| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Bruce Lipschultz |
| Physics operator(s): | Steve Wolfe |
| Engineering operator(s): | Steve Fairfax |
| Engineering Operator Run Comment |
| 1st: Get reliable plasma. 2nd: x-point and SOL characterization |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:08:977PM |
| Author: To Be Determined |
| Run of 930923 Physics Operator - Steve Wolfe Session Leader - B. Lipschultz This run was based on Mini Proposal 016 - Scrapeoff Layer Characterization I. The aim of the run was to achieve well diverted plasmas which could be used for MP016. The usual probe diagnostics were available. In addition we have just added a fiber optic viewing the outer divertor. This fiber is coupled into the U. Md OMA for measurement of the impurity source rates there. We started the run by loading shot 930921009. Most of the run was spent just trying to get reproducible shots. We started getting consecutive shots starting at # 15 - #21. These were quite good diverted shots with good clearance to the inner wall (> 2 cm). The plasma current was 460 kA and the density was ~ 5e19 nel. The Zeff was typically around 1.5 and sometimes at 1 (or below). Shot # 22 was the first change in plasma parameters with an increase in current to 560 kA. It also was quite different in that a large gas influx happened during the first 200 ms and the density rose to 8e19 nel. After that shot we just had fizzles or disruptions. Another shot of interest that occured early in the run was shot 8. At 700 ms the MARFE appears to move quickly (2 ms) from the inner wall to the divertor. The radiation in the divertor goes from almost nothing to saturation and the probe-measured density increases as well. The probe diagnostics were able to obtain data for the shots 15-21. The scanning probe missed being enabled on shots 16 and 18. The measurements of line emission in the divertor were made over the same shot range (15-21). We found that the molybdenum/Oxygen emission ratio in the divertor (ratio of the source rates) was much lower in the divertor than in the limiter case. |
| Physics Operator Summaries |
| Entered: Jul 7 2004 04:36:50:363PM |
| Author: To Be Determined |
| Physics Operator Summary of 930923 Session Leader: BLIP Physics Operator: Wolfe Eng. Operator: Fairfax The purpose of this run was to study SOL parameters in diverted plasmas. Given the difficulties of the last few days, it was anticipated that getting a reliable discharge would be a challenge. This proved to be correct. We started with shot 930921009, with several modifications: 1) Need to recalculate M's on wires 2 & 3 because of new gain of 4 in AFOL to Chopper. 2) Put BR_0 on wire 7 as yesterday. Use CUSTOM to modify VACUUM predictor to add 8e-3 on MINUS_1_VOLT. Draw zero for \S_BR_0 Load PID P=1.0 from -0.8sec to +0.03sec FACTOR = 40. M = OH2U -1500, OH2L + 1500 Turn off PID on Wire 8 3) Check of PIDs found that gain on wires 13,14 (IC_EF2U&L) was turning off at 0.5 sec. Changed end to 1.5sec Some fiddling with fields and gas got us to a reasonable discharge on shot 8. However, shot 9 was a dud and more tweaking ensued. Among the things changed, I think the more significant were: Got rid of an imbalance in EF2U&L before and just after commutation by programming a current imbalance of 50A to compensate an offset problem (?), getting rid of a voltage program imbalance, and finally adding EF2's to the BR_0 Controller. Raise the gain on BR_0 to 2.0 Set the BR_0 offset to 9mT (MINUS_1_VOLT = 0.009). This, combined with the other