Alcator C-Mod Run 1000614 Information

Back to runs

Miniproposals
Miniproposal:266
Date Filed: 4/1/2000
Title:DNB Conditioning
First Author:Bill Rowan
Session Leader:Steve Wukitch (shots 1-13)
Session Leader:Bill Rowan (shots 14-23)

Operators
Session leader(s):Steve Wukitch,Bill Rowan
Physics operator(s):Ron Parker
Engineering operator(s):Bill Cochran,Gary Dekow

Engineering Operator Run Comment
MP #268 ICRF Commissioning, MP #266 DNB Testing in H.Wukitch/Rowan/Cochr

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:24:150PM
Author: To Be Determined
MP 268 -- ICRF Commissioning
MP#266 DNB testing in H

Session leader: S. Wukitch/B. Rowan
Physics operator: R. Parker
Engineering operators: G. Dekow/B. Cochran

-------------------------------------------------------------------------------
Engineering setup for Wedensday, 1000614:

overnight ECDC in D2, stopping 1-2 hours prior to the run.

Run begins at 9:00 and ends at 17:00.

Power system setup as on 1000613 (yesterday morning).

Gas setup - fill B-top with 6 psi of D2 Hybrid enabled
fill B-side lower with 1 psi of Ar Hybrid DISABLED
--> **** fill B-side upper with 10 psi of H Hybrid DISABLED *** <-- NOTE
fill C-side with 30 psi of D2 Hybrid enabled
J-bottom Hybrid DISABLED

The following gate valves should be enabled, assuming no vacuum problems:
ECE, VUV
DNB gate valve should be DISABLED at the start of the run.

RF setup:

1. vacuum tune

2. recall tune from 1000516018 for D, J
ST1/PS1 ST2/PS2 ST3/PS3 ST4/PS4
602/845 2531/3000 197/112 333/378

3. 400 msec ramp from 1-500 kW

-------------------------------------------------------------------------------

Run plan:

Test shots after plasma shot with TF and Gas (3 shots max)
reload (1000607007)
****pulse length 1 sec ***** (ie. ramp current and field down at .5 sec)

First RF plasma shot, load from 1000516018 (1.0 MA, 5.2 T).

Perform Power scan for loading studies. [0.001-0.5 kW]

Outer gap scan [0.5,1.0,1.5,2,2.5]

H concentration scan [gas programming from 980206]

Turn run over to DNB at 3 pm

-------------------------------------------------------------------------------

001 plasma - early disruption
from the visible camera views
D-port was easily visible (multipacting)
E-port was faint
J-port was faintly visible

next shot: repeat

002 fizzle
from the visible camera views
D-port was faint
E-port was faint
J-port was faint
G_side_ratiomatic measure 1 mtorr

conclusion: all the antennas creat a plasma around the current straps @ 1 mtorr

next shot: try for RF plasmas

003 plasma
good shot
nl_01~1
BT=5.2 T
right gap 2 cm

next shot: repeat with retune on J3

004 plasma
good shot
nl_01~1
BT=5.2 T
right gap 2 cm

next shot: increase gap to 2.5 cm

005 plasma
good shot
nl_01~1
BT=5.2 T
right gap ~2.2 cm

next shot: increase gap to 2.5 cm

006 plasma
good shot
nl_01~1
BT=5.2 T
right gap ~2.2 cm

next shot: decrease gap to 1.5 cm

007 plasma
good shot
nl_01~1
BT=5.2 T
right gap ~1.5 cm

next shot: decrease gap to 1.0 cm

008 plasma
good shot
nl_01~1
BT=5.2 T
right gap ~.7 cm

next shot: decrease gap to .4 cm

009 plasma
good shot
nl_01~1
BT=5.2 T
right gap ~1 cm

next shot: decrease gap to .4 cm

010 plasma
good shot
nl_01~1
BT=5.2 T
right gap ~.4cm
J3 failed early

next shot: repeat

011 plasma
good shot
nl_01~1
BT=5.2 T
right gap ~.4cm
J3 failed early

next shot: recall 007 and begin pabs measurements

012 plasma
nl_01~1
BT=5.2 T
right gap 1.5
J3 failed early
1 MW from D and E-port
0.5 MW from J4 as programmed

next shot: repeat with 1.5 MW from each
013 plasma
nl_01~1
BT=5.2 T
right gap 1.5
1.5 MW from D, E, and J-port
D overloaded early - no pabs for D

next shot: repeat

014 plasma
nl_01~1
BT=5.2 T
right gap 1.5
1.5 MW from D, E, and J-port

D the driver anode current appears to be still oscillating,

next shot: turn over to DNB, reduce pulse length

Summary:

It appears that all the antennas produce some plasma during RF vacuum
test shots with BT and ~mtorr gas pressure levels. The test was
complicated by this because the antennas were not well matched. We
succeeded in obtaining 1-250 kW power ramps for gaps between 0.4 -2.5
cm. We also obtained good L-mode discharges for comparison of D, E,
and J-port. For similar injected RF powers, D and E heating
efficiency was 75-80% and J-port was 50-55%. This experiment
completed action items 2, 3, 4B, 4D, and 6 from the J-port antenna
workshop.

Entered: Jul 7 2004 03:49:24:257PM
Author: To Be Determined
Session Leader Summary for 1000614

MP 266. DNB Conditioning

Session Leader: W. Rowan
PhysOp: R. Parker

The purpose of this part of the run was to look at the effect of the DNB
on the H/D ratio when the DNB is generating a H beam.

Shot 014 was used as a reference shot. The DNB gate valve was first opened on
shot 015 and then opened on all remaining shots in the run.

Opening the gate valve affects the prefill, but this has been observed in the
past with D beams. Compare shots 014 through 017 to see this clearly. The
gate valve was not opened on shot 014. Shot 015 was a fizzle because the
prefill pressure was too high, although the operator did make a reduction in
the prefill gas puff.

Shots 016-020 have an H/D ratio at very early times that is larger than that on
the reference shot. This phenomenon is not continued in later shots so it is
unlikely that it is due to the beam. It is something to be aware of and to
watch for in subsequent runs.

The H/D ratio after the beam is injected appears to hover between 0.02 and 0.04.
This is the value for the reference shot as well. There does not appear to be
a significant affect on this ratio due to the beam.

Shot summary

1000614014 Reference shot. Beam gate valve not opened.
1000614015 Fizzle. Beam on from 0.5s to 0.6s
1000614016
1000614017 Fizzle
1000614018
1000614019
1000614020 Beam on from 0.6s to 0.7s
1000614021 Increment in DNB gas feed. Approx 10% increase in pressure.
1000614022
1000614023




Physics Operator Summaries
Entered: Jul 7 2004 04:37:11:363PM
Author: To Be Determined
Run Plan and Engineering Setup for 1000614

MP 268: ICRF Development 9:00-3:00
MP 266: DNB Testing in H 3:00-5:00

Session Leader: S. Wukitch/B. Rowan
Physics Operator: R. Parker
Engineering Operators: G. Dekow/B. Cochran

Engineering Setup:

ECDC in D2, stopping 1-2 hours before run.

Run begins at 9:00 and ends at 17:00.

Power system setup: Same as for 1000613

Set OH1, OH2U and OH2L fizzle delays at 300ms
Set TF fizzle delay at 400 ms


Gas setup: B-Top 6 psi D2 Hybrid Enabled
B-side lower 1 psi Argon Hybrid DISABLED
** B-side upper 10 psi H Hybrid Enabled ** NOTE!!
C-side 30 psi D2 Hybrid Enabled
J-bottom leave as is Hybrid DISABLED

The following Gate Valves should be ENABLED, assuming no vacuum problems:

ECE, VUV

DNB gate valve should be DISABLED at start of run

RF setup:

1. Vacuum tune

2. recall tune from 1000516018 for D,J
ST1/PS1 ST2/PS2 ST3/PS3 ST4/PS4
602/845 2531/3000 197/112 333/378

3. 400 msec ramp from 1-500 kW


Run Plan:

1. ICRF Development

Test shots after plasma shot with TF and Gas (3 shots max)
reload 1000607007
****Pulse length 1 sec**** (ramp current and field down at 0.5 sec)

First RF plasma shot, load from 1000516018 (1.0MA, 5.2 T).

