| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Brian Labombard |
| Physics operator(s): | Steve Fairfax |
| Engineering operator(s): | Frank Silva,David Gwinn |
| Engineering Operator Run Comment |
| Fairfax/Labombard run |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:08:087PM |
| Author: To Be Determined |
From: BRIGHT::LABOMBARD Date: 29-JUL-1993 12:31:47 Description: Physics Summary for 930728 Run The purpose of this run was to achieve part of the objectives stated in MP#016 - "Scrape-off Layer Characterization I." For this run, we were looking to set up a series of reproducible limited discharges to carefully insert the fast-scanning probe. The immediate goal was to record the scrape-off layer plasma characteristics (density, temperature, potential profiles) up to the last closed flux surface (LCFS). The fast-scanning probe currently reaches R=.74m, Z=-.27m at the end of full insertion (vertical scan). In order for the probe to reach the LCFS in a limited discharge, we needed to bring the plasma down and out to the probe. Still, we wanted to keep the scrape-off layer in primary contact with the inner limiter (or in the case of elongated discharges, on the upper and lower divertor tiles). Consequently, the RF limiter and antenna were moved back to R=.95m and R=.98m respectively. The first few shots were spent trying to switch over to the A-side piezo valve as the primary fill/pulse valve (faster time response). The valve did not behave very well (too long to stabilize fill pressure) and eventually we had to go back to the B-side upper valve. We fiddled around with loop voltage, fill pressure, Br feedback programming, coil temperatures (EF4), until finally we got our first plasma on shot 14. Does anyone really know why? Plasma shots where 14,16,17,18,19,24,25. The scanning probe was progressively inserted until by shot 24 it was fully inserted. We effectively got two good data shots. Also, starting at shot 18, we started moving the plasma position down and out over the time span of approx 200 to 280 msec. By shot 25 we had achieved about a -2.3 cm vertical movement of the current centroid. Kappa was about 1.3 at these times. The raw probe data on shot 25 looks reasonable. We should be able to get density and temperature profiles. Also I think we have the data to test the triple-probe's ability to record Te. However, in order to do this we need to get back to writting data analysis software. We had a problem with one of the four probe elements on the scanning probe - perhaps an intermittent short. This also needs to be looked at. I think the most positive result of this run was the reliable operation of the scanning probe. It appears that we can probe the scrape-off layer (at least in these 400 kA plasmas) without any noteable heating of the probe head. The TV monitor showed no 'afterglow' of the probe. No spectroscopists pointed any fingers at us for causing moly injection events (and you know how they enjoy doing this!). Also rough estimates of peak heat fluxes on the probe head appear to be well below 1MW/m2 (current safety limit of 350MW/m2), although we have yet to reach the LCFS (we are still a couple cm out). |
| Physics Operator Summaries |
| Entered: Jul 7 2004 04:36:50:253PM |
| Author: To Be Determined |
| The purpose of this run was to produce a series of identical shots for progressive insertion of the scanning plasma Probe. Brian Lambombard Session Leader Steve Fairfax Physics Operator Frank Silva Engineering Operator (morning) Dave Gwinn Engineering Operator (afternoon) Joan Orvosh State Jeff Paranay Power Joe Sorci Aux. Systems The fill gas was from B side upper port, but the pulsed gas was changed from B-side to A-side to take advantage of the faster response from this valve. The A-side programming (m-out 16, gas3) was copied from the B-side upper trace. A 10-volt offset was added because the A-side valve seems to require slightly higher voltages for the same throughput. Shot 1 was gas puff from B-side upper Shot 2 was gas puff from A-side with the B-side upper providing fill There was almost no gas from the A-side valve Shot 3 was gas puff from A-side with the A-side providing fill This provided about 3x pressure, with