| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Steve Golovato |
| Physics operator(s): | Earl Marmar |
| Engineering operator(s): | Frank Silva,Joe Daigle |
| Engineering Operator Run Comment |
| RF Feedback Control |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:14:413PM |
| Author: To Be Determined |
Run summary - 951205 SL: Golovato PO: Marmar EO: Silva/Daigle Run 951205 - Plasma Position Feedback Goals - (1) check out and learn to use plasma position feedback to control rf loading, keeping it constant to avoid trips at h-mode transitions (2) also, nitrogen puffing at a level that does not affect shot, from inner wall using ninja system. The run was quite successful. We got the position feedback going early and moved on to H-mode studies, getting some of the best H-modes we've seen. The initial problem was to determine the approriate gain in the A-matrix to influence rcur. We had some guidance from last year, when -2500 was too much and -400 too little. Starting on shot 7 we saw evidence of the feedback in the rcur error signal. This allowed us to get the sign right. The sign convention is as follows: when loading decreases, the feedback signal goes more positive and this moves the plasma out (toward antenna) when the hybrid gain is negative. It is important to remember that there is another gain at the hybrid input which is set to -10. Finally, the zeroing of the feedback signal to set the desired loading level is done by a bira arbitrary function generator camac module. This signal moves the level higher the more negative it is and the actual voltage out is one half of what you draw. Got all that, there will be a quiz on monday. For shot 10 the gain was -3000 and the rcur followed the feedback signal, moving the plasma in and out. Shot 10 was also the first N2 puffing shot. On shot 11 we went too far with a gain of -5000. The plasma went vertically unstable when the feedback pushed it away from the antenna too far (remembering that clearin is also maintained) elongating it too mcuh. With this gain the feedback was unstable overshooting and oscillating. Ian was not pleased. We decided that it is not really necessary to push the plasma away from the antenna, we can deal with too much loading. We will alter the feedback circuit so the feedback signal will have only one sign (positive). The plasma can still be moved in and out but not out beyond zero. We accepted our punishment of 4 fizzles, reduced the gain to -2000, and started raising the power to get h-modes. Thus far we were not overlapping the rf powers and kept e-port (which controls the feedback) at 800kw. We got h-modes starting on shot 18. We found that the feedback did not keep the loading constant during h-modes but reduced the decrease sufficiently to avoid rf trips during h-mode. This allowed us to get arguably the best h-modes we've seen to date. D-port was tripping frequently but this is a separate problem not related to loading. Contrary to conventional wisdom, our h-modes get better at higher density and with more gas during the h-mode. However they do begin to degrade with too much gas. Shot 29 was the best, a steady-state h-mode through the entire rf pulse with very low level (grassy?) elms. Reducing the gas during the h-mode shortened the h-mode (shot 28) and more gas degraded them somewhat (shot 39). It seems that moly accumulation and high radiated power are key elements in the quality of our h-modes. Therefore we get better h-modes at higher density where moly is better shielded. We got record stored energy for 800ka but h-factors were still about 1.4. We went to 900ka on shot 33 and more feedback gain (-2750) on shot 37. Finally on shot 40 we went to 1.05ma. The plasma disrupted when the rf turned off, too much density and moly with not enough input power. Earl predicted this in advance but still took the shot. We were again punished by 3 fizzles to end the day. It seems recovery from disruptions, especially full current disruptions, is more difficult now. For information on engineering problems and shot statistics, see the physics operator summary. For shot-to-shot comments, see the logbook under the session_leader topic. |
| Physics Operator Summaries |
| Entered: Jul 7 2004 04:36:55:490PM |
| Author: To Be Determined |
