Miniproposals

Miniproposal: 105 Date Filed: 3/24/1995 Title: Dependence of Detachment Threshold and Radial Extent on Plasma Current & q First Author: Bruce Lipschultz Session Leader: Bruce Lipschultz (shots 1-24)

Engineering Operator Run Comment

plasma

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:13:727PM

Author: To Be Determined

Run 950517 Engineering operator: V. Bertolino Physics operator: J. Goetz Session leader: BLip This run was to follow the work outlined in Mini-proposal # 105: 'Dependence of Detachment Threshold and Radial Extent on Plasma Current & q'. Unfortunately 2 problems limited the accomplishments: the vacuum break of the night before to remove the piece of Thomson dump; and the increase in OH2L resistances. The latter caused the biggest delay in that we discussed this (rightly so) for a number of hours. After deciding that the resistances were indeed increasing but were below a limit we continued with the run. In looking for something to say that we accomplished this run I would say that we did achieve breakdown and full current discharges at 3.5 Tesla. We also found that, not surprisingly, that the H-mode appeared with great 'strength' (no ELM's and the density + impurity density screaming up). This does not bode well for trying to do density scans at this field. The other positive result was that Darren & Earl got 2 Li-pellet shots with which to determine if they were ready for prime time with respect to the polarimeter measurement. The summary of shots follows: shot 1: The shot started very well. Unfortunately it disrupted shortly after 400 ms. shot 2: fizzle shot 3: disruption at 0.6 seconds. shot 4: no TF shot 5: disruption again shot 6: This shot went fine - 700 kA, nl04=1.e20. Detachment occurs late in shot at, what seems to be an unusually low density. shot 7: 800 kA, nl04=1.e20. No detachment or FSP. Still tuning. shot 8: dithering H-mode, 800 kA, nl04=1.e20. Strike point around probes 4 (outer div.) and 3 (inner). 5.3 Tesla shot 9: Dithering H-mode. nl04=1.05e20, FSP scan. 5.3 Tesla. shot 10: try at 3.5 Tesla - dud. shot 11-20: tests or duds shot 21: disruption, Bt=3.5 Tesla shot 22: Bt=3.5 Tesla: H-mode (ELM-free) and the density screams up. The radiations increases to 1.2 MW before it disrupts. This may be a problem for further 3.5 T operation. shot 23: Back to 5T (reload shot 9) for Li pellet tests. One large pellet. shot 24: Smaller Li pellet - delta_n = 1.e20 followed by dithering H-mode.

