Miniproposals

Miniproposal: 228 Date Filed: 1/15/1999 Title: Scrape-off Layer Transport Studies First Author: Brian Labombard Session Leader: Brian Labombard (shots 1-28)

Engineering Operator Run Comment

MP#228 SOL Transport Marmer,Silva

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:21:023PM

Author: To Be Determined

Session Leader's summary of run 990831 MP#228 - SOL Transport using Ohmic H-modes Physics Operator: Marmar Session Leader: LaBombard Although MP#228 did not originally call for ohmic H-modes, it was recognized that ohmic H-modes provide a nice way to study H-mode transport under a variety of toroidal fields which are not compatible with ICRF heating. Additionally, SOL transport studies rely heavily on the use of probes. Therefore, ohmic H-modes are a particularly nice discharge to study since they tend to have the lowest power densities and they lack any complications for probe interpretation in the presence of RF-sheath effects. The drawbacks are a limited range of qPsi95 and the inability to initiate an L-H transition at a particular time, relative to that of well-conditioned RF heated discharges. We were successful in getting a number of good H-modes during this run with the scanning probes recording profiles of n, Te, parallel flow, and fluctuations up to the separatrix. This required taking many repeat shots and walking the fine line between getting the probes deep enough to record interesting profile data and yet not inserting them so deep that they got destroyed. Hence the need for a dedicated run. On a number of discharges, the scanning probes (mostly ASP but sometimes FSP) appeared to poke into a 'shear layer'-like zone where the floating potential (Vf) dropped dramatically (100 V/mm) and the fluctuations appeared to be suppressed. The 'shear layer' Vf gradient also appeared to be much stronger in the 'elm-free' phase. Observations of C+2 plume dispersal on a few selected shots showed a qualitatively similar behavior: during 'elm-free' phases there was some very strong poloidal dispersion while in EDA-like phases the poloidal dispersal was much smaller. One should keep in mind that all these 'on the fly' observations are preliminary and need to be carefully checked. The run plan called for: (a) a Bt scan at fixed qPsi95 and (b) a qPhi95 scan at fixed Bt. We got a limited Bt scan. There was not enough time to do the qPhi95 scan. Although the data has not been analyzed yet, these data should provide a good start on H-mode SOL profile scaling (with Bt) and on SOL fluctuations. ________________________________________________________________________________ Posted Run Plan ________________________________________________________________________________ Objectives: Record cross-field SOL profiles of density, Te, parallel flow, and fluctuations in ohmic H-mode discharges with: (a) constant qPsi95 but different Bt and (b) fixed Bt and different qPsi95. Setup: FSP: - Operate in two bias modes: (a) West/East-sweep, North/South-float mode (b) West/South-sweep, North/East-float mode - Enable gas (C2H4) for optional plumes - Set up for a "deep" scan to the separatrix ASP: - Operate in two bias modes: (South probe is dead) (a) West/East-sweep, North-float mode (b) West-sweep, North/East-float mode - Set up for a "deep" scan to the separatrix FMP: - Operate in two bias modes: (a) Divertor probes in sweep and Vf mode with gated fast sampling (b) Divertor probes in Isat and Vf mode with continuous fast sampling Set fast triggers to capture Ohmic H-mode phase. Starting Discharge: Reload 990825003 and take shot. This was a dithering 1.0 MA NL04=1.0 discharge with good gaps and probes targeting. Reload segment 3 (which is presently a modified version of segment 3 from shot# 990819001): 1 MA, Ohmic H-mode ending with Bt at 5 tesla. Set gaps to 1.5 cm. Set lower x-point programming similar to 990825003. Shot plan: (a) Bt scan with constant q. Program to arrive at different Bt during end-of-shot 'flat-top'. Adjust Ip so that qPsi95 is roughly the same during end-of-shot 'flat-top'. 1 redo 990825003 2-3 setup Ohmic H-mode shot, optimized scanning probe targeting 4-6 FSP/ASP/FMP in bias mode (a) then (b) 7 Change end point Bt to 3.5 tesla, Ip = 0.7 MA. 8-10 FSP/ASP/FMP in bias mode (a) then (b) 11 Change end point Bt to 6.0 tesla, Ip = 1.2 MA. 12-14 FSP/ASP/FMP in bias mode (a) then (b) (b) q scan with constant Bt. Set Bt flat-top to 4.0 tesla. Scan Ip from 0.8 to 1.2 MA (may be 1.1 MA if we are afraid of a low q disruption!) 15-16 Ip=0.8MA, setup discharge with optimized scanning probe targeting 17-19 FSP/ASP/FMP in bias mode (a) then (b) 20 change to Ip=1.0 MA 21-23 FSP/ASP/FMP in bias mode (a) then (b) 24 change to Ip=1.2 MA 25-27 FSP/ASP/FMP in bias mode (a) then (b) ________________________________________________________________________________ Actual Shot summary: shot Ip Bt Probe Bias Plume Comment 1 OH coax test 2 1 5 Mach Dithering, shallow probe scan, G-side gauge off 3 1 4-5 Mach CIII No H-mode 4 1 4-5 Mach CIII H-mode, goes L at 5 tesla 5 1 4-5 Mach CIII H-mode, shallow insertion during H-mode 6 1 4-5 Mach CIII Nice H-mode, FSP too deep, no spectroscopy data! 7 1 4-5 Mach Nice ASP FSP data during H-mode 8 1 4-5 Fluctuation ASP FSP data 9 .7 3.5 Mach CIII Shallow insertion 10 .75 3.5 Mach CIII into H-mode at second probe scan, G-side ratiomatic was off 11 .75 3.5 Mach into H-mode at second probe scan 12 .75 3.5 Mach H-mode on both probe scans 13 .75 3.5 Mach H-mode on both probe scans, Data on first scan on ASP looks excellent! 14 .75 3.5 Fluctuation H-mode on both probe scans 15 .75 3.5 Mach H-mode on both probe scans 16 1.2 4-6 disrupted at 0.47 sec 17 1.2 4-6 Mach CIII disrupted at 0.92 sec, after first probe scan 18 1.1 4-6 Mach CIII no H-mode 19 1.15 4-6 Mach CIII H-mode, drops out of H then disrupts at 1.09 20 1.2 4-6 Mach CIII H-mode on first scan, L-mode on second 21 1.2 4-6 Mach CIII H-mode on first scan, H to L-mode on second 22 1.2 4-6 Mach CIII Probe induced disruption! 0.87 s 23 0.9 4 Mach CIII Shallow injection, first scan L second scan H 24 no plasma 25 0.9 4 Mach EDA-like H-mode on second scan 26 disrupted early 27 0.9 4 Fluctuation H-mode on two probe scans FSP goes in deep, sees drop in Vf at sep on both scans while ASP only sees drop in Vf on second scan 28 0.9 4 Mach H-mode on both scans, shallower insertion

