| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Unknown |
| Physics operator(s): | Steve Wolfe |
| Engineering operator(s): | Vinny Bertolino,Frank Silva,Dave Terry |
| Engineering Operator Run Comment |
| MP 170 Restart/Wolfe/Bertolino,Silva,Terry, D |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Physics Operator Summaries |
| Entered: Jul 7 2004 04:36:57:253PM |
| Author: To Be Determined |
| Physop Summary for Tuesday 970520 MP 170A: restart tokamak PO: wolfe EO: silva, bertolino Run plan: ========= We are still trying to get reproducible full length plasmas. We will start from the best shot from Monday, 970519032, but with the CLEARIN adjusted to increase the vertical stability a bit. This is an 800kA, 1.2 sec(EOF), SNB shot. The main emphasis will be to try to improve the robustness of the startup. Since this is probably a function of cleanliness, there isn't much I can do about it except bang away, but I'll try anyway. We may again want to try ECDC between shots, although it didn't seem very successful the one time Earl tried it on Monday. I may even ask for glow between shots, depending on how Jim's tests work out Monday night. If things seem to be going reasonably well, we will want to try hybrid control on the TF and ramp-down to 4T from a 5.4T startup. However, we will start the day with normal PLC TF control. Results: ------- The run got off to a late but promising start, went through a long frustrating middle period and then ended on a high note, getting good plasmas on 4 of the last 6 shots. We learned several things, at least some of which may be false. First, the plasma report: Shots 2,23,26,27,29 and 31 were 800kA plasmas, of which all but 23 had flat density traces and made it into ramp-down. All had essentially the same programming, based on 970519032 with CLEARIN set to -.005m (not -.01). The best of these is probably 31, which lasted until 1.5 sec, possibly due to changes in the ramp-down gains; the others, except 23, all went to about 1.38. Shot 23 was dirty and disruptive, lasting to only 650msec and getting to very high density. It is worth noting that all of the successful plasmas also had the x-pt Thomson laser firing into the dump, and that 28 and 30 did not, and were duds. Moreover, for most (maybe all) of the long string of duds in the middle of the run, the laser was not firing. There is a strong correlation for making the case that the laser-produced plasma in the beam dump area, which is visible on the TV before commutation, may be producing electrons and/or UV to help pre-ionize. There is also a correlation with base pressure being below 1.1e-6, but that is less robust. The start of the run was delayed until nearly 11:30 because of a problem at the alternator. Irby made use of the time by running glow discharge cleaning for a total of about 2 and a half hours, at relatively low current. GDC seems to be working reasonably well, but needs lots of conditioning time to get the current up without arcing. The plan is to run it all night tonight. Shot 1 had a huge fluorocarbon burst, essentially doubling the pressure at t=0; it was a dud. Many of the first attempts had large teflon bursts, with #2 being an exception. In an attempt to clarify the the dependence of the CF bursts on the poloidal voltage, we ran the TF at a PLC setting of 1200V, instead of 1600V, on shots 8 and 9. The early bursts and the 31,50, and 81 peaks on the RGA essentially vanished. An oscillation of several cycles was noted on the early part of the TF voltage trace; apparently there is insufficient damping in the voltage regulator circuit and the way it normally works is to run up to the available voltage, which is less than the set point of 1600V. Once the voltage sags a bit, the oscillation vanishes. Shot 10 we put the tf voltage back to 1600V, and the 31,50,81 peaks came back strongly on the RGA; DAQA crashed, taking much of the CAMAC data with it, so we couldn't check the pressure signal, but we got a fizzle. Shot 11 had the TF set to 1500V, which gave essentially the same voltage trace as 1600 and produced a big teflon burst (1.1e-5). On the following shots we got smaller bursts at 1400V and 1300V settings, and back at 1200V we ran shots 14-19 with small or non-existent teflon. However, when we set the PLC