Alcator C-Mod Run 1050823 Information

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Miniproposals
Miniproposal:433
Date Filed: 7/29/2005
Title:Fueling in H-modes as a function of pedestal density
First Author:Jerry Hughes
Session Leader:Jerry Hughes (shots 1-35)

Operators
Session leader(s):Jerry Hughes
Physics operator(s):Bill Rowan
Engineering operator(s):Andy Pfeiffer,Bill Byford,Ed Fitzgerald,Bill Byford,Ed Fitzgerald,Bill Parkin

Engineering Operator Run Comment
MP433: Fueling in H-modes as a function of pedestal density Session Lead

Session Leader Plans
Entered: Aug 22 2005 06:32:05:650PM
Author: Jerry Hughes
Continuation of run 1050822B
MP433: Fueling in H-modes as a function of pedestal density

Evening boronization (~2 hours), followed by 4 hours ECDC.
Remain ready for between-shot boronization.

1. Start by reproducing shot 1050822022, using same RF program.
Raise NINJA D2 pressure to 40psi and puff from inner wall capillary 1.2--1.5s
2. Lower Ip to 0.8MA, nl04 to 0.8e19. Get 3 shots with NINJA puff set to 10, 20, 40psi.
3. Ip-->0.6MA, nl04-->0.6e19. Repeat sequence of NINJA puffs.
4. Ip-->0.4MA, nl04-->0.4e19. Repeat sequence of NINJA puffs.
Remaining shots: Repeat promising shots with puffs from other poloidal
locations and/or repeat without RF to get Ohmic shots for fueling
comparison.

Physics Operators Plans
Entered: Aug 23 2005 08:22:57:030AM
Author: Bill Rowan
Engineering Setup and Run Plan for Tuesday, August 23, 2005. Run 1050823

MP433: Fueling in H-modes as a function of pedestal density

Session Leader: Hughes
Physics Operator: Rowan

Boronize for two hours and follow with 4 hours of ECDC


Setup for between shot boronization

Run begins at 9:00 and ends at 17:00 with an option of extending to 19:00.

Power Systems as on 1050822018

RF in run on by 6:15 (E and J-4 sources)

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 plus 1 psi neon Hybrid DISABLED (PG1)
leave B-side upper as is He3 Hybrid DISABLED (PG2)
fill B-main (C-side) with 40 psi D2 Hybrid enabled (PG3)

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

NINJA set up with D2. Start with fill pressure of 5psi, but will want
to go up to 40psi.


Session Leader Summaries
Entered: Aug 23 2005 05:48:39:463PM
Author: Jerry Hughes
MP433: Fueling in H-modes as a function of pedestal density

This run was the continuation the continuation of the run began the
previous day at about 14:00, in which a few useful shots were
obtained. The experiment was intended to test the effects of a gas
puff into an existing H-mode edge, intended to perturb the neutral
source in the pedestal region. Indications from modeling and limited
experimental probing have been that as the absolute pedestal density
is lowered, the effect of a neutral source perturbation on the density
pedestal (and possibly the associated gradient) should be more
pronounced. This premise was to be explored by running discharges
with values of plasma current ranging from 1.0MA to 0.4MA and
administering D2 puffs with the NINJA system.

This run successfully obtained data at all desired plasma currents,
using NINJA manifold pressures ranging from 10 to 40psi. Having a
fresh boronization the evening prior was quite helpful, as most shots
during the first half of the day exhibited steady H-modes with fairly
low radiated power. There were pesky injections, but their frequency
and intensity were reduced by keeping the outer strike point off the
divertor floor. Gas puffing into H-modes at 0.8 and 1.0 MA produced a
familiar result, with the density pedestal staying roughly fixed in
value, and shifting outboard of the temperature pedestal. By contrast,
more pedestal fueling seemed to be evident in puffed H-modes at 0.6
and 0.4MA, with the highest fueling rates quickly terminating the
H-modes

Because this experiment got a head start on the previous afternoon
(using between-shot boronization to maintain quality H-modes), and
because the number of shot requests was reduced, the H-mode puffs were
largely complete by mid-afternoon. At this point, the good effects of
boronization were effectively dissipated, and it was difficult to
obtain steady, low-radiation H-modes except at the lowest current. We
pressed on, though, and got data in 0.6 and 0.8MA plasmas comparing
puffs from inboard and outboard. No obvious difference in fueling
based on poloidal location was observed. The run was completed by
puffing hard into ohmic discharges at the four target currents, for
comparison of fueling rate.