From: PHYSOP::MARMAR Date: 5-DEC-1995 18:01:56 Subj: Physop run summary 951205 951205 EO: Silva/Daigle PO: Marmar SL: Golovato PB: McCracken MP67a RF loading position feedback with MP127 N_2 puffing on the back of the pig. A successful day. The RF loading feedback appears to work well, and we had many shots with "steady-state" H-modes. Density scans indicated that the generally better H-modes happened at higher densities, where the moly and radiated power were lower. We finally settled on a value of -2750 for the contribution of the RF_load signal to the RCUR estimator. Shot 11 demonstrated that -5000 was too large, causing a large inward excursion, increasing kappa and leading to a disruption. It has been suggested that the circuit be modified so that it calls for excursions toward the antennas when the loading is too low, but ignores loading that is higher than the nominal setting. Some adjustment of the maximum allowed excursion may also be necessary. Some effort was spent adjusting the early gas puffing to speed the density rise and reduce early moly influx. From shot 26 on, this appeared to be quite successful. The nitrogen piggy back also appeared to get good data. The TF cooling was working much better today compared to last week, with cooling times below 10 minutes on most shots. 1 PF test 2 load 951130019, increase prefill puff by 3 msec, add .5 mT B_R offset, add early gas puff, TF invert at 1.0, TF on PLC; plasma, H-mode during RF (2MW); this was a fiducial-style shot. 3 repeat; plasma; lower RF power (1MW) 4 raise nl_04 to 1.2e20; plasma; finning and slightly disruptive on rampdown 5 -100. into RF loading RCUR feedback; fizzle 6 2 msec less pre-fill puff; plasma; H-mode on second RF pulse (1.2 MW) 7 -1000 on RF loading RCUR feedback; plasma; 2.5 mm jog on X-ray centroid at time of programmed jog on input 81 H-mode, 1.1MW RF 8 repeat; plasma; higher RF power; H-modes 9 plasma; H-Mode; 1.2 MW 10 N2 puff at ~.75 s; -3000 on RF loading RCUR feedback; plasma; disrupt on rampdown (500 kA) 11 remove 1 msec from pre-fill puff; -5000 on RF loading RCUR feedback; plasma; disrupt at .68 s (.8 MA); RCUR decreased, kappa too high 12 remove 1 msec from pre-fill puff; -2000 on RF loading RCUR feedback; fizzle 13 repeat; fizzle 14 add 2 msec to pre-fill puff; N2 puff off; fizzle 15 add .5 mT to B_R; disrupt on rampdown (400 kA) 16 draw nl_04 down after 0.9 s; plasma; still ratty on rampdown, but made it to the end. 17 N2 back on; power supply dud; no PF's; breaker pulled 18 plasma; H-mode; looks like the feedback is doing the right thing 19 repeat; plasma 20 no N2; plasma; in and out of H-mode 21 N2 back on, start ~.8 s; H-Mode(s) 22 plasma 23 RF loading RCUR feedback turned off; plasma, multiple RF trips during H-modes 24 reduce nl_04 just before RF turn on; RF loading RCUR feedback on; N2 off; 25 fiducial; plasma; magnetics screwed up, so no efit. 26 reload 23; add early gas; raise nl_04 to 1.4e20; raise preprog gas voltage; plasma 27 more early gas; more preprog gas voltage; refill A side plenum to 21 psi; plasma; disrupt on rampdown (450 kA); long ELM free H-mode 28 turn gas off at 0.6 (program nl_04 to 7e19 at 0.601); plasma; in and out of ELM-free; 2.9 MW 29 program nl_04 up to 1.9e20 after RF on; N2 on; nice long H-mode; 120 kJ stored energy; disrupt on rampdown (530 kA) 30 repeat; RF tripped; plasma 31 increase nl_04 to 2.2e20 during RF; plasma; early funniness on density rise (fast) and current rise (slow) 32 raise EF3 PLC limit to 12 kA, tweak early segment 2 gas (lower); plasma; lower density during RF 33 increase Ip to .9 MA; plasma 34 turn off gas during RF (nl_04 to 7e19); fizzle 35 reduce prefill puff by 1 msec; plasma; RF tripped 36 retry; plasma; similar result; RF tripped 37 -2750 on RF loading RCUR feedback; fizzle 38 B_R offset .5 mT smaller (now .0065); plasma 39 raise density pre and during RF; N2 off; plasma 40 Ip 1.1 MA; disrupt at .9s 41 reload 29, raise Ip tp .9 MA; fizzle 42 decrease pre-fill puff by 2 msec; fizzle 43 decrease pre-fill puff by 2 msec; fizzle Tally: 43 shots, 32 plasmas, 9 fizzles, 1 PS dud, 1 test |
| Session Leader Comments | |||
| Dec 5 1995 09:11:55:010AM | Steve Golovato | run 951205
goals - (1) check outand learn to use plasma position feedback to control rf loading, keeping it constant to avoid trips at h-mode transitions (2) also, nitrogen puffing at a level that does not affect shot, from inner wall using ninja system. | |
| Dec 5 1995 09:12:36:800AM | 951205001 | Steve Golovato | shot 951205001 - magnet test shot.