changes, ended up giving a BR of -1 to -2MT, which it seemed to prefer. After getting success with this value, we did not try scanning further, so a different value may be better. The first shot of the sequence of "good" discharges was 15. The next several shots were spent tweaking the shape, including getting the RXL and ZXL control going and increasing the early inner gap (by manually adjusting OH2 voltages), and actually getting data for/by BLIP and BLAB. The RXL and ZXL control now seem to be working well, as the x-point was very well positioned at least until the current ramp-down. The strike points executed their sweep over the plates as the flux swung, as expected. Shot 20 was an attempt to raise the current. The current did rise, to 560kA, but ended in a hard disruption at 0.87 seconds. This shot was peculiar because the early density went up much faster than on the preceeding shots, although no changes were made early. The line density reached 8e19 by 250msec, then came down sharply. The shots after the disruption were fizzles and/or ugly. On the last two shots, Fairfax attempted to raise the TF to 5.3 Tesla in preparation ofr the RF runs. This failed on 22 due to an improperly set safety limit in the PLC, and succeeded on 23. Francesca reported Argon signals all day, despite the fact that we were not puffing Argon! This is something of a mystery, since we did ECDC this morning and there was only one Ar puff allowed yesterday. EFC was running close to zero current on several later shots. It may be necessary to put EF2's in the ZCUR controller to provide better bias for slow Z position control. Alternatively, the bias on the chopper could be increased. The EF1's were taken out of the slow Zcur controller so they wouldn't fight the ZXL control. The Z-postion seemed less stable than yesterday, before and after this was done. Part of this may be due to the above-noted behavior of the EFc going to zero current. Problems: --------- EF3 did not fire on the first 2 shots. It was left in PLC control. OH1 had a shoot-through with fuse loss on shot 14. EF4 had some probelms at crossover, only noticed on fizzles and duds. There was an Acknowledge failure on shot 13 transition to pulse. No shot. Score Card: ----------- Plasmas 9 Fizzles 10 (2 with no EF3) Duds 3 No shot 1 -------- -- Total 23 |
| Session Leader Comments | |||
| Sep 23 1993 09:05:49:840AM | Martin Greenwald | Run 930923
Session leader: Bruce Lipschultz Physics Operator: Steve Wolfe Mini-proposal: MP016; Scrapeoff Layer Characterization I The first priority of this run is to get consistent shots with x-points in the proper location (diverted and strike points below the nose) while at the same time have reasonable space between the plasma and the limiters (both inner wall and the antenna limiter). We are starting with a shot loaded in from 930921009 with changes specified under physics operator log (use the z and r- x-point controllers). Assuming that we do achieve reproducible shots then probe measurements and other SOL measurements will be made and vary the plasma current. | |
| Sep 23 1993 09:15:42:240AM | 930923001 | Martin Greenwald | Shot #1
No EF3 on this shot. Breakdown but no current. Try again. |
| Sep 23 1993 09:35:36:950AM | 930923002 | Martin Greenwald | Shot #2
Fizzle No EF3 again on this shot. Try again. |
| Sep 23 1993 09:54:50:130AM | 930923003 | Martin Greenwald | Shot #3
dud We had EF3 but did not even get breakdown. We changed the offset on Br0 to 9 mTesla. We increased the gas fill to 1.4e-5 from 1.2 e-5. |
