| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Bruce Lipschultz |
| Physics operator(s): | Steve Horne |
| Engineering operator(s): | Vinny Bertolino |
| Engineering Operator Run Comment |
| RF Heating |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:11:007PM |
| Author: To Be Determined |
| Run of 940607 Physics Operator - Steve Horne Session Leader - B. Lipschultz Engineering - V. Bartolino This run is based on Mini Proposal 37: Effect of Divertor Geometry on Divertor Detachment Goals: (1) Repeat 10/93 cases of detachment to determine if anything has (changed (baseline measurement). (2) Obtain a much better 'shapshot' of detachment with new diagnostics. (3) Try to obtain 'steady-state' local detachment over the outer divertor face. (4) Start process of moving the strike point and detailing effect on detachment threshold, extent and characteristics. This run ended up being a discharge development run for the most part. We spent most of the day chasing after problems: The upper x-point continues to be a problem. The inner and outer gaps can be kept to of order 1.5 to 2cm however, the gap to the lower part of the antenna limiter is not calculated and so is a concern. Yuichi reports that when the plasma diverts, the signals on the antenna probes at the top and midplane drop. However, the antenna probe near the bttom of the antenna does not drop very much. Another concern is the position of the lower x-point. Last fall the x-point (lower) z was ~ -41 cm. Now we get positions that vary from -40 to -38 and moving during the shot. There is also a problem with the length in time that we are able to achieve diversion. During this run we did not try to start pulling the lower x-point earlier than 600 ms. Given all the other concerns this was not attempted. At the time of diversion, there has been a consistent problem with the vertical position - an oscillation of the vertical position that can be as large as 6 cm. We tried briefly to fix this by slowly upping the gain on the feedback for the x-point position and the inner wall gap. This did not seem to help but there were alot of other things going on. It may be that moving the diversion time earlier will get rid of this problem. In summary, we made some progress in getting better divertor plasmas but there is a lot of work to do. We observed some of the symptoms of detachment but are concerned that the quality of the diverted plasma was keeping us from achieving proper detachment. The divertor diagnostics seem to be coming together: the scanning probe is consistently working, the divertor gas system is dependable... The best shots were 11,17,19,21,22,23,24. The shot by shot summary follows: Shot 1: Set up repeat of shot 940607023. This shot was the best diverted shot so far in the new run period. This was successful. The plasma appears to be somewhat diverted with strike points on the nose of the divertor. Disrupts at .8 seconds. Shot 2 disrupted arlier. no real improvement in elongation shot 3: Disrupted before 600 ms. Will return to shot 1 setup with less gas. shot 4: better, shot does not disrupt. This shot had the outer strike point down near probe 5 on the outer divertor but there is little current because the plasma is being scraped off on the antenna limiter. Will try to make some more improvements - turn on the z control of the x-point and reduce the gap to the inner wall. shot 5: this one also made it all the way to inversion. The strike point location was again pretty good but the position was still aginst the antenna limiter. The z-control worked slightly, will increase the gain for the next shot. Will also try to keep the density more constant. shot 6: very similar, changes made had very little effect. Will try additional gain for the x-point z position and the inner gap. shot 7: Not much improvement. Even though the outer gap is increasing, there is no improvement in the divertor plasma. Steve will try to pull the upper x-point out of the vessel Shot 8: double null or at times single-null at top. Will change to pull single null at bottom shot 9: some initial gas into private flux region with little effect. Did a little better on getting rid of the upper x-point but still nees a lot of work. Scanning probe will be fired on next shot. shot 10: x-point back at the bottom. Probe movement successful. shot 11: Position pretty good. On this shot we get some sort of divertor rearrangement at ~ 720 ms. This appeas on the probes and the UV bolos. shot 12: Disruption @ .6 seconds, density too low shot 13: Disruption @ .56 sec, reload shot 11. shot 14: Disruption @ .56 sec. Try to bring in feedback a little slower shot 15: power supply dud shot 16: disruption shot 17: good plasma, (reload of shot 10) shot 18: disruption at .55 sec, divertor gas puff quite high with resultant quick density rise. shot 19: good shot, divertor