response about 15 msec later There was a 5-8 minute delay waiting for the fill pressure to stabilize. The valve required over 45 volts to open, then filled the chamber to the high 10-4 range. The pressure oscillated with light damping for 3 or 4 cycles before settling at 8e-6. Piezo voltage 38.77 Shot 4 was plasma attempt with fill and puff from A-side. The program for the A-side valve was delayed 15 msec and dropped 10 volts. Extended delay for gas fill again; settled at 38.02 Fizzle It appears that the extended time in INIT allowed the EF1 coils to warm up. Since the pre-commutation charge current is controlled with proportional gain only, the increased EF1 resistance resulted in slightly lower EF1 currents; about 4670 amps vs 4800 yesterday with the same programming. The field null had a better index than yesterday; perhaps too much. Shot 5 DUD plasma attempt Gas valve still not responding with 38 volt offsett; requires 42 volts to open recycle to RECOOL; load 930727029 into hybrid; switch gas fill to B-side upper with A-side pulsing late in shot no flash Currents are slightly different; I strongly suspect that running with CRYO ready bit bypassed is altering the magnet initial conditions enough to cause these changes Shot 6 plasma attempt delayed 25 minutes to allow all coils to cool enough DUD to get CRYO ready bit no flash Shot 7 plasma attempt: I had lowered the OH2 demand voltage from -20 to -40 volts after 8 msec in order to raise the loop voltage and increase the index. The breakdown was late; I raised the fill pressure to 1.0E-5 for shot 8. Fizzle; Turned off radial field control from -1 msec to +50 msec Shot 8 Fizzle; Breakdown was at 8 msec rather than 10 msec changed OH1 program from -50 to -250 volts between 8 and 24 msec Shot 9 Fizzle; much better loop voltage; more light, but no go. lower gas back to 8x10-6 Shot 10 Fizzle; lower gas to 6.4x10-6 Shot 11 Fizzle; breakdown later, 1 bit more plasma current changed OH1 and OH2 programming to be in sync, changed pulse on loop voltage to 5 msec from 8 msec put gas back at 8.0E-6 Shot 12 Fizzle Shot 13 Fizzle Shot 14 Plasma! Nothing touched. Shot 15 Fizzle! Lowered OH1 demand after commutation from -150 to -100; Lowered OH2 demand after commutation from -20 to -10 Shot 16 Plasma. Increased OH1 drive from 200 to 350 msec from 0 volts to -200 V Added step in Z_cur at 240-250 msec -2 cm until 400 msec Shot 17 Plasma Changed Z_cur step to -200 to -250 msec terminated discharge starting at 350 msec deleted late b-side gas puff at 350 msec increased OH drive somewhat Shot 18 Plasma Increased OH1 drive 30 volts more changed z step to 170-300 msec increased OH2 drive 20 volts Shot 19 Plasma Nice shot Shot 20 Dud. Looks as if gas fill may not have been correct. Changed R_cur to step from -.638 to .65 at t=.17 to .3 seconds Did not mess with initial conditions Shot 21 Dud. Fill was 7.2E-6. Changed to 9E-6 Changed EF3 program from +100 to -100 volts 200-350 msec Changed EF3 program from 100 to 1200 volts 350 to 500 msec Trying to terminate discharge without disrupting on limiter Shot 22 Fizzle Set TF start from -1.5 to to -1.65 seconds. Set TF current from 149 to 141 kA TF was 4.9 out of 5.1 Tesla at breakdown; I suspect that a few kA variation in the TF is chaning our null. The TF magnet resistance trace shows that the last 3 shots the magnet has been about 10-15 degrees warmer than previously. Shot 23 Dud Set TF to 143 kA Raise gas pressure to 1.2E-5 Torr Shot 24 Plasma Changed nothing. Nice 400 kA flat-top with <200 kW radiated Shot 25 Plasma Good shot. Changed Z excursion to -4 cm. Sharpened transition to 2 msec instead of 10 msec. Couldn't load it. Changed put Z excursion back to 3 cm, Changed R demand pulse from .65 to .67 cm Shot 26 Fizzle Fields at breakdown have changed some, reason unknown. The commutation resistors show slightly higher values, as one would expect from heating. The EF1L resistor show a DECREASE; This is unlikely. Shot 27 Fizzle Final Score: 3 Tests 12 Fizzles 5 Dud 7 Plasma Shots (.292 of Plasma Attempts) 0 Engineering Failures |
| Session Leader Comments | |||
| Jul 28 1993 08:56:26:370AM | Brian Labombard | Todays run will focus on MP#016 - scrape-off layer characterization.