Physics Operator Summaries

Entered: Jul 7 2004 04:36:54:427PM

Author: To Be Determined

Physics operator summary for 950517 EO: Bertolino/Daigle PO: Goetz SL: Lipschultz Run 950517 was nominally in support of Mini-Proposal #105 - Dependence of Detachment Threshold and Radial Extent on Plasma Current & q. The goals of the MP are to determine the effect of plasma current and safety factor on: (1) detachment threshold, (2) the growth of detachment with density, and (3) the localized increase in plate plasma pressure. Program for this run: - Clean up the machine after the 950516 vent to helium to remove a piece of the Thomson viewing dump. If successful in the cleanup, then: - Take the cleanup shot being used (should already have the proper gaps, SEP's, etc.) and lower the field to 3.5T and do the detachment stuff - Raise the field to 6.5T and do the detachment stuff - If time, fill in some holes in the flat-plate divertor run at 0.8 and 1.0MA This program was not carried out due to the loss of many shots for OH2L testing purposes. Some things discovered today: 1) Considering that the machine was vented to helium yesterday, it was a remarkable run. Breakdowns at 5.3T were achieved routinely. The current rises were normal and the CII light levels were very low. 2) The TF invert time was moved to +1.0sec with no adverse effects on the rampdown. 3) A breakdown scenario for 3.5T plasmas was re-tuned up. See shots 021 or 022. Remember to use the correct commutation resistors. It was necessary to change the OH1 charging current to straighten out the curvature of the field and to make the vertical field more positive. Neither of these shots ran to completion, possible because of the qpsi=3 barrier. Engineering, computing, and diagnostics today: The resistance measurement of OH2L coax showed that the resistance was higher than usual. An extensive testing session was undertaken and the bottom line is that a limit of 3 micro-ohms for the joint resistance was set. No data acquisition problems today. Scorecard: 24 shots = 6 tests + 11 plasmas + 4 fizzles + 1 TF dud + 2 duds Shot summary for Run 950517: Reload of 950512022 NL_04 = 1.0e20 IP = -700000 Shot change result ____ _____ ______ 1 P_0 = 1.7e-5 plasma - disr. @ 0.42; no chopper b.d. @ .005; CII < .002 2 P_0 = 2.0e-5 strong fizzle - moves inside 3 P_0 = 1.8e-5 plasma - disr. @ 0.58; x-pt becomes low; i.strike on EF1 conic shield 4 FSP = -.01 dud - no TF 5 no changes plasma - disr. @ 0.57; looks like 003 6 FSP=-.005->-.075; IP gain = 4 plasma - all the way down!; gaps good - SEPs good - strikes too high 7 ZCUR=-.02; IP=-800000; FSP= plasma - disr. @ 1.45 -.007->-.0095 strikes too high 8 ZCUR=-.016; FSP=-.01->-.0115; plasma - disr. @ 1.45; FSP target o.k.; more early gas (0.1sec) strikes o.k.; RXL=.555; ZXL=-.04 9 more early gas (0.1sec) plasma - disr. @ 1.42; o.k. EDGE things 10 load seg 1 from 950404029 into dud - shouldn't have loaded an seg 1 and flip V's and P's; TF abnormal field shot start=-.52sec & TF curr.=103kA 11-16 tests to diagnose the OH2L coax 17 load seg 1 from 950214020 and fizzle - no current - not enough change comm. res.; P_0=2.2e-5 vertical field 18 IC_EF4 = -1130A fizzle - no current - b.d. @ .006 19 BR_0=5.5e-3; P_0=2.0e-5 fizzle - no current - b.d. @ .006 20 IC_OH1 = -16800A dud - no null - curvature very bad 21 IC_OH1 = -16400A; BR_0=6.0e-3 plasma - disr. @ 0.46; q=3? 22 FSP=-.0075 plasma - disr. @ 0.65; Mo death?!? 23 reload 950517009 and reset plasma - Li pellet - disr. @ 1.47 comm. resistors 24 no changes plasma - disr. @ 1.45 - small Li pel.

Session Leader Comments
May 17 1995 08:48:26:110AM		Bruce Lipschultz	Run 950517 Engineering operator: V. Bertolino Physics operator: J. Goetz Session leader: BLip Mini-proposal # 105: Dependence of Detachment Threshold and Radial Extent on Plasma Current & q. This is a continuatiion of the mp to cover the q scan at 800 kA. The plan is to start up at 800 kA at the normal field. Assuming that this settles down (after the vacuum break yesterday), then we will first try the low-field startup (3.5 Tesla). A number of different density shots will be run at that field ranging from nl04=0.7e20 to the maximum. Then we will raise the field to 6.5 Tesla and repeat. If time remains we will try again to obtain flat-plate plasmas at 1.0 MA given that the available voltage from OH2L has been increased substantially.
May 17 1995 08:50:23:080AM	950517001	Bruce Lipschultz	shot 1: The shot started very well. Unfortunately it disrupted shortly after 400 ms.
May 17 1995 08:50:35:270AM	950517001	Bruce Lipschultz	shot 1: The shot started very well. Unfortunately it disrupted shortly after 400 ms.
May 17 1995 08:59:05:230AM	950517002	Bruce Lipschultz	shot 2: fizzle
May 17 1995 09:29:36:020AM	950517003	Bruce Lipschultz	shot 3: disruption at 0.6 seconds.
May 17 1995 09:43:47:130AM	950517004	Bruce Lipschultz	shot 4: no TF
May 17 1995 10:25:08:690AM	950517005	Bruce Lipschultz	shot 5: disruption again
May 17 1995 10:26:45:710AM	950517006	Bruce Lipschultz	shot 6: This shot went fine - 700 kA, nl04=1.e20. Detachment occurs late in shot at, what seems to be an unusually low density.
May 17 1995 10:34:47:960AM	950517007	Bruce Lipschultz	shot 7: 800 kA, nl04=1.e20. No detachment or FSP. Still tuning.
May 17 1995 10:54:17:340AM	950517008	Bruce Lipschultz	shot 8: dithering H-mode, 800 kA, nl04=1.e20. Strike point around probes 4 (outer div.) and 3 (inner). 5.3 Tesla
May 17 1995 11:02:40:410AM	950517009	Bruce Lipschultz	shot 9: Dithering H-mode. nl04=1.05e20, FSP scan. 5.3 Tesla.
May 17 1995 11:34:30:030AM	950517010	Bruce Lipschultz	shot 10: try at 3.5 Tesla - dud.
May 17 1995 04:37:02:110PM	950517011	Bruce Lipschultz	shot 11-20: tests or duds
May 17 1995 04:39:13:000PM	950517022	Bruce Lipschultz	shot 22: Bt=3.5 Tesla: H-mode (ELM-free) and the density screams up. The radiations increases to 1.2 MW before it disrupts. This may be a problem for further 3.5 T operation.
May 17 1995 05:00:13:440PM	950517023	Bruce Lipschultz	shot 23: Back to 5T (reload shot 9) for Li pellet tests. One large pellet.
May 17 1995 05:01:12:090PM	950517024	Bruce Lipschultz	shot 24: Smaller Li pellet - delta_n = 1.e20 followed by dithering H-mode.

