| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Peter Oshea |
| Physics operator(s): | Earl Marmar,Steve Horne |
| Engineering operator(s): | Vinny Bertolino,Joe Daigle |
| Engineering Operator Run Comment |
| marmer/6.4Tesla |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:13:710PM |
| Author: To Be Determined |
| SESSION LEADER RUN SUMMARY: RUN 950511, MP 090A, RF Modulation (Mode Conversion Heating) =============================================================== Session leader: O'Shea Physop: Marmar =============================================================== The goal for today's run was to use modulated direct electron heating of mode converted waves in H(He3) plasmas to allow measurements of electron transport coefficients to be made, using GPC as the main diagnostic tool. Mode coversion heating studies were begun yesterday (MP 110A), and as modulation was used then to help diagnose heating profiles, some useful data had already been collected. The first part of the day was to be used to make scans of the He3 fraction and the magnetic field, to study and optimize the mode conversion heating. Then parameter scans relevant to transport studies would be made while maintaining good modulated RF heating. The run was quite successful, but probably more so in the first objective than the second. During the first few shots, we obtained evidence of Shear Alfven wave electron heating. On many shots, very strong direct electron heating was observed. On shot #16, central electron heating density reached a record value of approximately 25 MW/m^3 A combination of difficulties with first the plasmas and then the RF coupling, which began in the middle of the day, limited the number and variety of shots obtained where we had good centralized, modulated RF heating. However, when combined with some results from the day before, give a lot of valuable data to analyse for transport results. ================================================================= Notes on the day's run follow: **For first few shots, before beginning He3 puffs, will scan density in H plasmas at 6T. This is to investigate Shear Alfven wave heating. Shot 001: Going for nel_04 ~ 0.5 [10^20 assumed throughout] Fizzle Shot 002: Retry. Plasma. nel_04 ~0.6., 800kW RF. Injections? Some off axis heating. Shot 003: Trying for more RF and slighty lower density Plasma nel_04 ~0.65 1.4 MW RF More heating. Sawteeth become very small at end of pulse. Zeff rises mightily, so ST effect may be due to impurity heating. Shot 004: Going up in density, still no He3 Plasma nel_04 ~1.0 PRF~1.1MW. VERY little heating Shot 005: Moving to high field 6.5T , nel_04~1.5 (Baseline for scans) Plasma. Disrupts at 1.05 sec PRF ~ 1.1 MW VERY little heating Shot 006: Want low density, 6.5T (Shear Alfven res. near center) Plasma. nel_04 ~ 0.6. PRF ~ 1.1 MW Heating comes back, still off axis, broad. ---------------------------------------------------------------------- ****** Going to start He3 puffing. Will implement density feedback on both valves. Will establish a density of nel_04~1.5 and scan the mixture of He3:H by adjusting relative gains in the feedback. Shot 007: Still 6.5T. nel_04 ~ 1.5 PRF ~ 1.3MW. Heats. Affects sawteeth. Zeff and Spectroscopic measurements indicate 'lots' of He3, perhaps 50-50 He3-H electron contributions. Shot 008: Reducing He3 conc...shooting for 33-66 (He3:H), same overall density. PRF ~ 1.4 MW. Good density control. Word is that we got maybe 20% less He3 this time. Heating definately seems to have moved outward. Shot 009: No He3 puff (use residual to give a very low fraction). Best guess is that we are "down by a factor 2" in He3. (5-10%?) PRF ~ 1.1 MW . Some heating, off axis. Shot 010: Going for "Big" He3 puff.