Session leader: Brian LaBombard, Physics Operator: Steve Fairfax, Engineers: Frank Silva, Dave Gwinn. We are looking for a series of reproducible discharges (?) to insert (carefully) the fast-scanning probe. In order to allow the probe to reach the last closed flux surface, we will need to produce elongated (kappa approx 1.4), limited discharges. The RF limter is moved to R=.95 and antenna to R=.98 to give us bigger plasmas. We will start with the programming for shot 930727029, trying to extend the equilibrium at about 150msec to longer. The probe needs 100msec or so 'flat-top' for good data. | |
| Jul 28 1993 08:58:39:680AM | 930728001 | Brian Labombard | Gas pulse test shot using B-side upper gas pulse valve. We will keep the same gas
fill and try to get the A-side valve to produce the same response. |
| Jul 28 1993 09:29:28:840AM | 930728002 | Brian Labombard | Another gas pulse shot - this time using the same programming that was on B-side
upper on A-side valve. Did not repeat previous gas pulse. |
| Jul 28 1993 09:44:26:780AM | 930728003 | Brian Labombard | Another gas pulse shot - using the same gas programming on A-side valve
but also prefilling through A-side valve. There was a bit of delay in waiting for fill pressure to stablize. |
| Jul 28 1993 10:27:08:190AM | 930728004 | Brian Labombard | Trying for plasma. The A-valve gave us (on shot 3) gas at about 10msec earlier than
the B-valve did with the same programming. Also, the A-valve results in a factor of 2 or so more gas. We are delaying the gas pulse by 15 msec and dropping the piezo voltage program by 10 volts. Slight delay - EF4 needed more LN2 flow to cool - this resulted in a slight leak (mass 28 on RGA). The pump was subsequently backed off. The leak resealed. Also a slight delay wainting for fill pressure to stabilize. Piezo voltage 38.02 Flash only. |
| Jul 28 1993 10:53:59:030AM | 930728005 | Brian Labombard | A-side valve takes too long to settle for fill pressure. Changing back to B-side
for both fill and pulsed gas. Reloaded 930727029. no flash |
| Jul 28 1993 11:25:53:120AM | 930728006 | Brian Labombard | Try again - same settings (mumble some magic words)
This time we waited for EF4 to be below -165C. (Before, we had bypassed it.) The hope is is to get the coils at a repeatable temperature to minimize variations between shots from resistance changes. Flash only. |
| Jul 28 1993 11:59:53:400AM | 930728007 | Brian Labombard | Changing OH2-U and L program from -20.0 volts at 10 to 26 msec to -40.0 volts over
same time range - looking for more loop voltage. Gas fill is still at 8.0e-6 Flash |
| Jul 28 1993 12:19:12:770PM | 930728008 | Brian Labombard | Changing gas fill is still at 1.0e-5
Turned off Br feedback control over time range 0 to 50msec. Brighter (?) flash only (more gas) |
| Jul 28 1993 12:38:22:890PM | 930728009 | Brian Labombard | Changing OH1 program over range 8-24msec from -50 to -250 volts.
Flash (a very expensive flash lamp) |
| Jul 28 1993 12:56:24:330PM | 930728010 | Brian Labombard | Lowered fill pressure to 8.0e-6
flash only |
| Jul 28 1993 01:06:35:740PM | 930728011 | Brian Labombard | Lowered fill pressure to 6.4e-6
Flash |
| Jul 28 1993 01:26:46:710PM | 930728012 | Brian Labombard | Raised fill pressure back to 8.0e-6
Change OH1 and 2 voltage programming to provide higher loop voltage earlier: OH1-> -50 volts at 5msec (changed from 8msec) OH2U&L -> -250 volts at 5msec (changed from 10msec) Change EF3 program to -3000 at -1msec Flash - looks like it almost went? |
| Jul 28 1993 01:53:20:320PM | 930728014 | Brian Labombard | Change OH1& 2 programming: Reduce program voltages at 5msec
OH1 -> -250 changed to -150 OH2 -> -40 changed to -20 Fill Pressure same at 8.0e-5 We got plasma!! Hard X-rays also. |
| Jul 28 1993 01:59:34:780PM | 930728015 | Brian Labombard | Don't touch those dials. Same conditions.
