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 1-34)

Engineering Operator Run Comment

detached divertor q-scan

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:13:897PM

Author: To Be Determined

Run # 950607 Engineering operator: V. Bertolino Physics operator E. Marmar Session leader B. Lipschultz The aim of today's run was to complete the q scan section of MP# 105, 'Dependence of Detachment Threshold and Radial Extent on Plasma Current and q". The difference noted at first glance at the data was that q has a strong effect on the detachment threshold. The detachment threshold today was nl04=1.5 (3.6 T), 1.2 (5.3 T) and 1. (7 T). This could be indicative that the field line length is very important for the interaction of neutrals with ions in the divertor. This result is similar to the flat-plate divertor result; those equilibria have higher detachment thresholds and shorter field line lengths in the divertor. There is also the possibility that the 1MA plasma result (higher threshold) is at least partly due to the q dependence found today. The q for 1 MA (5.3 T) was only slightly higher than that for the 800 kA, 3.6 T shots to day (20 %) and the detachment threshold was similar. The caveat to all these musings about q is that we need to properly look at the power flowing into the SOL and the separatrix Te for all of these shots to determine if there are significant changes there. I have only been able to glance at a few shots. For example one can compare shots 20 (3.5 T), 26 (5.3 T) and 28 (7 T), all at nl04=1.2e20. The power flowing into the SOL for these shots is .65, .45 & .25 respectively. Unfortunately, shot 28 is detached so not a good comparison. The difference between shots 20 & 26 is due to changes in both the input power and core radiated power. The other quick comparison is between shots 12 (3.6 T, nl04~1.0) and 30 (7T, same nl04). The P_SOL for the 2 shots is similar. Unfortunately, shot 12 is not steady state. There is only a short period when the density is correct and no H-mode soon after the injection at .6 seconds. So at first glance there does not seem to be large differences in P_SOL. The only other significant aspect of the day was the operating space at 3.6 T. We found that at too low a density that we were constantly being jerked in and out of H-mode. As the density was raised the operation was more dependable, but fewer H-modes. For future cases it appears that the fix to all our injections (shots 14-19) were fixed by raising the FSP feedback point. The run summary follows: shot #1: disruption early. shot #2: Disruption at 800 ms following H-mode. Strike point in region of probes 2 & 3. shot #3: Another disruption at 450 ms. The q is hovering around 3. We will lower the current slightly to see if we can obtain reproducible discharges. shot #4: 700 kA, another disruption at .75 seconds. Try again. shot #5: This shot went till 1.2 seconds with the usual dithering the whole time. Strike point betwen probes 2 & 3 for most of the shot. No FSP yet. Still 700 kA. shot #6: 700 kA. This shot lasted well through inversion. Next shot switch to FSP control and raise current to 750. shot #7: 750 kA, lasts till 1.16 seonds. nl04 oscillating around 1.e20 because of H-modes. shot #8: 800 kA, no FSP. Everything went fine. Next shot with FSP. shot #9: dud due to power supply problems shot #10: Elm-free H-modes galore. FSP fired. We aimed for constant density at ml04=1.e20 and got densities as high as 1.5. shot #11: fizzle shot #12: H-modes again with uncontrollable density, FSP scans ok. shot #13: fizzle shot #14: disruption at .5 seconds. shot #15: disruption at .48 seconds. shot #16: Disruption after .8 seconds. nl04=1.25e20. shot #17: Another disruption due to a large injection 'brick dropping'. shot #18: This one makes it to inversion. nl04=1.e20, FSP scans ok. H-modes as usual. shot #19: nl04=0.5e20. disruption at 0.6 seconds. FSP scan fine shot #20: Very nice. nl04=1.2e20. No FSP scans. Injection at .6 seconds ends H-mode. shot #21: Repeat of 20 with FSP scan. shot #22: nl04=1.5e20. FSP scans ok. Slight amount of detachment. shot #23: nl04 reaches 1.7e20. FSP scans ok. definite detachment shot #24: fizzle at 7 Tesla shot #25: nasty disruptive shot at 5.3 Tesla. shot #26: Nice shot at 5.3 Tesla. No FSP scan. nl04=1.2e20. Possible detachment. Next shot 7 Tesla. shot #27: fizzle shot #28: Shot fine at 7 Tesla (ramp reaches 7 Tesla at .8 seconds or so). nl04=1.2e20, FSP scans ok. Definite detachment! shot #29: nl04=1.4e20. FSP scan fine and detachment occurred. shot #30: nl04 ramps from .95 - 1.05 from 0.6-1.0 seconds. During that period the plasma detaches (near 1.05 e20), but not all the way up the divertor plate. FSP scans ok. shot #31: nl04=0.85e20. FSP scans fine. No detachment. shot #32: nl04 dropping from.7 to .55e20 through shot. FSP scans ok. No detachment. shot #33: repeat of shot 32 because some of the FSP data was not taken. FSP scan fine. shot #34: Back to 3.6 Tesla to try for lower density once again. Obtained usual H-modes with density varying from 1.3 to .8e20. Not a pretty shot.