Perform power scan for loading studies (.001-0.5 kW)

Outer gap scan (0.5, 1.0, 1.5, 2.0, 2.5)

H concentration scan (gas programming from 980206)

2. DNB testing in H

Setup low-to-mid 10^19 m^-3 shot, similar to 1000613008

Continue with this shot for remainder of run for evaluation of
DNB penetration.

RUN SUMMARY

The run started 45 minutes late due to CAMAC hardware problems.

The first shot was a short one requested by the ICRF group to test
antenna-induced plasma conditions in the neighborhood of the various antennas.
The idea was to fire the RF power into a vacuum, but with some residual
ionization left from the main discharge. Although programmed to be short, the
shot ended with a disruption. Nevertheless, the shot was sufficient for the
intended purpose. Probably due to the disruption, or too low fill pressure,
the next shot was a fizzle.

Beginning with shot 3, more normal shots were produced with the goal of
studying the effect of the "right gap" on RF performance. These shots were
inside limited to avoid H-mode. The gap was varied from 5 to 25 mm. This was
carried out over shots 3-11. Then, in shot 12, a baseline shot was made
to prepare for the study of the effect of H concentration on RF performance.
However, no H was puffed; instead, the run was turned over on shot 15 to
W. Rowan who requested low density shots to measure the penetration of the DNB.
The RF group felt that it could get useful H/D data from the H that would be
injected by the DNB.

In the remaining shots, shots 15-23, low density (~5-6 e19 m-3) discharges were
established to check beam penetration. The RF piggy-backed on these shots, but
the combination of low density and high RF power caused disruptions late in
the discharge. Finally, in shots 22 and 23, the density was raised after the
DNB pulse terminated to 1 e20 m-3 and the discharge ran well. Notable was the
high RF power (3 MW) injected by J-port. About 3 MW was injected,but the
heating, although significant, was clearly not as strong as that produced by
3 MW injected from D and E ports.

The machine performed well for this run and most run objectives were reached.
There were 20 useful shots, one dud or fizzle and two definite fizzles. The
first was probably due to a disruption on the first shot, and the others were
due to the upsetting of the initial fill by gas from the DNB.

Session Leader Comments
Jun 14 2000 10:10:18:997AM1000614001Steve Wukitch001 plasma - early disruption
from the visible camera views
D-port was easily visible (multipacting)
E-port was faint
J-port was faintly visible

next shot: repeat

Jun 14 2000 10:18:38:293AM1000614002Steve Wukitch002 fizzle
from the visible camera views
D-port was faint
E-port was faint
J-port was faint

conclusion: all the antennas creat a plasma around the current straps

next shot: try for RF plasmas

Jun 14 2000 10:39:06:247AM1000614003Steve Wukitch003 plasma
good shot
nl_01~1
BT=5.2 T
right gap 2 cm

next shot: repeat with retune on J3

Jun 14 2000 11:16:05:903AM1000614004Steve Wukitch004 plasma
good shot
nl_01~1
BT=5.2 T
right gap 2 cm

next shot: increase gap to 2.5 cm

Jun 14 2000 11:42:41:247AM1000614006Steve Wukitch006 plasma
good shot
nl_01~1
BT=5.2 T
right gap ~2.2 cm

next shot: decrease gap to 1.5 cm

Jun 14 2000 12:09:12:000PM1000614007Steve Wukitch007 plasma
good shot
nl_01~1
BT=5.2 T
right gap ~1.5 cm

next shot: decrease gap to 1.0 cm

Jun 14 2000 12:47:35:217PM1000614008Steve Wukitch008 plasma
good shot
nl_01~1
BT=5.2 T
right gap ~.7 cm

next shot: decrease gap to .4 cm

Jun 14 2000 12:48:27:717PM1000614009Steve Wukitch009 plasma
good shot
nl_01~1
BT=5.2 T
right gap ~1 cm