|
| Dec 5 1995 09:12:56:660AM | 951205002 | Steve Golovato | shot 951205002 - fiducial shot,
|
| Dec 5 1995 09:14:10:310AM | 951205003 | Steve Golovato | shot 951205003 - setting up rf for l-mode with around 7 ohms loading,
outer gap of 1.5-2cm. plasma. still getting dithering, raise nl form 1.0 to 1.2 |
| Dec 5 1995 09:16:27:330AM | 951205004 | Steve Golovato | shot 951205004 -
plasma. getting nl=1.1, loading about 6 ohms, this is ok. set bira to down .05 volts to 2.95 to zero feedback. |
| Dec 5 1995 09:23:25:530AM | 951205004 | Steve Golovato | shot 951205004 -
plasma. getting nl=1.1, loading about 6 ohms, this is ok. set bira to down .05 volts to 2.95 to zero feedback. put +/- 0.05 volt wiggle in bira signal and -100 in A matrix. lokk for level of error caused by wiggle to calibrate A matrix level. this should not actually move plasma enough that we can see it. |
| Dec 5 1995 09:44:49:850AM | 951205005 | Steve Golovato | shot 951205005 -
fizzle. |
| Dec 5 1995 09:47:15:200AM | 951205006 | Steve Golovato | shot 951205006 -
plasma. bira comews in about 20ms earlier than programming says. turning off bira in 1ms to avoid large offset at end of rf pulse. see jog in feedbeack signal but not on rcur phys a-out. raise a-matrix to -200 from -100 for next shot. |
| Dec 5 1995 10:19:12:450AM | 951205007 | Steve Golovato | shot 951205007 -
changed a-matrix to -1000 for this shot. plasma. 0.2 volt offset at end of rf pulse (which shouldn't be there) can be seen on rcur error signal, plasma moves about 2.5mm. we now have a calibration. increased programmed wiggle to +/- 0.2v, remembering now that the actual wiggle will be half of this or +/- 0.1v. |
| Dec 5 1995 10:20:44:360AM | 951205008 | Steve Golovato | shot 951205008 -
plasma. rf timing wrong by mistake. |
| Dec 5 1995 10:35:10:310AM | 951205009 | Steve Golovato | shot 951205009 -
plasma. can see plasma move at transition from - to + .1v (.2v change). moves out (toward antenna) about 2mm when signal goes more positive. this is correct direction since the siganl goes more positive when loading decreases. increase a-matrix to -3000. form -1000. for next shot. |
| Dec 5 1995 10:45:06:180AM | 951205010 | Steve Golovato | shot 951205010 -
plasma. can now see all the changes in the feedback signal in the phys a-out rcur signal. gain looking good. first shot with nitrogen puffing, got what was expected but see density increase. |
| Dec 5 1995 10:56:48:540AM | 951205011 | Steve Golovato | shot 951205011 -
increase a-matrix to -5000 from -3000. plasma. disrupted, too much feedback gain. go back to -3000 and eliminate programmed wiggle, see if the loading is kept constant. |
| Dec 5 1995 11:00:32:180AM | 951205011 | Steve Golovato | shot 951205011 -
increase a-matrix to -5000 from -3000. plasma. disrupted, pushed too hard, with clearin set, plasma elongated too much. too much feedback gain. go back to -2500 and eliminate programmed wiggle, see if the loading is kept constant. |
| Dec 5 1995 11:09:23:120AM | 951205012 | Steve Golovato | shot 951205012 -
fizzle. |
| Dec 5 1995 11:14:09:070AM | 951205013 | Steve Golovato | shot 951205013 -
fizzle. a-matrix at -2000, not -2500. |
| Dec 5 1995 11:21:51:140AM | 951205014 | Steve Golovato | shot 951205014 -
fizzle.. |
| Dec 5 1995 11:26:43:560AM | 951205014 | Steve Golovato | shot 951205014 -
fizzle.. |
| Dec 5 1995 11:44:51:770AM | 951205015 | Steve Golovato | shot 951205015 -
lowered bira to 2.85 from 2.95 to better zero feedback for current conditions. plasma. feedback zeroed. |
