Miniproposals

Miniproposal: 355 Date Filed: 11/12/2003 Title: ICRF Testing & Conditioning First Author: Steve Wukitch Session Leader: Yijun Lin (shots 1-35)

Engineering Operator Run Comment

Continued recovery from vacuum opening and Ti dust Nominal MP #355: ICRF

Session Leader Plans

Physics Operators Plans

Entered: May 26 2005 04:25:22:883PM

Author: Steve Wolfe

Engineering setup for Friday, May 27, 2005 Continued recovery from vacuum opening and Ti dust Nominal MP #355: ICRF Conditioning Possible piggyback: MP#419 Wall pumping (Blip) Session leader: S. Wukitch, Y. Lin Physics operator: wolfe Overnight ECDC in D2, 2.e-4 torr; Bake at 60 C. Run begins at 09:00 and ends at 17:00. Power systems as on 1050526028 (1.05 MA, 5.4 T upper null plasma) 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 Hybrid DISABLED (PG1) leave B-side upper with whatever Hybrid disabled fill B-main (C-side) with 40 psi D2 Hybrid enabled (PG3) NINJA not used today Torvac setup: machine gate valves to remain open for first shot. We may run a gate valve closed shot during run to evaluate effective wall condition. Enable the following gate valves, assuming no vacuum problems: ECE, VUV, Z-bolo shutters Necessary diagnostics: titanium monitoring, video monitors, H/D ratio ------------------------------------------------------------------------------- ICRF Setup: All transmitters in run on at 08:30. ------------------------------------------------------------------------------- Run plan: Continue trying to bring up ICRF to reliable high power level. May try going to lower field (4.5 T) and 2 s pulse lengths to increase the RF on time in plasma. May also try limiter discharges to clean other areas of the vessel, and see if it affects the RF conditioning. On Thursday the RF was happier in Upper Null than in lower null.

Session Leader Summaries

Physics Operator Summaries

Entered: May 27 2005 05:47:52:683PM

Author: Steve Wolfe

This was a bad day. As far as I can tell, no progress was made on the RF. We ran upper null shots for #1-10, with a lot of disruptions. Shots#11-28 were inner wall limited (with small negative dsep), and also a relatively high disruptivity. We did some conditioning of fresh surfaces in both configurations, but with RF on the density is still uncontrolled. J ran reliably at 1MW most of the day, and above 2MW on a few shots when Yijun turned it up, but the associated density rise was pretty bad. Also, there were a lot of dust events not associated with the antennas in both inner wall and upper null discharges, leading to early disruptions. Startup was less robust all day (after Joe's 36 in a row, it couldn't have been better). However, the last 7 shots of the day all failed; a fizzle, 5 duds, and a final fizzle which didn't break down until 13msec. Fields were tweaked to no avail; I reloaded the supposedly "tuned up robust startup" from the end of 1050524, and that didn't help either. Most of the day I had late breakdowns (7-9msec), with a few non-reproducible exceptions, including one before 4msec. We also had some bad runaway shots. My attempts to get rid of these may have contributed to the bad startups early on, but the end of the day problem was something else. It is possible that ECDC would have helped, but by that time I felt it was too late to try it. I expect that ecdc over the long weekend will fix the breakdown problem. It would be good to understand what's going on. One possibility is that something happens to the wall or residual gas that suppresses the avalanche. The other is that somehow the disruptions are causing some structure to acquire a permanent magnetization sufficient to kill the null; of course we can't see dc fields on the magnetics, so we would be tuning in the dark. The one good thing today was that Brian exercised his probes and got them cleaned up, so they should be ready for ohmic runs next week. Scorecard: 35 shots. 24 plasmas. 5 fizzles. 6 duds. 0 System Error. (Plasma = Ip gt 50.0 kA Dud = H_alpha lt 0.40 V) Total plasma duration: 32.27 s (exceeding -118 kA)