Physics Operator Summaries

Session Leader Comments
Aug 23 2005 09:23:07:890AM1050823001Jerry Hughes1MA shot, NINJA 40psi puffing during t=[1.2,1.5]. Drops out of H-mode at about 1.4s.
Decent shot. YAG alignment is a little off, so the edge n_e data may need some correction.
There are some apparent injections in the flat part of the H-mode, but they don't seem
to be a severe problem. Density, Prad traces look as expected during puff.
Next shot: 0.8MA, 8e19 target. NINJA at 10psi.
Aug 23 2005 09:31:06:250AM1050823002Jerry Hughes0.8MA shot, NINJA 10psi puffing during t=[1.2,1.5].
YAG alignment is better. More injections, including one that kills the H-mode at about 1.37s.
to be a severe problem. Density, Prad traces look as expected during puff.
Next shot: 0.8MA, 8e19 target. NINJA at 20psi.
Aug 23 2005 09:48:15:797AM1050823003Jerry Hughes0.8MA shot, NINJA 20psi puffing during t=[1.2,1.5]. H-mode initiated with 700kW RF.
YAG alignment is suitable. Injections kill H-mode at 0.97, just as the RF comes to full power.
Next shot: Retry
Aug 23 2005 10:07:53:517AM1050823004Jerry Hughes0.8MA shot. Big disruption at 0.91s.
Next shot: Retry
Aug 23 2005 10:20:49:610AM1050823005Jerry Hughes0.8MA shot. NINJA at 20psi, 1.2--1.5s. No significant injections, and H-mode
is sustained. Good shot, from my point of view.
Next shot: Increase NINJA manifold to 40psi, and repeat.
Aug 23 2005 10:33:46:610AM1050823006Jerry Hughes0.8MA shot. NINJA at 40psi, 1.2--1.5s. Tough injections ruin the steady H-mode.
Seems consistent with Rowan's hypothesis that the injections being caused by outer strike
point hitting the floor.
When H-mode recovers, there is a short interval of steady H-mode from
1.15--1.2 prior to NINJA puff.
Next shot: Repeat, with a small PhysOp change in the X-point location to
keep strike pt off the floor.
Aug 23 2005 10:50:21:170AM1050823007Jerry Hughes0.8MA shot. NINJA at 40psi, 1.2--1.5s. Injections starting at 1s, despite the strike pt not
hitting the floor this time. This and the previous shot should have sufficient data, so
move on.
Next shot: Ip-->0.6MA, nl04-->6e19. No NINJA.
Aug 23 2005 10:55:13:843AM1050823008Jerry Hughes0.6MA shot. No NINJA. Injections kill H-mode at first, but it comes back, steady.
E has some trips, but, J4 is ok.
Good baseline 600kA shot.
Next shot: NINJA at 10psi, 1.2--1.5
Aug 23 2005 11:03:29:240AM1050823009Jerry HughesShot failed to run.
Next shot: Retry.
Aug 23 2005 11:24:26:447AM1050823010Jerry Hughes0.6MA shot. NINJA at 10psi. No substantial effect of puff on H-mode
Next shot: Raise NINJA manifold to 20psi
Aug 23 2005 11:41:25:963AM1050823011Jerry Hughes0.6MA shot. NINJA at 20psi. Injection around 0.93s. Some effect of gas puff is being seen now.
Next shot: Repeat
Aug 23 2005 11:55:23:290AM1050823012Jerry Hughes0.6MA shot. NINJA at 20psi. No major injections, RF well-behaved. Clear fueling enhancement
begin at 1.2s. There appears to be an enhancement of the density pedestal, relative to
shot 008. (comparing the interval [1.4,1.45])
Next shot: NINJA to 40psi
Aug 23 2005 12:03:07:417PM1050823013Jerry Hughes0.6MA shot. NINJA at 40psi. No major injections. RF well-behaved, at least until puff starts,
then E-port goes away. Clear fueling enhancement after 1.2s. n_ePED increases from 1.3 to 1.6x10^20
Next shot: 0.4MA. No NINJA.
Aug 23 2005 12:14:46:133PM1050823014Jerry Hughes0.4MA shot. No NINJA. Injections again. Would like a cleaner baseline shot at this
