Miniproposals

Miniproposal: Date Filed: Title: First Author: Session Leader: Steve Wolfe (shots 1-20)

Engineering Operator Run Comment

Lower diverter strike points

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:07:960PM

Author: To Be Determined

Summary of Run 930623 Physics Operator: Goetz Asst. Operator: Wolfe Eng. Operator: Silva/Bertolino The goal of this run was to work on the location of the strike points during lower divertor operation. A secondary goal was to determine if plasma breakdown could be initiated without commutation of the OH1 current. A piggyback run directed by Horne consists of EFC-chopper operation after the plasma has terminated. The run showed that control of the outer strike point location during lower divertor operation is achievable. The strike point can be moved up-down and in-out using the EF1's, EF2L, and the position controllers presently in use. The inner strike point location is much more difficult to change and was not under our control this run. Large oscillations were seen in the z-position of the discharge and attention must be paid to the PID gains of ZCUR. Non-commutation of the OH1 current was never attempted. Data were gathered on the behavior of the chopper-EFC system and will be used for initial EFC operation during Run 930624. Problems: --------- The run began at 10:30, with the delayed start being attributable to three causes. The TF bus was being repaired because of evidence of melted solder on the shunt (see run summary 930622). Next, an increase to just below 1.E-9 in the partial pressure of the 28 peak on the RGA occured, coincident with the cooling of the EFCL magnet. The final delay was due an unexplained crash and reboot of XHARPO. Throughout the day there was an unexplained oscillation in the EF3 current. It was not determined if the hybrid programming was at the root of the problem. EF3 turn-on timing drifted during the run but it is not clear that the fizzles were caused by this drift. Wall Conditioning/Vacuum: ------------------------- ECDC was run for about an hour prior to the run, ending at 08:30. A small mass 28 event occured before the run. The base pressure was in the 2.E-6 range with the cryo pump valved shut. Detailed Summary: ----------------- The day began with programming similar to shot 930618024. This shot was a lower null shot with ZCUR programming of -2cm and an FFIT elongation of 1.6. Changes made to this shot include decreasing the derivative gain on ZCUR and moving the turn-on time of the IC_EF1L and IC_EF1U proportional gains earlier to match the EF1 crowbar times. Shots 1-5 were attempts to move the inner and outer strike points, as determined by FFIT, by changing the EF1 current programming. The EF1 currents were made less negative in order to get the strike points to be below the inner and outer noses. All these shots were diverted (except the fizzle) with the outer strike point being below the nose. As the "scan" progressed the outer strike point moved down the outer divertor and on shot 5 the strike point was actually on the floor tiles. The inner strike point remained above the nose for all of these shots. For shots 6-10, the EF1's were removed from the ZCUR controller. The EF1's were being current controlled by IC_EF1x. These shots showed large excursions in the z position after the ramp down to -2 cm. Changes were made to the ZCUR and BR_0 controllers to stop the oscillation. It was difficult to determine the behavior of the strike points due to these large oscillations. The large number of tweaks to ZCUR and IC_EF1x led to the fizzles on shots 11-13. During this set of shots the argon puffing was enabled to allow HIREX to obtain ion temperature measurements. At this point a retreat was sounded and shot 003 was loaded into the model. Shots 14-16 were a "scan" of EF2L current to pull the x-point out. The x-point location as determined by FFIT R_XL showed .54m -> .55m -> .56m through this series of shots as the EF2L current went 700A -> 900A -> 1100A during the times of interest. The outer stike point location remained satisfactory during this scan. The inner strike point have moved slightly lower but never went below the nose tile. Shots 17-19 were attempts to move the plasma down with the EF2L current of shot 16. These shots were programmed with a ZCUR of -3 cm and had large oscillations in the z positions. The plasma moved down on shot 17 but the x-point didn't (determined by FFIT Z_XL) Changes in the EF1 currents on shots 18 and 19 were made and led to early disruptions so no analysis of strike point location could be done. Shot 20 was a reload of shot 15 with a change in the RCUR controller from 0.638m to 0.65m. The discharge did indeed move out as determined by FFIT_RCUR ( 0.64 -> 0.65m) and the x-point moved from R_XL = 0.55 -> 0.56m. This change moved the outer strike point location above the nose tile while the inner strike point remained above the nose as always. Score-card: ----------- 15 "good" shots 5 fizzles 0 no-breakdowns -- 20 total shots

