Miniproposals

Miniproposal: 154a Date Filed: 1/12/1999 Title: H modes in Helium Plasmas First Author: Rejean Boivin Session Leader: Rejean Boivin (shots 1-20)

Engineering Operator Run Comment

MP 154A H-modes in Helium, Boivin/Granetz/Hutchinson/Cochran/Dekow.

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:21:647PM

Author: To Be Determined

MP 154A Helium H-modes Oct 27 1999 P.O. D. Mossessian S.L. R. Boivin After a late start trying to get XMTR 1 back on its feet, we were able to get power out of the 2 transmitters, in a run which we knew would be able to get H-mode. Plasma was achieved on shot 004, and basically stayed on until the end except for shot 19. Breakdown in deuterium is a good thing, and little affect the rest of the discharge. Although it has been found that the RF was heating the core nicely, it was very difficult to achieve H-mode, which we obtained on shot 013, with up to 3MW, basically the most we could get from the 2 transmitters in those conditions. As expected we had a fair amount of radiation, while the edge remained pretty hot nonetheless. In many shots between 7 and 12, the average edge (95%) temperature was slightly below the usual Deuterium edge temperature thresholds, but peak temperatures, following sawtooth crashes exceeded those temperatures. When the plasma did go into H-mode, the edge temperature threshold was found to be higher than in deuterium, with the exact number to be verified. We raised the current in an attempt to get more power with little obvious effects. H-modes were again very short in nature, and a density scan was all but impractical to do with so little time left and the inherent difficulty. At the end of the run, we attempted to inject some deuterium but the walls absorbed it readily and only a marginal change was seen in the last shot. Helium rotation data was obtained, but further analysis is required before we can look at the consequences for roation in L and/or H-mode. Rejean Boivin Alcator C-Mod Plasma Science and Fusion Center NW17-182, MIT 77 Massachusetts Ave Cambridge, MA 02139 (617) 253-8695 (617) 253-0627 FAX

