| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Peter Oshea |
| Physics operator(s): | Steve Horne |
| Engineering operator(s): | Joe Daigle,Vinny Bertolino, Unknown |
| Engineering Operator Run Comment |
| modulated electron heating |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:13:913PM |
| Author: To Be Determined |
| ***************************** * Run 950608 Modulated RF heating ( Mode Conversion at 6.4 T , H[He3] plasmas ) * Session Leader : O'Shea * Physics Operator : Horne ***************************** Plan is to revisit the best heating parameters from 950511 (shot #25 is target) and to do a current scan (Currents of 0.4,0.6,0.8,1.0 MA) at that density ( nel_04 ~ 1.0 ) while achieving good RF modulation. Following that, we will attempt to get robust trains of modulation pulses at lower density. If time permits, we will try to increase power by getting both transmitters to run simultaneously. ----------------------------------------------------------- ***************************************************************************** * Thanks to all who tried. I think we got some good modulation/transport data * with a semblance of a current scan. RF coupled quite well to what plasmas * we made. The heating seemed to be very sensitive to both density and helium * fraction, which we seemed to be able to control earlier in the day with some * success. After a few disriptions/fizzles the heating seemed much harder to * control (wall effects?, dirt...) Problems with the machine later on limited * the extent of the scans we could perform ***************************************************************************** * Score card: * ---------- * Good heating examples at 0.8 and 0.6 MA at two (albeit similar) densities. * Some heating at 1.0 MA though He3 not optimized * * Shots: 31, Fizzles: 5, Disrupts before RF: 8, No He3 gas: 2, No TF: 1. *************************************************************************** Shot summary follows: Shot Ip Nel_04 Comments ==== ==== ======== =========================================== 001 0.8 1.0 Got the target plasma. No Helium puff. Establish baseline (!). D/(D+H) ~ 3-4% from CX. No heating. 002 " " Great plasma, Great RF, No voltage on the He valve (!), No heating :( 003 Fizzle Fixed the He puff problem. 004 0.8 1.0 Plasma. Good RF . Good heating early which moves off axis. No McPh Helium signal for this shot. 005 0.8 1.0 Plasma. Repeat of last shot. Moved GPC ch.'s out a bit. Heating shows signs of moving through center. Changing He puff programming 006 0.8 1.0 Heating time evolution is more even. Take it and move to 0.6 MA 007 0.6 1.0 Heating moves to center late in the RF. Still pretty good. Going on to 0.4 MA, lowering He programming a little 008 0.4 1.0 Disrupts. In trouble at 0.35 sec. Bumping up the current at little, reducing the Argon injection. 009 0.4 Fizzle 010 0.4 Disrupts early. Abandon this current, go to 1 MA. 011 1.0 1.0 Nice Plasma. Good RF. Heating is not great. He signal is low. Retrying with increased Gain on He. 012 1.0 1.0 Good Plasma and RF. Heating is less central still, We moved the wrong way. Try again with less He. 013 1.0 Disrupts. Have to move on. Want to take a shot 014 0.8 1.25 Want to visit this density to fill in the database. Shot had a lot of hard X-rays, and the RF tuning was not optimized. Retry. 015 0.8 1.25 Better. Some heating though RF power sags. He signal rising through shot. Reduced to 32 016 0.8 1.25 No RF till last pulse. He signal flat, but higher than before...!! go figure...can't linger 017 0.8 0.9 Great!! Decide to try a little lower density b4 Ip scan He signal was a steady 4 units during RF 018 0.8 0.8 RF stays in there, but heating is a little worse. He signal is 3.5--->3.0 during RF, though with lower density we'd expect that tendancy... Going back to 17 and try to do a current scan 019 Fizzle. Try again at 500 kA 020 0.5 0.9 Disrupts at 0.6 seconds.VDE. Plasmas are pretty elongated seems to be a problem so changing it and trying again. 