Physics Operator Summaries

Entered: Jul 7 2004 04:37:08:990PM

Author: To Be Determined

Physop run summary -- 990831 MP#228 SOL Transport using Ohmic H-modes SL: LaBombard PO: Marmar EO: Silva, Cochrane, Dekow ______________________________________________________________________________________ Plan: Start (after Tuesday OH test) with standard 1MA 5.1T plasma (like 990825003). Then introduce TF ramps to get ohmic H-mode. Current and field will be scanned shot to shot according to the miniproposal requirements. ICRF will piggyback as possible at the end of flattop, to test and condition J3 and J4. ______________________________________________________________________________________ The run went reasonably well. We got some nice looking EDA ohmic H-modes (shots 7, 12, 14, 15, 25, 27 and 28). A number of the shots ended in high current disruptions (e.g. 16, 17, 19, 22, 26, 27); for 19, 22, 26 and 27, the disruptions were preceded by large step increases in radiated power. J3 and J4 were run into plasma at the 1.5 MW total level. Startup reliability was excellent. There was one power supply dud, due to the OH2L breaker pulling on shot 24. Shot 6 suffered a paranormal loss of spectroscopy data; it appears that a spectroscopy_start event was generated after initialization, but before the start of the discharge. There were no camac errors, but all data looked like they had been digitized during a period with no plasma. Scorecard: 26 plasmas 1 PS dud 1 test _______ 28 shot cycles