next shot: decrease gap to .4 cm

Jun 14 2000 12:56:59:763PM1000614010Steve Wukitch010 plasma
good shot
nl_01~1
BT=5.2 T
right gap ~.4cm
J3 failed early

next shot: repeat

Jun 14 2000 01:15:54:467PM1000614011Steve Wukitch011 plasma
good shot
nl_01~1
BT=5.2 T
right gap ~.4cm
J3 failed early

next shot: recall 007 and begin pabs measurements

Jun 14 2000 01:38:13:997PM1000614012Steve Wukitch012 plasma
nl_01~1
BT=5.2 T
right gap 1.5
J3 failed early
1 MW from D and E-port
0.5 MW from J4 as programmed

next shot: repeat with 1.5 MW from each

Physics Operator Comments
Jun 14 2000 12:16:19:873PM1000614001Ron ParkerRun delayed due to CAMAC hardware failure. First shot off at 9:45
Computer is hanging up intermittently.

The first shot went off as planned: a short shot for RF testing purposes. The shot
was supposed to ramp down after 0.5 s, but disrupted around that time instead. Disruption
was probably due to density demand extending beyond current rampdown.

The next shot is scheduled to be a repeat of shot 1, but with density ramped down earlier.
Jun 14 2000 10:18:54:920AM1000614002Ron ParkerThis shot was a dud, probably because the initial fill pressure was too low.
Also could have failed because the first shot ended in disruption.

Cell entry granted after shot.

Next shot will be normal 1.0 MA, 5.2 T loaded from 1000516018.
Jun 14 2000 10:58:48:920AM1000614003Ron Parker
Shot 1000516018 was loaded and ran as programmed. Initial current rise hesitates, possibly
due to low fill pressure.

Next shot will be a repeat of shot 3. Prefill pulse will be increased to 25 msec.
Jun 14 2000 11:06:19:827AM1000614004Ron ParkerShot 4 was a repeat of shot 3. It ran as programmed, however initial current ramp
has a hesitation even though fill pulse was increased to 25 msec.

Next shot: increase right gap by 5 mm.





Jun 14 2000 11:24:41:610AM1000614005Ron Parker
Shot 5 ran as programmed, with right gap increased by 5 mm.

Next shot will have right gap again increased by 5 mm.
Also EF4 current will be increased from 1290 to 1280 to try to correct hesitation
in startup.
Jun 14 2000 11:49:40:153AM1000614006Ron ParkerShot 6 ran as planned with gap increased by ~5 mm. Adding 10 A to EF4 also
improved the initial current ramp.

The right gap for this shot was 2.5 cm . In the next shot, the right gap will be
programmed to be 1.5 cm.

Note: The actual gap achieved seems to be about half that programmed -- i.e., about the same
as the change in RCUR.

In the next shot, RCUR will be increased by 7.5 mm in order to try to bring the right
gap to 1.5 cm.
Jun 14 2000 12:08:12:717PM1000614007Ron ParkerShot 7 ran as programmed, with the right gap at 1.4 cm.

Next shot: repeat, with right gap set for ~1.0 cm (RCUR increased by 3.5 mm).
Jun 14 2000 12:23:40:653PM1000614008Ron ParkerShot ran as programmed, but right gap was ~0.6-0.8 cm, rather than 1.0 cm as expected.

Next shot: Take 1.5 mm off RCUR to try to bring right gap to 1 cm.
Added 5 A to EF 4 to help startup.
Jun 14 2000 12:51:25:030PM1000614009Ron Parker
Shot 9 ran well, but gap was ~1cm, (as programmed, operator error!) whereas
0.5 cm was requested.

Next shot: program 0.5 cm gap.
Jun 14 2000 12:58:33:327PM1000614010Ron ParkerShot 10 ran as programmed, with right gap ~ 0.5 cm.

Next shot: repeat of shot 10.

EF 4 current increased again by 5 A.
Jun 14 2000 01:28:46:437PM1000614011Ron Parker
Shot 11 ran as programmed, a repeat of shot 10.

Next shot: Return to shot 7 as baseline to begin H concentration scan.
Jun 14 2000 01:42:56:937PM1000614012Ron Parker
Shot 12 ran well, but no RF from No.3.