gas puffing brings the density 1.3e20 nebar. The strike points continues to move the entire time. shot 20: density disruption at .73 sec. nebar=1.6e20. shot 21: longer pulse, possible localized detachment at outer divertor. Delay the divertor gas pulse next shot to allow equilibrium in divertor before density rise. shot 22: gas pulse delayed until well into diverted (mixture of double-null and single null). Again there seems to be a localized detachment. shot 23: shortened the divertor gas pulse from 200 to 100 ms to reduce the density rise and possibly get rid of disruption. Steve will try to increase the inner and outer wall gaps as well as move the upper x-point out of the machine. We do appear to get detachment on this shot (760 ms). However, the signature is weak on the divertor probes, the extent of detachment is up to probe 4, not probe 7, the density in the main plasma does not take off afterwards. The divertor bolos all drop in signal intensity. shot 24: divertor gas pulse did not go so low density. Shot went to the end without disruption. Scanning probe got a nice scan of the SOL and the MACH probe shows some flow. The next shot we will try to tweak the position and get the divertor gas puff going. shot 25: Disruption at .58 seconds due to the vertical oscillation. |
| Physics Operator Summaries |
| Entered: Jul 7 2004 04:36:51:710PM |
| Author: To Be Determined |
run 940609 Blip (sl) Horne (po) MP 39 We began with shot 940607023 and got plasma the first shot. This shot has an incipient upper xpoint which we need to remove. The strategy was to run EFIU more positive, compensate the br due to that with ef2u. The net result should be to flatten out the flux contours above the plasma and to reduce the triangularity and elongation. As a result of these changes a vertical bounce developed between .5 and .6 seconds which was only 2 cm on shot 10, but increased dramatically on later shots. Shot 14 was a reload of shot 11, which died at the bounce. Shot 17 was a reload of shot 10, which also died. Unknown to the P.O., the ninja system was puffing more or less gas, at various times including before this vertical bounce. From shot 19 on the puff was delayed, and the plasma flattop extended to 1.2 sec to allow more time for the effects of the puff to be observed. Probably shots 10, 11, or 23 (if you want a 1.2 sec flattop) are good shots to load from this run. Shot 25 had an asymmmetric plasma current controller (shot died becfore the assymetry came into play, though) which might be a way to make that upper xpoint less sensitive to the flux evolution changes due to gas puffing. The only shot today which failed to run was due to a problem with OH2 U during precharge. No duds, No fizzles. shot 1 load 940607023, gas at 1.1e-5 Plasma. 2 Remove Lukes gas glitch. -1000 A on ef2u, extended P gain +1000 A on ef1U. Objective is to reduce elongation and triangularity. Plasma 3 Small change to gas programming -- reduce late. died early 4 Reloaded shot 1, reduced gas. Full shot. 5 zxl p on at .6 clearin programming reduced from .01 to .005 from .6 0n Full shot. The inner gap obediently changed .5 cm. ZXL drifts, but not as much as shot 4. 6 Reduce gas a bit Raise zxl p from 1 to 3 clearin programming reduced from .005 to zero from .6 sec Reduce rcur by .5 cm to try to get better outer gap. 7 rcur in .5 cm clearin in .5 cm zxl p gain from 3 to 5 Long shot, xrays at end. 8 Add some gas in middle, +400 A in ef1u - about 500 programmed in ef2u -- P gain change to 1. from 0. 250 A in ef2u would cancel br due to ef1 change. zxl gain from 5 to 9.9. Long shot; zxl on a_out looks better -- error reduced; Efit shows shot was a nice double null. 9 drop gas a bit; r_xl to -.005 from -.01 Drop exl ef2u controller from 4.e-3 to 1.e-3. Reduce ef1u current slightly. It seems to be dominating the other controllers. 10 tweak ef1u late (tiny change) ef2 L drawn to -3000 A (based on shot 5.) Very nice shot. Upper xpoint not as incipient. 11 ef4 U current programming flat-top extended -- help to buck ef2 change. ef1U frrom +400 to + 450 -- move that xpoint further. rxl gain dropped from 5 to 4 plasma 12 ef4 extendef further gas drop after 500 msec clearin from -.005 to 0 rxl gain from 4 to 3 Plasma, died early -- killed by the vertical glitch that's been accompanying the ef1u programming changes. 13 gas back approx as shot 11 ef1u early (500 msec) made a bit more + -- now ramos 350 to 450 A. Died at same time. Time for EFIT to come up approx = cooling time. Allows negligible free thinking time. Need to speed up efit somehow. 14 Reload shot 11, refigure tweaks from there. Just like 13 -- checked, did do the load. 15 step rxl and zxl to bring them in more gently. "Bad Shot" -- power supplies failed before t=0. 