Session Leader Comments
Aug 31 1999 09:44:21:233AM		Brian Labombard	MP#228 SOL Transport using Ohmic H-Modes Objectives: Record cross-field SOL profiles of density, Te, // flow, and fluctuations in ohmic H-mode discharges with: (a) constant qPsi95 but different Bt and (b) fixed Bt and different qPsi95. Setup: FSP: - Operate in two bias modes: (a) West/East-sweep, North/South-float mode (b) West/South-sweep, North/East-float mode - Enable gas (C2H4) for optional plumes - Set up for a "deep" scan to the separatrix ASP: - Operate in two bias modes: (South probe is dead) (a) West/East-sweep, North-float mode (b) West-sweep, North/East-float mode - Set up for a "deep" scan to the separatrix FMP: - Operate in two bias modes: (a) Divertor probes in sweep and Vf mode with gated fast sampling (b) Divertor probes in Isat and Vf mode with continuous fast sampling Set fast triggers to capture Ohmic H-mode phase. Starting Discharge: Reload 990825003 or equivalent. This was a dithering 1.0 MA NL04=1.0 discharge with good gaps and probes targeting. Reload segment 3 (which is presently a modified version of segment 3 from shot# 990819001): 1 MA, Ohmic H-mode ending with Bt at 5 tesla. Set gaps to 1.5 cm. Set lower x-point programming similar to 990825003. Shots: (a) Bt scan with constant q. Program to arrive at different Bt during end-of-shot 'flat-top'. Adjust Ip so that qPsi95 is roughly the same during end-of-shot 'flat-top'. 1 redo 990825003 2-3 setup Ohmic H-mode shot, optimized scanning probe targeting 4-6 FSP/ASP/FMP in bias mode (a) then (b) 7 Change end point Bt to 3.5 tesla, Ip = 0.7 MA. 8-10 FSP/ASP/FMP in bias mode (a) then (b) 11 Change end point Bt to 6.0 tesla, Ip = 1.2 MA. 12-14 FSP/ASP/FMP in bias mode (a) then (b) (b) q scan with constant Bt. Set Bt flat-top to 4.0 tesla. Scan Ip from 0.8 to 1.2 MA (may be 1.1 MA if we are afraid of a low q disruption!) 15-16 Ip=0.8MA, setup discharge with optimized scanning probe targeting 17-19 FSP/ASP/FMP in bias mode (a) then (b) 20 change to Ip=1.0 MA 21-23 FSP/ASP/FMP in bias mode (a) then (b) 24 change to Ip=1.2 MA 25-27 FSP/ASP/FMP in bias mode (a) then (b)
Aug 31 1999 09:58:43:107AM	990831002	Brian Labombard	Shot #2 - Standard 1MA , 5T ohmic discharge with dithering G-side ionization gauge was dead. Went into cell and connected to spare filament. Gauge looks ok for now. Next shot, setup for Ohmic H-modes. Do shallow probe scan.
Aug 31 1999 10:05:03:497AM	990831003	Brian Labombard	Shot #3 - didn't get H-mode. Next shot repeat with lower NL04 and optimized FSP Target. Probes in A2 bias mode.
Aug 31 1999 10:23:26:547AM	990831004	Brian Labombard	Shot #4 - H-mode, goes L at 5 tesla Next Repeat, hoping H-mode continues in 5 tesla portion. Changed FSP target. Probes firing at .85, .65 and 1.05 sec, bias mode A2.
Aug 31 1999 10:42:45:263AM	990831005	Brian Labombard	Shot #5 - Nice H-mode, persisting at 5 tesla FSP/ASP/FMP in A2 bias mode, deep scan, gated A14 digitizers Target moves away during H-mode! Next shot, repeat Set to only two probe scans with deep insertion during H-mode - cross your fingers!
Aug 31 1999 11:14:56:513AM	990831006	Brian Labombard	Shot #6 - Nice H-mode, ASP and FSP got in nicely, FSP is a little too deep. FSP/ASP/FMP in A2 bias mode, deep scan, gated A14 digitizers Next shot, repeat with no plume
Aug 31 1999 11:15:32:920AM	990831007	Brian Labombard	Shot #7 - Nice H-mode, ASP and FSP got in nicely, FSP/ASP/FMP in A2 bias mode, deep scan, gated A14 digitizers Next shot, repeat with probes in B2 bias mode