Session Leader Comments

Physics Operator Comments
May 27 2005 07:41:38:440AM		Steve Wolfe	Load from 1050526028 (upper null in seg4) Increase seg1 pg4 from 21 to 25msec for first shot Change Br0 from -.0005 to 0.000 Leave Rcur offset at 1500, IC_EF4u at -1300 Import seg2 from 1050526008 (lower null); leave off Import seg3 from 1050405006 (limited seg3,nl04=.8); leave off (note outer gap on this was 2.2cm, may need to tweak) *** Note- Upper Null in Seg 4 to start run ***
May 27 2005 07:52:03:373AM		Steve Wolfe	For some reason, both seg2 and seg3 Ip waveforms drop from 1.05 to 1.0 between 1.3 and 1.5sec Set both to 1.05@1.5 and reload
May 27 2005 09:10:52:220AM	1050527001	Steve Wolfe	Shot#1: Program for upper null (like 1050526028) in seg4 plasma, looks like runaways, disrupted at 1.3sec Hard bounce in the startup, needs more gas, rcur offset Breakdown early (4.7ms) E-port looked good at 1.5MW, D still awful, J ok at 1MW All rf off by the disruption time, except maybe D Density still climbing to nl04=1.5e20 next shot: rcur offset to 2000
May 27 2005 09:50:39:563AM	1050527002	Steve Wolfe	Shot#2: rcur offset from 1500 to 2000, leave gas alone (instead of dropping it after disruption) First fizzle in two days! breakdown was later, 6.8msec; current got to 37msec and choked. CIII up to .01 chalk it up to the disruption and try again.
May 27 2005 09:51:06:873AM	1050527003	Steve Wolfe	Shot#3: plasma into rampdown, disrupts at 1.7 late breakdown again, 7.1msec, decent current rise, no bounce. D looks happier (.5MW), E and J doing their thing) F-side pressure still rising throughout pulse, to 1mTorr nl0 flat or slightly rising to 1.25e20 next shot: Br0 to -.3mT, seg4 pg3 puff off.
May 27 2005 09:51:47:250AM	1050527004	Steve Wolfe	Shot#4: Br0 from 0 to -.0003, seg4 pg3 puff off.No pg4 change. Early disruption .51sec, RF just turned on; injection? bd still late, 7.1ms, no bounce. Swarm of fireflies at .35sec on DANT camera next shot: ef4 10amps more negative
May 27 2005 10:02:17:307AM	1050527005	Steve Wolfe	Shot#5:ef4 from -1300 to -1310 disrupted at 1.46sec bd maybe a bit earlier, 6.8msec, slight hesitation; no bounce but there are some early hards. Bz didn't seem to change midplane pressure rises strongly starting ~1.3sec, so does pradmain. next: repeat
May 27 2005 10:11:34:040AM	1050527006	Steve Wolfe	Shot#6: plasma to about 1.75sec, still getting lots of hards. breakdown earlier this time, 5.6ms; no obvious bounce but the runaways are still bad neutral pressure rising from .6sec on this time, to 2mTorr at 1.5sec next: raise pg4 2msec
May 27 2005 10:22:47:440AM	1050527007	Steve Wolfe	Shot#7:pg4 from 25 to 27msec fizzle, bd a little later 6.2ms, slower current rise CIII, dalpha rise at 20msec next:pg4 back to 25ms
May 27 2005 10:38:15:857AM	1050527008	Steve Wolfe	Shot#8:pg4 from 27 to 25msec Disrupts at .7sec bd at 5.6 msec, current rise ok Dant camera seems to have died this time. D is faulting at 0.6MW, E at 1.5MW, J ok at ~1MW no runaways this time next shot: repeat
May 27 2005 10:47:23:400AM	1050527009	Steve Wolfe	Shot#9: fizzle. What happened to our robust startup? very early breakdown (3.6msec) next: Br0 back to 0
May 27 2005 10:59:33:067AM	1050527010	Steve Wolfe	Shot#10: Br0 from -.0003 to -0.0000 disruption at .6sec, got crowbars. breakdown back to 7msec, current rise ok Next shot: try inner wall
May 27 2005 11:23:40:527AM	1050527011	Steve Wolfe	Shot#11: Turn on seg3, inner wall from 1050405006 Note this one has nl04 programmed for 8e19, may want to decrease it later. drop pg4 from 25 to 23msec plasma full length. Bd at 6.1msec, nice current rise nl04 flat at 1.15e20 (programmed for 0.8) This one is barely limited, dsep=-2mm, right gap=2cm next shot: reduce outer gap
May 27 2005 11:38:43:350AM	1050527012	Steve Wolfe	Shot#12:rcur from .648 to .6505 plasma full length. NL04 still at 1.15e20 after 1sec Neither D or E seems happy now. J has no faults at 1MW Next: Brian will exercise probes, no PCS changes
May 27 2005 11:56:08:873AM	1050527013	Steve Wolfe	Shot#13:no PCS changes disruption at 1sec, density is rising again. J was up to 2MW this time. next shot: J back to 1MW, no other changes
May 27 2005 12:06:54:993PM	1050527014	Steve Wolfe	Shot#14:no PCS changes plasma to 1.63sec, nl04 is flat around 1.5e20 E is a little better, D still not good Lots of fireballs on the video Midplane pressure 0.2mTorr Next: Brian turns probes off. Otherwise repeat
May 27 2005 12:18:20:177PM	1050527014	Steve Wolfe	There will be a delay while a problem on the pumping stack is investigated. There will be a (hopefully) brief cell access