Physics Operator Summaries

Entered: Jul 7 2004 04:37:09:803PM

Author: To Be Determined

Physics operator summary for 991027: SL: R.Boivin PO: D.Mossessian __________________________ Engineering Setup and Run Plan for Tuesday, 991026: Run will begin at 09:00 and end at 17:00. Setup power supplies from shot 991022025 (0.8 MA, 5.3 T, flattop to 1.5 s, extended Bt flattop at 50 kA, fizzle detector off at t=1.7 s). ECDC in ** HELIUM ** over the weekend, as well as Monday, and Monday night, stopping 1-2 hours before the run. Gas setup - fill B-top with 6 psi of D2 Hybrid enabled fill B-side lower with 1 psi of Ar Hybrid DISABLED fill B-side upper with 10 psi of H2 Hybrid DISABLED fill C-side with 30 psi of He Hybrid enabled leave J-bottom as is Hybrid DISABLED NOTE: THAT'S HELIUM IN C-SIDE, NOT DEUTERIUM !! The following gate valves should be enabled, assuming no vacuum problems: ECE, VUV Physics operator's setup for Tuesday, 991026: MP 154A -- H-modes in Helium After the standard Tuesday OH test, Load shot 991026000, prepared by R. Granetz, that has Ip = 1.0 MA, target density nl_04=1.0e20 m-2. The fizzle detector "off" time is set to t=1.7 s, and Disable B-side-upper (H2) valve for the first shot. We'll probably turn this on for a 150 ms puff after we get the first plasma. Disable B-side-lower (Ar) valve (probably for the entire run). Program RF power to provide a break-in-slope analysis of the RF absorption fraction. Monitor density (target nl = 1.0e20 m-2) and outer gap (target = 8 mm) and correct as necessary. See Rejean's posted run plan for more details about goals and procedures during the run. ____________________________________________ Summary: The run was delayed because of RF problems. We started around 10:30 and ran till 18:00. First two shots after the OH test were fizzles caused by too low Bz. After that the run went well. There was one disruption on shot 16, probably caused by OH1 running against the limit. Right gap, target density and current were changed several times to satisfy RF people (see below). No H2 puffs were performed. At the end of the run the attempt was made to run mixture of D2 and He. Shot 18 has pulse_gas4 programed to puff D2 during plasma and target density was lowered to 9e19 to decrease the amount of He puffed. For next shot the C-side plenum was filled with 50/50 D2/He and programming returned to shot 17 (no D2 puff after t=0, n0=1.1e20). A fizzle followed, then a plasma on the last shot. Scorecard: 20 shots 1 test 3 fizzles 16 plasmas ************************ 991027001 OH test. 991027002 Fizzle. Br too negative. For next shot: increase Br offset by 2 mT. Changed TF current in segment 1 to be consistent with segment 2. 991027003 Fizzle. Br still too negative. For next shot: increase Br offset by 2 mT. 991027004 Plasma. RF ramps up to .7 MW at .5 sec. nl_04=1.15e20, right gap changes from 1 to 1.5 cm. For next shot: Drop pulse_gas3 to get nl_04 to 1e20. Change RCUR to keep right gap at 8 mm. 991027005 Plasma. Right gap is around .8 cm. nl_04 still to high. Strong hesitation in current rise. For next shot: increase Bz at startup (add 15 A to EF4) trying to push plasma in and fix current. Drop pulse_gas3 again. 991027006 Plasma. Less hesitation in current rise although Bz didn't seem to change much. For next shot: no PCS change 991027007 Plasma. Still hesitation in current rise. Density is 1.1e20. RF ramps from 1 to 2 MW. For next shot: drop target density to 8e19 to get 1e20. 991027008 Plasma. Density 8e19. RF around 2 MW. Heating the core, but no H-mode. For next shot: increased right gap by 2 mm (change RCUR) 991027009 Plasma. Density 8e19. RF up to 2.5 MW. Heating the core, but no H-mode. For next shot: increased inner gap by 2 mm keeping outer gap the same (change CLEARIN and RCUR) 991027010 Plasma. Same as above. For next shot: Changed RCUR to improve inner gap at .5 sec. Add step in target density from 8e19 to 1.2e20 at 1 sec 991027011 Plasma. Some RF, core heating, no H-mode. For next shot: no PCS change 991027012 Plasma. Some RF, core heating, no H-mode. For next shot: increase n0 to 1.e20 between .5 and 1 sec 991027013 Plasma. Up to 3 MW RF, short H-modes. For next shot: decrease right gap by 2 mm, set current 1.1 MA, and n0 to 1.2e20. 991027014 Plasma. Up to 3 MW RF, short H-modes. For next shot: set current 1.2 MA, and n0 to 1.1e20. 991027015 Plasma. Up to 3 MW RF, short H-modes. For next shot: Bt to 5 T 991027016 Plasma. Up to 3 MW RF, short H-modes. Disruption at 1.55 sec. OH1 and EF1_U ran up against the limit. For next shot: no PCS changes. The limit on OH1 was increased to 29000. 991027017 Plasma. Up to 3 MW RF, short H-modes. EF1_U still saturated. For next shot: trying to run mixture of He and D2. Programed pulse_gas4 (used for D2 prepuff) to puff after .029 sec. Dropped target density to 9e19. 991027018 Plasma. Up to 3 MW RF, short H-modes. For next shot: filled C-side plenum with mixture 50-50 D2 and He. Set pulse_gas4 back to 0 in Segment2, set target to 1.1e20 991027019 Fizzle. Reason unknown. For next shot: no PCS changes 991027020 Plasma. Up to 3 MW RF, multiple short H-modes.