Aug 31 1999 11:39:48:060AM	990831008	Brian Labombard	Shot #8 - H-mode during .85 sec scan. ASFSP/ASP/FMP in B2 bias mode, deep scan, continuous A14 digitizers Next shot, go to 3.5 tesla, .75 MA Probes in shallow scan A2 mode.
Aug 31 1999 12:33:54:733PM	990831010	Brian Labombard	Shot #10 - into H-mode at second probe scan G-side ratiomatic was off ASFSP/ASP/FMP in A2 bias mode, gated A14 digitizers Next shot, repeat with reduced Bt early.
Aug 31 1999 12:51:21:123PM	990831011	Brian Labombard	Shot #11 - into H-mode at second probe scan ASFSP/ASP/FMP in A2 bias mode, gated A14 digitizers Next shot, repeat with lower gas, better FSP targeting
Aug 31 1999 12:56:51:233PM	990831012	Brian Labombard	Shot #12 - got H-mode on both probe scans ASFSP/ASP/FMP in A2 bias mode, gated A14 digitizers Next shot, repeat Delay ASP/FSP targeting to .9, 1.1
Aug 31 1999 01:09:53:153PM	990831013	Brian Labombard	Shot #13 - got H-mode on both probe scans Data on first scan on ASP looks excellent! ASFSP/ASP/FMP in A2 bias mode, gated A14 digitizers Next shot, repeat with probes in B2 bias mode
Aug 31 1999 01:27:01:060PM	990831014	Brian Labombard	Shot #14 - H-mode on both probe scans Nice FSP/ASP data FSP/ASP/FMP in B2 bias mode, continuous A14 digitizers Next shot, repeat with probes in A2 bias mode to get Mach data during EDA segment of H-mode
Aug 31 1999 01:40:47:263PM	990831015	Brian Labombard	Shot #15 - H-mode on both probe scans Nice FSP/ASP data FSP/ASP/FMP in A2 bias mode, gated A14 digitizers Next shot, go to 6 tesla, 1.2 MA at end of shot Probes in shallow scan, A2 bias mode with plumes.
Aug 31 1999 02:12:04:263PM	990831016	Brian Labombard	Shot #16 - Disrupted early
Aug 31 1999 02:12:28:327PM	990831017	Brian Labombard	Shot #17 - Disrupted just after first probe scan
Aug 31 1999 02:25:17:343PM	990831018	Brian Labombard	Shot #18 - No H-mode plumes on FSP
Aug 31 1999 02:59:29:590PM	990831019	Brian Labombard	Shot #19 - H-mode, drops out of H then disrupts Next shot, reload 990831008
Aug 31 1999 03:06:04:827PM	990831020	Brian Labombard	Shot #20 - H-mode on first scan, L-mode on second Next shot, increase Ip and Bt at end of shot
Aug 31 1999 03:26:28:717PM	990831021	Brian Labombard	Shot #21 - H-mode on first scan, H to L-mode on second Next shot, increase Ip to 1.2 MA and Bt to 6.0 T at end of shot
Aug 31 1999 03:47:23:593PM	990831022	Brian Labombard	Shot #22 - Probe induced disruption! Did not go into H-mode and as a consequence the FSP was over-inserted by 2mm Next shot, dial up Bt=4 tesla, Ip =0.9 MA Probes in shallow scan.
Aug 31 1999 04:05:11:420PM	990831023	Brian Labombard	Shot #23 -H-mode at .95 sec Shallow probe injection with plumes Next shot, repeat
Aug 31 1999 04:05:39:420PM	990831024	Brian Labombard	Shot #24 no plasma Next shot, repeat shot 23
Aug 31 1999 04:31:56:593PM	990831025	Brian Labombard	Shot #25 EDA-like H-mode on second scan A2 bias Next shot, repeat with B2 bias (fluctuation mode)
Aug 31 1999 04:45:25:967PM	990831026	Brian Labombard	Shot #26 disrupted early, no data Next shot, repeat shot 25 with B2 bias (fluctuation mode)
Aug 31 1999 05:04:02:263PM	990831027	Brian Labombard	Shot# 27 H-mode on two probe scans Probes in B2 bias mode (fluctuation) FSP goes in deep, sees drop in Vf at sep on both scans while ASP only sees drop in Vf on second scan. FSP and ASP also see two dithers (or something) in Vf profile data. Next shot, go to 1.1 MA in A2 bias mode
Aug 31 1999 05:46:04:000PM	990831028	Brian Labombard	Shot# 28 - Turned out to be a repeat of shot #27 H-mode on both probe scans.

