Alcator C-Mod Run 1010723 Information

Back to runs

Miniproposals
Miniproposal:
Date Filed:
Title:
First Author:
Session Leader:Steve Wukitch (shots 1-24)
Miniproposal:297
Date Filed: 6/28/2001
Title:Neutral Particle Control, Fueling, and Gas Inventory Experimentsusing Helium
First Author:Brian Labombard
Session Leader:Brian Labombard (shots 1-24)

Operators
Session leader(s):Brian Labombard,Steve Wukitch
Physics operator(s):Bill Rowan,Steve Wolfe
Engineering operator(s): Unknown

Engineering Operator Run Comment
Boronization Recovery, MP#297 and RF Cond. SL:Labombard, Wukitch; PO: Ro

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:27:600PM
Author: To Be Determined
Session leader summary for 1010723

MP# 297: Neutral particle control, fueling, and gas
inventory experiments using helium

Session Leader - Brian LaBombard

Purpose:
The goals of these experiments are twofold: (1) quantify
the relative contributions to the midplane neutral pressure of divertor
neutral leakage and main-chamber plasma recycling, and (2) perform full
accounting of the fuel particle inventory in the vessel including gas and
plasma phases in the lower divertor, main-chamber, and upper chamber regions.

Shot Plan:
- overnight ECDC in helium, helium discharges
- vary the flappers that are operated from shot to shot, flapper
opening time 0.3 - 1.5 seconds, opening and closing with a period of 200 ms.
1-2) get shot set up. Probe set up. Maximize density w/o saturating
Penning gauges.
3) J,K A
4) B,C,D
5) C,D,E
6) F,G,H
7) A,B,C
8) higher density (nl04 ~ 1.4) F,G,H
9) higher density A,B,C
10) fizzle programmed if needed.

Result:
Shots 1-9 (5 actual plasmas) were spent tweaking the conditions
for the MP. We learned the hard way that there is a narrow operating window
in helium discharges where there is sufficient helium pressure in the
divertor (> 40 mtorr) to allow the flappers to 'fuel' the plasma
yet the divertor is not detached. We decided to ramp the density slowly
during the discharge to avoid the detachment state or to delay it until
the end of the shot. This seemed to work with the exception of shot 12
when we tried to ramp the density too fast and got the detached state
early in the shot.

It appears that the response of helium plasmas to the flapper opening
is very similar to deuterium plasma, suggesting that wall pumping
does not affect the gas-fueling transient that occurs when the flapper
is opened. As in the deuterium plasma, the midplane pressure is more
tied to the line-averaged density than the magnitude of the local divertor
bypass conductance.

We did two shots with a fixed pulsed gas programming. To our surprize
this resulted in a noticeably smaller wiggle in the line-averaged
density in response to the flapper modulation. This suggests that the delay in
the pulsed gas affecting the plasma combined with the chosen 200 ms flap period
might have amplified of the influence of the flapper on the line
density.

The following shots are good for detailed analysis.

-> similar density programing with active pulsed gas feedback:
Shot 10 - B C D flapper
Shot 11 - C D E flapper
Shot 14 - F G H flapper
Shot 15 - A B C flapper
Shot 18 - J K A flapper

- > fixed gas programing using that of shot 14:
Shot 21 - F G H J flapper
Shot 22 - B C D flapper

-> Fizzles for Penning gauge calibration:
Shot 1 - two of three Penning gauges operating
Shot 6 - higher pressure, three gauges
Shot 9,13 - three gauges
Shot 16 - two gauges
Shot 17 - three gauges

Detailed Shot Log:

Shot 1 - Fizzle. D2 prefill with a short He puff.
-> may be able to use this as a Penning gauge calibration.
CB_OutL and KA_OutL turned on - signal is very clean.
KA_OutU did not turn on.

Flappers J K A will be operated on the next shot:
open/close with 200 msec period starting at 0.35 seconds.

Shot 2 - No power shot

Shot 3 - Helium plasma, NL04 around .95
J K A flappers operating - no density modulation seen.
A very weak pressure modulation is seen on the KA_OutL gauge.
Neutral pressures are low everywhere. B-bottom is around 20 mtorr.