| Sep 23 1993 10:11:28:040AM | 930923004 | Martin Greenwald | Shot #4
fizzle We got a fast breakdown. The fields appear off so the current never took off. We raised EF4 by 30 Amps and dropped the Br offset. |
| Sep 23 1993 10:29:50:840AM | 930923005 | Martin Greenwald | Shot #5
fizzle We got a fast breakdown (5ms start of Halpha). Lowered the radial field a little for the next shot. gas set back to 1.2e-5. |
| Sep 23 1993 11:11:04:910AM | 930923006 | Martin Greenwald | Shot #6
We got a shot. It disrupted at 680 ms. It diverted pretty early. However, the plasma doesn't move off the inner wall (as defined by spectroscopic diagnostics) until almost 500 ms. At this time EFIT claims the inner wall gap is 1.5 cm. The strike points are on the noses of the divertors most of the time. We need to move the x-point down and mover the plasma off the inner wall. We got a fast breakdown (5ms start of Halpha). Lowered the radial field a little for the next shot. gas set back to 1.2e-5. For the next shot we will move both the plasma and the antenna out by 1 cm. We raised the gas in the latter part of the shot. |
| Sep 23 1993 11:30:49:860AM | 930923007 | Martin Greenwald | Shot #7
We got a fizzle after the disruption - no surprise. The plasma current tryed to take off but, according to the SXR's it kept zipping upward and bouncing off the top of the machine. We will just change the gain on B radial for the next shot. |
| Sep 23 1993 11:55:38:190AM | 930923008 | Martin Greenwald | Shot #8
We got a good shot. A number of natural injections occurred. The density increased steadily during the shot due to the increased gas puffing. Maximum density is 5 e14. The position of the x-point is fairly good from 250 ms on. The plasma slowly increases its distance from the inner wall with real diverting action (probes on the upper side of the inner divertor seeing signal) occurring around 500 ms. The plasma current did not stay constant as the density was increased (the loop voltage stayed constant(. This may indicate that the gain on the Ip feedback needs to be increased. For the next shot we will increase the proportional gain on Ip and zxl. The gas will be decreased after 500 ms by about 40%. The plasma center will be lowered by 1 cm to reduce the elongation somewhat. |
| Sep 23 1993 12:06:30:170PM | 930923009 | Martin Greenwald | Shot #9
This was a dud. Steve W. feels that the radial field was too high and will change it for the next shot. |
| Sep 23 1993 12:20:49:700PM | 930923010 | Martin Greenwald | Shot #10
This was a fizzle. Things are being kept the same for the next shot. |
| Sep 23 1993 12:35:30:570PM | 930923011 | Martin Greenwald | Shot #11
This was a fizzle. some small changes in fields for the next shot. |
| Sep 23 1993 12:52:55:120PM | 930923012 | Martin Greenwald | Shot #12
This was a fizzle again. |
| Sep 23 1993 02:26:18:750PM | 930923014 | Martin Greenwald | Shot #15
Finally a good shot again. This seems very similiar to shot 8. The x-point position appears to be a little far out so that the outer strike point is above the nose. The density starts dropping around 500 ms due to the lowering of the pulsed gas after shot 8. There is a very unusual occurrence at 700 ms. The plasma current increases suddenly. This is accompanied by a decrease in density and Halpha. The probe signals in the divertor and the div. bolos increase dramatically. For the next shot we will add gas at around 80 ms to increase the density early. We also turned on the rxl control to try to pull the x-point back in major radius. |
