| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Ian Hutchinson |
| Physics operator(s): | Steve Fairfax |
| Engineering operator(s): | David Gwinn |
| Engineering Operator Run Comment |
| Increase OH precharge for more volt seconds. |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:08:070PM |
| Author: To Be Determined |
| Summary of Run of 22 Jul 93 I.H.H. 26 shots total. 8 plasma. 11 fizzles, Various tuning and power supply faults. The purpose of the run was partially accomplished. Plasma initiation was obtained at flux precharge of about 1.25 VS, nominally 1.5 times the previous value. No attempt was made to proceed to the higher (times 2) precharge because it was belatedly decided that the MOVs were not safe enough at the required OH2 current. Therefore some time was spent on increasing the plasma current. The first 11 shots were tuning. 12 was a runaway including gettering. Thereafter rather typical irreproducibility was experienced: about 50% success. The successful shots are fairly typical in most respects. It is clearly not significantly more difficult to get these plasmas to go at this precharge than at the lower value. However we have not solved the reproducibility problems for these lower voltage, seriesed EF3 startups. It is evident from the flux reconstructions that some, at least, of the irreproducibility is caused by power-supplies. For all plasma shots today, the OH1 was run with only 1 cabinet because the oscillations that appear due to the OH1/OH2 interaction have not been fixed, despite the correction of the regulator oscillation problem that was done yesterday by lowering its gain. With only 1 OH1 cabinet, 300Hz oscillations due to the power-supply phasing are all too evident on the currents and fields. These are potentially sufficient to cause the problems we have seen, although they are not yet proven to be the problem. However, it is becoming very clear that IT IS URGENT TO FIX THE OH SUPPLY OSCILLATION PROBLEMS A new current record of 0.44MA was obtained. Pushing the current up was hampered by the observation that the R-position controller was not performing as expected. When the demand from the feedback was large, the voltage applied to OH2 was out of proportion to the OH1 (and EF3). This had the effect of producing some strongly D-shaped plasmas with the x-points on the inner wall. It is not understood why we now find better performance with the nominal OH1 gain 10 times higher than that on OH2. The first guess at the right ratio is something like the turns ratio, which is approximately 5 to 1. The present controller works OK and indeed quite well during a steady flat top but does not succeed in maintaining as good a position control as we would like during the current ramp. It would perhaps be fine if there were a painless way to copy the previous voltage into the voltage program. At the moment, we fear to do this automatically because the whole time history gets replaced, not just some selected time. It is recommended that shot 26 be used as a basis for future discharge development. It has low elongation and a q of about 4. |
| Physics Operator Summaries |
| Session Leader Comments | |||
| Jul 22 1993 08:55:33:620AM | Steve Fairfax | The session leader is Ian Hutchinson. Physics Assistant is Fairfax. Engineering Operator
is Gwinn. Fridberg on power systems, Orvosh on state, Sorci on Aux. systems. This run is devoted to Ian Hutchinson's Mini-Proposal 003, raise Plasma Initiation with greater OH precharge. The OH prechage currents will be raised in two steps. The first step will be approximately 1.5x the present "standard" precharge. The OH1 current will be increased from 11.1 to 16.6 kA, the OH2 from 14.8 to 22.2, and the EF1 from 3.2 to 14.8. The commutation resistors have been lowered to keep the plasma initiation voltage approximately constant. The initial plan was to then raise the currents to 2x the initial levels, but this would result in currents of 29.5 kA in OH2U. The varistor protection networks for OH2, will designed for 50 kA, have only 25 kA installed capacity as an economy measure. The Engineering Operator (Gwinn) strongly recommends against exceeding the rating. | |
| Jul 22 1993 09:11:29:220AM | 930722001 | Steve Fairfax | Fill pressure set 1.4e-5.
No pulse. Acknowledge failure in engineering control system blocked start pulse to timing highway. This interlock had been disabled for some time and was re-enabled last night. The interlock is designed to block a pulse of any of the engineering PLC/PC systems fail to acknowledge the transition from CHECK to PULSE state in 2 seconds. The engineering operator has elected to disable the interlock again and monitor the system to determine which PLC/PC is not acknowledging the transition. Nitrogen event after the shot. Base pressure did not change significantly, but partial pressure of 28 peak increased an order of magnitude. The AUX systems operator shut off the LN2 pump almost immediately and the partial pressure of 28 quickly dropped. No increase in the He peak was observed. |
| Jul 22 1993 09:29:02:090AM | 930722002 | Steve Fairfax | No hybrid. It appears that MDS-Plus maintenance set most of the nodes to /noinclude
last night for testing, then forgot to turn the nodes back on. The hybrid was not included in the pulse file, along with most of the diagnostic nodes. |
| Jul 22 1993 09:45:01:640AM | 930722003 | Steve Fairfax | Hybrid OK now, but EF2s did not fire. EF2 switch was fired when there was no voltage
available. |
| Jul 22 1993 09:56:22:830AM | 930722004 | Steve Fairfax | Still no EF2's. EF1L crowbar at +10 msec.