Physics Operator Comments
May 17 1995 07:59:33:780AM		John Goetz	Run 950517 Nominally in support of Mini-Proposal #105 - Dependence of Detachment Threshold and Radial Extent on Plasma Current & q. The goals of the MP are to determine the effect of plasma current and safety factor on: (1) detachment threshold, (2) the growth of detachment with density, and (3) the localized increase in plate plasma pressure. Today's section of the run will concentrate on the safety factor investigation. This will be true only if the machine is operating well after the 950516 vent to helium to remove a piece of the Thomson viewing dump.
May 17 1995 08:01:57:460AM		John Goetz	Run 950517 Coldstart hybrid - all matrices respond Load shot 950512022 lower NL04 to 1e20 lower IP to 0.7MA (negative) TF start time = -1.; TF invert time = +1. fill pressure = 1.7e-5 Clean up the machine. We will change horses in midstream if the machine does clean up.
May 17 1995 08:47:59:660AM	950517001	John Goetz	Shot 950517001 P_0 = 1.7e-5 Results: plasma - disrupts @ 0.42sec b.d. @ .005; current rise > 0.1MA/.03sec; CII light <.002 chopper problems - off by 0.12sec growing vertical oscillation beginning @ 0.25
May 17 1995 09:04:19:320AM	950517002	John Goetz	Shot 950517002 P_0 = 2.0e-5 Results: Strong fizzle moves inside and rubs on the inner wall beginning @ .02 probably too much fill gas
May 17 1995 09:30:07:220AM	950517003	John Goetz	Shot 950517003: P_0 = 1.8e-5 Results: plasma - disrupts @ 0.58sec x-point is very low; inner strike point ends up on the EF1 conic heat shield
May 17 1995 09:43:45:440AM	950517004	John Goetz	Shot 950517004: FSP = -.01 Results: dud - no TF
May 17 1995 10:02:51:670AM	950517005	John Goetz	Shot 950517005: FSP = -.01 Results: plasma - disrupts @ 0.57 looks a lot like 003 inner strike doesn't make it to the EF1 shield this time
May 17 1995 10:23:41:520AM	950517006	John Goetz	Shot 950517006: FSP = -.005 -> -.075 IP gain = 4 (was 6) Results: plasma - all the way down ( <.05MA ) gaps good; SEP's good; strikes too high though
May 17 1995 10:36:18:180AM	950517007	John Goetz	Shot 950517007: FSP = -.007 -> -.095 ZCUR = -.002 IP = -0.8MA Results: plasma - disrupts @ 1.45 (0.07MA) Zeff = 1.4; Prad = 0.3MW out Pin= 1.0MW strikes still too high
May 17 1995 10:54:20:410AM	950517008	John Goetz	Shot 950517008: FSP = -.01 -> -.0115 ZCUR = -.016 more early gas (0.1sec) to reduce Mo Results: plasma - disrupts @ 1.45 FSP target o.k.; strikes o.k.; ZXL=-.04; RXL=.555 early Mo down by 25%
May 17 1995 11:13:08:580AM	950517009	John Goetz	Shot 950517009: more early gas (0.1sec) to reduce Mo Results: plasma - disr. @ 1.42 o.k. for the EDGE parameters
May 17 1995 03:20:05:210PM	950517010	John Goetz	Shot 950517010: load segment 1 from 950404029 into segment 1 and flip the relevant voltages and currents TF start = -0.52sec; TF current = 103kA (3.5T) Results: dud - shouldn't have used a shot from the abnormal field runs as there were many changes made to the breakdown
May 17 1995 03:39:13:490PM	950517011	John Goetz	Shot 950517011: test of OH2L coax
May 17 1995 03:39:19:300PM	950517012	John Goetz	Shot 950517012: test of OH2L coax
May 17 1995 03:39:26:530PM	950517013	John Goetz	Shot 950517013: test of OH2L coax
May 17 1995 03:39:33:030PM	950517014	John Goetz	Shot 950517014: test of OH2L coax
May 17 1995 03:39:40:780PM	950517015	John Goetz	Shot 950517015: test of OH2L coax
May 17 1995 03:39:47:590PM	950517016	John Goetz	Shot 950517016: test of OH2L coax
May 17 1995 03:38:53:700PM	950517017	John Goetz	Shot 950517017: load segment 1 from 950214020 into segment 1 and change the commutation resistors TF start = -0.52sec; TF current = 103kA (3.5T) P_0 = 2.2e-5 Results: fizzle - breakdown @ .006 - no current rise not enough vertical field at breakdown
May 17 1995 03:51:56:470PM	950517018	John Goetz	Shot 950517018: IC_EF4 = -1130A (was -1180A) Results: fizzle - breakdown at .006 - no current vertical field in faster - maybe a little positive radial field
May 17 1995 04:10:04:120PM	950517019	John Goetz	Shot 950517019: BR_0 = 5.5e-3 P_0 = 2.0e-5 Results: fizzle - breakdown @ .006 - no current some curvature to the fields
May 17 1995 04:11:16:770PM	950517020	John Goetz	Shot 950517020: IC_OH1 = -16800A to change the curvature Results: dud - curvature is really bad now - must have gone the wrong way
May 17 1995 04:27:37:870PM	950517021	John Goetz	Shot 950517021: IC_OH1 = -16400A to change the curvature the other way Results: plasma - disrupts @ 0.46 slow current rise - breakdown @ .005 density rolls over @ 0.41sec; liberating deuterium and junk
May 17 1995 04:42:35:310PM	950517022	John Goetz	Shot 950517022: FSP = -.0075 Results: plasma - disrupts @ 0.65 maybe a Mo injection killed it? made it through the qpsi=3 this time
May 17 1995 04:51:03:340PM	950517023	John Goetz	Shot 950517023: reload 950517009 and reset commutation resistors practice shots for 950518 Results: plasma - disrupts @ 1.47 (<80kA)
May 17 1995 05:07:02:940PM	950517024	John Goetz	Shot 950517024: no changes Results: plasma - disrupts @ 1.45 (100kA) small Li pellet - dithering away like mad