| Sep 23 1993 02:53:56:270PM | 930923016 | Martin Greenwald | Shot #16
Two shots in a row! The density seems to be quite high and flat at 5 e14 late in time. The Zeff during this period is low (1 or below). We will try to fill in the density hesitation early in time (100 ms) and go for this shot again. The rf has been given a release to fire 10 kW at 700 ms. It will extend to 900 ms (current ramp down). |
| Sep 23 1993 03:20:56:250PM | 930923017 | Martin Greenwald | Shot #17
Three shots in a row! We managed to fill in the density early in time. The x-point position looks good through most of the shoit. The gap to the inner wall opens up to 2 cm by 400 ms and stays fairly constant for the remainder of the shot. For the next shot we plan to try and raise the density early in the shot (80 - 100 ms) some more. There is a rather large injection of impurities at that time. |
| Sep 23 1993 03:35:59:850PM | 930923018 | Martin Greenwald | Shot #18
Four shots in a row! This seems to be what we are looking for. The injection of impurities early in time is probably due to the oscillations in position. We will repeat this shot because the scanning probe was not enabled last shot. |
| Sep 23 1993 04:01:29:080PM | 930923019 | Martin Greenwald | Shot #19
Five shots in a row! This shot seems to be again what we wanted; flat density and current vs time. It is diverted from about 200 ms on. The scanning probe went in to the separatrix. For the next shot we will try to increase the plasma current by 100 kA. |
| Sep 23 1993 04:29:59:680PM | 930923020 | Martin Greenwald | Shot #20
This shot barely made it up because of some enormous gas load. The plasma disrupted at the beginning of current rampdown. The density achieved is a record for gas puffing - 8e19 nel. My guess is that the gas came from the disruption during durrent decay on the previous shot. For the next shot we will try to lower the gas puff to compensate for the4 gas from the disruption on this shot. ps: the current decay rate for that disruption was 560 kA/msec. |
| Sep 23 1993 04:39:55:570PM | 930923021 | Martin Greenwald | Shot #21
Fizzle as expected due to the disruption on the previous shot. We will lower the fill pressure to 1.0e-5. |
| Sep 23 1993 04:53:46:460PM | 930923022 | Martin Greenwald | Shot #22
This shot barely survived bast breakdown. It had injections occuring into the plasma from 25 ms on. The density screamed up to 6e19 before the plasma disrupted at 350 ms. We will put the fill pressure back to 1.2e-5. |
| Physics Operator Comments | |||
| Sep 23 1993 08:47:17:860AM | Martin Greenwald | Start from 930921009 withthe following changes:
1) Need to recalculate M's on wires 2 & 3 because of new gain of 4 in AFOL to Chopper. 2) Put BR_0 on wire 7 as yesterday. Use CUSTOM to modify VACUUM predictor to add 8e-3 on MINUS_1_VOLT. Draw zero for \S_BR_0 Load PID P=1.0 from -0.8sec to +0.03sec FACTOR = 40. M = OH2U -1500, OH2L + 1500 Turn off PID on Wire 8 3) Check of PIDs found that gain on wires 13,14 (IC_EF2U&L) was turning off at 0.5 sec. Changed end to 1.5sec Plan: Get plasma - hopefully this won't take all day. Get acceptable diverted shot by: Move RCUR out Move Zcur down Use ZXL and maybe RXL control. Probably want to move the limiter/antenna out (now at 92/94) Try using less EF2 U current to help lower elongation. | |
| Sep 23 1993 09:17:22:270AM | 930923001 | Martin Greenwald | Shot #1
Fizzle No EF3 on this shot. BR is negative -1.5e-3 to -1.0e-3. A_OUT on wire 7 is -0.5e-3 |
| Sep 23 1993 09:29:19:320AM | 930923002 | Martin Greenwald | Shot #2