( might be hard to maintain density ) nl_04~1.4. PRF ~ 1.2 MW...heating only in the edge...too much He3! ---------------------------------------------------------------------- ** Going back to puffing as in 007, scanning down in field Shot 011: nel_04 ~ 1.4, B=6.25T PRF ~ 1.1 MW , Heating, but not as central as 007. Shot 012: Go to 6.0T to make contact with earlier in the day, stiil nl_04~1.5 Get decent heating, but no break in slope and no evidence of faster reheats. - Generally not getting the heating that were getting yesterday. Going back to nl_04~1.0 and 6.5T. Shot 013: Got the shot, RF not retuned, transmitter trips out after 60 ms. Very good indications of heating though! Very peaked (from reheat) Shot 014: Try again with slightly lower density, nl_04 ~0.75 RF a little "ratty", PRF ~ 1MW Has huge effect on ST, peaked heating Evidence of strong direct electron channel. Again, no RF modulation. Shot 015: Lower density again,shoot for ne_04 ~ 0.5, B=6.5 Big density rise during RF (up to ~0.8). Good modulation, PRF~1.5 MW Heating is good, but not as good. Going back up in density and try to get the RF modulation to work. Shot 016: Similar to 014. nel_04 programmed at 0.8, goes up to 1.0 during RF. Transmitter trips out early. Heating is very effective, centralized. Physop:Horne Shot 017: No changes....fizzle. (somewhat mysterious) Shot 018: No changes....fizzle Shot 019: Lower fill pressure....Plasma ! PRF~1.3MW. Sucessive heating power peaks have successively less central heating. Perhaps due to He3 depletion throughout discharge. Shot 020: Increase the ratio of He3/H later in the shot to try to keep the power from degrading. RF stays around, loading effects make modulation shape rounded. nel_04 programmed at 0.8 and rises to ~1.0 during RF Shot 021: Tried to both increase ratio of He3/H and compensate for the density rise. Seems to be effective in controlling nel, however the quick puffing changes is making it hard for the RF to match. Transmitter trips early. Shot 022: Only 2 RF pulses...loading is a problem. Shot 023: Got only the late RF pulse to go. Loading seems to be all over. Shot 024: Still having trouble getting sustained,modulated, heating at the lower density. Going back to 013. target nel_04 is 1.0. Shot 025: Got nel_04 ~1.0 (bit of overshoot) Heating is great. Shot 026 Going up in current. 0.9MA nel_04~1 ...Disrupts at 0.65 sec. Shot 027 Go for one more try at heating at nel_04~0.8 Disrupts at 0.71 sec (again mysteriously). Lost it vertically . Looks like something fell in. Shot 028 Retry of 027. RF power waveform is ragged but see good heating. Shot 029 Go for a Bt rampdown shot for the X-calibration of ECE system. Target Ip=600kA, nel_04 ~ 0.8, ramping down starting at 0.8 sec. Would like rampdown to make it to 5.3 Tesla at least. Disrupts at 4.4 Tesla. ok. Shot 030 Lower torroidal field to 6.25T. nel_04~1.0. Trying to use both transmitters. Density and field look good. Heating is weak and off axis, though some central sawtooth modulation is seen. |
| Physics Operator Summaries |
| Entered: Jul 7 2004 04:36:54:190PM |
| Author: To Be Determined |
From: PHYSOP::MARMAR Date: 11-MAY-1995 18:45:50 Description: Physop run summary, 950511 950511 MP 090A, Modulated transport SL OShea PO Marmar/Horne EO Bertolino/Daigle This was the second run at 6.5 Tesla. The machine ran well. Density and H/3He scans were accomplished, as well as small scans of the TF, from 6.0 to 6.5 Tesla. On the last 2 shots, the TF inversion was moved to occur during the shots, at 0.8 seconds on shot 29 and 1.0 seconds on shot 30. There were no apparent power supply problems as a result, at least not at the inversion times, and the plasmas both ran through nicely to .2 MA. The was a PF breaker problem at the end of each of these shots; Joe Daigle did not think it was related to the earlier TF ramp. The shot cycle was again often dominated by the wait for the TF scanner. Assuming that gets fixed, and the breaker problem is unrelated to the TF invert, I recommend that TF invert be routinely put back to end of flat-top. In an attempt to control H/3He ratios while scanning the density, I put both valves into the feedback loop, with different weights at different times. This seemed to work reasonably well, although atttention has to be paid to the preprogrammed voltage waveforms as well as to the relative weights in the controllers. We had some "fizzles" today (40 to 80 kA plasma current); they appeared to crash to the inner wall. They may have been due to drifting B_R at breakdown. The superstitious among us might conclude that changing physops in mid-run causes fizzles. The one attempt (shot 26) at .9 MA failed due to EF2 curent rails followed by disruption. Shot 27, a .8 MA shot, also disrupted; it looked like something fell in. The