Session Leader Comments
Oct 27 1999 11:10:57:497AM		Rejean Boivin	MP 154A H-Modes in helium Prior to run, as much as possible ECDC in helium to unload deuterium from walls. 0) Tuesday OH test. 1) Scan density in helium * 1 MA discharge, (with the possibility of 0.8 MA if RF coupling/voltage limits become intolerable. monitor outer gap 0.8 cm is a good target, tweak as needed. * STart at standard nl_04 ~1e20 * Use deuterium in breakdown on all shots * Use programmed Hydrogen pulse from 991021 or 22 to give the equivalent 5% H concentration * Monitor Pabs (break in slope) (appropriate notch in Prf) * Use slow ramp to determine Pthres. (D and E only) from 0.6 sec to ~1.3 sec, notch after that for Pabs. * Use absolute Ha (from the Ha/Da monitor) to attempt to measure the H concentration. Use neutron to estimate the D concentration. At low density look especially at fuelling and density rises, edge Thomson is very important here. 2) Reintroduce deuterium progressively and monitor H mode behavior, at nl_04 ~1e20. Diagnostics * Hirex for Ti * Normal ECE,GPC, VB, Thomson, Xray, for edge diagnostic (if H modes are long enough, put in a TF waggle) * FSP and ASP, for SOL profiles. * McP, helium lines with a few D Lyman alpha shots * Yes Rob, go for it with the Omegatron! * All rotation measurements, helium is the majority ions and we should try to measure edge rotation directly. * Bolos as usual
Oct 28 1999 09:02:27:170AM	991027006	Rejean Boivin	RF ramps ok, both XMTRs now behaving. Central Te up to 2.2 keV, no H -mode yet.
Oct 28 1999 09:04:03:530AM	991027007	Rejean Boivin	007 Higher RF ramps, more power out of XMTR 2 Central Te up to 2.6 keV, no H -mode yet.
Oct 28 1999 09:05:45:797AM	991027008	Rejean Boivin	008 Lower density, a little above 2 MW total Central Te above 3 kEv, yag says above 4keV Nice heat pulses to edge, still no H mode.
Oct 28 1999 09:13:16:420AM	991027011	Rejean Boivin	011 XMTR 2 went further but not to the high part of XMTR 1
Oct 28 1999 09:14:06:187AM	991027012	Rejean Boivin	012 Try higher density of 2nd part of the pulse, XMTR 2 ratty
Oct 28 1999 09:15:05:793AM	991027013	Rejean Boivin	013 Move high power part of XMTR 1 to beginning GOT 4 small h-modes ! They trip XMTR 2 though
Oct 28 1999 09:22:08:200AM	991027014	Rejean Boivin	014 Higher current 1.1 MA Got 2 small h_modes E did a bit better, try to keep it on for the Hmodes Tweaked the gap again, to help stay in H mode. MAX power available from RF.
Oct 28 1999 09:22:36:687AM	991027015	Rejean Boivin	015 Higher current 1.2 MA Got 2 small h_modes E did a bit better, try to keep it on for the Hmodes Tweaked the gap again, to help stay in H mode. MAX power available from RF.
Oct 28 1999 09:32:15:123AM	991027018	Rejean Boivin	018 Puff D at the ram-up to see the effects of neutrals. Many small H -modes, is D helping now?
Oct 28 1999 09:40:22:780AM	991027020	Rejean Boivin	020 Put D-He 50-50 in plenum A few small H modes, Walls are taking the D as we put it. Check the actual D concentration.

