Miniproposals

Miniproposal: Date Filed: Title: First Author: Session Leader: Yuichi Takase (shots 1-25)

Engineering Operator Run Comment

icrf heating

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:12:023PM

Author: To Be Determined

Session Leader's Run Summary for 950120 (ICRF Heating) SL: Takase PO: Horne EO: Bertolino/Daigle The run objective was to explore ICRF heating with 3MW of RF power. This was the first RF run with two transmitters and two antennas after the RF conditioning has been completed (Full power injection of 3.5MW was achieved during the 950118 run). The run was successful, and several interesting phenomena were observed: On Tuesday (950118) we piggy-backed on J. Rice's run @ nel_04=0.6e20. Today, we ran at target densities of nel_04=0.8e20 and 1.0e20. The outer gap (separatrix - outboard limiter) varied from 0.8 to 1.2cm. Because of coax reconfiguration, we had to spend some time trying to figure out the tuning again (for the D-port antenna), resulting in not-so-perfect RF pulse shapes. However, this actually gave us data at intermediate power levels, which are useful. We had 23 useful plasma shots (shot 10 dosrupted early and shot 25 was a power supply dud), with 15 shots with over 2.5MW for at least a short time. Shots 6 and 14 did not have high power RF, and are good OH comparison shots. Shots 11, 13, 15, 19,21, and 24 had both antennas for 200msec. Virtually all shots with high RF power (two antennas) transitioned into H-mode. The H-mode character appears to be different for different densities (nel_04=0.8e20 compared to 1.0e20 or 0.6e20). At both nel_04=0.8e20 and 1.0e20, we were able to sustain the H-mode (ELM-free then becoming ELMy) for the duration of high power RF (200msec). Following the density rise in the ELM-free period, a new steady-state density level is maintained until the RF pulse is terminated. The H-factor during this quasi-steady-state H-mode was not very large (only marginally greater than 1). At all three densities, the stored energy (EFIT) roughly doubles from 50kJ to almost 100kJ with 3MW of RF power (the temperature increases are consequently more spectacular at lower densities, with central Te and Ti approaching 5keV). Shot 16 had a medium Li pellet 50msec prior to the RF pulse, and a record neutron rate (almost 1e14/sec) was obtained during the "PEP" phase when the density profile is highly peaked. The E-port transmitter was running reliably with 2MW (occationally even higher) of output power. However, the peak voltage in the 9" coax was 50kV and some evidence of tuner arc was observed. The E-port coax will be reconfigured over the weekend to lower this voltage. The D-port transmitter has not been delivering 2MW, and needs to be improved. P_RF > 2.5MW @ nel=1.0e20 --- Shots 011, 013, 015, 019 P_RF > 2.5MW @ nel=0.8e20 --- Shots 003, 021, 023, 024 Li pellet + ICRF "PEP" --- Shot 016