Next shot: Shot 12 will be repeated without change.
Jun 14 2000 02:05:53:857PM1000614013Ron ParkerShot 13 ran as programmed. Initial current rise was a little too rapid causing a
hesitation. For next shot, increase prefill pulse width by 2 ms and bring EF 4 up
to -1275 A.

Next shot: repeat.


Jun 14 2000 02:20:42:860PM1000614014Ron ParkerThis shot ran as programmed, and RF ran well also.

Next, W. Rowan becomes session leader and the DNB part of the run plan will
be implemented.

ICRF will continue with minority concentration studies, using H injected from DNB.

For next shot, no change except DNB will be pulsed. Fill pulse reduced by 5 ms in length
to accommodate extra gas injected by DNB.
Jun 14 2000 02:40:28:700PM1000614015Ron ParkerThis shot was, gulp, a fizzle presumably due to too much gas injected by the DNB.
Initial pressure was 0.08 mT, even though pulse gas fill had been reduced by 5 ms.

For next shot, pulse gas fill pulse width set at 18 ms, down from 22.
Jun 14 2000 02:58:49:343PM1000614016Ron ParkerShot ran as programmed, but fill pressure remains a bit high. Pulse gas fill width reduced
by 2 ms for next shot.

Next shot: Same I, B but density lowered to 0.8 10^20 m^-3.


Jun 14 2000 03:23:41:450PM1000614017Ron Parker
Shot 17 was a fizzle, even though initial fill pressure was reduced to ~0.07.
Still too high?

Next shot: reload 16, but reduce density to 0.8e20 m-3.
Jun 14 2000 03:30:56:090PM1000614018Ron ParkerShot 18 ran as programmed. Good current rise.

Next shot: Density will be reduced to 0.6e20 m-3.
Jun 14 2000 03:50:05:950PM1000614019Ron Parker
Shot 19 ran as programmed, but the density is running a little higher than programmed.
Good current rise.

Next shot: lower density to ~ 5e-19 m-3.
Jun 14 2000 04:11:12:293PM1000614020Ron ParkerShot 20 ran as programmed, but density programming was still set for 6e19 m-3.

Next shot: reduce density again to 5e19 m-3.
Jun 14 2000 04:37:24:780PM1000614021Ron Parker
Shot 21 ran as programmed, with the density at ~5.5e19 m-3. However, there was a
severe disruption at ~1.1 s, probably due to low density and RF.

Next shot: same startup, but density will ramp to 1e20 m-3 after DNB turns off.

Jun 14 2000 05:05:40:107PM1000614022Ron Parker
Shot ran well, with density rising to 1e20 m-3 after a low density phase (for DNB).

3 MW delivered to J-port antenna with resonable heating.

Fill pressure creeping up due to higher gas pressure in DNB. Nevertheless no tuning
will be attempted for the last shot.


Jun 14 2000 05:07:22:797PM1000614023Ron Parker
Shot 23 ran well with good power (3 MW per pair) from all ICRF antennas.

Next shot: tomorrow morning

Engineering Operator Comments
ShotTimeTypeStatusComment
109:49:19:543AMPlasmaOk
210:05:32:780AMPlasmaOk
310:29:53:263AMPlasmaOk
410:48:18:187AMPlasmaOk
511:13:29:827AMPlasmaOk
611:30:29:763AMPlasmaOk
711:50:45:780AMPlasmaOk
812:09:48:467PMPlasmaOk
912:29:44:343PMPlasmaOk
1012:49:53:373PMPlasmaOk
1101:09:25:153PMPlasmaOk
1201:29:58:200PMPlasmaOk
1301:49:25:280PMPlasmaOk
1402:08:45:513PMPlasmaOk
1502:27:22:623PMPlasmaOk
1602:48:46:577PMPlasmaOk
1703:06:27:640PMPlasmaOk
1803:22:47:030PMPlasmaOk
1903:43:50:687PMPlasmaOk
2004:00:20:763PMPlasmaOk
2104:23:23:090PMPlasmaOk
2204:42:47:340PMPlasmaOk
2305:00:15:577PMPlasmaOk