Fizzle No again EF3 on this shot. It was under PLC control! That explains it, I guess. BR is still negative -1.5e-3 to -1.0e-3. Breakdowns are late 10:11msec on Halpha K-port, no signal on Z-meter? Bz is quite positive when it goes. |
| Sep 23 1993 09:52:10:560AM | 930923003 | Steve Wolfe | Shot 3:
Yuichi moved the limiter out to 93 cm. Antenna still at 94. DUD !! Maybe BR0 really is too low. |
| Sep 23 1993 10:07:46:710AM | 930923004 | Steve Wolfe | Shot 4:
Gas to 1.4e-5 Offset on BR0 to 9mT (from 8mT) Horne says that the previous one had too negative a BZ. I don't think so,but I'll keep it in mind. Result: Fizzle. Breakdown at 6.8msec. Br is now zero+/- 1mT |
| Sep 23 1993 10:27:38:260AM | 930923005 | Steve Wolfe | Shot 5:
Raise ef4 30Amps at 1msec Drop BR offset to 8.5e-3 Result: Fizzle again Earlier breakdown - 5.6msec |
| Sep 23 1993 10:41:01:750AM | 930923006 | Steve Wolfe | Shot 6:
Drop BR offset to 8.e-3 Lower pressure back to 1.2e-5 Result: Plasma Breaks down about 6msec. Small hesitation. Disrupts at 690msec. Lots of natural injections. |
| Sep 23 1993 11:25:55:020AM | 930923007 | Steve Wolfe | Shot 7:
MOve RCUR from 67 to 68cm Change IC_EF2U @ 0.8 sec from 1500 to 1000. Limiter and antenna move out to 94/95 Turn on ZXL controller at 0.2sec P=2.0 Set EF1 M controllers on ZCUR2 to zero at 0.2sec Raise gas puff between 200msec and 800msec Result: Fizzle - late breakdown. Br -1mT Current got to 40kA It went up fast. |
| Sep 23 1993 11:46:53:280AM | 930923008 | Steve Wolfe | Shot 8:
Raise PID gain on BR (wire7) to 2.0 Result: Good PLasma Br = -1.5 mT, maybe less of a glitch at 6msec Density is rising through shot. Current droops a little. ZXL is rising a little but seems pretty well controlled. Marginally diverted from 200 msec |
| Sep 23 1993 12:05:09:260PM | 930923008 | Steve Wolfe | Shot 9:
Raise PID gain on IP to 2.0 Raise gain on ZXL 2.0 Lower gas Between 500msec and 800msec Lower zcur by 1cm from -2 to -3. Result: Dud Br = -2mT |
| Sep 23 1993 12:21:32:300PM | 930923009 | Steve Wolfe | Shot 10:
Increase offset on Br to 9e-3 Result: Fizzle - breaksdown at 7msec |
| Sep 23 1993 12:28:03:740PM | 930923010 | Steve Wolfe | Shot 11:
No change Result: Same |
| Sep 23 1993 12:48:27:100PM | 930923011 | Steve Wolfe | Shot 12:
The EF2U & L programming was different around commutation. Also, the EF2L has higher current by 60A (which was not programmed). Add a point on EF2L at -.008,1700 (level had been 1750.) Move value at -.285 from 1750 to 1700 Get rid of point at 0.017,1750 Result: Another fizzle Breakdown at 6msec |
| Sep 23 1993 12:57:33:920PM | 930923012 | Steve Wolfe | Shot 13:
Add EF2's to controller on BR. with gains of +/- 5000. Change factor on unused wire 8 from 1e-4 to 1e-5 Result: Ack Failure on STATE? No shot. |
| Sep 23 1993 01:13:42:530PM | 930923014 | Steve Wolfe | Shot 14:
Retry of 13. Changes from 12 were: Add EF2's to controller on BR. with gains of +/- 5000. Change factor on unused wire 8 from 1e-4 to 1e-5 Result: Dud! maybe a weak flash on the TV? OH1 blew fuses - looks like a shoot-through Null doesn't look good. May need to boost EF4 to compensate for drop in EF2U? |
| Sep 23 1993 02:15:46:600PM | 930923015 | Steve Wolfe | Shot 15:
Increase IC_EF4 by 30Amps; now at 1160. Delay pulse gas 3msec. Result: Plasma lasts 1sec looks good. BR = -1.5 to -2 mT There is a hesitation but it runs ZXL is pretty good ,but elongation is still up there. |
| Sep 23 1993 02:30:30:460PM | 930923015 | Steve Wolfe | Shot 16:
Increase gas at 70-80msec and between 500 and 800msec Reduce gain on IC_EF1L at 300 msec to 0.48 (was 2.0) Turn on RXL control at 0.2sec P=1 M_EF2L=.005 Result: Good plasma |
| Sep 23 1993 03:19:12:770PM | 930923017 | Steve Wolfe | Shot 17:
Raise OH2 voltage to -10V between .2 and .4 sec (was -18) Raise ZXL gain to 10. RXL gain to 5.0 Increase gas by 10% between 70 and 100msec Result: Looks good. Xpt is right where it wants to be and inner gap is constant from 400 msec on. |
| Sep 23 1993 03:31:57:970PM | 930923017 | Steve Wolfe | Shot 18:
Raise gas between 80 and 100msec Results: Looks real good. |
| Sep 23 1993 03:44:15:790PM | 930923019 | Steve Wolfe | Shot 19:
Raise D on RCUR from 1 to 2 to try to control early osciallation. Results: Looks real good. Disrupts at 0.9 vertically |
| Sep 23 1993 04:17:27:760PM | 930923020 | Steve Wolfe | Shot 20:
Raise D on RCUR from 2 to 4 to try to control early oscilation. Try to raise current by 100kA by extending the same slope on the ramp Results: got 560kA, but disrupts hard at .87. This one has a big problem early with a gas burst. |
| Sep 23 1993 04:37:01:010PM | 930923020 | Steve Wolfe | Shot 21:
Drop D on RCUR back to 1.0 Lower OH2 voltages from -10 to -14 between 200 and 400 msec Lower gas 15% between 80 and 120msec Results: Fizzle |
| Sep 23 1993 04:52:11:920PM | 930923021 | Steve Wolfe | Shot 22:
Reduce EF2U current end point from 1000V to 500V Lower fill to 1.0e-5 (BLIP insists) SF will extend the TF to reach 5.2 T Results: Short and unpleasant. EFC faulted at the VDE 330msec Lots of little injections from the beginning. Lots of hards |
| Sep 23 1993 04:52:20:210PM | 930923022 | Steve Wolfe | Shot 22:
Reduce EF2U current end point from 1000V to 500V Lower fill to 1.0e-5 (BLIP insists) SF will extend the TF to reach 5.2 T Results: Short and unpleasant. EFC faulted at the VDE 330msec Lots of little injections from the beginning. Lots of hards |
| Sep 23 1993 05:06:37:230PM | 930923023 | Steve Wolfe | Shot 22:
Pressure back to 1.2e-5 Results: Fizzle |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 09:07:17:150AM | Plasma | Bad | No EF3 |
| 2 | 09:22:41:910AM | Plasma | Bad | No EF3: EF3 was in PLC control |
| 3 | 09:42:37:210AM | Plasma | Ok | |
| 4 | 09:56:24:640AM | Plasma | Ok | Fizzle |
| 5 | 10:14:46:070AM | Plasma | Ok | Fizzle |
| 6 | 10:31:38:420AM | Plasma | Ok | 490 ka disruption |
| 7 | 11:14:00:200AM | Plasma | Ok | Fizzle; 37 minutes in RECOOL |
| 8 | 11:31:06:640AM | Plasma | Ok | Good 490 kA plasma, disrupted at 150 kA |
| 9 | 11:57:08:650AM | Plasma | Ok | Fizzle |
| 10 | 12:08:57:590PM | Plasma | Ok | Fizzle |
| 11 | 12:22:45:010PM | Plasma | Ok | fizzle |
| 12 | 12:36:24:220PM | Plasma | Ok | fizzle |
| 13 | 12:54:02:070PM | Plasma | Bad | IGOR? Ack Failure |
| 14 | 01:01:35:050PM | Plasma | Ok | Fizzle followed by shoot-thru failure in OH1; 5 fuses blown in forward c |
| 15 | 01:56:30:740PM | Plasma | Ok | 470 kA; 1 sec; disrupted at 71 kA. Best shot of the day |
| 16 | 02:27:08:640PM | Plasma | Ok | Good shot; 460 ka; 1 sec, disrupted at 150 kA |
| 17 | 02:53:40:070PM | Plasma | Ok | Good shot; similar to last 2; disrupted at 100 kA |
| 18 | 03:21:15:950PM | Plasma | Ok | Good; disrupted at 150 kA after 1 sec |
| 19 | 03:37:08:110PM | Plasma | Ok | PLasma shot 450KA NO faults. |
| 20 | 04:01:39:970PM | Plasma | Ok | Nasty 500ka/msec disruption from 560 kA |
| 21 | 04:29:03:830PM | Plasma | Ok | Fizzle |
| 22 | 04:42:08:630PM | Plasma | Ok | Early disruption; TF set to 5.1 Tesla OK |
| 23 | 05:00:15:390PM | Plasma | Ok | Fizzle, TF reached 5.4 Tesla without incident. TF did not behave at cro |