16 short, presumably same problem. Looks very different from shot 16, even earlier than any change we made. 17 reload shot 10. Plasma, but coil currents are significantly different. even before n The vertical wiggle at .5 or so is 6 cm, compared to 2 cm on shot 10. ef2u currents more like drawn than were on shot 10. 18 z_xl to -1.5; change drawn ef2u to be more like shot 10 Short -- probably lost at same place. 19 try stepping gain on ef2u more gently. Have just been informed that gas puffing in divertor changed significantly between shots 10 and 17, Put DGP back to as it was on shot 10. (Actually not completely -- was at 550 on 10, moved to 450 for shot 19.) (Discovered this after shot 20.) Complete shot. That was it. 20 change ef1's in ip controller from -1.6e-4 to -2.e-4, to try to keep them more +. Disruption, but after the bounce. Probably density limit. 21 plasma flat top increase 200 msec . Very sim to 20. 22 no magnetics change; reduce DGP. Disrupts at 1.18 or so. 23 more + on ef1u, reduce DGP pulse length. Change IP controller to reflect 1.2 sec flat top. complete shot. 24 clearin to +.5 cm, ef1u 50 A more + gas puff reduced to affect density at .5 sec. Nice long shot. 25 ADJUST IP CONTROLLER ASYMMETRICALLY!! ef1 u more negative from -2.e-4 to -3.e-4 at .6 sec, to try to keep that upper xpoint farther away. Lost it on the vertical bounce. |
| Session Leader Comments | |||
| Jun 9 1994 09:20:26:760AM | Bruce Lipschultz | Session leader: B. Lipschultz
Physics operator: Steve Horne Engineering op: V. Bartolino Mini-proposal # 39: Effect of Divertor Geometry on Divertor Detachment Goals: (1) Repeat 10/93 cases of detachment to determine if anything has (changed (baseline measurement). (2) Obtain a much better 'shapshot' of detachment with new diagnostics. (3) Try to obtain 'steady-state' local detachment over the outer divertor face. (4) Start process of moving the strike point and detailing effect on detachment threshold, extent and characteristics. Shot 1: Repeat of shot 940607023. This shot was the best diverted shot so far in the new run period. This was successful. The plasma appears to be somewhat diverted with strike points on the nose of the divertor. Disrupts at .8 seconds. Horne will try to reduce elongation and upper triangularity (push x-point out of chamber). | |
| Jun 9 1994 09:42:50:500AM | Bruce Lipschultz | Shot 2: shot still has problems. Alot of shaking up and down and 'stuff'
going in the plasma. Will try to lower the gas and steady the position. | |
| Jun 9 1994 09:56:54:000AM | Bruce Lipschultz | Shot 3: shot still has problems. Disrupted even earlier. Reload shot 1 with
lower gas. | |
| Jun 9 1994 10:17:43:090AM | 940609004 | Bruce Lipschultz | Shot 4: shot much better, makes it through inversion. The inner and outer gaps
are fine after 600 ms. The strike point location is fairly far down the divertor plate bu the outer gap is not large enough. For the next shot turn on the controller for the x-point z position. |
| Jun 9 1994 10:31:58:370AM | 940609004 | Bruce Lipschultz | Shot 5: again ok, makes it through inversion. The inner gap was reduced
by the change in clearin to 2 cm. The outer gap is similar. Steve will reduce the plasma radius on the next shot in order to pull it off the antenna limiter properly. The z feedback on the x-point worked a little bit, Steve will turn up the gain on that. |
| Jun 9 1994 10:58:43:890AM | 940609006 | Bruce Lipschultz | Shot 6: again ok, changes made had little effect. Will turn up the gains
on the x-point z-position and the inner wall gap for the next shot. |
| Jun 9 1994 11:17:52:090AM | 940609007 | Bruce Lipschultz | Shot 7: still slight improvements on plasma position. Even though the
outer gap is getting better, the divertor plasma is not getting denser. Perhaps the upper x-point is pulling to much plasma north. Steve will work on that. |
| Jun 9 1994 11:54:58:920AM | 940609008 | Bruce Lipschultz | Shot 8: double null or at times single-null at top. Will change to pull
single null at bottom . |
| Jun 9 1994 12:10:01:240PM | 940609009 | Bruce Lipschultz | shot 9: some initial gas into private flux region with little effect. Did a
little better on getting rid of the upper x-point but still nees a lot of work. Scanning probe will be fired on next shot. |
| Jun 9 1994 12:35:55:350PM | 940609010 | Bruce Lipschultz | shot 10: x-point back at the bottom. Probe movement successful.
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| Jun 9 1994 12:58:09:160PM | 940609011 | Bruce Lipschultz | shot 11: Position pretty good. On this shot we get some sort of divertor
rearrangement at ~ 720 ms. This appeas on the probes and the UV bolos. |
| Jun 9 1994 01:06:14:030PM | 940609012 | Bruce Lipschultz | shot 12: Disruption @ .6 seconds, density too low.
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| Jun 9 1994 01:20:32:520PM | 940609013 | Bruce Lipschultz | shot 13: Disruption @ .56 sec, reload shot 11.