For shot 5, PID gain on EF4 raised from 2.5 to 5.0 |
| Jul 22 1993 10:55:56:120AM | 930722005 | Steve Fairfax | EF2 OK.
For shot 6, Raised the OH2 voltage to 20 V prior to commutation; also raised EF4 current to 1100 A |
| Jul 22 1993 11:02:20:740AM | 930722005 | Steve Fairfax | EF2 OK.
For shot 6, Raised the OH2 voltage to 20 V prior to commutation; also raised EF4 current to 1100 A. Delayed the toroidal field by 150 msec. |
| Jul 22 1993 11:17:11:580AM | 930722006 | Steve Fairfax | EF2 OK.
For shot 6, Raised the OH2 voltage to 20 V prior to commutation; also raised EF4 current to 1100 A. Delayed the toroidal field by 150 msec. got closer but no flash. |
| Jul 22 1993 11:50:27:650AM | 930722007 | Steve Fairfax | increase pid gain on ef2s from 1 to 2
got the flash. still not reaching full voltage on ef2s |
| Jul 22 1993 12:11:19:640PM | 930722008 | Steve Fairfax | increased ef2 voltage demands to 200V before commutation.
Got almost as much EF2 current as desired. Flash; less than 10 kA plasma current. |
| Jul 22 1993 12:24:28:480PM | 930722008 | Steve Fairfax | Lowered EF4 to 1050 amps. Started EF3 1 second earlier.
No pulse. Init cycle seemed very short. |
| Jul 22 1993 12:43:49:220PM | 930722010 | Steve Fairfax | Lowered EF4 to 1050 amps. Started EF3 1 second earlier.
No pulse. Init cycle seemed very short. This entry may be logged erroneously under shot 8 or shot 10. Shot 9 was a dud; no power supplies fired at all due to a camac problem. Apparently shot 9 did not meet the MDS-Plus standard for a shot. Shot 10 is next. Entry after shot 10: Flash, 20 kA plasma current. For shot 11: Removed 100 point in OH1 V program at 6 msec Raised Br demand from 7e-3 to 8e-3 Tesla |
| Jul 22 1993 12:58:46:400PM | 930722011 | Steve Fairfax | No flash on shot 11. Changes did pretty much exactly what was asked for.
Lack of flash on this shot is puzzling. Moved EF4 S demand from 1050 to 1080 amps at commutation. |
| Jul 22 1993 01:18:22:820PM | 930722012 | Steve Fairfax | Shot 12. 180 kA runaway discharge.
For shot 13: Lower voltage on OH1 and OH2; added points just before commutation and raised voltage demand 20 volts on OH2 and 80 volts on OH1 |
| Jul 22 1993 01:20:08:390PM | 930722012 | Steve Fairfax | Shot 12. 180 kA runaway discharge.
For shot 13: Lower voltage on OH1 and OH2; added points just before commutation and raised voltage demand 25 volts on OH2 and 70 volts on OH1 |
| Jul 22 1993 01:37:03:300PM | 930722013 | Steve Fairfax | Shot 13: 370 kA for almost 400 msec. Very low elongation.
Low density; 4e19 for much of shot. Shot 14 will be an attempt to repeat shot 13 |
| Jul 22 1993 01:54:00:390PM | 930722014 | Steve Fairfax | Shot 14 very similar to shot 13.
For shot 15: Increased voltage drive to plasma using OH1, OH2 (decreased voltage prog) Decrease current feedback demands on OH1 and OH2 after commutation. Set Ip controller for 500 kA but PID gain still at 0. |
| Jul 22 1993 02:04:46:490PM | 930722015 | Steve Fairfax | Shot 15 was an early fizzle.
For shot 16: raised OH2 voltage program after commutation from 24 to 30 volts raised OH1 voltage program after commutation from 70 to 100 volts |
| Jul 22 1993 02:28:23:760PM | 930722016 | Steve Fairfax | Shot 16: New plasma current record: 410 kA
Major position excursion at 100-200 msec, divided opinion as to cause. For shot 17: Removed S demand pulse on EF2 (left over from earlier run's elongation experiments) No other changes |
| Jul 22 1993 02:45:10:660PM | 930722017 | Steve Fairfax | Shot 17 was a fizzle.