021 Fizzle. 022 0.5 0.9 Re-Retry. Disrupts at 0.57 sec. 023 0.8 0.8 Retry of shot 18, try to get a plasma and get coupling back. There is ok heating, with good RF modulation. Disrupts at 1.05 seconds (uhhhh) 024 1.0 0.8 Disrupts 0.57 seconds. 025 Disrupts at 0.5 seconds 026 0.8 0.9 Retrying 017. Got plasma, rampdown starting at 0.9 for ECE X-calibration. Heating is not as good as 017, though He sig looks the same. 027 0.6 0.8 Try lower current. Good plasma, Good rf Ok heating which moves out late in the RF pulse. Retry with lower He3 and try for higher power later in shot. 028 0.6 0.8 Fizzle (80kA) 029 NO TF 030 Runaway! Plenty o Hard XRays. 031 0.8 0.9 Plasma. Rerun of 17, tried to run both transmitters, didn't get any more power than usual. Again, heating is not what it was on 17. |
| Physics Operator Summaries |
| Entered: Jul 7 2004 04:36:54:690PM |
| Author: To Be Determined |
| Run 950608; Peter O'Shea,(SL) Horne (PO) Bertolino, Daigle, Paranay (EO). Mode conversion, He3 minority in H. SUMMARY: Machine has run better. More runaways than usual. Most of the shots I called fizzles in the log had 40-80 KA of current. Shot 17 was the "trophy" as far as heating is concerned; see Peter's writeup. Cooling problems; early in the run, we had the E-port leak. Later in the day the LN2 tank was refilled; Joe D claims this drops the pressure in the tank, hence reduces our cooling rate. The rf loading feedback was tested; see shot 23. A change in rf loading signal of about .4 volts at 1.02 sec generates a 2 cm change in xray centroid, and about a 1.5 - 2 cm change in the right gap. This was probably the cause of a vertical disruption, as the OH2 supplies went to their voltage rail. I was aiming for changes 1/10 this amount; still haven't found the decimal point. For subsequent shots gain was reduced by factor of 25 & no effects (of any sort) were seen. ============= SETUP -- Engineering setup -- Discharge clean in H. Please set up A side with Hydrogen, 20 lbs. Set up as on shot 950530006; TF start time -1.4 sec, but TF setting so as to give flattop at 6.45 T or about 180 KA on rogowski. Take whatever precautions are necessary RE TF fizzle detector delay. He3 system enabled. Initial fill from A side, 2.0e-5. Physics notes -- Segment 2 will be from 950511025. This shot has nl feedback controlling both a side and b side. 6/8/95 Coldstart done 7:45 ====================== LOG 1 Plasma. TF flatttop starts at t=0. This is much too generous. Move TF start to -1.2 sec. extend flatop to 1.1 sec on IP, nearly everything else. WHY NO HE3? 2 Plasma. Still no HE3. turns out i had segment 2 off, segment 3 on. Can't imagine why. Focus problem? Move TF start to -1.1sec. 3 80 ka fizzle. Fill to 2.2e-5 4 Plasma. Perhaps some signs of hards. HE3 , heating worked. fill to 2.3e-5 5 Nice heating. Resonance is sweepingt through center of machine. Adjust he3 v to increase slightly after .6 sec. 6 That worked well; nice heating. Drop IP to -600 000 A Enable argon, 300 msec, 25 msec pulse, 4 lbs Tweak x-point for blip 7 Plasma. Rampdown is too fast. Small E-port leak is back. Drop IP to 400 KA; slow rampdown a bit. reduce HE3 a little. 8 Died early -- probably gassed to death. Raise IP to 450 KA, drop argon pulse to 15 msec. 9 FIZZLE!. Late breakdown. raise fill to 2.4e-5 10 Plasma, breakdown is better but still late. Similar to 8 Try -15 A on ef4 to fix breakdown set IP = -1.0 MA. 11 Good shot. Breakdown a6 6 msec. Increase He3 V to 50 v. 12 Good shot. Reduce HE3 for next 13 Disrupted; ef2s railed. Move IP down to 800 KA. 14 Shot went, but had x-rays. Plenum pressure had dropped to 18 lbs. Raise to 20; fill to 2.6e-5 Shot was ok otherwise, ramped fown to 400 KA. 15 Good shot. 16 Ok but OH1 fault in rampdown. Reduce NL to 9.e19 17 Good shot."Great things happened" -- lots of heating. Therefore change something. Reduce NL to 8.e19 18 Not as good heating. Reload 17, drop IP to 500 KA. Long huddle; cooling isn't working right. The RF feedback signal is working. While waiting, set up rf feedback. To use it (by offsetting the RCUR predictor) 1) + A OUT V ==> plasma error is +, R > R programmed. This puts voltage on the controller so as to move plasma IN. So - a_out voltage should be applied to move plasma closer to antenna. 