current.
Next shot: Retry, with PO attempting to lift the outer strike off the floor again.
Aug 23 2005 12:26:07:603PM1050823015Jerry Hughes0.4MA shot. No NINJA. This is a good shot.
Next shot: Turn NINJA back on, 10psi
Aug 23 2005 12:39:07:323PM1050823016Jerry Hughes0.4MA shot. 10psi in NINJA, 1.2--1.5s. No significant effect on discharge.
Injection at 1.15s, but not a killer.
Next shot: NINJA to 20psi
Aug 23 2005 12:54:04:853PM1050823017Jerry Hughes0.4MA shot. 20psi in NINJA, 1.2--1.5s. Marginal enhancement of pedestal/core fueling.
Next shot: Repeat
Aug 23 2005 01:07:10:947PM1050823018Jerry Hughes0.4MA shot. 20psi in NINJA, 1.2--1.5s. Similar to shot 17. The impact of this
level of puff on the pedestal seems to be less than it was in the 0.6MA case, and perhaps
less than the 0.8MA case!
Next shot: Raise NINJA fill to 40psi.
Aug 23 2005 01:22:56:307PM1050823019Jerry Hughes0.4MA shot. 40psi in NINJA, 1.2--1.5s. Too much puff, H-mode killed at approx. 1.3s.
Next shot: Lower NINJA fill to 30psi.
Aug 23 2005 01:34:46:883PM1050823020Jerry Hughes0.4MA shot. 30psi in NINJA, 1.2--1.5s. H-mode is killed after puff applied. Either the fueling
kills the H-mode directly or the increased neutral pressure causes too much RF faulting.
There is some potentially useful transient pedestal data shortly before H-mode collapse at
1.32s.
Next shot: Ip-->0.6MA
Aug 23 2005 01:48:19:523PM1050823021Jerry Hughes0.6MA shot. 30psi in NINJA, 1.2--1.5s.
Multiple H-modes, poorer performance. The indication seems to be that the boronization has worn off.
I'll take another baseline shot now, with no puff, to compare with shot 008.
Next shot: Same shot, no NINJA.
Aug 23 2005 01:59:56:167PM1050823022Jerry Hughes0.6MA shot. No NINJA.
By comparison with shot 008, Prad is up about 2x. Wp down 75-->55kJ. Transient H-modes.
nl04 somewhat higher now than on shot 8, as is central n_e. Edge n_e, however, seems to
be quite similar.
Next shot: Same shot, NINJA inboard, 30psi, 1.2--1.5s.
Aug 23 2005 02:16:40:180PM1050823023Jerry Hughes0.6MA shot. NINJA inboard, 30psi, 1.2--1.5s.
Next shot: Same shot, NINJA outboard, 30psi, 1.2--1.5s.
Aug 23 2005 02:28:14:527PM1050823024Jerry Hughes0.6MA shot. NINJA outboard 30psi. Trigger for NINJA was 1.13s, and the gas puff appears
to have arrived at 1.25s or later. I will push back the trigger 100ms for next shot.
Next shot: Same shot, NINJA outboard, 30psi, 100ms earlier.
Aug 23 2005 02:41:13:480PM1050823025Jerry Hughes0.6MA shot. NINJA outboard 30psi. Trigger for NINJA was 1.03s, and the gas puff is observed
to begin at 1.13s. There is an enhanced n_e pedestal during the puff.
There does not appear to be a significant difference between inboard and outboard puff
at this current.
Next shot: Same shot, NINJA outboard, 30psi, 1.1--1.3s
Aug 23 2005 03:03:05:917PM1050823026Jerry Hughes0.6MA shot. NINJA outboard 30psi. 1.1--1.3s. The gas puff pretty effectively kills radiation
and stabilizes the plasma.
Next shot: Go back to 0.8MA, NINJA @30psi, outboard puff beginning at approx. 1.2s
Aug 23 2005 03:15:37:697PM1050823027Jerry Hughes0.8MA shot. NINJA outboard 30psi, hits plasma about 1.23s. Edge Te depressed, ne slightly
enhanced. Prad reduced.
Next shot: Inboard puff again.
Aug 23 2005 03:37:29:243PM1050823028Jerry Hughes0.8MA shot. NINJA inboard 30psi, hits plasma about 1.23s. Looks much like shot 27.
TCI registers higher peak value, however.
Next shot: Do an Ohmic shot for comparison.

