Miniproposals

Miniproposal: Date Filed: Title: First Author: Session Leader: Steve Horne (shots 1-27)

Engineering Operator Run Comment

silva has the con

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Physics Operator Summaries

Entered: Jul 7 2004 04:36:51:397PM

Author: To Be Determined

Physics Operator Summary for 5/20/94 (Part II: shots 13-27) MP 041 (again) SL: Horne PO: Wolfe EO: Fairfax Granetz will (maybe already has) written the report for the morning. These runs are so frustrating that sharing the pain is a necessity. BP coils continued to be an endangered species. Just prior to my taking over the PO chair for shot 13, a mass swap of BP coils removed from the hybrid all of the coils coming from D-bottom. On shot 13, which ran for about half a second, BP26_BC, which had just been reconnected, died. It was replaced with BP26_GH for shot 14. Shot 13 also uncovered a very unpleasant PCS bug. Wire 8 had had, several shots earlier, an unused RCUR on it, and had been changed to a KAPPA predictor. Before shot 13, the drawn waveform for KAPPA was zeroed; it had been the same as RCUR(1) because of vertical linking. However, it turns out that even though the name on the wire had changed, the link still pointed to the RCUR (wire 1) waveform, so when we zeroed the KAPPA it actually zeroed (or set to its minimum limit of 0.44) the RCUR. The resulting shot was hard up on the inner wall. Josh has now fixed this bug, but did not put up the new code during the run. A patch that worked was to manually load a valid signal into the wire 8 node in place of the reference to wire 1. Subsequent shots used an RCUR waveform pasted in from SEGment 2. Shots 14-19 were fizzles, and a few duds. Attempts to play with the null seemed to be getting nowhere, so finally we reloaded shot 11, and recalculated all the magnetics predictors to pick up the new BP coils. Shot 20 ran well for 600+msec. Note that sometime before shot 11 the offset of 18000 on RXL was removed. I left it off for shot 20 and all subsequent shots. Shot 21 fizzled, possibly due to too much H20 and CO left around from 20. Shot 22 ran for 650msec. The only change from 20 was to try to increase the gas puff after 400 msec, because the density was falling like mad after the plasma diverted. This shot also had falling density. Shots 23-26 were fizzles (24 was a dud). Various tweaks were made to the null and fill pressure. Shot 27 had a -15A tweak to EF4, relative to 22, and P=1.0e-5. This ran well, probably the best shot of the day. The RXL was drawn to zero for the whole shot, rather than stepping in by 1cm. The gas puff was increased after 400msec, and the density actually was close to flat. Elongation was over 1.65, with good clearance in and out. Shot died at 590msec with an upward VDE, but the plasma had disrupted before the VDE. Reason was not clear, but radiation increased prior to the disruption; H-alpha showed a lot of activity during the preceding 20-40 msec. Horne wants to declare MP#041 done. IMHO the primary goal of this miniproposal, well controlled plasma suitable for the general physics program, has not been met. However, it is perhaps time to start doing some physics tasks that are compatible with the present state of things, and try to get the remainder of the problems worked out as we go. Run s in the near futureshould operate with lower ZCUR to reduce the elongation and hopefully improve vertical stability; I recommend going back to -2cm. Work needs to be done on the current ramp down, but today we weren't making it to the rampdown, so we couldn't do anything about it. One problem is that we aren't pulling off the inner wall until .4sec. Formerly, we diverted much earlier, around 200-250msec, but now we are running the centroid further inboard and we haven't gotten CLEARIN to bring it off the wall until later in the discharge. The big problem this week has been fizzles and duds. Today we had 9 useable plasmas out of 27 shots. The fizzles may be attributable to cleanliness problems but the duds are a real puzzle, as the nulls look essentially identical to shots that go. With luck, things will improve next week.

Entered: Jul 7 2004 04:36:51:427PM

Author: To Be Determined

Physics operator's summary for the first half of run 940520 SL: S. Horne PO: R. Granetz/S. Wolfe EC: V. Bertolino Plasma operation picked where we left off yesterday. All plasmas had Ip=0.80-0.85 MA and were lower x-point diverted. We got into a very regular pattern of alternating fizzles and plasmas, with all the plasma shots ending in disruptions during the flattop. Most of these disruptions were the result of high elongation (kappa=1.65-1.67), which we are trying to control with current programming of EF2U and EF1U. During the run, we played with the CLEARIN control, which now seems to be trying to do the correct thing, although there's a significant offset. We also resurrected Ian's old KAPPA predictor, to test it out. At the end of my part of the run, no conclusions had been made about it. The run was plagued with further failures of the magnetics, with all but one problem related to the feedthroughs at the D-bottom port. This is the other flange that was connected up during my absence, apparently no better than B-bottom was. By halfway through the run, all hybrid inputs that had used BP_DE's were changed to BP's at other quadrants/ports. Even with this action, there was apparently one intermittant problem with one of the BP_BC's, which had been secured during the vacuum break on Monday. These Amphenol connectors truly bite the big one, and it's really having a very bad impact on machine operation. Because the plasma current rogowskis come out D-bottom, that flange will probably have to be opened up and the connectors screwed on properly at some point in the not too distant future. There also seemed to be an appreciable number of problems with camac data acquisition on the engineering, magnetics, and perhaps other crates. Statistics: 5 plasmas 7 fizzles 0 duds 0 engineering problems ? several data acquisition problems