back to 1600V on shot 20 the bursts did not reappear, so what looked like a good correlation and a possible fix did not hold up. It may be worthwhile to try reducing the TF voltage again if the teflon recurs tomorrow though; it did seem to do something. After a long series of duds (3-7) following the first plasma, we stopped and ran ECDC for 20 minutes. This did not seem to help much. We had a few fizzles, but no more plasmas until 23. I did a lot of fiddling with fields and fills, but while I made the null look better (and worse) the plasma was not impressed. One thing that may be worth revisiting is that I found I could balance the EF2's better, and make some improvement in the shape of the null, by putting an offset of 50A in the EF2U predictor. This seemed to be consistent with the fact that the Phys_A_out was showing zero error for each when they actually had a difference current of about 50A. However, this tweak was thrown away when I reloaded shot 2 into shot 23. Power systems were well-behaved, with only one shot lost (as if) to an early PF crowbar. This was on shot 12, and it was initiated by a spurious COM fault on OH2L, just like one shot yesterday. CAMAC was throwing MEDOFL errors all day, but Tom eventually found a patched driver from before we did the last system upgrade that seemed to work. However, putting the RF crate on gave more errors, so it's not fully fixed yet. The new highway driver unit from JORWAY is overdue. On the last shot I tried turning on the Argon for John, but it didn't give him any signal even with 47msec of pulse width at 100V. He will try exercising the valve tonight. The 2pi bolo is apparently reading high. Shot 23 claimed to be radiating 5MW. Regular bolos are seeing more normal levels. Summary ------- All in all, a difficult day, but encouraging in that we got some good shots at the end. The x-point laser effect may turn out to be a superstition, but it can't hurt. The plasmas seemed happy with 17msec gas puffs. I got duds at all fills, but in some cases higher pressure gave fizzles. We may be closing in on reproducible full length plasmas. The between shot ECDC seems to be not helpful. I didn't get to try the hybrid TF control, but the tf voltage effect (?) on the teflon bursts is interesting. Scorecard: ---------- Duds 20 fizzles 5 plasmas 6 ------- -- shots 31 |
| Session Leader Comments |
| Physics Operator Comments | |||
| May 20 1997 07:18:37:510AM | Steve Wolfe | Tuesday 970520 MP 170A: restart tokamak PO: wolfe EO: silva, bertolino coldstart successful at 20-MAY-1997 07:12:32.49 Run plan: ========= We are still trying to get reproducible full length plasmas. We will start from the best shot from Monday, 970519032, but with the CLEARIN adjusted to increase the vertical stability a bit. This is an 800kA, 1.2 sec(EOF), SNB shot. The main emphasis will be to try to improve the robustness of the startup. Since this is probably a function of cleanliness, there isn't much I can do about it except bang away, but I'll try anyway. We may again want to try ECDC between shots, although it didn't seem very successful the one time Earl tried it on Monday. I may even ask for glow between shots, depending on how Jim's tests work out Monday night. If things seem to be going reasonably well, we will want to try hybrid control on the TF and ramp-down to 4T from a 5.4T startup. However, we will start the day with normal PLC TF control. | |
| May 20 1997 07:51:33:440AM | Steve Wolfe | Load_from 970519032 Set CLEARIN to -.005 in seg 2 Load at 20-May-1997 07:51:17.00 | |
| May 20 1997 08:49:44:640AM | Steve Wolfe | We are having a delay while the alternator crew replaces an actuator that burned out this morning. Should be ready at about 10AM. GDC is on- it's hard to tell from the TV picture, but the RGA sees it. | |
| May 20 1997 09:47:54:680AM | Steve Wolfe | The latest word from the alternator is that we should be on the air at about 10:45 | |
| May 20 1997 10:25:43:120AM | Steve Wolfe | The later latest word is another hour for the alternator, i.e. 11:45AM. Meanwhile, GDC is proceeding. | |
| May 20 1997 11:28:06:080AM | 970520001 | Steve Wolfe | Shot 1: PCS from 970519032 with CLEARIN adjust. Pre-puff still at 17msec GDC before operation for about 2.5 hours GDC off at 10:50AM 11:22 Base pressure=4.5e-7 Got a burst of 28 when Thomson valve was re-opened, came back down ok Dud. Huge Teflon burst. Ratiomatic F-side was up to 3.3e-5 at t=0, about half CxFy. |