Physics Operator Summaries

Session Leader Comments
Jun 23 1993 05:28:37:910PM		Steve Wolfe	Run 930623 Physics Op: Goetz Assist. Op: Wolfe Eng. Op: Silva/Bertolino Goal: Improve divertor strike point location. Background task: Try EFC with chopper hooked up, firing after the plasma pulse; this is being done by Horne.
Jun 23 1993 05:25:29:400PM	930623001	Steve Wolfe	Shot 930623001 Started with shot 930618024 Lower derivative gain from 4. to 2. on ZCUR IC_EF1U&L Proportional gain at 2. moved to 30msec from 60msec Copied S-waveform from IC_EF1L to IC_EF1U even though we aren't controlling on IC_EF1U now. Set up for EFC tests: EFC is disconnected for this shot because of worries about its strngth while warm -- it isn't cooling well. EFC control is on Hybrid on Wire 11. Fill pressure 4.0e-5 Diverted at 160msec, looks a lot like the original shot.
Jun 23 1993 11:41:50:700AM	930623002	Steve Wolfe	Ramp ef1 cuurent from 3000A @ 160msec to 2000 Amps at 200msec Looks good. Outer strike point is right on. Inner is still on upper side of baffle. Stops being diverted at 212. EF3 current trace shows some funny steps.
Jun 23 1993 12:04:33:680PM	930623003	Steve Wolfe	Shot 930623003 Change RCUR programming to 0.638 to get rid of out of range. No other changes. Should be almost a repeat. It looks ok. Still got the EF3 glitches. It seems to be coming from one of the two halves of the EF3 supply
Jun 23 1993 12:16:52:800PM	930623004	Steve Wolfe	Shot 930623004 Raise P gain on IC_EF1U&L from 2. to 3. from 30 msec on Try to get closer to programmed currents (we only were ramping to 2500 instead of 2000 on previous shots) Fizzle. EF3 shows an early blip of current and may come on early.
Jun 23 1993 12:30:30:690PM	930623005	Steve Wolfe	Shot 930623005 Raise hold-off voltage on EF3 to +150V Ok - EF3 gets to 300A around 4.5 msec as opposed to 3.3 last shot Shot went - hard xrays went up some. Lasted to 325. Not much different from 3.
Jun 23 1993 12:48:48:230PM	930623006	Steve Wolfe	Shot 930623006 Turn off Zcur controller on EF1's and turn on IC_EF1U control M=.111 and take off EF1L controller to V_EF1U. EFC is now connected. Supply on from .45 to .6 Programming from .47 on IC_EFCU on wire 11. Fizzle. EF3 reaches -300a at 2.9msec EFC shows up ok.
Jun 23 1993 01:14:43:280PM	930623007	Steve Wolfe	Shot 930623007 No change. Got it back EF3 sawteeth are back and it turns on later again. EF1's now are balanced again. Plasma lasts till 345msec Hard xrays are up. Still in a similar position on strike points but lose the divertor earlier.
Jun 23 1993 01:38:26:070PM	930623008	Steve Wolfe	Shot 930623008 Ramp on EF1 is now 300A at 160 to 1750 at 200msec (demand) EF3 looks clean, 300 amp at 4.9 msec. Disruption at 190. EF1 current traces look the same. Big vertical oscillation starts at 130 msec.
Jun 23 1993 02:04:17:690PM	930623009	Steve Wolfe	Shot 930623009 Raise Deriv gain on ZCUR from 2 to 4. Lots of oscillations on Z position small disruption at 270 and disrupts at 305.
Jun 23 1993 02:29:27:020PM	930623010	Steve Wolfe	Shot 930623010 Lowered the V_ef1u&l from 0 to -200V until 200msec to try to help the current feedback. Change ZCUR gains: P from 0.5 to 1.0,D from 4. to 3. EF1 currents peakat 2500 and drop to 1500 Mini disruption at 260-plasma moves in; then goes vertically unstable. Outer separatrix goes down the slot, but it doesn't stay diverted. Went too far down on the EF1s.
Jun 23 1993 02:50:39:000PM	930623011	Steve Wolfe	Shot 930623011 Raised V_ef1u&l back to -100V at 110msec Reduced BR_0 PID gain from .5 to 0.1 during 50:400msec Fizzle. EF3 timing looks ok this time:300A at 4.68msec Bz is too positive and Bz' is negative until 8msec.
Jun 23 1993 03:06:20:860PM	930623012	Steve Wolfe	Shot 930623012 Raised V_ef1u&l back to 0V at 110msec Change EF3 pre-pulse voltage back to +100 from +150. Another fizzle. This time it's earlier: 300A at 4.01 msec
Jun 23 1993 03:15:59:970PM	930623013	Steve Wolfe	Shot 930623013 Lower gas to 3.7e-5 (was 4.0) Three fizzles in a row. Bz' is negative and Bz positive relative to shot #3.
Jun 23 1993 03:29:24:390PM	930623014	Steve Wolfe	Shot 930623014 Reloaded Shot#3. Still at 3.7e-5 Got it back. More hard xrays. Strike points look good. EF3 junk is back.
Jun 23 1993 03:52:26:230PM	930623015	Steve Wolfe	Shot 930623015 Start a "scan" of EF2L current, trying to move the x-point out. Raised IC_EF2L to 900 A from 50msec to 400msec (used to have a dip and then 700A, then ramp down to 0.) Also gave them back the Argon pulse. X-point out about a cm (.54 to .55) and outer strike still ok.
Jun 23 1993 04:13:18:640PM	930623016	Steve Wolfe	Shot 930623016 Continue a "scan" of EF2L current, trying to move the x-point out. Raised IC_EF2L to 1100 A from 50msec to 250msec Also pulse gas increase 38 to 42V from 80msec to 180msec Raise fill pressure to 4e-5 Disrupts at about 250msec. Moved x-point out to .56 but then swings back Strike point now on the nose-piece.
Jun 23 1993 04:28:55:100PM	930623017	Steve Wolfe	Shot 930623017 Change ZCUR demand to -3cm and moved Ar puff 50msec earlier. Oscillations seem worse. Disrupt at 265ms, first mini at 250. 4cm p-p vertical oscillations, centered at -3cm. Z of x-point oscillates about -.35 (previous was steady at -.35) Outer strike was on nose piece.
Jun 23 1993 04:44:22:120PM	930623018	Steve Wolfe	Shot 930623018 Load IC_EF1 demands from shot #8 (lower EF1 currents should lower elongation and bring x-point down). Moved Ar puff 5msec earlier and 5msec wider. Disrupted around 170. Higher P_rad. Vertical instability right away on the step down.
Jun 23 1993 04:52:50:140PM	930623019	Steve Wolfe	Shot 930623019 Changed EF1 demand to 2000amps from 1750. Disruption at 175ms
Jun 23 1993 05:13:11:080PM	930623020	Steve Wolfe	Shot 930623020 Loaded shot 15 and moved RCUR from 0.638 to 0.65 Raise pressure to 4.4e-5 Disrupts at 230msec Hard xrays saturated. It did seem to move out by 1cm (based on FFIT) Also moves the x-point out by 1 cm.
Jun 24 1993 09:36:33:670AM	930623020	Gerry Tinios	Start with shot 930623017 from yesterday. EFC-rogowski AFOL transmitter was replaced, so the EFC current offset from yesterday shoud be fixed. Limits on EFC-chopper voltage trace set to [-1000.,1000.] Start with negative EFC-chopper demand voltage so as to smooth out the kicking in of the EFC without having to program the EFC-TMX. Log of partial pressure of mass-28: -8.58 (normal cool leak?) Fill pressure: 4.e-5 like yesterday. Dispupted at 184 msec. Not many hard X-rays. EFC-current offset is zero.

