pulse width) for next shot. Other than that, no changes for next shot.
Jun 27 2001 10:11:43:200AM1010627004Ron ParkerShot 4 was a no power shot caused by a false I^2 t fault indication.
Try again on shot 5.
Jun 27 2001 10:31:35:293AM1010627005Ron ParkerShot 5 ran well with a slightly improved startup.

Shot 6 will be another repeat with no changes.
Jun 27 2001 10:58:44:587AM1010627006Ron ParkerShot 6 repeated as programmed. The next shot will be inner wall limited, similar
to 1010621021.
Jun 27 2001 11:23:19:140AM1010627007Ron ParkerShot 7 had smaller inner gap, but was not limited. Next shot should be inner wall
limited (Inner gap =-2cm)
Jun 27 2001 11:35:53:157AM1010627008Ron ParkerShot 8 was indeed inner wall limited. Next shot will be a repeat.
Jun 27 2001 12:25:54:390PM1010627009Ron ParkerShot 9 ran well, still inner wall limited.
Shot 10: Another repeat. Cell entry after shot 9 caused a delay
of ~15 minutes.
Jun 27 2001 12:40:56:633PM1010627010Ron ParkerShot 10 was a repeat of shot 9 and ran as programmed. Strong disruptions are occurring
during the rampdown.
Jun 27 2001 01:22:10:743PM1010627011Ron ParkerShot 11 was a dud, due to opening of neutral beam gate valve?
Jun 27 2001 01:22:25:103PM1010627012Ron ParkerShot 12 was also a dud, even though neutral beam valve didn't open.
Jun 27 2001 01:46:18:483PM1010627013Ron ParkerShot 13 went off as programmed after 2 duds. The reason for the duds was not clear, but the
EF4 current was decreased from -1280 to -1290 A. ECDC is nw being applied between shots.
Jun 27 2001 02:34:38:543PM1010627014Ron ParkerShot 14 ran well, density was reduced to ~ 9x10^19 m-3.
Jun 27 2001 06:36:25:053PM1010627015Ron Parker
Shot 15 was a fizzle, but had a very late breakdown. It may have been due to gas injected
from opening the Thomson valve, or maybe the BR was too high (-.1 mT). In next shot, we'll
drop BR by .5 mT. Still running ECDC between shots.
Jun 27 2001 03:20:34:233PM1010627016Ron Parker
Shot 16 started up well and ran as programmed.
Jun 27 2001 03:20:55:813PM1010627017Ron ParkerShot 17 ran well, as programmed. Terminated by severe disruption at 1.38 ms.

Next shot: plasma current reduced to 800 kA.
Jun 27 2001 03:42:09:597PM1010627018Ron ParkerShot 18 was a fizzle -- impurity level too high after last disruption?
Try again.
Jun 27 2001 04:04:50:693PM1010627019Ron ParkerShot 19 ran well, following the programming.
Next shot: 1.2 MA.

Jun 27 2001 06:35:06:610PM1010627020Ron Parker
Shot 20 ran as programmed at 1.2 MA, although it disrupted early in the ramp-down.
Next shot: repeat
Jun 27 2001 06:35:43:707PM1010627021Ron ParkerShot 21 ran again as programmed, I=1.2 MA, again disrupting on ramp-down


Jun 27 2001 05:09:54:497PM1010627022Ron ParkerShot 22 ran as programmed (I=1 MA), although it disrupted on the rampdown @ 0.5 MA.
This was the last shot of the day.

Engineering Operator Comments
ShotTimeTypeStatusComment
108:59:03:840AMPlasmaOk
209:26:55:570AMPlasmaOk
309:46:47:850AMPlasmaOk
410:05:16:050AMPlasmaBadNo Power Shot
510:18:07:320AMPlasmaOk
610:38:09:257AMPlasmaOk
710:58:47:257AMPlasmaOk
811:21:59:700AMPlasmaOk
911:42:34:903AMPlasmaOk
1012:23:59:810PMPlasmaOk
1112:46:08:013PMPlasmaOk
1201:00:59:773PMPlasmaOk
1301:21:41:680PMPlasmaOk
1401:49:04:503PMPlasmaOk
1502:20:23:380PMPlasmaOk
1602:44:34:803PMPlasmaOk
1703:07:08:667PMPlasmaOk
1803:30:49:250PMPlasmaOk
1903:53:27:927PMPlasmaOk
2004:15:35:147PMPlasmaOk
2104:38:30:463PMPlasmaOk
2205:00:57:983PMPlasmaOk