Physics Operator Summaries

Entered: Jul 7 2004 04:36:52:910PM

Author: To Be Determined

Run 950120 RF group (SL), Horne(PO), Bertolino, Daigle (EO) Load shot 950118033 (Yuichi specified it), segment 3 from 950119023 (diverted rampdown) fill at 1.5e--5 "Piggyback" experiments -- observe hybrid input 81, the RF loading monitor -- observe new disruption trigger -- Possibly tweak the rampdown sequence. Summary -- Very successful run. 24 good shots out of 25; no fizzles. 3-segment operation, with diverted rampdown in segment 3, starting with shot 1. shot 25 was a dud to the OH2 switches not closing. One full-current disruption (shot 10); otherwise worst disruption was 400 kA; most at less than 200. Granetz became bored. Shot 16 had RF + lithium pellet; 1.e14 neutron rate. Shot list shot 1 plasma. rampdown to 100 ka. RF 1.5 MW. Feedback signal doesn't work No changes. 2 See 1. The right gap is growing slightly starting at about 600 msec. This is affecting RF loading. There's very little or no change in aout, but predictor shows the change. Sure enough, shot is programmed to move rcur in slightly. Fixed for next shot. Bounce scope (early ECE) shows strange and complicated breakdown behavior. 3 see 1. Argon enabled. outer gap is responding to rf beta increase, possibly too much. 4 No change. 5 no change. There is a z jog at rampdown, due to programming mismatch. Fix it. Raise line density to 1.0e15. 6 400 KA disruption on rampdown; 7 Change density programming in segment 3; Adjust (make longer via stretch on gains) IP rampdown in segment 3 Disrupt on rampdown at 300 kA. Try moving time of negative NL programming earlier. (to .9 sec) Slow ramp rate some more., seg 3. 8 disruption at 200 ka. Sharkfin at 1.15, possibly due to becoming limited. 9 lithium pellet at 1.0 sec. Same sharkfin. Try limiting earlier. 10 disrupted when ef2 hit rail at .35 sec or so. Try ramping clearin more slowly 11 That worked; we're off the ef2 rail. Disruption at 200 ka on rampdown. Bolo shows spikes, etc. Could the edge be too hot? Try increasin rampdown rate. 12 ece signals show high frequency (mhd?) wiggles at disruption time. Try increasing rate some more. It doesn't seem to be responding to these gain changes (IP P in segment 3.) 13 Nice RF h-mode. plasm current increases during RF by 20 KA or so. 14 rf faults of some sort. The density during rampdown is simply not dropping. Try moving density rampdown to .85. 15 Another RF h-mode. Disrupts below 200 kA. Try holding clearin diverted longer for next shot. Medium lithium pellet at .65. PEP mode,... 16 Nice shot, pellet, H-mode, RF, etc. Record neutron rate? Disruption earlier on rampdown -- Undo clearin change -- reload 15. 17 disruption on rampdown at 200 kA. No change for next shot. 18 See 17. Adjust IP seg 3 gains to stretch and flatten rampdown. 19 No problems. NL programmed to 8.e19 20 Nice shot. 21 no changes. For next shot, turn nl feedback off, and program gas valve, to try to keep source constant during h-mode. One theory is that density will continue to rise, since the source won't drop to zero. However, since nl doesn't drop for 150 msec when we turn off the gas, I doubt this theory. The shape of the nl curve suggests that instead, a new loss mechanism turns on when the density rises. 22 not enough RF to test the theory, though the density didn't rise much. back to density feedback. 23 Nominal shot. For next, change rcur by 2 mm. 24 Nominal shot. Apparently the RF transmitters have no water flow. Long expedition into power room to investigate. 25 After expedition returns, shot is a dud. oh2 Switches don't close.