Actually, upon further review, I puffed from both inboard and outboard
capillaries. I will redo this inboard puff for shot 30.
Aug 23 2005 03:39:09:557PM1050823029Jerry Hughes0.8MA shot. No RF. NINJA inboard + outboard 30psi.
Next shot: Redo shot 28 (with RF) using inboard puff only.
Aug 23 2005 03:49:29:760PM1050823030Jerry Hughes0.8MA shot. RF good. Puff is successful. Basically reproduces shot 27.
Next shot: Ohmic, inboard puff only, triggered at 1.0s.
Aug 23 2005 04:08:58:527PM1050823031Jerry Hughes0.8MA Ohmic discharge. Puff comes in at about 1.1s. Fueling is almost immediate. Edge n_e
seems to almost saturate within 100--200ms, so that it looks almost like an H-mode.
Central ne and TCI continue to rise more slowly out to current rampdown.
Next shot: 1.0MA Ohmic, same puff.
Aug 23 2005 04:14:03:807PM1050823032Jerry Hughes0.8MA Ohmic discharge. The desired changes to the shot were not loaded.
Shot looks essentially identical to 031.
Next shot: 1.0MA Ohmic, same puff.
Aug 23 2005 04:28:28:307PM1050823033Jerry Hughes1.05MA Ohmic discharge. NINJA loaded to 30psi, inboard puff comes in at about 1.1s.
Next shot: 0.6MA Ohmic, same puff.
Aug 23 2005 04:44:03:120PM1050823034Jerry Hughes0.6MA Ohmic discharge. NINJA loaded to 30psi, inboard puff comes in at about 1.1s.
Next shot: 0.4MA Ohmic, same puff.
Aug 23 2005 05:35:04:417PM1050823035Jerry Hughes0.4MA Ohmic discharge. NINJA loaded to 30psi, inboard puff comes in at about 1.1s.
End of run.

Physics Operator Comments
Aug 23 2005 08:35:27:343AMBill RowanLoad shot 1050822022 to continue the run from yesterday.
Aug 23 2005 09:18:31:657AM1050823001Bill Rowan001.
Reset the prefill for 18 ms.
Plasma disrupted at 1.5 s
Shot ok for SL

Next shot
ip to 0.8 MA
nel04 to 0.8e+19
Aug 23 2005 09:31:48:640AM1050823002Bill Rowan002. Plasma.
nell04=0.84e+19 prior to RF and h-mode
ip = 0.8 MA

Next shot.
No PCS changes

Aug 23 2005 09:49:43:220AM1050823003Bill Rowan003. Plasma
Early injection is gone.

Next shot.
Repeat
Aug 23 2005 10:07:28:093AM1050823004Bill Rowan004. Plasma
Disruption at 0.91 s. Injections.

Next shot.
No pcs changes

Aug 23 2005 10:16:53:703AM1050823005Bill Rowan005. Plasma

Next shot.
Repeat

Aug 23 2005 10:29:47:170AM1050823006Bill Rowan006. Plasma
Injections starting at 0.85 s

Next shot.
RXL changed from -0.005 to 0.0 from 0.917 s to 1.5 s

Aug 23 2005 10:45:10:330AM1050823007Bill Rowan007. Plasma
Injections starting at 1 s

Next shot.
IP to 0.6 MA
nel_04 to 0.6e+19

Aug 23 2005 10:58:09:580AM1050823008Bill Rowan008. Plasma
Injections starting at 0.84s

Next shot.
No PCS changes

Aug 23 2005 11:10:18:353AM1050823009Bill Rowan009. No shot
Igor had an ACK failure?

Next shot,
No PCS changes.

Aug 23 2005 11:20:21:277AM1050823010Bill Rowan010. Plasma
Injections starting at 0.89s

Next shot.
No PCS changes
Aug 23 2005 11:38:38:213AM1050823011Bill Rowan011. Plasma
Injections starting at 0.0.93s

Next shot.
Changed ZXL from -0.01 to 0.0

Aug 23 2005 11:45:28:853AM1050823012Bill Rowan012. Plasma
Fewer/no injections

Next shot,
No PCS changes

Aug 23 2005 12:02:11:463PM1050823013Bill Rowan013. Plasma
Disruption during rampdown

Next shot.
IP to 0.4 MA
nel_04 to 0.4E+19

Aug 23 2005 12:12:10:917PM1050823014Bill Rowan014. Plasma
Injections

Next shot.
rxl to +0.005

Aug 23 2005 12:24:00:493PM1050823015Bill Rowan015. Plasma

Next shot,
No PCS changes


Aug 23 2005 12:38:06:993PM1050823016Bill Rowan016. Plasma

Next shot,
No PCS changes

Aug 23 2005 12:49:35:947PM1050823017Bill Rowan017. Plasma

Next shot.
Add 1 ms to the prefill.