Physics Operator Summaries

Session Leader Comments
Jun 7 1995 08:24:16:240AM		Bruce Lipschultz	Run # 950607 Engineering operator: V. Bertolino Physics operator E. Marmar Session leader B. Lipschultz Today we plan to try and complete MP# 105, 'Dependence of Detachment Threshold and Radial Extent on Plasma Current and q". The aspect we will study today is the q dependence of divertor and SOL paramteters. We plan to start at 3.5 Tesla, 800 kA and vary the density (from shot to shot) from nl04=0.7 - 1.5 or shigher. After this is finished we will go on to 7 Tesla or thereabout. The density scan will be repeated at that field. The usual perscription for good gaps all around the plasma is needed so that the SOL plasma is not limited from one divertor plate to the other. If both of these programs are finished (Ha ha!) we may return to the 800 kA flat-plate to finish some of that work.
Jun 7 1995 08:49:48:080AM	950607001	Bruce Lipschultz	shot #1: disruption early.
Jun 7 1995 08:55:50:390AM	950607002	Bruce Lipschultz	shot #2: Disruption at 800 ms following H-mode. Strike point in region of probes 2 & 3.
Jun 7 1995 08:56:57:000AM	950607002	Bruce Lipschultz	shot #2: Disruption at 800 ms following H-mode. Strike point in region of probes 2 & 3.
Jun 7 1995 08:59:12:710AM	950607003	Bruce Lipschultz	shot #3: Another disruption at 450 ms. The q is hovering around 3. We will lower the current slightly to see if we can obtain reproducible discharges.
Jun 7 1995 09:14:44:680AM	950607004	Bruce Lipschultz	shot #4: 700 kA, another disruption at .75 seconds. Try again.
Jun 7 1995 09:35:15:640AM	950607005	Bruce Lipschultz	shot #5: This shot went till 1.2 seconds with the usual dithering the whole time. Strike point betwen probes 2 & 3 for most of the shot. No FSP yet.
Jun 7 1995 09:40:56:880AM	950607006	Bruce Lipschultz	shot #6: 700 kA. This shot lasted well through inversion. Next shot switch to FSP control and raise current to 750.
Jun 7 1995 10:01:49:200AM	950607007	Bruce Lipschultz	shot #7: 750 kA, lasts till 1.16 seonds. nl04 oscillating around 1.e20 because of H-modes.
Jun 7 1995 10:17:27:110AM	950607008	Bruce Lipschultz	shot #8: 800 kA, no FSP. Everything went fine. Next shot with FSP.
Jun 7 1995 10:19:03:460AM	950607009	Bruce Lipschultz	shot #9: dud due to power supply problems
Jun 7 1995 10:56:09:900AM	950607011	Bruce Lipschultz	shot #11: fizzle
Jun 7 1995 10:58:07:870AM	950607012	Bruce Lipschultz	shot #12: H-modes again with uncontrollable density, FSP scans ok.
Jun 7 1995 11:05:18:890AM	950607013	Bruce Lipschultz	shot #13: fizzle
Jun 7 1995 11:19:35:350AM	950607014	Bruce Lipschultz	shot #14: disruption at .5 seconds.
Jun 7 1995 11:48:48:140AM	950607015	Bruce Lipschultz	shot #15: disruption at .48 seconds.
Jun 7 1995 11:51:13:290AM	950607016	Bruce Lipschultz	shot #16: Disruption after .8 seconds. nl04=1.25e20.
Jun 7 1995 12:00:52:800PM	950607017	Bruce Lipschultz	shot #17: Another disruption due to a large injection 'brick dropping'.
Jun 7 1995 12:16:40:340PM	950607018	Bruce Lipschultz	shot #18: This one makes it to inversion. nl04=1.e20, FSP scans ok. H-modes as usual.
Jun 7 1995 12:16:55:190PM	950607018	Bruce Lipschultz	shot #18: This one makes it to inversion. nl04=1.e20, FSP scans ok. H-modes as usual.
Jun 7 1995 12:32:57:720PM	950607019	Bruce Lipschultz	shot #19: nl04=0.5e20. disruption at 0.6 seconds. FSP scan fine
Jun 7 1995 12:34:40:970PM	950607019	Bruce Lipschultz	shot #19: nl04=0.5e20. disruption at 0.6 seconds. FSP scan fine
Jun 7 1995 12:42:55:750PM	950607020	Bruce Lipschultz	shot #20: Very nice. nl04=1.2e20. No FSP scans. Injection of zirconium at .6 seconds ens H-mode.
Jun 7 1995 12:53:12:660PM	950607021	Bruce Lipschultz	shot #21: Repeat of 20 with FSP scan and Zr injection (.6 seconds)
Jun 7 1995 01:26:40:440PM	950607022	Bruce Lipschultz	shot #22: nl04=1.5e20. FSP scans ok. Slight amount of detachment.
Jun 7 1995 01:31:42:140PM	950607023	Bruce Lipschultz	shot #23: nl04 reaches 1.7e20. FSP scans ok. definite detachment
Jun 7 1995 02:11:56:710PM	950607024	Bruce Lipschultz	shot #24: fizzle at 7 Tesla
Jun 7 1995 02:12:27:710PM	950607025	Bruce Lipschultz	shot #25: nasty disruptive shot at 5.3 Tesla.
Jun 7 1995 02:34:16:810PM	950607026	Bruce Lipschultz	shot #26: Nice shot at 5.3 Tesla. No FSP scan. nl04=1.2e20. Possible detachment. Next shot 7 Tesla.
Jun 7 1995 02:38:14:800PM	950607027	Bruce Lipschultz	shot #27: fizzle
Jun 7 1995 02:58:17:960PM	950607028	Bruce Lipschultz	shot #28: Shot fine at 7 Tesla (ramp reaches 7 Tesla at .8 seconds or so). nl04=1.2e20, FSP scans ok. Definite detachment!
Jun 7 1995 03:16:48:140PM	950607029	Bruce Lipschultz	shot #29: nl04=1.4e20. FSP scan fine and detachment occurred.
Jun 7 1995 03:36:43:020PM	950607029	Bruce Lipschultz	shot #30: nl04 ramps from .95 - 1.05 from 0.6-1.0 seconds. During that period the plasma detaches (near 1.05 e20), but not all the way up the divertor plate. FSP scans ok.
Jun 7 1995 03:44:21:390PM	950607030	Bruce Lipschultz	shot #30: nl04 ramps from .95 - 1.05 from 0.6-1.0 seconds. During that period the plasma detaches (near 1.05 e20), but not all the way up the divertor plate. FSP scans ok.
Jun 7 1995 04:00:27:650PM	950607031	Bruce Lipschultz	shot #31: nl04=0.85e20. FSP scans fine. No detachment.
Jun 7 1995 04:11:08:220PM	950607032	Bruce Lipschultz	shot #32: nl04 dropping from.7 to .55e20 through shot. FSP scans ok. No detachment.
Jun 7 1995 04:41:22:210PM	950607033	Bruce Lipschultz	shot #33: repeat of shot 32 because some of the FSP data was not taken. FSP scan fine.
Jun 7 1995 05:09:09:470PM	950607034	Bruce Lipschultz	shot #34: Back to 3.6 Tesla to try for lower density once again. Obtained usual H-modes with density varying from 1.3 to .8e20. Not a pretty shot.
Jun 7 1995 05:31:43:650PM	950607034	Bruce Lipschultz	shot #34: Back to 3.6 Tesla to try for lower density once again. Obtained usual H-modes with density varying from 1.3 to .8e20. Not a pretty shot.