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	08:32:44:440AM	Plasma	Bad	chopper ioc
2	08:54:28:330AM	Plasma	Ok
3	09:12:27:400AM	Plasma	Ok
4	09:34:44:570AM	Plasma	Bad	no tf
5	09:48:14:260AM	Plasma	Ok
6	10:03:06:770AM	Plasma	Ok
7	10:18:35:780AM	Plasma	Ok
8	10:35:44:990AM	Plasma	Ok
9	10:53:02:040AM	Plasma	Ok
10	11:14:35:340AM	Plasma	Ok
11	11:34:28:480AM	Test	Ok	coax test
12	01:19:59:920PM	Test	Ok	coax test
13	02:30:27:520PM	Test	Ok	coax test
14	02:41:42:620PM	Test	Ok	oh2l coax test
15	02:51:46:520PM	Test	Ok	oh coax and tf at 5.3T
16	03:01:43:880PM	Test	Ok	oh coax test and tf at 5.3T
17	03:28:13:180PM	Plasma	Ok
18	03:39:39:110PM	Plasma	Ok	No Faults.
19	03:52:56:540PM	Plasma	Ok	No Faults.
20	04:02:29:340PM	Plasma	Ok	No Faults.
21	04:13:34:270PM	Plasma	Ok	No Faults.
22	04:26:23:680PM	Plasma	Ok	No Faults.
23	04:43:18:270PM	Plasma	Ok	No Faults.
24	04:51:39:160PM	Plasma	Ok	NO Faults.