| Dec 5 1995 11:46:17:270AM | 951205016 | Steve Golovato | shot 951205016 -
raised power to 1mw from .8mw to get h-mode. plasma, no h-mode during e-port, raise power some more. h-mode during d-port at 1,.2mw. |
| Dec 5 1995 11:59:09:820AM | 951205017 | Steve Golovato | shot 951205017 -
raised power to 1.5mw from 1.mw dud. oh's pulled out. |
| Dec 5 1995 12:12:20:260PM | 951205018 | Steve Golovato | shot 951205018 -
plasma. 1.4mw, elm-free h-mode for 60ms. outer gap reduced from 16mm to 9mm, to maintain loading. loading dropped to 4 ohms from 7.5, which is less than usual for elm-free h-modes, where loading can go below 3. |
| Dec 5 1995 12:34:48:920PM | 951205019 | Steve Golovato | shot 951205019 -
plasma. repeat of shot 18. |
| Dec 5 1995 12:37:29:830PM | 951205020 | Steve Golovato | shot 951205020 -
plasma. extended e-port to .9 sec, got train of elm-free, elmy, elm-free h-modes. no interrupts. now add d-port power for next shot. outer gap shows plasma motion toward antenna but xray centroid seems to move out of phase with h-modes, away from antenna during elm-free, toward during elmy. |
| Dec 5 1995 12:45:52:770PM | 951205021 | Steve Golovato | shot 951205021 -
plasma. 65ms elmfree h-mode, about the longest we've ever seen. raising e-port power. d-port tripped early. |
| Dec 5 1995 12:56:45:830PM | 951205022 | Steve Golovato | shot 951205022 -
plasma. 1.8mw from e-port. d-port 1.1mw in lmode, .9 in h-mode. |
| Dec 5 1995 01:07:36:080PM | 951205023 | Steve Golovato | shot 951205023 -
feedback turned off using gate enable. plasma. hmodes are shorter, lots of rf interrupts. outer gap flat at 16mm. clearly the feedback helps, though it doesn't make the loading constant. drops to 3 ohms, 40kv at |
| Dec 5 1995 01:16:29:580PM | 951205024 | Steve Golovato | shot 951205024 -
feedback back on. try reducing gas before rf pulse to reduce density rise. plasma. looks much like last shot, but with much fewer the rf trips. h-modes not as good. |
| Dec 5 1995 01:29:02:160PM | 951205025 | Steve Golovato | shot 951205025 -
redo fiducial with more diagnostics. plasma. go back to feedback studies. |
| Dec 5 1995 01:50:12:630PM | 951205026 | Steve Golovato | shot 951205026 -
raise density to nl=1.4e20. plasma. 75ms elmfree h-mode. plasma movee about 5mm according to xray centroid. variation of loading with outer gap seems less sensitive in h-mode than in l-mode we still see a large decrease but not as much as without feedback and we don;t get as many trips, usually we get none on e-port. d-port has other problems which lead to crowbars. density still not what was requested, only got 1.1e20 before rf. |
| Dec 5 1995 02:06:11:140PM | 951205027 | Steve Golovato | shot 951205027 -
plasma. long elmfree h-mode, 130ms, lost when d-port trips. density stops steep rise when gas valve shuts off, stays in elmfree h-mode with slower density rise. wp=114kj, highest we've seen at 800ka, non-pep. |
| Dec 5 1995 02:12:46:710PM | 951205028 | Steve Golovato | shot 951205028 -
turned off gas at rf turnon, see effect on density rise. plasma. 2.9mw. no trips. h-modes shorter, not as good as previous shot. try keeping gas on instead of turning it off. |
| Dec 5 1995 02:25:25:670PM | 951205029 | Steve Golovato | shot 951205029 -
plasma. elmfree? or grassy elms for the whole rf pulse. it wants more gas, not less. wp=120kj. 3mw, no trips. |
| Dec 5 1995 02:42:24:350PM | 951205030 | Steve Golovato | shot 951205030 -
plasma. lost d-port early, lost h-mode. in l-mode, loading is higher than set point, feedback pushes plasma away from antenna to 24mm. |
