| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Steve Wolfe,Brock Bose |
| Physics operator(s): | Ron Parker |
| Engineering operator(s): | Gary Dekow |
| Engineering Operator Run Comment |
| Recovery Startup, MP481a Stereo imaging of Li Pellet Ablation Striations |
| Session Leader Plans |
| Entered: Jul 26 2007 05:33:24:850PM |
| Author: Jerry Hughes |
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****RUN CANCELLED**** Session leader run plan for 1070727 (AM) MP452: Reversed field pedestal studies SL: Hughes PO: Parker The goal for this experiment is to acquire and characterize H-modes and pedestals with the direction of field and current reversed, in order to make a comparison with similar discharges in the normal configuration. We will attempt to run a range of currents and densities in this configuration, tracking pedestal parameters (both dimensional and dimensionless), confinement and edge fluctuations. How these quantities differ between forward and reversed field will be studied and analyzed. Also of interest is comparing local L-H threshold conditions with those in the forward-field case. This experiment was attempted during the reversed field mini-campaign of 2006 (runs 1060524 and 1060602), but only a limited number of shots were obtained at 800kA. The main focus today will be to expand the range in current at which we have reversed field data. We will begin with a suitable 800kA target from 1070726 and repeat with density scan as necessary, then perform target density scans at 1.1MA and 0.5MA. SETUP: *NO overnight boronization *Required diagnostics: Edge and core Thomson, ECE diagnostics, CXRS, bolometer arrays, PCI, reflectometry, Hirex. *Gas: --NINJA plenum loaded with 10psi D2 --Argon puff: 50ms at 0.3s (Argon at 1psi) *RF power requested: 0.70--1.00s: 3.0MW flat 1.00--1.30s: max. available, flat Tentative shot sequence (subject to change, depending on how the run is going): 1. Load 1070726020 (LSN 5.4T, 0.8MA rev.; nl04~8e19m^-2). Obtain H-modes of duration greater than 150ms. 2. Attempt to change edge collisionality by scanning target nl04 shot to shot. Try targets of a. 1.2e20m^-2 b. 1.0e20m^-2 c. 0.6e20m^-2 d. either 0.4e20m^-2 or 1.4e20m^-2, depending on results of a--c. 3. Go to 1.1MA. Attempt to obtain H-modes at target nl04 of a. 1.0e20m^-2 b. 1.2e20m^-2 c. 0.8e20m^-2 d. 0.6e20m^-2 e. either 0.4e20m^-2 or 1.4e20m^-2, depending on results of a--d. 4. Go to 0.5MA. Attempt to obtain H-modes at target nl04 of a. 0.6e20m^-2 b. 0.8e20m^-2 c. 0.4e20m^-2 d. either 0.3e20m^-2 or 1.0e20m^-2, depending on results of a--c. |
| Entered: Jul 27 2007 01:08:52:893PM |
| Author: Brock Bose |
| SL-Plan
MP#: 481 "Stereo Imaging of Lithium Pellet Ablation Striations" SL: Brock Bose PURPOSE: To gather data on the statistics of the variation of the poloidal motion of striated ion structures that form during lithium pellet ablation using the pellet imaging diagnostic. GOAL: To perform radial scans of the pellet ablation during SNU H-mode (with 2.5 MW of rf) during reversed field operation. The radial scan will be accomplished by adjusting the time delay in data acquisition after the trigger on the PSI-4 camera. Run Plan: (1) 6 shots SNU with 2.5 MW of RF power from D&E antenas to perform radial scan of pellet ablation during L-mode plasmas For SNU: load 1070718014 programed for nl04 = 8e19 m^-2, Ip = 800 kA |
| Entered: Jul 27 2007 02:01:49:657PM |
| Author: Steve Wolfe |
Session Leader plan for first part of afternoon run on Friday, 27-Jul-2007 MP#298a SL: wolfe PO: Parker The goal is to recover startup with predictors that are not using the failed flux loop f19, and determine whether we can run plasmas. It is presently believed that the original problem leading to disruptions after shot 1070726022 was NOT related to the flux loop failure, which seems to have occurred at the disruption on shot 1070726027. We suspect there may be something sticking in from the inner wall which is heating up and causing fatal injections. We have been unable to see any such object from the available ports, but something was observed to be glowing brightly on shot 15 in the wide 1 view. If we continue to have problems, we may need to open up next week. I have prepared (and loaded) a PCS model that uses new predictors for fluxihh, vacuum, and filament algorithms. The shot is based on 1070726005, an