Flash |
| Jul 28 1993 02:25:13:350PM | 930728016 | Brian Labombard | Change OH1&2 programming: at 5 msec
OH1 -> from -150 to -100 OH2 -> from -20 to -10 Got plasma. |
| Jul 28 1993 02:42:15:550PM | 930728017 | Brian Labombard | Change OH1 programming: 200 to at 350 msec, change program to -200
attempt to hold current up 240 to 400msec: Step Z_CUR down 2 cm Good Plasma. |
| Jul 28 1993 03:03:23:500PM | 930728018 | Brian Labombard | Tweeked OH1 programming for flatter current.
Stepped Z_CUR down 2 cm from 210 to 400msec. Turned off B-port gas puff at 350msec. Got plasma. Some injections? |
| Jul 28 1993 03:18:52:280PM | 930728019 | Brian Labombard | Stepped Z_CUR down 2 cm from 180 to 400msec.
Increase OH2 drive to avoid divertor and keep plasma current constant. Plasma, nice current flat-top |
| Jul 28 1993 03:29:10:430PM | 930728020 | Brian Labombard | Stepped Z_CUR down 3 cm from 180 to 275msec.
Flash only. |
| Jul 28 1993 03:40:52:650PM | 930728021 | Brian Labombard | Changed R_CUR programming at 210msec from R=.638 to .65 m
No flash |
| Jul 28 1993 03:57:39:120PM | 930728022 | Brian Labombard | Fill pressure drifted down a bit on the last shot. (~7.0e-6)
Compensating by setting fill pressure to 9.0e-5 Flash only. Lost the null. |
| Jul 28 1993 04:12:05:840PM | 930728023 | Brian Labombard | May be TF warming up. Compensation for toroidal currents in TF no longer correct?
Some adjustments made to TF ramp programming. No Flash |
| Jul 28 1993 04:23:57:490PM | 930728024 | Brian Labombard | Change fill pressure to 1.2e-5
Minor changes to TF programming (raised 2 kA) Good shot. Fast-scanning probe also fully inserted in this one. |
| Jul 28 1993 04:57:14:220PM | 930728026 | Brian Labombard | Changed R_CUR program to R=.67 from 180 to 300 msec.
Flash only |
| Physics Operator Comments |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 08:52:09:460AM | Test | Ok | pulse gas test |
| 2 | 09:21:16:460AM | Test | Ok | pulse gas test |
| 3 | 09:31:29:620AM | Test | Ok | pulse gas test |
| 4 | 10:07:56:990AM | Test | Ok | plasma |
| 5 | 10:38:26:770AM | Plasma | Ok | no bd |
| 6 | 11:20:01:930AM | Plasma | Ok | plasma |
| 7 | 11:50:20:940AM | Plasma | Ok | breakdfown |
| 8 | 12:06:28:780PM | Plasma | Ok | breakdown |
| 9 | 12:21:46:020PM | Plasma | Ok | breakdown |
| 10 | 12:43:24:520PM | Plasma | Ok | breakdown |
| 11 | 12:57:13:970PM | Plasma | Ok | breakdown |
| 12 | 01:16:23:300PM | Plasma | Ok | breakdown |
| 13 | 01:29:13:820PM | Plasma | Ok | brebreakdown |
| 14 | 01:42:41:040PM | Plasma | Ok | at last |
| 15 | 01:55:00:690PM | Plasma | Ok | breakdown |
| 16 | 02:08:32:760PM | Plasma | Ok | back again |
| 17 | 02:29:43:510PM | Plasma | Ok | two in a row |
| 18 | 02:49:57:220PM | Plasma | Ok | good shot |
| 19 | 03:10:12:760PM | Plasma | Ok | 450 ka |
| 20 | 03:23:47:410PM | Plasma | Ok | no plasma |
| 21 | 03:35:36:950PM | Plasma | Ok | |
| 22 | 03:46:29:270PM | Plasma | Ok | |
| 23 | 04:02:21:220PM | Plasma | Ok | |
| 24 | 04:16:42:040PM | Plasma | Ok | good shot 450 Ka plasma |
| 25 | 04:29:04:490PM | Plasma | Ok | 450 ka |
| 26 | 04:48:00:370PM | Plasma | Ok | fizzle |
| 27 | 04:59:01:670PM | Plasma | Ok | fizzle |