No changes for shot 18 |
| Jul 22 1993 03:03:19:920PM | 930722018 | Steve Fairfax | Shot 18 was a fizzle.
Several minutes delay trying to make changes for shot 19: PCS zoom, pan, etc broke. Shot 19: Raised OH2 at commutation from 30 to 35 volts |
| Jul 22 1993 03:13:55:270PM | 930722019 | Steve Fairfax | Shot 19 was a fizzle.
For shot 20: Raised Br demand from 8 to 8.5 mTesla |
| Jul 22 1993 03:26:19:900PM | 930722020 | Steve Fairfax | Shot 20 was a fizzle.
For shot 21: Reduce OH1 Voltage program from +100 to +90 volts after commutation |
| Jul 22 1993 03:42:30:180PM | 930722021 | Steve Fairfax | Shot 21: 400 kA . Change is field structure is hard to see, but can't argue with results.
For shot 22: Move OH1 crowbar from 70 to 100 msec. Change OH1 program to invert -600 volts from 72 to 98 msec Reduce fill pressure from 1.4e-5 to 1.1e-5 Torr. |
| Jul 22 1993 03:58:46:210PM | 930722022 | Steve Fairfax | Shot 22: 390 kA
For shot 23: Increased step in OH2 from -50 to -60 volts at 60 msec (was 70 msec) Increase EF3 voltage to 1000 volts at 100 msec |
| Jul 22 1993 04:19:11:240PM | 930722023 | Steve Fairfax | Shot 23 was a fizzle.
Changes for shot 24: Changed OH1 programming at 1 and 6 msec from 90 to 80 volts |
| Jul 22 1993 04:34:56:330PM | 930722024 | Steve Fairfax | Shot 24 430 kA. Radiated power >300 kW for much of shot.
Changes for shot 25: Changed OH2 gain in R_CUR controller from -2e-3 to -1e-3 Changed Prop. Gain in R_CUR PID from 1 to 2 Changed Deriv. Gain in R_CUR PID from .5 to 1 |
| Jul 22 1993 04:55:47:980PM | 930722025 | Steve Fairfax | Shot 25: Fizzle
Changes for Shot 26: Move pulse gas from -5 mSec to -10 mSec |
| Jul 22 1993 05:01:59:340PM | 930722026 | Steve Fairfax | Shot 26: 440 kA
Field structure at beginning substantially different but why? Position control with better; stays circular instead of elongating when position changes |
| Physics Operator Comments |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 08:57:00:510AM | Plasma | Bad | ack failure on state , no pulse |
| 2 | 09:12:24:300AM | Plasma | Ok | no pf comp.prob |
| 3 | 09:30:45:160AM | Plasma | Ok | no ef2 |
| 4 | 09:46:41:590AM | Test | Bad | |
| 5 | 10:37:05:220AM | Plasma | Ok | no breakdown |
| 6 | 10:56:28:990AM | Plasma | Bad | ef1,oh1, fault ? |
| 7 | 11:38:43:030AM | Test | Bad | |
| 8 | 11:57:17:070AM | Test | Bad | |
| 10 | 12:28:36:570PM | Plasma | Ok | breakdown |
| 11 | 12:46:27:780PM | Plasma | Bad | no bd |
| 12 | 01:01:24:300PM | Plasma | Ok | |
| 13 | 01:20:57:730PM | Plasma | Ok | good |
| 14 | 01:38:08:710PM | Plasma | Ok | good shot 340 KA plasma current. |
| 15 | 01:54:37:520PM | Plasma | Ok | Good shot |
| 16 | 02:05:40:750PM | Plasma | Ok | good shot 410 KA plasma current. |
| 17 | 02:28:43:540PM | Plasma | Ok | Good shot plasma fizzled. |
| 18 | 02:45:38:660PM | Test | Ok | plasma shot no faults. |
| 19 | 03:06:07:400PM | Plasma | Ok | No faults plasma fizzled |
| 20 | 03:15:58:520PM | Plasma | Ok | plasma shot no faults. |
| 21 | 03:28:35:330PM | Plasma | Ok | Plasma shot no faults. |
| 22 | 03:43:56:880PM | Plasma | Ok | 390 ka |
| 23 | 04:03:11:690PM | Test | Ok | fizzle |
| 24 | 04:20:04:900PM | Plasma | Ok | good shot plasma current 435KA. |
| 25 | 04:36:58:190PM | Plasma | Ok | fizzle |
| 26 | 04:49:53:100PM | Plasma | Ok | record high plasma current! |