Aug 23 2005 01:02:39:337PM1050823018Bill Rowan018. Plasma

Next shot,
No PCS changes
Aug 23 2005 01:19:20:430PM1050823019Bill Rowan019. Plasma

Next shot
No PCS changes

Aug 23 2005 01:33:41:463PM1050823020Bill Rowan020. Plasma

Next shot,
Reloac shot 1050823013
Aug 23 2005 01:46:02:230PM1050823021Bill Rowan021. Plasma
IP = .6 MA
nel04=0.6e+20 before H-mode

Next shot.
No PCS changes

Aug 23 2005 02:02:20:370PM1050823022Bill Rowan022. Plasma

Next shot.
No PCS changes

Aug 23 2005 02:11:08:743PM1050823023Bill Rowan023. Plasma

Next shot.
No PCS changes

Aug 23 2005 02:21:59:243PM1050823024Bill Rowan024. Plasma

Next shot.
No PCS changes

Aug 23 2005 02:37:08:540PM1050823025Bill Rowan025. Plasma

Next shot.
Add 1 ms to the prefill

Aug 23 2005 03:01:09:057PM1050823026Bill Rowan026. Plasma

Next shot,
Load shot 1050823005

Aug 23 2005 03:15:19:073PM1050823027Bill Rowan027. Plasma

Next shot.
No PCS changes.

Aug 23 2005 03:26:32:760PM1050823028Bill Rowan028. Plasma

Next shot,
RF off for ohmic shots

Aug 23 2005 03:36:28:103PM1050823029Bill Rowan029. Plasma

Next shot.
RF on

Aug 23 2005 03:50:02:260PM1050823030Bill Rowan030. Plasma

Next shot,
RF off. Ohmic shot
Aug 23 2005 04:12:53:197PM1050823031Bill Rowan031. Plasma

Next shot.
Ohmic shot
Aug 23 2005 04:12:24:057PM1050823032Bill Rowan032. Plasma.
Ohmic

Next shot
Load from 1050823001

Aug 23 2005 04:28:28:133PM1050823033Bill Rowan033. Plasma
Ohmic

Next shot.
Load from 1050823013
Aug 23 2005 04:42:31:213PM1050823034Bill Rowan034. Plasma.
Ohmic.

Next shot.
Load from 1050823020

Aug 23 2005 04:49:07:010PM1050823035Bill Rowan035. Plasma
Ohmic.
Marfing discharge

Last shot.

Engineering Operator Comments
ShotTimeTypeStatusComment
109:07:48:657AMPlasmaOk
209:20:24:220AMPlasmaOk
309:38:39:860AMPlasmaOk
409:51:16:783AMPlasmaOk
510:10:53:157AMPlasmaOk
610:23:33:077AMPlasmaOk
710:36:12:407AMPlasmaOk
810:49:02:733AMPlasmaOk
911:01:23:533AMPlasmaOk
1011:15:07:260AMPlasmaOk
1111:28:12:540AMPlasmaOk
1211:41:00:210AMPlasmaOk
1311:54:17:883AMPlasmaOk
1412:06:49:573PMPlasmaOk
1512:19:31:323PMPlasmaOk
1612:31:54:323PMPlasmaOk
1712:44:51:103PMPlasmaOk
1812:58:44:480PMPlasmaOk
1901:11:27:930PMPlasmaOk
2001:24:31:103PMPlasmaOk
2101:38:20:650PMPlasmaOk
2201:50:58:570PMPlasmaOk
2302:03:48:680PMPlasmaOk
2402:16:35:870PMPlasmaOk
2502:29:27:667PMPlasmaOk
2602:47:59:353PMPlasmaOk
2703:02:49:777PMPlasmaOk
2803:16:20:930PMPlasmaOk
2903:28:57:027PMPlasmaOk
3003:41:45:807PMPlasmaOk
3103:54:22:837PMPlasmaOk
3204:06:57:337PMPlasmaOk
3304:20:09:260PMPlasmaOk
3404:33:56:087PMPlasmaOk
3504:46:36:633PMPlasmaOk