Physics Operator Comments

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	08:28:03:880AM	Plasma	Ok
2	08:42:12:910AM	Plasma	Ok
3	08:53:01:480AM	Plasma	Ok
4	09:03:15:570AM	Plasma	Ok
5	09:14:41:120AM	Plasma	Ok
6	09:26:59:510AM	Plasma	Ok
7	09:40:15:590AM	Plasma	Ok
8	09:52:53:200AM	Plasma	Ok
9	10:04:55:060AM	Plasma	Bad	power supply faults
10	10:22:43:050AM	Plasma	Ok
11	10:37:05:100AM	Plasma	Ok
12	10:47:37:740AM	Plasma	Ok
13	11:00:21:380AM	Plasma	Ok
14	11:12:02:430AM	Plasma	Ok
15	11:23:15:230AM	Plasma	Ok
16	11:38:14:170AM	Plasma	Ok
17	11:52:47:860AM	Plasma	Ok
18	12:05:44:700PM	Plasma	Ok
19	12:17:53:810PM	Plasma	Ok
20	12:30:58:580PM	Plasma	Ok
21	12:43:29:240PM	Plasma	Ok
22	12:56:38:960PM	Plasma	Ok
23	01:12:34:020PM	Plasma	Ok	Comm Fail OH1 then 1SCR EF1U
24	01:53:27:190PM	Plasma	Ok
25	02:07:21:940PM	Plasma	Ok
26	02:20:08:790PM	Plasma	Ok
27	02:31:36:110PM	Plasma	Ok
28	02:48:29:090PM	Plasma	Ok
29	03:04:42:150PM	Plasma	Ok
30	03:19:44:370PM	Plasma	Ok
31	03:45:19:170PM	Plasma	Ok
32	04:05:34:230PM	Plasma	Ok
33	04:18:46:260PM	Plasma	Ok
34	04:41:56:500PM	Plasma	Ok