| May 20 1997 03:20:56:860PM | 970520002 | Steve Wolfe | Shot 2: try that again. PCS from 970519032 with CLEARIN adjust. Pre-puff still at 17msec base=4.0e-7 plasma, lasts 1.36sec some kind of injection at .77sec, left gap ~1.3cm bd looks good: bd at 5.4msec 140kA @30msec, ECE has signal on 8 of 9 channels. CII peaks at .01mW/cm2/ster Ratiomatic at 1.7e-5 |
| May 20 1997 11:51:59:460AM | 970520003 | Steve Wolfe | Shot 3: No changes base=1.2e-6 dud. had a Teflon burst, but smaller. P0 = 1.75-1.8e-5 |
| May 20 1997 11:58:38:250AM | 970520004 | Steve Wolfe | Shot 4: No changes base= 9.5e-7 dud. P0=1.5e-5 (maybe there was Teflon on 2?) For next shot prepuff to 20msec from 17 (and move it t0 -.52 : -.50) |
| May 20 1997 12:08:23:260PM | 970520005 | Steve Wolfe | Shot 5: prepuff to 20msec from 17 (and move it t0 -.52 : -.50) base = 7.4e-7 another dud? Imbalance on EF4 now at near zero, was at -60 null looks fair. Ratiomatic= 2.0e-5 very small teflon burst. Next shot raise Pre-puff to 25msec |
| May 20 1997 12:19:32:360PM | 970520006 | Steve Wolfe | Shot 6: raise Pre-puff to 25msec base=6.0e-7 dud. More teflon: 7.2e-6 @-.52sec, -1.3e-6@-11.sec bz is coming in pretty late. No changes |
| May 20 1997 12:25:01:770PM | 970520007 | Steve Wolfe | Shot 7: no changes base=5.5e-7 dud - another big teflon burst, up to 1.3e-5 at -.5sec. ECDC for 20minutes |
| May 20 1997 01:03:13:080PM | 970520008 | Steve Wolfe | Shot 8: ECDC for 20minutes Drop pre-puff back to 16msec Drop TF voltage to 1200V (from 1600) start at -1.2sec base=1.7e-6 fizzle. late bd (20msec!) No Teflon burst (or very small) ratiomatic=1.5e-5 Unfortunately, the TF voltage rings for the first 250msec; not good |
| May 20 1997 01:14:56:160PM | 970520009 | Steve Wolfe | Shot 9: repeat, same tf setting; maybe it's not too bad. base=7.4e-7 dud, but no Teflon. The TF voltage seems to matter. Ratiomatic at 1.4e-5 |
| May 20 1997 01:34:08:960PM | 970520010 | Steve Wolfe | Shot 10: tf back to normal setting, pre-puff to 20msec base=6.2e-7 fizzle. Got a burst. DAQA crashed so I'm missing the data; |
| May 20 1997 01:42:20:220PM | 970520011 | Steve Wolfe | Shot 11: tf to 1500V, start=-1.0sec Vinnie thinks the reason the ringing stops is the max voltage sags to the voltage limit. base=5e-7, no other changes. fizzle, late bd (11msec) teflon burst - 1.1e-5 at -.5sec |
| May 20 1997 01:51:08:820PM | 970520012 | Steve Wolfe | Shot 12: tf to 1400V, start=-1.0sec base=5.2e-7 dud - pf breaker pulled early oh2l? got a teflon burst. delta = 2.5e-6 this one looks bigger on the RGA than 11, so it must have had a big post pulse too. |
| May 20 1997 02:05:22:580PM | 970520013 | Steve Wolfe | Shot 13: tf to 1300V, start=-1.0sec base=4.3e-7 dud burst, but it must be after (on the invert). Pressure at -.5=1.25e-6, compared to 1/13e-6 at -1.7sec ratiomatic at 1.7e-5 at t=0 |
| May 20 1997 02:16:19:270PM | 970520014 | Steve Wolfe | Shot 14: tf to 1200V, start=-1.0sec base=4.1e-7 dud still a burst on the RGA, but no early burst, or hardly any (1.4-1.1=.3e-6 delta) |
| May 20 1997 02:27:55:780PM | 970520015 | Steve Wolfe | Shot 15: +15Amps on EF4 leave tf at 1200V. Tom is trying to fix the CAMAC MEDOFL errors; the last driver he tried made it worse. Note: pre-pulse is at 19msec, not 20. base=3.7e-7 dud. no teflon on RGA, or on ratiomatic (1.1e-6 across the board.) null looks a little worse |
| May 20 1997 02:37:43:110PM | 970520016 | Steve Wolfe | Shot 16: Put a +50 A offset on ic_ef2u base=3.7e-7 dud, tiny burst on RGA, none on ratiomatic the offset tweak seems to improve the balance on the ef2's, but obviously no help on the breakdown. |
| May 20 1997 02:45:32:540PM | 970520017 | Steve Wolfe | Shot 17: put back the 15 amps on ef4 (to -1375) base=3.6e-7 dud. no teflon. ratiomatic=1.65e-5 try raising the pressure again |
| May 20 1997 02:53:56:410PM | 970520018 | Steve Wolfe | Shot 18: raise pre-fill to 22msec at least I got a flash. fizzle - bd at 7msec tiny little teflon on RGA, none on ratiomatic, |
| May 20 1997 03:02:59:300PM | 970520019 | Steve Wolfe | Shot 19: ICOH1 to -20650 from -20750, ICef4 to -1360 from -1360 dud, No teflon null looks like to much Bz early, but the index moved the right way (at least the way I meant it to) |