| Dec 5 1995 03:01:54:520PM | 951205031 | Steve Golovato | shot 951205031 -
raise density. plasma. too much early gas. hmode not quite as good as shot 29. |
| Dec 5 1995 03:10:58:080PM | 951205032 | Steve Golovato | shot 951205032 -
tweaking early gas. plasma. lose elmfree early, elmy the rest of time. |
| Dec 5 1995 03:29:16:200PM | 951205033 | Steve Golovato | shot 951205033 -
plasma. 900ka, 125kj. long elmy h-mode. |
| Dec 5 1995 03:36:40:070PM | 951205034 | Steve Golovato | shot 951205034 -
fizzle. |
| Dec 5 1995 03:46:06:700PM | 951205035 | Steve Golovato | shot 951205035 -
cutting gas during rf. plasma. e-port port tripped early, screen overload. lost h-mode. |
| Dec 5 1995 03:53:44:030PM | 951205036 | Steve Golovato | shot 951205036 -
plasma. e-port tripped again. |
| Dec 5 1995 04:04:00:500PM | 951205037 | Steve Golovato | shot 951205037 -
raising feedback gain to -2750 from -2000, plasma not moving far enough. lowered e-port power a little. fizzle. |
| Dec 5 1995 04:24:53:770PM | 951205038 | Steve Golovato | shot 951205038 -
plasma. hmode short, rf stayed on. |
| Dec 5 1995 04:32:44:290PM | 951205039 | Steve Golovato | shot 951205039 -
gas back on. plasma. h-mode unitl rf trips out. almost elm free. |
| Dec 5 1995 04:46:49:880PM | 951205040 | Steve Golovato | shot 951205040 -
raise ip to 1ma. plasma. 1.05ma. lost d-port early again. |
| Dec 5 1995 04:48:42:320PM | 951205041 | Steve Golovato | shot 951205041 -
last shot disrupted at e-port turnoff, lower ip to 900ka and go back to shot 29. fizzle after disruption. |
| Dec 5 1995 04:59:48:950PM | 951205042 | Steve Golovato | shot 951205042 -
fizzle. |
| Dec 6 1995 08:40:35:440AM | 951205043 | Steve Golovato | shot 951205043 -
fizzle. three fizzles for every full current disruption. |
| Physics Operator Comments |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 08:23:00:240AM | Test | Ok | oh test |
| 2 | 08:40:11:840AM | Plasma | Ok | |
| 3 | 08:55:06:090AM | Plasma | Ok | |
| 4 | 09:07:17:100AM | Plasma | Ok | |
| 5 | 09:22:31:490AM | Plasma | Ok | |
| 6 | 09:34:43:080AM | Plasma | Ok | |
| 7 | 09:55:47:980AM | Plasma | Ok | |
| 8 | 10:06:34:180AM | Plasma | Ok | |
| 9 | 10:22:03:110AM | Plasma | Ok | |
| 10 | 10:34:04:980AM | Plasma | Ok | |
| 11 | 10:48:43:380AM | Plasma | Ok | |
| 12 | 11:04:34:100AM | Plasma | Ok | fizzel |
| 13 | 11:12:15:140AM | Plasma | Ok | |
| 14 | 11:20:16:880AM | Plasma | Ok | |
| 15 | 11:29:01:340AM | Plasma | Ok | |
| 16 | 11:39:58:390AM | Plasma | Ok | |
| 17 | 11:49:02:390AM | Plasma | Ok | |
| 18 | 11:56:48:670AM | Plasma | Ok | |
| 19 | 12:09:19:410PM | Plasma | Ok | |
| 20 | 12:18:07:810PM | Plasma | Ok | |
| 21 | 12:37:16:840PM | Plasma | Ok | |
| 22 | 12:47:55:840PM | Plasma | Ok | |
| 23 | 12:58:47:270PM | Plasma | Ok | |
| 24 | 01:10:46:920PM | Plasma | Ok | |
| 25 | 01:23:00:740PM | Plasma | Ok | |
| 26 | 01:37:22:040PM | Plasma | Ok | |
| 27 | 01:51:42:890PM | Plasma | Ok | |
| 28 | 02:05:24:170PM | Plasma | Ok | |
| 29 | 02:16:45:500PM | Plasma | Ok | |
| 30 | 02:29:55:760PM | Plasma | Ok | |
| 31 | 02:47:40:940PM | Plasma | Ok | |
| 32 | 03:01:42:950PM | Plasma | Ok | |
| 33 | 03:18:12:130PM | Plasma | Ok | |
| 34 | 03:30:44:740PM | Plasma | Ok | |
| 35 | 03:38:39:190PM | Plasma | Ok | |
| 36 | 03:49:39:180PM | Plasma | Ok | |
| 37 | 04:02:24:640PM | Plasma | Ok | |
| 38 | 04:09:57:490PM | Plasma | Ok | |
| 39 | 04:21:34:050PM | Plasma | Ok | |
| 40 | 04:34:23:390PM | Plasma | Ok | |
| 41 | 04:47:04:770PM | Plasma | Ok | |
| 42 | 04:55:31:310PM | Plasma | Ok | |
| 43 | 05:03:47:580PM | Plasma | Ok | |