early shot from yesterday. I've also updated the coefficients in ANALYSIS::TOP:FLUXIHH which are used for the zcur and rcur traces in the INIT scopes. MFLUX and VACBRBZ (which provides the Br0 and Bz0 traces) depend on the processed flux signals, and these have not been re-done because there doesn't seem to be a reasonable way of fixing the ones that depend on f19. Therefore, we are going to be flying blind on these, and the Br and Bz signals will probably be bouncing around shot-to-shot as the loop continues to misbehave. Plan: Try for startup using the pre-loaded PCS model. Tweak settings as well as we can, mostly trial and error until we get current rise. If the plasmas run through normally, then we conclude that whatever was responsible for the disruptions yesterday afternoon is gone, and turn over to Brock to get his lithium pellet shots. EFIT has been set to ignore the signals that depend on f19, and I'll monitor the results, and try to assemble a database that may indicate how compromised it is, and perhaps in what direction. Note that segment 3 of the PCS I've already loaded came from 1070718015, and the only difference between this and what Brock wants 1070718014 was a 2.5mm change in RCUR, which will be different at that level anyhow. Therefore, I think if we go to Brock's run we (Ron) can just change to segment 3 and go from there. If we can get startup but continue to have early disruptions that don't seem to be due to magnetics, we will try to determine where the problem is using whatever cameras are available. Based on results, we may need to decide whether to start warming up for a clean vent next week. |
| Physics Operators Plans |
| Entered: Jul 26 2007 04:26:02:847PM |
| Author: Ron Parker |
| Engineering setup for Friday July 27, 2007
MP452: Reversed field pedestal studies (AM) MP486: ICRF impurity generation and boron erosion (PM) SL: Hughes (AM), Wukitch (PM) PO: Parker Setup same as for 1070726020 Run begins at 9:00 and ends at 17:00. ECDC overnight in D2, pressure=2e-4 Torr. Rmin/Rdwell/Rmax = 44/45/103 cm. Bake at 60 C. A-coil configuration for reversed field: [Dtop +Dbot +Jtop -Jbot] and enabled. Gas Setup: fill B-Top with 6 psi D2 Hybrid enabled (PG4) fill B-side lower with 1 psi Ar Hybrid ENABLED (PG1) leave B-side upper as is Hybrid DISABLED (PG2) fill B-main (C-side) with 40 psi D2 Hybrid enabled (PG3) NINJA filled with 10 psi D2 ENABLED Enable the following gate valves and shutters: ECE, VUV, DNB, Z-bolo shutters Torvac setup: Gate valves open after the shot Required diagnostics: Edge and core Thomson, ECE diagnostics, CXRS, bolometer arrays, PCI, reflectometry, Hirex. ICRH Power (Requested to be available for first shot): 0.70--1.00s: 3.0MW flat 1.00--1.30s: max. available, flat LH Setup: No LH DNB: DNB requested if available Cryopump: Cryopump not available for this run |
| Session Leader Summaries |
| Entered: Jul 27 2007 04:25:53:197PM |
| Author: Brock Bose |
| For various reasons, the run was a no go. Maybe monday? |
| Entered: Jul 27 2007 04:44:25:530PM |
| Author: Steve Wolfe |
Run summary for Friday 27-Jul-2007 MP#298a SL:wolfe PO: Parker EO: Dekow The goal was to recover plasma after the flux loop f19 failed on Thursday, which followed a series of unexplained early disruptions. PCS was loaded based on 1070726005 with the predictors in all segments changed to eliminate f19. Details are in the MHD topic with username='wolfe' for runs 1070726 and 1070727. Segment 2 is the lower null target shot, and segment 3 was based on 1070718014, which was very similar to the upper null shot called for by Brock Bose for the MP#481a part of the run. The run started about 14:30. Shot#1 had a successful startup but disrupted for no obvious reason at .32sec. It looked like the bad shots from Thursday, with high radiation and injections. No source was obvious from the videos. For shot#2 we reduced rcur by 2mm to increase the outer gap, which EFIT claimed was big but I didn't trust. We also changed the first point in seg02 ZCUR from -.009 to 0. to reduce the jump in this quantity at segment switch. Amazingly, this was successful (or at least not harmful) and shot#2 ran full length with few injections and fairly normal radiation levels. The run was then turned over to Brock for MP#481a. Unfortunately, there was an inadvertant change made to segment 1 for shot#3 that resulted in the OH and EF1 power supplies being driven AC rail to rail during pre-charge, causing faults and breakers to pull. It turns out that this event also caused fuse and SCR loss in the Ef4 supply, which was not noticed until shot#4 when the PF breaker pulled out in CHECK. Replacing the fuses and SCR's took until after 17:00, so the rest of the run was cancelled, eliminating Brock's experiment for today. On the basis of the successful shot#2 we declared success on the MP298a plasma restart, although we still don't understand the disruptions. |