Next shot: raise NL04 to 1.3. Also tweak outer gap.

Shot 4 - Helium plasma, NL04 out of control, up to 2.2!
Divertor appears to detach when NL04 goes above 1.35
J K A flappers operating - no density modulation seen.
During detachment, E-top and B-bottom have same pressure.

Next shot: try NL04 1.2 . Drop x-point by 1 cm.

Shot 5 - Helium plasma, NL04 high, flat at ~1.6
J K A flappers operating - no density modulation seen.
Very low pressures in lower divertor.
We seem to be stuck in a detached divertor mode at the moment.

Next shot: try to get control on NL04. Increase distance to
secondary separatrix.

Shot 6 - Fizzle. Torus pressure goes to 2.5 mtorr.
Penning gauges are operating - may be good calibration shot.

Shot 7 - Helium plasma, NL04 steady at 0.9 until H-mode after 1.2 seconds.
Only 15-20 mtorr in divertor. A K J flappers running. Very weak modulation
on KA_OutL gauge seen.

Next shot ramp NL04

Shot 8 - Helium plasma, NL04 ramps from .9 to 1.2 prior to H-mode at 1.2 sec.
- better. divertor pressure rises to 32 mtorr.
A K J flappers running. Stronger modulation on KA_OutL gauge seen.

Next shot - higher density ramp.

Shot 9 - Fizzle. Torus pressure goes to 0.6 mtorr. Penning gauges are operating.
- can use this shot for calibration.

Shot 10 - Helium plasma, NL04 ramps to 1.4 at 1.2 seconds.
B C D flappers running. Density modulations seen.
Divertor pressure goes to 40 mtorr.

Next shot: increase NL04 ramp rate. Go to C,D,E flappers.

Shot 11 - Helium plasma, NL04 ramps to 1.5 at 1.2 seconds.
C D E flappers running. Density modulations seen.
Divertor pressure goes to 50 mtorr.

Next shot: again increase NL04 ramp rate. Go to F,G,H flappers.

Shot 12 - Helium plasma, NL04 out of control again, exceeding 1.8
F G H flappers running. No density modulations seen.
Detached divertor.

Next shot: go back to density program for shot 11 with small tweak.

Shot 13 - Fizzle - good Penning gauge calibration shot.

Shot 14 - Helium plasma, NL04 ramping to 1.5
F G H flappers running. Density modulations seen near 1.2 s.

Next shot: repeat with A B C flappers.

Shot 15 - Helium plasma, NL04 ramping to 1.5
A B C flappers running. Large density modulations.

Next shot: repeat with J K A flappers.

Shot 16 - Fizzle. KA_OutL and CB_OutL gauges operating (KA_OutU did not ignite)
Potential calibration shot.

Shot 17 - Fizzle. KA_OutL, CB_OutL, and KA_OutU gauges operating.
Potential calibration shot.

Shot 18 - Helium plasma, NL04 ramping to 1.5
J K A flappers running. Density modulations seen

Shot 19 - no power cycle

Shot 20 - Dud

Shot 21 - Helium plasma, NL04 ramping to 1.5
Gas programming from shot #14 loaded for this shot.
F G H J flappers running. No density modulation seen! Why?

Next shot: same gas programming with B C D flappers running.

Shot 22 - Helium plasma, NL04 ramping to ~1.5
Gas programing from shot #14 loaded for this shot.
B C D flappers running. Density modulation seen. - Not
any stronger than when gas feedback was on.

This is the last shot for this MP. RF taking over last shots of run.

Shot 23 - no power cycle

Shot 24 - This shot was for the RF group; 3 MW RF injected.