Session Leader Comments

Physics Operator Comments
May 20 1994 09:37:56:960AM	940520001	Robert Granetz	Start with last shot from yesterday. On those last few shots, the null was being tweaked, so we may have to continue doing some of that. This morning I swapped a couple of hybrid BP inputs: BP17_DE --> BP17_JK and BP25_DE --> BP25_BC
May 20 1994 09:38:53:580AM	940520001	Robert Granetz	Fizzle. Next shot, lower pre-fill from 1.2 to 1.0e-5 and go again.
May 20 1994 09:55:19:890AM	940520002	Robert Granetz	Plasma. Ip=0.80 MA, duration=0.57 s. Density went too high (nl=1.33e20). Joe Snipes reports there was a locked mode. Disruptions started at 0.432 s. Position was finally lost at 0.468 s, after most of the thermal energy was lost. Next shot, reduce gas puff. Also change EF1U&L current programming in an effort to get better D-shaping.
May 20 1994 10:22:54:460AM	940520003	Robert Granetz	Fizzle. Next shot, lower EF4 by 15 amps (BZ by -1 mT). Also, the TRAQ_1 digitiser of the magnetics didn't trigger. This may have also happened on shot 2.
May 20 1994 10:48:04:360AM	940520004	Robert Granetz	Plasma. Ip=0.86 MA, duration=0.67 s. VDE upwards. Next shot, increase EF1U demand a little after 0.2 s.
May 20 1994 10:58:24:530AM	940520005	Robert Granetz	Fizzle. Next shot, lower EF1U programmed demand.
May 20 1994 10:59:32:780AM	940520005	Robert Granetz	Upward VDE was due to excessive elongation.
May 20 1994 11:17:56:000AM	940520006	Robert Granetz	Plasma. Ip=0.85 MA, duration=0.60 s. Density drops too much late in the shot. VDE upwards due to excessive elongation. Next shot, move CLEARIN to start at 0.4 s, and increase pulse gas after 0.2 s.
May 20 1994 11:18:55:110AM	940520006	Robert Granetz	Also for next shot raise pre-fill from 1.0 to 1.2e-5
May 20 1994 11:32:37:020AM	940520007	Robert Granetz	Fizzle. We're in the alternating pattern...maybe something to do with disruption recovery. Next shot, change programmed demand of EF2U from -3 kA to -3.5 kA, in a ramp-like fashion.
May 20 1994 11:43:02:510AM	940520008	Robert Granetz	Fizzle again. Next shot, reduce pre-fill from 1.2 to 1.0e-5
May 20 1994 12:04:24:710PM	940520009	Robert Granetz	Plasma. Ip=0.85 MA, duration=0.56 s. Moving CLEARIN earlier seemed to have little or no deleterious effects, and may actually be trying to do the right thing. Density starts falling quickly at t=0.4 s, which is also when the plasma becomes diverted. Plasma shaping is improving, but we are still reaching elongations of 1.67, resulting in loss of vertical control. Next shot, increase early pulse gas (but not the first data point) and put another -500 amp change on EF2U current demand.
May 20 1994 12:17:17:400PM	940520010	Robert Granetz	Fizzle. Next shot, no changes. But, we have loaded Ian's KAPPA predictor into wire 08, which is not being used, just to check it out.
May 20 1994 01:11:30:910PM	940520011	Robert Granetz	Plasma. Ip=0.85 MA, duration=0.58 s. Shaping is getting better. Another BP coil went bad, BP18_DE, which is also on D-bottom. Before the next shot, we opened the cell and swapped away all DE coils: BP18_DE --> BP18_BC BP19_DE --> BP19_JK (BC might still be flaky) BP24_DE --> BP24_BC BP26_DE --> BP26_BC No other changes for next shot.
May 20 1994 01:17:02:680PM	940520012	Robert Granetz	Fizzle.
May 20 1994 01:17:26:370PM	940520012	Robert Granetz	I'm handing over the physics operator reins to Steve Wolfe.
May 20 1994 01:53:22:860PM	940520013	Steve Wolfe	940520013: Shot ran to .45 or so BP26_BC, which was just put back into the hybrid, has now died. Plasma was inside the whole time - PCS bug : the kappa (8)was still linked to RCUR(1)
May 20 1994 02:07:09:770PM	940520014	Steve Wolfe	940520014: Redrew the RCUR (actually pasted from SEG2) Put BP26_GH into the hybrid, and recalled all relevant algs. Result: fizzle
May 20 1994 02:16:55:610PM	940520015	Steve Wolfe	940520015: Double the P gain on ICEF2U to try to get more pull from there. Result: This one is a fizzle Maybe the EF2U gain screwed up the null a little. Should have only made the change late.
May 20 1994 02:29:01:130PM	940520016	Steve Wolfe	940520016: Double the P gain on ICEF2U after .16sec to try to get more pull from there. Result: A dud. Something is broken!
May 20 1994 02:41:26:740PM	940520017	Steve Wolfe	940520017: -15A on EF4 (-1020 to -1035) Result: fizzle. breaks down at 5msec.
May 20 1994 02:58:19:400PM	940520018	Steve Wolfe	940520018: Another -15A on EF4 (-1035 to -1050) Result: Another fizzle
May 20 1994 03:04:58:830PM	940520019	Steve Wolfe	940520019: Back off on EF1's by 100a (-4500 to -4400) before commutation Result: Another fizzle. Looks thge same.
May 20 1994 03:11:53:910PM	940520019	Steve Wolfe	940520019: Back off on EF1's by 100a (-4500 to -4400) before commutation Result: Another fizzle. Looks thge same.
May 20 1994 03:28:31:890PM	940520020	Steve Wolfe	940520020: Reload shot 11 and recalc algs. Note: there was no offset on RXL Result: Finally, a plasma. LAsts till 600msec. Has a low density problem after 400msec
May 20 1994 03:34:05:320PM	940520021	Steve Wolfe	940520021: Extend gas puff till 600+msec Result: Fizzle. Noted the H20 and mass 28 (CO ?) were very high after the last plasma and had not come down much.
May 20 1994 03:54:43:310PM	940520022	Steve Wolfe	940520022: No change except lengthen John Rice's Ar pulse. Result: Plasma. Lasts till 650msec or so , dies vertically
May 20 1994 04:01:33:630PM	940520023	Steve Wolfe	940520023: INcrease ZXL gain at 450msec from 4 to 8. Result: dud
May 20 1994 04:10:41:800PM	940520024	Steve Wolfe	940520024: INcrease ZXL gain at 450msec from 4 to 8. Raise pressure to 1.2e-5 Gas puff increased after 400msec. Result: another dud.
May 20 1994 04:24:46:060PM	940520025	Steve Wolfe	940520025: INcrease ZXL gain at 450msec from 4 to 8. (done earlier) Raise pressure to 1.2e-5 (done last shot) Gas puff increased after 400msec. (done last shot) Redraw RXL to zero for whole shot Make EF4 more negative by 30 A (to -1050) : Bz was everywhere positive Result: fizzle
May 20 1994 04:39:17:870PM	940520026	Steve Wolfe	940520026: INcrease ZXL gain at 450msec from 4 to 8. (done earlier) Gas puff increased after 400msec. (done last shot) Redraw RXL to zero for whole shot Make EF4 more negative by 30 A (to -1050) : Bz was everywhere positive Drop gas back to 1.0e-5 Result: Another fizzle.
May 20 1994 04:49:37:260PM	940520027	Steve Wolfe	940520027: INcrease ZXL gain at 450msec from 4 to 8. (done earlier) Gas puff increased after 400msec. (done last shot) Redraw RXL to zero for whole shot Drop gas back to 1.0e-5 Make EF4 more positive by 15a, (-1050 to -1035) Result: A good shot to leave on the drum