| May 20 1997 03:18:43:310PM | 970520020 | Steve Wolfe | Shot 20: ICef4 back to -1375 tf voltage back to 1600V for this shot. dud, Tiny TEFLON, none on ratiomatic - so much for that theory. Leave the voltage high then, see if it comes back. Null doesn't look bad. maybe a tiny Br |
| May 20 1997 03:25:48:140PM | 970520021 | Steve Wolfe | Shot 21: increase pre-puff to 24msec dud no teflon. Try a Br tweak |
| May 20 1997 03:32:47:290PM | 970520022 | Steve Wolfe | Shot 22: Br from .0065 to .0060 If this doesn't work, I'll reload shot 2. No MEDOFL errors after shot 21 (twf, et al. have been playing musical drivers, and finally hit on one that seems to work). dud. I don't know where it went, but I'll revert to shot 2. |
| May 20 1997 03:49:19:100PM | 970520023 | Steve Wolfe | Shot 23: reload of shot 2, short early pre-puff and all. plasma - bd at 5.2 msec, some hesitation but over 100kA at 30msec, 500kA at 100msec dies at .65sec, big density burst at 0.4 sec, density rises to 2.65e20 nl4. This may be a density limit disruption, Joe says there was a locked mode. Note that the Boris went down to fix something in the cell before the shot, and the edge thomson laser was firing, as it was on #2. Another superstition is born! |
| May 20 1997 03:54:48:280PM | 970520024 | Steve Wolfe | Shot 24: No changes. base= 9.8e-7 dud. Here we go again. tiny teflon, nothing to speak of on ratiomatic. |
| May 20 1997 04:06:08:480PM | 970520025 | Steve Wolfe | Shot 25: increase pre-puff to 20msec, move it to -.500 base=6.8e-7 fizzle. bd at 5.5msec some positive radial field two bounces, it was trying |
| May 20 1997 04:16:47:470PM | 970520026 | Steve Wolfe | Shot 26: decrease pre-puff back to 17msec base=6e-7 plasma- lasts to 1.38sec in rampdown. nice flat density, small h-alpha burst around 220msec, near when it diverts, also ef4 crossover. Null looks horrible, but breakdown is nice and early and current rise is pretty good. |
| May 20 1997 04:31:47:850PM | 970520027 | Steve Wolfe | Shot 27: No changes base=1.1e-6. plasma: 2 in a row! disrupts in rampdown at almost exactly the same time. bd at 5.0msec, reasonable current rise |
| May 20 1997 04:36:03:590PM | 970520028 | Steve Wolfe | Shot 28: No changes base=1.1e-6 dud. Note that the x-pt Thomson laser did not fire this time. |
| May 20 1997 04:47:14:790PM | 970520029 | Steve Wolfe | Shot 29: No changes base=7.8e-7 plasma. Laser was firing again. the pulse length is identical! Something happens then. |
| May 20 1997 04:54:18:230PM | 970520030 | Steve Wolfe | Shot 30: Turn on Ar pulse for JR, 47msec at 0.3sec No other changes. There are lots of gain drops at that time. base=1.4e-6 dud. No laser; they're still batting 1000 |
| May 20 1997 05:30:15:410PM | 970520031 | Steve Wolfe | Shot 31: Kill late gain switches on RXU, ZXU, RXL, ZXL base=1.0e-6 plasma: made it to 1.5sec; takinmg aout the gains seems to help. This one had a shark fin at the end. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 11:23:10:640AM | Plasma | Ok | |
| 2 | 11:35:37:620AM | Plasma | Ok | |
| 3 | 11:46:20:120AM | Plasma | Ok | |
| 4 | 11:53:25:460AM | Plasma | Ok | |
| 5 | 12:02:06:330PM | Plasma | Ok | |
| 6 | 12:12:19:510PM | Plasma | Ok | |
| 7 | 12:20:37:500PM | Plasma | Ok | |
| 8 | 12:54:22:290PM | Plasma | Ok | |
| 9 | 01:09:44:460PM | Plasma | Ok | |
| 10 | 01:17:42:510PM | Plasma | Ok | |
| 11 | 01:36:25:710PM | Plasma | Ok | |
| 12 | 01:44:05:910PM | Plasma | Bad | oh2 fault |
| 13 | 01:58:24:930PM | Plasma | Ok | |
| 14 | 02:07:36:980PM | Plasma | Ok | |
| 15 | 02:22:30:160PM | Plasma | Ok | |
| 16 | 02:31:54:420PM | Plasma | Ok | |
| 17 | 02:40:43:240PM | Plasma | Ok | |
| 18 | 02:48:43:500PM | Plasma | Ok | |
| 19 | 02:57:55:940PM | Plasma | Ok | |
| 20 | 03:07:13:040PM | Plasma | Ok | |
| 21 | 03:23:20:410PM | Plasma | Ok | |
| 22 | 03:30:04:060PM | Plasma | Ok | |
| 23 | 03:39:09:730PM | Plasma | Ok | |
| 24 | 03:50:26:850PM | Plasma | Ok | |
| 25 | 04:00:47:510PM | Plasma | Ok | |
| 26 | 04:09:34:450PM | Plasma | Ok | |
| 27 | 04:19:21:480PM | Plasma | Ok | |
| 28 | 04:32:37:690PM | Plasma | Ok | |
| 29 | 04:42:51:830PM | Plasma | Ok | |
| 30 | 04:51:28:800PM | Plasma | Ok | |
| 31 | 04:58:35:780PM | Plasma | Ok | |