Physics Operator Summaries
Entered: Jul 7 2004 04:37:14:113PM
Author: To Be Determined
Physop Summary for 1010723

Session leader (MP297): Brian Labombard
Session leader (RF Conditioning): Steve Wukitch
Physics operator: Bill Rowan/Steve Wolfe

ENGINEERING SETUP

BEFORE BORONIZATION: Starting at the end of the run on Friday,
GDC in Helium
AFTER BORONIZATION: ECDC in HELIUM stopping by 8:00 am on Monday.
Run begins at 10:00 and ends at 17:00.
Power systems the same as for shot 1010720006.
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 10 psi D2 Hybrid DISABLED (PG2) (for ECDC)
fill C-side with 30 psi HELIUM Hybrid enabled (PG3)
fill J-Bottom with 30 psi He Hybrid DISABLED(PG5)
Enable the following gate valves, assuming no vacuum problems:
ECE, DNB, VUV
RF STATUS:
Transmitters 1 and 2 in run-on started at 08:00.
Transmitters 3 and 4 in run-on started at 08:00.


RUN PLAN

Boronization Recovery
MP#297 Neutral Particle Control
RF conditioning

Start with MP 297 and continue until complete. RF conditioning in
piggyback mode.
After MP 297, continue with RF conditioning.


RUN SUMMARY
Began with shot 1010720006. The first shot was a fizzle. The second
a no power shot due to a breach. At this point, we were able to begin
experiments. Refer to the Session Leader summary for that. The setup
for the experiments consisted of various forms of density ramps with
small variation in the x-point location.
Except for some gas control problems, the boronization recovery was
uneventful.

SCORE CARD

Plasmas 14
Fizzles 6
Duds. 1
No power cycles 3 (1 breach, I2t fault, camac alarm during init)
Total 24



Session Leader Comments
Jul 23 2001 09:54:53:537AM1010723001Brian LabombardShot 1 - Fizzle. D2 prefill with a short He puff.
-> may be able to use this as a Penning gauge calibration.
CB_OutL and KA_OutL turned on - signal is very clean.
KA_OutU did not turn on.

Flappers J K A will be operated on the next shot:
open/close with 200 msec period starting at 0.35 seconds.
Jul 23 2001 10:42:47:763AM1010723003Brian LabombardShot 3 - Helium plasma, NL04 around .95
J K A flappers operating - no density modulation seen.
A very weak pressure modulation is seen on the KA_OutL gauge.
Neutral pressures are low everywhere. B-bottom is around 20 mtorr.

Next shot: raise NL04 to 1.3. Also tweak outer gap.
Jul 23 2001 11:00:02:887AM1010723004Brian LabombardShot 4 - Helium plasma, NL04 out of control, up to 2.2!
Divertor appears to detach when NL04 goes above 1.35
J K A flappers operating - no density modulation seen.
During detachment, E-top and B-bottom have same pressure.

Next shot: try NL04 1.2 . Drop x-point by 1 cm.
Jul 23 2001 11:40:27:777AM1010723005Brian LabombardShot 5 - Helium plasma, NL04 high, flat at ~1.6
J K A flappers operating - no density modulation seen.
Very low pressures in lower divertor.
We seem to be stuck in a detached divertor mode at the moment.

Next shot: try to get control on NL04. Increase distance to
secondary separatrix.
Jul 23 2001 12:05:36:940PM1010723006Brian LabombardShot 6 - Fizzle. Torus pressure goes to 2.5 mtorr.
Penning gauges are operating - may be good calibration shot.
Jul 23 2001 12:25:33:800PM1010723007Brian LabombardShot 7 - Helium plasma, NL04 steady at 0.9 until H-mode after 1.2 seconds.
Only 15-20 mtorr in divertor. A K J flappers running. Very weak modulation
on KA_OutL gauge seen.

Next shot ramp NL04
Jul 23 2001 12:38:38:693PM1010723008Brian LabombardShot 8 - Helium plasma, NL04 ramps from .9 to 1.2 prior to H-mode at 1.2 sec.
- better. divertor pressure rises to 32 mtorr.
A K J flappers running. Stronger modulation on KA_OutL gauge seen.

Next shot - higher density ramp.
Jul 23 2001 12:44:25:080PM1010723009Brian LabombardShot 9 - Fizzle. Torus pressure goes to 0.6 mtorr. Penning gauges are operating.
- can use this shot for calibration.
Jul 23 2001 01:07:29:160PM1010723010Brian LabombardShot 10 - Helium plasma, NL04 ramps to 1.4 at 1.2 seconds.
B C D flappers running. Density modulations seen.
Divertor pressure goes to 40 mtorr.