Session Leader Comments
Jan 20 1995 09:06:38:190AM	950120001	Yuichi Takase	Shot 001: RF Heating run with 2 transmitters. Try higher density than Wednesday. Transmitter #2 (E port) tripped. About 1.5MW from D port.
Jan 20 1995 09:07:34:490AM	950120002	Yuichi Takase	Shot 002: Transmitter #2 (E port) tripped again. About 1.5MW from D port. nel_04=0.8
Jan 20 1995 09:28:36:430AM	950120003	Yuichi Takase	Shot 003: Transmitter #2 (E port) worked halfway. Hitting 50kV. target nel_04=0.8. Trying to get into H-mode?
Jan 20 1995 09:44:03:790AM	950120004	Yuichi Takase	Shot 004: Transmitter #2 (E port) worked (lowered power). D port mistuned. target nel_04=0.8.
Jan 20 1995 10:14:56:700AM	950120005	Yuichi Takase	Shot 005: Transmitter #2 (E port) worked (0.9MW). D port mistuned. target nel_04=0.8.
Jan 20 1995 10:37:47:420AM	950120006	Yuichi Takase	Shot 006: Raised target density to nel_04=1.0 Both antennas mistuned.
Jan 20 1995 10:39:42:880AM	950120007	Yuichi Takase	Shot 007: target nel_04=1.0 D-port antenna still mistuned.
Jan 20 1995 11:06:55:040AM	950120008	Yuichi Takase	Shot 008: target nel_04=1.0 D-port antenna still mistuned. E-port 1.1MW
Jan 20 1995 12:02:14:430PM	950120009	Yuichi Takase	Shot 009: target nel_04=1.0 D-port antenna better, but trips after transition into H-mode. E-port OK.
Jan 20 1995 12:05:03:840PM	950120010	Yuichi Takase	Shot 010: Bad shot, disrupted @ 0.4sec.
Jan 20 1995 12:28:16:490PM	950120011	Yuichi Takase	Shot 011: Good shot. Both antennas. E-port still needs tuning.
Jan 20 1995 12:40:56:320PM	950120012	Yuichi Takase	Shot 012: Good shot. Both antennas. E-port tripping @ H-mode transition.
Jan 20 1995 12:58:50:400PM	950120013	Yuichi Takase	Shot 013: Good shot. Long (200msec) H-mode. Both antennas stayed on (2.8MW). Density saturates after ELM starts.
Jan 20 1995 01:14:57:480PM	950120014	Yuichi Takase	Shot 014: No RF (comparison shot).
Jan 20 1995 01:41:46:170PM	950120015	Yuichi Takase	Shot 015: H-mode (ELMy).
Jan 20 1995 01:54:29:440PM	950120016	Yuichi Takase	Shot 016: Li pellet @ .65sec. H-mode @ .73sec (nel_04=1.65).
Jan 20 1995 02:13:44:590PM	950120017	Yuichi Takase	Shot 017: Short H-mode. D-port tripping.
Jan 20 1995 02:14:14:740PM	950120017	Yuichi Takase	Shot 017: Short H-mode. E-port (not D-port) tripping.
Jan 20 1995 02:27:41:440PM	950120018	Yuichi Takase	Shot 018: Short H-mode. D-port tripped.
Jan 20 1995 02:50:33:570PM	950120019	Yuichi Takase	Shot 019: H-mode, both antennas on. target nel_04=1.0, increases to 1.4 during H-mode.
Jan 20 1995 03:14:08:640PM	950120020	Yuichi Takase	Shot 020: no H-mode, D-port tripped. target nel_04=0.8
Jan 20 1995 03:34:35:440PM	950120021	Yuichi Takase	Shot 021: H-mode, both antennas. target nel_04=0.8
Jan 20 1995 03:42:07:210PM	950120022	Yuichi Takase	Shot 022: Turned off ne feedback. no H-mode, D-port tripped. target nel_04=0.8, increases to 0.9 during RF.
Jan 20 1995 04:09:02:150PM	950120023	Yuichi Takase	Shot 023: Turned ne feedback on. H-mode, ELM-free for 40msec. target nel_04=0.8, increases to 1.1 during H-mode.
Jan 20 1995 04:24:34:480PM	950120024	Yuichi Takase	Shot 024: outer gap increased to 1.2cm (was 0.8cm). H-mode, shorter ELM-free period. target nel_04=0.8, increases to 1.0 during H-mode.

Physics Operator Comments

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	08:34:10:440AM	Plasma	Ok	no faults
2	08:51:49:660AM	Plasma	Ok	no faults
3	09:07:47:650AM	Plasma	Ok	no faults
4	09:31:17:060AM	Plasma	Ok	no faults
5	09:54:54:070AM	Plasma	Ok	no faults
6	10:16:27:600AM	Plasma	Ok	no faults
7	10:34:38:580AM	Plasma	Ok	no faults
8	10:54:22:230AM	Plasma	Ok	no faults
9	11:11:44:470AM	Plasma	Ok	no faults
10	11:39:00:690AM	Plasma	Ok	no faults
11	11:58:46:580AM	Plasma	Ok	no faults
12	12:21:24:420PM	Plasma	Ok	no faults
13	12:42:14:430PM	Plasma	Ok	no faults
14	12:57:33:230PM	Plasma	Ok	no faults
15	01:16:08:330PM	Plasma	Ok	no faults
16	01:36:07:790PM	Plasma	Ok	no faults
17	01:55:39:810PM	Plasma	Ok	No Faults.
18	02:14:14:490PM	Plasma	Ok	No faults
19	02:33:28:500PM	Plasma	Ok	No Faults.
20	02:53:35:240PM	Plasma	Ok	No Faults
21	03:11:03:350PM	Plasma	Ok	No Faults.
22	03:29:34:120PM	Plasma	Ok	no faults
23	03:51:15:500PM	Plasma	Ok	No Faults.
24	04:10:22:680PM	Plasma	Ok	No Faults.
25	04:49:55:000PM	Plasma	Ok	No Faults