May 27 2005 12:39:29:950PM	1050527015	Steve Wolfe	Shot#15: plasma to 1.66 nl04 is flat at 1.6e20 next shot: try dropping the nl04 demand to 5e19
May 27 2005 12:54:05:070PM	1050527016	Steve Wolfe	Shot#16: drop nl04 demand to 5e19, which should turn off gas before .5sec plasma to 1.7sec, nl04~1.2e20 late breakdown 7.2msec; fields look the same injection at .25sec next: tweak the rampdown
May 27 2005 01:09:27:157PM	1050527017	Steve Wolfe	Shot#17:tweak the rampdown- take jog out of rxl, move rcur in faster. dud? Seem to have all the fields and gas. For some reason the BsideMain gas puff signal failed on this and the previous shot, but the ratiomatic signal is where it should be. next shot: pg4 back to 25ms
May 27 2005 01:19:55:933PM	1050527018	Steve Wolfe	Shot#18: pg4 from 23 to 25ms plasma full length; very late breakdown 10msec Bz seems to have drifted up a bit nl04~8.5e19 and flat. next: ef4 down 15A
May 27 2005 01:32:57:447PM	1050527019	Steve Wolfe	Shot#19:ef4 from -1310 to -1325 plasma full length. bd at 6.8msec nl04 rising to 1.1e20 next shot: repeat
May 27 2005 01:47:26:347PM	1050527020	Steve Wolfe	Shot#20: repeat short disruption .36sec, looks like a monster injection from the inner wall.
May 27 2005 02:07:27:417PM	1050527021	Steve Wolfe	Shot#21: lower nl04 before .5sec Another short disruption, about the same time .32sec bd at 6.2msec, startup isn't the problem, although current rise is rather slow this time. Looks like some current rise mhd and a marfe. next: just repeat and see if whatever it is burns away
May 27 2005 02:16:25:647PM	1050527022	Steve Wolfe	Shot#22: No changes, I should have raised the gas in seg3, previous was running away. plasma full length, but some runaways. nl04 still rising to 1e20 during shot. next: put nl04 back up a bit early
May 27 2005 02:24:12:957PM	1050527023	Steve Wolfe	Shot#23: put nl04 back up a bit early. Could have just put in a pg3 puff. Another short one .31sec, had runaways again. current rise too fast for Bz again. next: rcur to 2500
May 27 2005 02:40:01:017PM	1050527024	Steve Wolfe	Shot#24:rcur offset from 2000 to 2500 increase ramp rate on Ip in seg3 plasma disrupted in rampdown, 1.58sec Still has some runaways, not as bad. MHD absent. nl04 pretty flat around 8e19. next: repeat, see if it will rampdown
May 27 2005 02:55:06:493PM	1050527025	Steve Wolfe	Shot#25:repeat plasma into rampdown 1.8sec nl04 back up to 1.1e20. ECE gatevalve closed Still have some hards next: add 2ms to pg4
May 27 2005 03:09:34:307PM	1050527026	Steve Wolfe	Shot#26: pg4 from 25 to 27ms plasma full length. nl04 ramping up to 1.2e20 hards better, but startup is late? 8ms J on at 2MW this time, that's probably where the gas is coming from. D seems to work better after J is off next shot: no pcs changes, Yijun will re-program the rf
May 27 2005 03:20:49:290PM	1050527027	Steve Wolfe	Shot#27: no pcs changes, Yijun will re-program the rf Another short disruption; thought I'd fixed that. .43sec Lots of current-rise mhd again. Runaway dump around .3sec Still a late bd, around 7msec. Bz seems to have drifted down next: pg4 to 29ms
May 27 2005 03:34:21:230PM	1050527028	Steve Wolfe	Shot#28: pg4 from 27 to 29ms plasma to 1.6sec again bd at 6.6ms, almost choked D still not happy,J at 2MW between .8,1.2sec; D doesn't notice nl04~0.9e20 next: raise nl04 program to 1.2e20, see if D likes that
May 27 2005 03:42:38:150PM	1050527029	Steve Wolfe	Shot#29: raise nl04 program to 1.2e20, see if D likes that also, rcur back from .6505 to .648 (2cm gap) fizzle, should have dropped the gas? late bd again, big CIII lump next: pg4 down 2ms
May 27 2005 03:55:05:853PM	1050527030	Steve Wolfe	Shot#30:pg4 29ms to 27ms dud. br0 to -.0005
May 27 2005 04:06:22:713PM	1050527031	Steve Wolfe	Shot#31:Br0 from 0 to -.0005, pg4=27ms Another dud. It isn't Br0 load seg1 from 1050524032
May 27 2005 04:18:40:103PM	1050527032	Steve Wolfe	Shot#32:load seg1 from 1050524032 (Ian's tuned up shot) Note that this has an even shorter pg4 puff. If this one is a dud, then increase pg4 to 30msec; the lower rcur offset should rescue a slow current rise. result:dud next raise pg4 to 30msec
May 27 2005 04:30:57:900PM	1050527033	Steve Wolfe	Shot#33:raise pg4 from 21ms to 30msec Another dud. Try dropping ef4
May 27 2005 04:49:03:433PM	1050527034	Steve Wolfe	Shot#34: ef4 from -1310 to -1340 dud! There's something broken Close gv1; raise pg4 to 33msec
May 27 2005 05:00:29:480PM	1050527035	Steve Wolfe	Shot#35: Close gv1; raise pg4 to 33msec fizzle. bd at 13msec! That's all for this week.