Next shot: increase NL04 ramp rate. Go to C,D,E flappers.
Jul 23 2001 01:19:42:320PM1010723011Brian LabombardShot 11 - Helium plasma, NL04 ramps to 1.5 at 1.2 seconds.
C D E flappers running. Density modulations seen.
Divertor pressure goes to 50 mtorr.

Next shot: again increase NL04 ramp rate. Go to F,G,H flappers.
Jul 23 2001 01:36:42:253PM1010723012Brian LabombardShot 12 - Helium plasma, NL04 out of control again, exceeding 1.8
F G H flappers running. No density modulations seen.
Detached divertor.

Next shot: go back to density program for shot 11 with small tweak.
Jul 23 2001 02:02:49:667PM1010723013Brian LabombardShot 13 - Fizzle - good Penning gauge calibration shot.
Jul 23 2001 02:15:43:500PM1010723014Brian LabombardShot 14 - Helium plasma, NL04 ramping to 1.5
F G H flappers running. Density modulations seen near 1.2 s.

Next shot: repeat with A B C flappers.
Jul 23 2001 02:32:30:853PM1010723015Brian LabombardShot 15 - Helium plasma, NL04 ramping to 1.5
A B C flappers running. Large density modulations.

Next shot: repeat with J K A flappers.
Jul 23 2001 02:49:46:147PM1010723016Brian LabombardShot 16 - Fizzle. KA_OutL and CB_OutL gauges operating (KA_OutU did not ignite)
Potential calibration shot.
Jul 23 2001 03:04:32:683PM1010723017Brian LabombardShot 17 - Fizzle. KA_OutL, CB_OutL, and KA_OutU gauges operating.
Potential calibration shot.
Jul 23 2001 04:04:36:167PM1010723018Brian LabombardShot 18 - Helium plasma, NL04 ramping to 1.5
J K A flappers running. Density modulations seen
Jul 23 2001 04:24:37:823PM1010723021Brian LabombardShot 21 - Helium plasma, NL04 ramping to 1.5
Gas programming from shot #14 loaded for this shot.
F G H J flappers running. No density modulation seen! Why?

Next shot: same gas programming with B C D flappers running.
Jul 23 2001 05:12:49:007PM1010723022Brian LabombardShot 22 - Helium plasma, NL04 ramping to ~1.5
Gas programing from shot #14 loaded for this shot.
B C D flappers running. Density modulation seen. - Not
any stronger than when gas feedback was on.

This is the last shot for this MP. RF taking over last shots of run.

Physics Operator Comments
Jul 23 2001 09:08:32:590AMBill RowanRun Plan and Engineering Setup for Monday 1010723

Boronization Recovery
MP#297 Neutral Particle Control
RF conditioning

Start with MP 297 and continue until complete. RF conditioning in
piggyback mode.
After MP 297, continue with RF conditioning.

Session leader (MP297): Brian Labombard
Session leader (RF Conditioning): Steve Wukitch
Physics operator: Bill Rowan

BEFORE BORONIZATION: Starting at the end of the run on Friday, GDC in Helium

AFTER BORONIZATION: ECDC in HELIUM stopping by 8:00 am on Monday.

Run begins at 10:00 and ends at 17:00.

Power systems the same as for shot 1010720006.

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 10 psi D2 Hybrid DISABLED (PG2) (for ECDC)
fill C-side with 30 psi HELIUM Hybrid enabled (PG3)
fill J-Bottom with 30 psi He Hybrid DISABLED(PG5)

Enable the following gate valves, assuming no vacuum problems:
ECE, DNB, VUV

RF STATUS:

Transmitters 1 and 2 in run-on started at 08:00.
Transmitters 3 and 4 in run-on started at 08:00.

Run plan for 1010723

MP# 297: Neutral particle control,fueling,and gas inventory experiments using
helium

session leader - Brian LaBombard

Purpose - The goals of these experiments are twofold: (1) quantify
the relative contributions to the midplane neutral pressure of divertor
neutral leakage and main-chamber plasma recycling, and (2) perform full
accounting of the fuel particle inventory in the vessel including gas and
plasma phases in the lower divertor, main-chamber, and upper chamber regions.