Physics Operator Comments
Oct 27 1999 08:42:04:843AM		Dmitri Mossessian	Loaded shot 991026000 prepared by R.Granetz for He run. ip=-1.e6, n0=1.e20. Load shot. Coldstart OK.
Oct 27 1999 10:26:11:577AM	991027001	Dmitri Mossessian	OH test.
Oct 27 1999 10:48:04:950AM	991027002	Dmitri Mossessian	PLasma attempt. Fizzle. Br too negative. For next shot: increase Br offset by 2 mT. Changed TF current in segment 1 to be consistent with segment 2.
Oct 27 1999 11:08:57:840AM	991027003	Dmitri Mossessian	Fizzle. Br still too negative. For next shot: increase Br offset by 2 mT.
Oct 27 1999 11:46:04:607AM	991027004	Dmitri Mossessian	Plasma. RF ramps up to .7 MW at .5 sec. nl_04=1.15e20, right gap changes from 1 to 1.5 cm. For next shot: Drop pulse_gas3 to get nl_04 to 1e20. Change RCUR to keep right gap at 8 mm.
Oct 27 1999 12:25:50:623PM	991027005	Dmitri Mossessian	Plasma. Right gap is around .8 cm. nl_04 still to high. Strong hesitation in current rise. For next shot: increase Bz at startup (add 15 A to EF4) trying to push plasma in and fix current. Drop pulse_gas3 again.
Oct 27 1999 01:20:10:107PM	991027006	Dmitri Mossessian	Plasma. Less hesitation in current rise although Bz didn't seem to change much. For next shot: no PCS change
Oct 27 1999 01:48:58:560PM	991027007	Dmitri Mossessian	Plasma. Still hesitation in current rise. Density is 1.1e20. RF ramps from 1 to 2 MW. For next shot: drop target density to 8e19 to get 1e20.
Oct 27 1999 02:15:06:230PM	991027008	Dmitri Mossessian	Plasma. Density 8e19. RF around 2 MW. Heating the core, but no H-mode. For next shot: increased right gap by 2 mm (change RCUR)
Oct 27 1999 02:35:49:607PM	991027009	Dmitri Mossessian	Plasma. Density 8e19. RF up to 2.5 MW. Heating the core, but no H-mode. For next shot: increased inner gap by 2 mm keeping outer gap the same (change CLEARIN and RCUR)
Oct 27 1999 02:58:58:123PM	991027010	Dmitri Mossessian	Plasma. Same as above. For next shot: Changed RCUR to improve inner gap at .5 sec. Add step in target density from 8e19 to 1.2e20 at 1 sec
Oct 27 1999 03:23:43:543PM	991027011	Dmitri Mossessian	Plasma. Some RF, core heating, no H-mode. For next shot: no PCS change
Oct 27 1999 03:39:47:687PM	991027012	Dmitri Mossessian	Plasma. Some RF, core heating, no H-mode. For next shot: increase n0 to 1.e20 between .5 and 1 sec
Oct 27 1999 04:00:08:200PM	991027013	Dmitri Mossessian	Plasma. Up to 3 MW RF, short H-modes. For next shot: decrease right gap by 2 mm, set current 1.1 MA, and n0 to 1.2e20.
Oct 27 1999 04:17:45:857PM	991027014	Dmitri Mossessian	Plasma. Up to 3 MW RF, short H-modes. For next shot: set current 1.2 MA, and n0 to 1.1e20.
Oct 27 1999 04:31:51:653PM	991027015	Dmitri Mossessian	Plasma. Up to 3 MW RF, short H-modes. For next shot: Bt to 5 T
Oct 27 1999 04:59:03:530PM	991027016	Dmitri Mossessian	Plasma. Up to 3 MW RF, short H-modes. Disruption at 1.55 sec. For next shot: no PCS changes.
Oct 27 1999 05:29:40:920PM	991027017	Dmitri Mossessian	On shot 16 OH1 and EF1_U ran up against the limit. Before shot 17 the limit on OH1 was increased to 29000. Plasma. Up to 3 MW RF, short H-modes. EF1_U still saturated. For next shot: trying to run mixture of He and D2. Programed pulse_gas4 (used for D2 prepuff) to puff after .029 sec. Dropped target density to 9e19.
Oct 27 1999 05:34:26:170PM	991027018	Dmitri Mossessian	Plasma. Up to 3 MW RF, short H-modes. For next shot: filled C-side plenum with mixture 50-50 D2 and He. Set pulse_gas4 back to 0 in Segment2, set target to 1.1e20
Oct 27 1999 05:57:11:607PM	991027019	Dmitri Mossessian	Fizzle. Reason unknown. For next shot: no PCS changes
Oct 27 1999 06:13:25:920PM	991027020	Dmitri Mossessian	Plasma. Up to 3 MW RF, multiple short H-modes.

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	10:23:22:607AM	Test	Ok	oh coax and ef1u ,ef1L only
2	10:38:49:107AM	Plasma	Ok	Fizzle
3	11:00:46:437AM	Plasma	Ok	Fizzle
4	11:20:18:043AM	Plasma	Ok	(null)
5	12:06:19:780PM	Plasma	Ok	(null)
6	01:06:15:170PM	Plasma	Ok	(null)
7	01:27:02:123PM	Plasma	Ok	(null)
8	01:50:30:140PM	Plasma	Ok	(null)
9	02:16:25:640PM	Plasma	Ok	(null)
10	02:41:45:750PM	Plasma	Ok	(null)
11	03:01:44:263PM	Plasma	Ok	(null)
12	03:23:29:230PM	Plasma	Ok	(null)
13	03:45:07:390PM	Plasma	Ok	(null)
14	04:04:59:593PM	Plasma	Ok	(null)
15	04:22:11:420PM	Plasma	Ok	(null)
16	04:42:56:577PM	Plasma	Ok	(null)
17	05:04:26:670PM	Plasma	Ok	(null)
18	05:26:49:903PM	Plasma	Ok	(null)
19	05:46:51:247PM	Plasma	Ok	(null)
20	06:03:05:140PM	Plasma	Ok	(null)