2) The signal from RF is "reflection coefficient". It goes + as loading gets worse. 3) Therefore we need to negate it, before summing it into a_out, since we assume closer = better. 4) Since the numbers on predictor screen get negated when converting to loadable, we input a + number. 5) Since the P_TO_V for the RF is 1.0, the absolute value of the number in the screen can be interpreted in units of IP_RCUR. (I think). We will type in a number to be interpreted as "change in ip_rcur per volt of reflection" The RF signal can be as much as 10V, but is typically 2 V or less. 1 cm change in edge is noticable; that's .5 cm in rcur, or 1.e6 * 5.e-3 = 5000 units of ip_rcur = 2 v, or magick # = 2500. 19 Fizzle. Waited too long, probably. Drop fill to 2.4e-5 for next. Turn on RF feedback at 1.0 sec. An identifiable feature has been programmed into the BIRA used to provide the offset; I expect a +/- wiggle of about 1200 units of IP_RCUR 20 Plasma, disrupted at .6 sec. Looks like VDE; lower IP = less stable. Long cooling time. Problems of some sort. 21 Fizzle. Try another - 15 A; 22 Plasma, but disrupted again at .6 sec. EF4 programming is inappropriate for such low current. reload shot 18 segment 2, pull back rcur wire from 22 to recover rf feedback programming. Set TF invert to .9 sec. 23 Good shot -- disrupts at 1.05 sec or so. Looks like the RF feedback MAY have done it. Reduce weight of RF from 2500 to 100 in predictor. 24 disrupted when ef2L hit rail. Ef4 is managing to go through zero twice; the gain switch at .3 sec is causing a large negative voltage spike. The ef4 voltage looks insane, but that must be the digitizer acting up. adjust ic_ef4 gains (taper them down). 25 That helped but not enough. Reload 17, which was way off the rail. 2.6e-5 on fill; tf invert still at .9. 26 That ran. Earl claims plasma quite dirty. Reduce IP to 600 KA. (nl still .8e20) 27 Good shot. Increase he3 as in shot 15 28 Fizzle. Why? flux plot looks ok. Try fill to 2.8e-5. 29 dud, no tf 30 Nasty runaway shot. Reload seg 2 from 17 (again), since the next will be the last shot. Try raising early gas to 3.0e-5 on fill. Tweak early puff a little. 31 Plasma, Ramped down. No x-rays. ======== The end. ======= |
| Session Leader Comments |
| Physics Operator Comments |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 08:40:15:510AM | Plasma | Ok | |
| 2 | 08:58:45:480AM | Plasma | Ok | |
| 3 | 09:19:45:510AM | Plasma | Ok | |
| 4 | 09:31:27:110AM | Plasma | Ok | |
| 5 | 09:46:05:780AM | Plasma | Ok | |
| 6 | 10:05:05:800AM | Plasma | Ok | |
| 7 | 10:20:29:460AM | Plasma | Ok | |
| 8 | 10:42:08:480AM | Plasma | Ok | |
| 9 | 10:56:17:440AM | Plasma | Ok | |
| 10 | 11:18:28:820AM | Plasma | Ok | |
| 11 | 11:34:39:230AM | Plasma | Ok | |
| 12 | 11:50:50:020AM | Plasma | Ok | |
| 13 | 12:04:34:130PM | Plasma | Ok | |
| 14 | 12:19:23:900PM | Plasma | Ok | |
| 15 | 12:34:24:840PM | Plasma | Ok | |
| 16 | 12:49:07:580PM | Plasma | Ok | |
| 17 | 01:07:39:310PM | Plasma | Ok | |
| 18 | 01:22:03:490PM | Plasma | Ok | |
| 19 | 02:00:48:390PM | Plasma | Ok | |
| 20 | 02:20:04:770PM | Plasma | Ok | |
| 21 | 02:35:13:550PM | Plasma | Ok | |
| 22 | 02:49:18:340PM | Plasma | Ok | |
| 23 | 03:04:43:050PM | Plasma | Ok | |
| 24 | 03:26:45:940PM | Plasma | Ok | |
| 25 | 03:43:00:780PM | Plasma | Ok | |
| 26 | 03:55:43:290PM | Plasma | Ok | |
| 27 | 04:10:08:780PM | Plasma | Ok | |
| 28 | 04:27:52:790PM | Plasma | Ok | |
| 29 | 04:39:55:850PM | Plasma | Bad | Ross Relay Fault Held off Robicons. No Shot |
| 30 | 04:49:24:380PM | Plasma | Ok | |
| 31 | 05:00:46:070PM | Plasma | Ok | |