ECDC overnight in He
All shots with D prefill, He puff

Setup: reload shot 1010720006 with the following changes:
nl04 = 1.2e20 as soon as possible.
outer gap 1.3 cm
scan the lower x-point in in major radius 1 cm over the period 0.5-1.5
seconds. This will keep the outer strike point more controlled.
RF on from 1.2 - 1.5 seconds

Shot sequence: vary the flappers that are operated from shot to shot, flapper
opening time 0.3 - 1.5 seconds, opening and closing with a period of 200 ms.
1-2) get shot set up. Probe set up. Maximize density w/o saturatin
Penning gauges.
3) J,K A
4) B,C,D
5) C,D,E
6) F,G,H
7) A,B,C
8) higher density (nl04 ~ 1.4) F,G,H
9) higher density A,B,C
10) fizzle programmed if needed.
Jul 23 2001 09:26:17:380AMBill RowanLoaded 1010720006.
Will make no changes until I get a plasma and find out what I have.


23-JUL-2001 09:21:02.02
END COLD START ******************
*************** END COLDSTART ******************

Jul 23 2001 10:03:44:657AM1010723001Bill Rowan001. fizzle.

For next shot. Increase prefill from 20 ms to 22 ms.
Change ic_ef4 from -1300 to -1270.
Jul 23 2001 10:11:52:467AM1010723002Bill Rowan002. No power shot. There was a breach. Traced to a person trying to service
film badges. There was no actual entry. The door was only pushed. Misunderstanding
due to the unusual Monday run.

Next shot. No changes.
Jul 23 2001 10:38:19:227AM1010723003Bill Rowan003. Plasma. At last. Moved the fizzle detector to 0.16 and will leave it there until
after the next fizzle (heaven forbid). This is for the edge guys to calibrate a gauge.

Next shot. Increase the density target to nl_04=1.2e+20
Increase the outer gap toward 1.3 cm from 1 cm.
Jul 23 2001 11:05:20:943AM1010723004Bill Rowan004. Disruption at 0.67s. nl_04 took off and reached 2e20.
Density exceeded demand. May be a TCI problem.

For the next shot:
Changed the density demand to 1.1e+20.
Lowered the x-point by 1 cm at request of probe-folk
Reduced the inner gab by 0.5 cm.
Reduced RCUR by 0.2 cm to maintain the outer gap
Jul 23 2001 11:26:20:630AM1010723005Bill Rowan005. Plasma. Disruption on the rampdown: 1.6 s
Density exceed demand. Gas valve is off so it is doing this on its own.

Next shot. Reduce demand to 0.85e+20

Jul 23 2001 11:37:47:757AM1010723005Bill Rowan
Moved rxu by +2 cm. Moved zxu by -2 cm
Jul 23 2001 11:54:35:440AM1010723006Bill Rowan006. Fizzle


Next shot. Return the fizzle detector to 80 ms
Raise BZ by 1 mT
Reduce prefill by 2 ms to 20 ms
Jul 23 2001 12:14:23:940PM1010723007Bill Rowan007. Plasma. NL_04 approx 0.93e+20

Next shot. Ramp the density toward 1.ee+20
Add 1 ms back to the prefill. Resulting in 21 ms prefill.
Jul 23 2001 12:34:05:563PM1010723008Bill Rowan008. Plasma

Next shot. Raise the base from which the ne ramp starts.
Jul 23 2001 12:50:47:230PM1010723009Bill Rowan009. Fizzle

Next shot. Changed the ne ramp at the request of the SL
Increased BR by 0.5 mT
Jul 23 2001 01:04:30:517PM1010723010Bill Rowan010. Plasma.

Next shot. Increased the ne ramp rate
Jul 23 2001 01:18:35:257PM1010723011Bill Rowan011. Plasma

Next shot. Increase the ne ramp rate.
Jul 23 2001 01:36:54:270PM1010723012Bill Rowan012. Plasma. Disruption at 1 s.

Reduced the ne ramp rate.
Jul 23 2001 02:03:03:510PM1010723013Bill Rowan013. Fizzle
Both BR and BZ are reasonable. Not sure why this failed.