Physics Operator Comments
Aug 31 1999 05:16:13:123PM		Earl Marmar	hybrid coldstart; no errors; all matrices respond
Aug 31 1999 05:16:29:827PM		Earl Marmar	MP#228 SOL Transport using Ohmic H-modes SL: LaBombard PO: Marmar Start (after Tuesday OH test) with standard 1MA 5.1T plasma (like 990825003). Then introduce TF ramps to get ohmic H-mode. Current and field will be scanned shot to shot according to the miniproposal requirements. ICRF will piggyback as possible at the end of flattop, to test and condition J3 and J4. Gas setup - fill B-top with 6 psi of D2 Hybrid enabled fill B-side lower with 1 psi of Ar Hybrid enabled fill B-side upper with 6 psi of H2 Hybrid DISABLED fill C-side with 30 psi of D2 Hybrid enabled leave J-bottom as is Hybrid DISABLED The following gate valves should be enabled, assuming no vacuum problems: ECE, VUV.
Aug 31 1999 05:17:19:717PM	990831001	Earl Marmar	OH coax test; PLC control.
Aug 31 1999 05:18:56:293PM	990831002	Earl Marmar	Load from 990825003, segment 1 from 990824002 move end of Ip flat-top out to 1.5 seconds reduce Argon pulse to 25 msec plasma
Aug 31 1999 05:18:35:077PM	990831003	Earl Marmar	Turn off segment 2, turn on segment 3, TF scan to try for ohmic H-mode Plasma no H-mode
Aug 31 1999 10:14:34:263AM	990831004	Earl Marmar	reduce nl_04 to 0.9e20 move zxl down 4 mm at 1.2 seconds reduce argon puff to 10 msec add .5mT to B_R offset (now 0.000) plasma ohmic H-mode 1.5 MW RF late in shot
Aug 31 1999 10:47:15:857AM	990831005	Earl Marmar	ZXL tweak (ramp down 4 mm between 0.8 and 1.2 s) plasma long ohmic H-mode (EDA-ish?) 1 MW RF
Aug 31 1999 11:04:49:577AM	990831006	Earl Marmar	repeat plasma H-modes No spectroscopy data
Aug 31 1999 11:29:55:780AM	990831007	Earl Marmar	repeat plasma H-modes Spectroscopy data ok
Aug 31 1999 11:47:53:013AM	990831008	Earl Marmar	repeat plasma H-modes
Aug 31 1999 11:55:01:107AM	990831009	Earl Marmar	3.5 Tesla program for 0.75 MA no RF removed RCUR jog plasma got 0.71 MA Goes into H-mode at about 1.08 s
Aug 31 1999 12:15:29:937PM	990831010	Earl Marmar	Program for 0.8 MA plasma H-mode after 1.04 s
Aug 31 1999 12:32:11:810PM	990831011	Earl Marmar	Reduce I_TF to -82000 before 0.8 s, to get into H-mode sooner Start TF rampdown later (1.6 s) plasma H-Mode at 0.89 s
Aug 31 1999 05:20:16:030PM	990831012	Earl Marmar	lower nl_04 to 0.7e20 plasma H-Mode after 0.83 s
Aug 31 1999 01:04:00:297PM	990831013	Earl Marmar	Tweak ZXU so it doesn't ramp down after 1.2 s plasma
Aug 31 1999 01:19:58:857PM	990831014	Earl Marmar	Bring TF back up after 1.2, to try to avoid the rampdown disruption Plasma The TF tweak helped the disruption
Aug 31 1999 01:41:34:623PM	990831015	Earl Marmar	Repeat plasma
Aug 31 1999 01:51:57:950PM	990831016	Earl Marmar	1.2 MA, 6 Tesla plasma Disrupt at 0.47 seconds (around q_95=3)
Aug 31 1999 02:11:29:140PM	990831017	Earl Marmar	Raise I_p more slowly Small CLEARIN tweak (increase 2 mm) slow early TF rampdown plasma Disrupt at 0.92 s; got very resistive heading towards the disruption
Aug 31 1999 02:20:29:670PM	990831018	Earl Marmar	lower I_P to 1.1 MA raise nl_04 to 1e20 reduce time at lowest TF plasma no ohmic H-mode brief RF H-mode late
Aug 31 1999 02:38:17:937PM	990831019	Earl Marmar	Raise I_p to 1.15 MA lower nl_04 to 0.9e20 keep lowest TF value longer plasma disrupt at 1.09 s
Aug 31 1999 03:10:14:077PM	990831020	Earl Marmar	reload 990831008 plasma
Aug 31 1999 03:22:39:687PM	990831021	Earl Marmar	1.2 MA 6 Tesla plasma TF PLC limit was 160 kA, so got 5.7 T
Aug 31 1999 03:35:44:997PM	990831022	Earl Marmar	Raise TF PLC limit to 175 kA Raise I_p demand to 1.25 MA Disrupt at 0.87 s
Aug 31 1999 03:55:47:797PM	990831023	Earl Marmar	4 tesla across plasma H-mode after 0.94
Aug 31 1999 04:14:17:233PM	990831024	Earl Marmar	repeat dud; OH2L breaker pulled before the shot
Aug 31 1999 04:30:33:903PM	990831025	Earl Marmar	No PCS changes plasma Ohmic H-mode after 1.015 (EDA)
Aug 31 1999 04:55:59:030PM	990831026	Earl Marmar	Repeat early disrupt; something fell in
Aug 31 1999 04:56:23:530PM	990831027	Earl Marmar	No PCS changes Plasma Ohmic H-Mode (EDA)
Aug 31 1999 05:07:37:717PM	990831028	Earl Marmar	repeat plasma Ohmic H-Mode