halo currents were below 150 kA in each case (more evidence for I/q scaling?). Start from 950510016, but TF 6T, nl_04=.5e20, H2 only; go to 3He later 1 fill 2.3e-5, H2 fill and puff only; argon enabled; fizzle (40 kA) 2 fill 2.5e-5, reduce B_R offset by .5 mT, plasma; .8 MW RF 3 lower nl_04 program to .43e20; plasma; 1.4 MW RF 4 nl_04 1.e20; plasma; 1.2MW RF; no heating 5 6.5 Tesla TF; nl_04 1.5e20; disrupt on R.D. at .69MA 6 nl_04 .5e20; plasma; 1.2 MW RF 7 nl_04 1.5e20; add 3He with both valves on feedback, equal weights 2.5e-19 on the controller, starting at .3 s; plasma; disrupt at .48MA on R.D., 1.3 MW RF 8 decrease 3He , now 1.67e-19, 3.33e-19 on H2; plasma 9 no 3He (hybrid disable); plasma 10 reduce preprogrammed voltages on valves, 4.9e-19 3He, 5e-20 H2; increase Ip rampdown rate; increase gain on ZXL at .5 s; plasma 11 back to shot 7 for the feddback settings, but V's from 10, increase Ip ramp even more, disrupted a little earlier; 6.25 Tesla 12 6 Tesla; slow Ip ramp; disrupt later (.44 MA) 13 extend RXL gain beyond 1.2 s, turn off argon; 6.5 Tesla, nl_04 1.0e20, keep gas going at end of shot, 1.5 MW, good heating 14 nl_04 7.5e19; speed Ip ramp a little, late; plasma; disrupt at .4MA 15 nl_04 5e19; slow late Ip ramp; disrupt at .33MA 16 nl_04 8e19; tweak RXL and ZXL during rampdown (go up and in); much better rampdown Horne takes over as physop 17 No changes. 60 KA Fizzle!. Bounce scope says plasma hits on inside. While bringing up flux plot, do repeat. 18 40 KA fizzle. Fields, flux, etc look same as 16. Drop fill to 2.2e-5. 19 Plasma again. Adjust pre-programmed voltages on H and He3 -- a notch in H, a bump in He3. Objective is to raise He3 concentration around .7 sec. 20 Plasma. The notches had the expected effect; tweak them for next to reduce density perturbation. 21 Plasma. RF complains that the notches cause edge variations that mess up loading -- even though NL is held more constant. Take the notches out. Change the weights on the valves in the density controller to h=2, he=3 (*e-19) 22 Plasma, RF tripping 23 Plasma Marmar takes over as physop 24 reload shot 13, tweak the rampdown to match 23; 80 kA, crashed to the inside; noticed that ion gauge read 2.0e-5 at "Entering Pulse" 25 fill 2.4e-5, B_r offset down by .5 mT, retry; plasma, good RF; ion gauge 2.4e-5 at "Entering Pulse" 26 .9 MA, clearin ramp tweak to keep EF2's off rail on the way to .9MA; disrupt at .63s, .8 MA, both EF2's hit current limit 27 nl_04 .8e20, .8MA, undo clearin tweak, disrupt during RF, something fell in? 28 repeat, good shot 29 TF invert to 0.8 seconds, .6MA, good, no apparent EF3 problem at TF invert 30 TF invert to 1.0, 6.25 Tesla, .8 MA, nl_04=1.0e20; good; still no evidence of a problem at the TF invert time. 26 plasmas, 4 fizzles |
| Session Leader Comments |
| Physics Operator Comments |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 08:29:09:070AM | Plasma | Ok | |
| 2 | 08:45:50:740AM | Plasma | Ok | |
| 3 | 09:03:54:270AM | Plasma | Ok | |
| 4 | 09:22:26:500AM | Plasma | Ok | |
| 5 | 09:41:10:110AM | Plasma | Ok | |
| 6 | 09:59:02:670AM | Plasma | Ok | |
| 7 | 10:15:41:260AM | Plasma | Ok | No Faults |
| 8 | 10:37:01:200AM | Plasma | Ok | |
| 9 | 10:56:50:040AM | Plasma | Ok | |
| 10 | 11:14:25:540AM | Plasma | Ok | |
| 11 | 11:31:50:650AM | Plasma | Ok | |
| 12 | 11:49:31:060AM | Plasma | Ok | |
| 13 | 12:07:47:420PM | Plasma | Ok | |
| 14 | 12:25:03:390PM | Plasma | Ok | |
| 15 | 12:41:31:560PM | Plasma | Ok | |
| 16 | 12:58:30:330PM | Plasma | Ok | No Faults, |
| 17 | 01:15:58:820PM | Plasma | Ok | No Faults. |
| 18 | 01:32:29:340PM | Plasma | Ok | No Faults |
| 19 | 01:49:30:920PM | Plasma | Ok | No Faults. |
| 20 | 02:12:22:600PM | Plasma | Ok | NO Faults. |
| 21 | 02:29:59:510PM | Plasma | Ok | No Faults. |
| 22 | 02:47:41:860PM | Plasma | Ok | NO Faults. |
| 23 | 03:04:24:060PM | Plasma | Ok | NO Faults. |
| 24 | 03:22:52:120PM | Plasma | Ok | No Faults. |
| 25 | 03:38:49:030PM | Plasma | Ok | no faults |
| 26 | 03:55:53:090PM | Plasma | Ok | NO Faults. |
| 27 | 04:14:48:540PM | Plasma | Ok | No Faults. |
| 28 | 04:30:44:780PM | Plasma | Ok | No Faults. |
| 29 | 04:47:30:850PM | Plasma | Ok | Comm Fault OH1 OH2l,ef1u |
| 30 | 05:04:34:130PM | Plasma | Ok | comm fail oh2l, ef1u, oh1 |