Next shot. Increase the prefill by 1 ms.
Jul 23 2001 02:19:08:770PM1010723014Bill Rowan014. Plasma.

Next shot. No changes
Jul 23 2001 02:30:34:023PM1010723015Bill Rowan015. Plasma. Disruption on the rampdown; that is, at 1.7s.

Next shot. No changes
Jul 23 2001 02:56:21:280PM1010723016Bill Rowan016. Fizzle

Next shot. Small change in BZ. Changed IC_EF4 from -1260 to -1250
Jul 23 2001 03:09:11:863PM1010723017Bill Rowan017. Fizzle.

Next shot. Added 2 ms to the prefill for 24 ms of gas
Changed BZ. Changed IC_EF4 from -1250 to -1270
Jul 23 2001 03:25:49:170PM1010723018Bill Rowan018. Plasma. Disruption during rampdown; that is, at 1.7s

Next shot. No changes.
Jul 23 2001 03:41:44:320PM1010723019Steve Wolfeshot#19: wolfe taking over as physop during the DNB meeting.
no power cycle - RF and CAMAC alarms in INIT

Jul 23 2001 03:56:14:827PM1010723020Steve Wolfeshot#20: dud! - thanks, Bill.

next shot: EF4 to -1290, pressure up another 2ms
Jul 23 2001 04:12:49:197PM1010723021Steve Wolfeshot#21: EF4 to -1290, pressure up another 2ms
also turn off density feedback and pg3 load voltage from shot 14
per instruction of Blip.

plasma. disrupts in rampdown. Some runaways, may need even more gas.
Br is more positive again, Bz looks good to me
but it's a late breakdown; barely made it.
density isn't very modulated this time.

next shot: raise pg4 another 2ms, drop Br by .5mT
Jul 23 2001 04:36:15:873PM1010723022Steve Wolfeshot#22: raise pg4 by 2ms, drop Br by .5mT

plasma, disrupted in rampdown
breakdown still late, but current rise is fast
still some runaways

next shot: load seg2 from shot 7 and lower nl4 from .85 to .75e20 (per Wukitch)
Jul 23 2001 04:46:52:887PM1010723023Steve Wolfeshot#23:reload seg2 from shot 7 and lower nl4 to 0.75e20 (per Wukitch)
leave startup alone, since I'm not sure what to tweak.

no power cycle - I2t fault in INIT #!_*_$*_!*+~#

Jul 23 2001 05:05:24:790PM1010723024Steve Wolfeshot#24:reload seg2 from shot 7 and lower nl4 to 0.75e20 (per Wukitch)
leave startup alone, since I'm not sure what to tweak.

plasma, full length, had runaways again.
3 hmodes, the last one looks eda-ish
RF got to 3MW, with a nice ramp up for threshold measure.
breakdown is still late at 6.8msec.
Maybe should have put EF4 back up to -1280, since the higher Bz
cases had earlier breakdown; it would also help with the runaways perhaps.

END OF RUN; at least we left a good one on the drum.

Engineering Operator Comments
ShotTimeTypeStatusComment
109:43:57:503AMPlasmaOk
210:05:01:097AMPlasmaOk
310:20:38:060AMPlasmaOk
410:39:54:260AMPlasmaOk
511:13:34:953AMPlasmaOk
611:39:45:637AMPlasmaOk
712:03:24:813PMPlasmaOk
812:22:32:093PMPlasmaOk
912:38:19:490PMPlasmaOk
1012:54:27:733PMPlasmaOk
1101:10:47:650PMPlasmaOk
1201:28:09:350PMPlasmaOk
1301:48:48:727PMPlasmaOk
1402:04:59:763PMPlasmaOk
1502:21:17:307PMPlasmaOk
1602:43:53:200PMPlasmaOk
1702:59:42:757PMPlasmaOk
1803:13:44:823PMPlasmaOk
1903:38:24:720PMPlasmaBadNo Power shot. Camac init error
2003:51:00:193PMPlasmaOk
2104:04:19:230PMPlasmaOk
2204:25:03:403PMPlasmaOk
2304:45:42:777PMPlasmaOk
2404:57:19:593PMPlasmaOk