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	09:14:53:187AM	Test	Ok	OH co-ax test ok
2	09:24:52:140AM	Plasma	Ok	no faults/plasma
3	09:52:58:263AM	Plasma	Ok	no faults/plasma
4	10:08:35:340AM	Plasma	Ok	no faults/plasma
5	10:24:05:187AM	Plasma	Ok	no faults/plasma
6	10:49:46:873AM	Plasma	Ok	no faults/plasma
7	11:04:15:077AM	Plasma	Ok	no faults/plasma
8	11:29:37:983AM	Plasma	Ok	no faults/plasma
9	11:46:05:530AM	Plasma	Ok	no faults/plasma
10	11:58:49:873AM	Plasma	Ok	no faults/plasma
11	12:25:51:403PM	Plasma	Ok	no faults/plasma
12	12:38:41:763PM	Plasma	Ok	no faults/plasma
13	12:54:26:437PM	Plasma	Ok	no faults/plasma
14	01:14:08:123PM	Plasma	Ok	(null)
15	01:27:22:937PM	Plasma	Ok	(null)
16	01:44:30:200PM	Plasma	Ok	(null)
17	01:58:25:640PM	Plasma	Ok	(null)
18	02:11:59:450PM	Plasma	Ok	(null)
19	02:31:54:357PM	Plasma	Ok	(null)
20	02:56:52:373PM	Plasma	Ok	(null)
21	03:13:11:170PM	Plasma	Ok	(null)
22	03:33:34:950PM	Plasma	Ok	(null)
23	03:47:34:623PM	Plasma	Ok	(null)
24	04:01:56:187PM	Plasma	Bad	PF Power supply Faults
25	04:22:43:390PM	Plasma	Ok	(null)
26	04:36:12:983PM	Plasma	Ok	(null)
27	04:49:25:500PM	Plasma	Ok	(null)
28	05:03:35:937PM	Plasma	Ok	(null)