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	09:02:25:393AM	Plasma	Ok
2	09:15:07:607AM	Plasma	Ok
3	09:27:47:133AM	Plasma	Ok
4	09:40:18:707AM	Plasma	Ok
5	09:52:44:843AM	Plasma	Ok
6	10:05:21:557AM	Plasma	Ok
7	10:18:15:660AM	Plasma	Ok
8	10:30:51:500AM	Plasma	Ok
9	10:43:15:590AM	Plasma	Ok
10	10:55:50:680AM	Plasma	Ok
11	11:16:44:373AM	Plasma	Ok
12	11:29:22:680AM	Plasma	Ok
13	11:46:23:423AM	Plasma	Ok
14	11:59:48:323AM	Plasma	Ok
15	12:33:16:187PM	Plasma	Ok
16	12:46:49:527PM	Plasma	Ok
17	01:00:08:380PM	Plasma	Ok
18	01:13:13:140PM	Plasma	Ok
19	01:27:11:417PM	Plasma	Ok
20	01:39:41:990PM	Plasma	Ok
21	01:53:41:407PM	Plasma	Ok
22	02:06:39:323PM	Plasma	Ok
23	02:19:36:537PM	Plasma	Ok
24	02:31:57:147PM	Plasma	Ok
25	02:49:18:463PM	Plasma	Ok
26	03:02:17:290PM	Plasma	Ok
27	03:15:11:603PM	Plasma	Ok
28	03:27:27:290PM	Plasma	Ok
29	03:39:50:807PM	Plasma	Ok
30	03:52:09:323PM	Plasma	Ok
31	04:04:31:057PM	Plasma	Ok
32	04:17:11:180PM	Plasma	Ok
33	04:29:28:573PM	Plasma	Ok
34	04:42:32:447PM	Plasma	Ok
35	04:54:50:137PM	Plasma	Ok