| Physics Operator Summaries |
| Entered: Jul 27 2007 04:39:47:667PM |
| Author: Ron Parker |
| The run was delayed until 2:30 while Steve implemented a workaround to the problem posed by a flux loop that had failed yesterday. The first shot started up, but disrupted at 0.325 s. Shot 2 went off, after causes of the disruption were investigated without conclusion, and it was a very good full length shot. Shot 3 did not go since the PF breaker pulled before the shot. Steve noticed that buttons 9-12 in Segment 1 on the PCS were referenced to Ip and not the 10 V supply as they should have been. Apparently this was an inadvertent operator error and it caused the PF supplies to go rail to rail, which in turn caused the PF breakers to pull. The latter action resulted in a loss of fuses and SCR's in EF4, which would have taken over an hour to repair. Since there was less than an hour left in the run, the run was terminated about 4:15. The good news is that a good full length discharge was run, showing that the PF flux loop workaround was successful and that the machine was in good shape. Unfortunately, only one shot was run so there were no meaningful physics data obtained. |
| Session Leader Comments | |||
| Jul 27 2007 03:11:03:220PM | 1070727001 | Steve Wolfe | Shot#1:Injections are starting at 0.06 seconds, and there is a big jump at .1sec. For next shot: in seg2 move rcur in by 2mm and change initial zcur point to 0 from -.009 to try to reduce thrash |
| Jul 27 2007 04:45:26:080PM | 1070727001 | Steve Wolfe | Shot#1: ready to try the new predictors which do not use f19 (or f20, except for filament ZCUR). I have changed the Br_0 offset to .003 and the RCUR offset to -900, based on testing against 1070726005 data, as described in notes under MHD topic. The PG4 puff is 20msec. IC_EF4U is set to 1310. The shot is from 1070726005 lower null 800kA. Parker is still in a meeting, so I'm going to push the button. Plasma started ok, disrupts at 0.32sec. |
| Jul 27 2007 03:20:04:623PM | 1070727002 | Steve Wolfe | Shot#2: in seg2 move rcur in by 2mm and change initial zcur point to 0 from -.009 to try to reduce thrash Plasma full length. Shall we declare it fixed? It claims to have 2cm outer gap now, and it doesn't have a lot of injections. I think we may as well run Brock's shots now. |
| Jul 27 2007 03:31:02:323PM | 1070727003 | Brock Bose | Not sure what happened on that one. We'll try again. |
| Jul 27 2007 03:48:47:903PM | 1070727003 | Brock Bose | No power shot. |
| Physics Operator Comments | |||
| Jul 27 2007 02:51:51:277PM | 1070727001 | Ron Parker | Good afternoon. After yesterday's flux loop failure, Steve did a workaround and today we have begun plasma operations at 2:30 PM.
The first shot started up well, however it disrupted at 0.325 s, similar to although later than the disruptions that occured at the end of yesterday's run. |
| Jul 27 2007 03:22:12:717PM | 1070727002 | Ron Parker | A full length shot! Nice startup, nice rampdown, good shot.
Next: Intentional disruption -- pellet injection |
| Jul 27 2007 03:39:30:097PM | 1070727003 | Ron Parker | Shot 3 was unsuccessful PF breaker pulled. No loop voltage.
Problem seems to have been buttons 9-12 set on Ip reference, not 10 V. |
| Jul 27 2007 03:48:53:750PM | 1070727004 | Ron Parker | Breaker pulled again, no power shot. |
| Jul 27 2007 04:19:46:643PM | 1070727004 | Ron Parker | That's it for today. Fuses and SCR's need to be replaced, which will take us past 5:00.
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| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 02:40:11:730PM | Plasma | Ok | |
| 2 | 03:12:36:020PM | Plasma | Ok | |
| 3 | 03:26:51:177PM | Plasma | Ok | |
| 4 | 03:45:44:650PM | Plasma | Bad | EF4 Supply Faults |
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