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| Jun 9 1994 01:38:41:430PM | 940609014 | Bruce Lipschultz | shot 14: Disruption @ .56 sec. Try to bring in feedback a little slower
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| Jun 9 1994 01:55:34:240PM | 940609015 | Bruce Lipschultz | shot 15: power supply dud
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| Jun 9 1994 02:15:05:250PM | 940609015 | Bruce Lipschultz | shot 15: power supply dud
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| Jun 9 1994 02:17:04:500PM | 940609016 | Bruce Lipschultz | shot 16: disruption.
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| Jun 9 1994 02:33:25:140PM | 940609017 | Bruce Lipschultz | shot 17: good plasma, (reload of shot 10)
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| Jun 9 1994 02:53:54:340PM | 940609018 | Bruce Lipschultz | shot 18: disruption at .55 sec, divertor gas puff quite high with
resultant quick density rise. |
| Jun 9 1994 03:21:15:370PM | 940609019 | Bruce Lipschultz | shot 19: good shot, divertor gas puffing brings the density 1.3e20 nebar.
The strike points continues to move the entire time. |
| Jun 9 1994 04:12:20:310PM | 940609021 | Bruce Lipschultz | shot 21: longer pulse, possible localized detachment at outer divertor.
Delay the divertor gas pulse next shot to allow equilibrium in divertor before density rise. |
| Jun 9 1994 04:27:33:660PM | 940609022 | Bruce Lipschultz | shot 22: gas pulse delayed until well into diverted (mixture of double-null
and single null). Again there seems to be a localized detachment. |
| Jun 9 1994 04:41:22:430PM | 940609023 | Bruce Lipschultz | shot 23: shortened the divertor
gas pulse from 200 to 100 ms to reduce the density rise and possibly get rid of disruption. Steve will try to increase the inner and outer wall gaps as well as move the upper x-point out of the machine. We do appear to get detachment on this shot (760 ms). However, the signature is weak divertor probes, the extent of detachment is up to probe 4, not probe 7, the density in the main plasma does not take off afterwards. The divertor bolos all drop in signal intensity. |
| Jun 9 1994 05:04:25:650PM | 940609024 | Bruce Lipschultz | shot 24: divertor gas pulse did not go so low density. Shot went to the
end without disruption. Scanning probe got a nice scan of the SOL and the MACH probe shows some flow. The next shot we will try to tweak the position and get the divertor gas puff going. |
| Physics Operator Comments |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 08:58:08:750AM | Plasma | Ok | no faults |
| 2 | 09:21:09:270AM | Plasma | Ok | no faults |
| 3 | 09:40:26:740AM | Plasma | Ok | no faults |
| 4 | 09:58:36:130AM | Plasma | Ok | oh1 comm fault in inversion |
| 5 | 10:17:49:290AM | Plasma | Ok | no faults |
| 6 | 10:36:00:710AM | Plasma | Ok | no faults |
| 7 | 11:00:01:480AM | Plasma | Ok | no faults |
| 8 | 11:27:06:070AM | Plasma | Ok | no faults |
| 9 | 11:53:54:190AM | Plasma | Ok | no faults |
| 10 | 12:14:21:780PM | Plasma | Ok | no faults |
| 11 | 12:36:44:290PM | Plasma | Ok | no faults |
| 12 | 12:54:42:080PM | Plasma | Ok | no faults |
| 13 | 01:14:38:800PM | Plasma | Ok | no faults |
| 14 | 01:27:06:230PM | Plasma | Ok | another 600 kA disruption at 0.6 sec |
| 15 | 01:41:16:510PM | Plasma | Bad | OH2U failed during charge; strange failure |
| 16 | 01:54:42:240PM | Plasma | Ok | another 600 kA disruption |
| 17 | 02:13:07:130PM | Plasma | Ok | nice shot with 0.5 sec at 600 kA; terminates at 85 kA |
| 18 | 02:35:01:250PM | Plasma | Ok | a 600 kA disruption |
| 19 | 02:55:07:860PM | Plasma | Ok | No faults. |
| 20 | 03:21:08:280PM | Plasma | Ok | another 550 kA disruption |
| 21 | 03:48:37:780PM | Plasma | Ok | 600 kA disruption at 1.1 seconds |
| 22 | 04:12:20:290PM | Plasma | Ok | 600 kA disruption at 1.15 seconds |
| 23 | 04:28:25:550PM | Plasma | Ok | good shot, no faults |
| 24 | 04:48:55:210PM | Plasma | Ok | nice shot; over 1.4 seconds; terminated at less than 50 kA |
| 25 | 05:03:31:310PM | Plasma | Ok | 600 kA disruption at 0.6 seconds |