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	09:22:49:900AM	Plasma	Ok	silva in control
2	09:33:18:760AM	Plasma	Ok	good shot
3	09:56:12:890AM	Plasma	Ok	ok
4	10:23:22:800AM	Plasma	Ok	comm.fail oh2l
5	10:45:52:720AM	Plasma	Ok	nopl
6	11:00:02:880AM	Plasma	Ok	plasma comm fail oh2l
7	11:20:02:420AM	Plasma	Ok	no pla
8	11:34:10:060AM	Plasma	Ok	nopla
9	11:46:55:860AM	Plasma	Ok	plasma
10	12:05:58:200PM	Plasma	Ok	nopla
11	12:19:41:420PM	Plasma	Ok	plasma
12	01:11:17:820PM	Plasma	Ok	nopla
13	01:21:16:380PM	Plasma	Ok	800 kA disruption; no faults
14	01:55:34:890PM	Plasma	Ok	Fizzle;
15	02:09:58:150PM	Plasma	Ok	Fizzle again
16	02:20:51:920PM	Plasma	Ok
17	02:33:18:280PM	Plasma	Ok	4 fizzles in a row
18	02:46:07:480PM	Plasma	Ok
19	03:00:48:230PM	Plasma	Ok
20	03:14:14:070PM	Plasma	Ok	800 kA disruption; 4 diverter shunts saturated hard
21	03:30:42:670PM	Plasma	Ok	fizzle
22	03:41:47:640PM	Plasma	Ok	800ka disrupt
23	03:55:29:490PM	Plasma	Ok
24	04:07:35:310PM	Plasma	Ok
25	04:19:28:890PM	Plasma	Ok	Fizzle
26	04:31:25:300PM	Plasma	Ok	Fizzle; TF inverting slighlty harder
27	04:47:03:100PM	Plasma	Ok	Another 800 kA disruption.