Physics Operator Comments

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	10:44:31:600AM	Plasma	Ok	at last
2	11:08:40:170AM	Plasma	Ok
3	11:44:14:680AM	Plasma	Ok	330ka plasma -- no faults
4	12:06:19:790PM	Plasma	Ok	fizzle
5	12:19:35:050PM	Plasma	Ok	330ka plasma -- efc+chopper will be connected for next shot
6	12:38:13:540PM	Plasma	Ok	fizzle
7	12:50:24:430PM	Plasma	Ok	330ka plasma -- no faults
8	01:22:04:500PM	Plasma	Ok	310ka plasma -- no faults
9	01:47:00:700PM	Plasma	Ok	330ka plasma
10	02:09:59:670PM	Plasma	Ok	320ka plasma -- no faults
11	02:33:11:270PM	Plasma	Ok	fizzle
12	02:55:26:960PM	Plasma	Ok	fizzle
13	03:07:26:070PM	Plasma	Ok	fizzle
14	03:18:28:830PM	Plasma	Ok	340ka plasma
15	03:38:45:180PM	Plasma	Ok	340ka plasma -- no faults
16	03:56:14:980PM	Plasma	Ok	320ka plasma
17	04:14:48:920PM	Plasma	Ok	320ka plasma -- no faults
18	04:33:11:620PM	Plasma	Ok	280ka plasma -- no faults
19	04:46:22:650PM	Plasma	Ok	300ka plasma
20	04:59:26:390PM	Plasma	Ok	300ka plasma