| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Brock Bose,Robert Granetz |
| Physics operator(s): | Joseph Snipes |
| Engineering operator(s): | Bill Cochran,Bill Byford,Bill Cochran |
| Engineering Operator Run Comment |
| MP #4?? -- Gas jet disruption mitigation of VDEs |
| Session Leader Plans |
| Entered: Apr 13 2006 05:16:11:860PM |
| Author: Joseph Snipes |
| Run Plan for MP#404a TAE Damping with ICRF Begin with 1060309020 inner wall limited moderate elongation plasmas with nl04 = 9 x 10^19 m^-2, Ip = 0.8 MA, and BT = 5.4 T. Reduce nl04 to 7 x 10^19 m^-2. Sweep the active MHD antennas through the calculated center of the gap TAE frequency multiple times throughout the discharge and look for resonances. From shot to shot slowly increase the ICRF power in steps of 0.25 MW from 0.5 to 1.5 s up to 2.5 MW or until unstable TAEs are observed. Measure the TAE damping rate for each ICRF power level. |
| Entered: Apr 13 2006 06:05:24:500PM |
| Author: Brock Bose |
| or mini-proposal 353 we would like 3 shots of standard SNL with Toroidal field: 5.4 T Plasma Current: 800 kA NL04=1*1020 Standard shape During these shots we be injecting lithium pellets and captuing images of the lithium ablation proces. We will be making a radial scan of the li ablation process using the psi4 camera with varing numbers of post trigger samples. Next we would like 5 shots same parameters with an additional 2.5 MW of RF from D and E antennas from .7s to 1.0s. Again we will inject li pellets and make a radial scan of the ablation process using varing numbers of post trigger samples on the psi4 |
| Entered: Apr 14 2006 05:42:05:397PM |
| Author: Robert Granetz |
| MP #449 -- Gas jet disruption mitigation of VDEs Session leaders: R. Granetz Physics operator: J. Snipes ECDC overnight and bake at 60 C. This miniproposal is only for a partial run day. It will follow MP 353 (Brock Bose, Li pellet injection). Power systems as on 1060308026 (1.0 MA, 5.4 T, LSN fiducial) A-coil configuration: normal [+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 + 2 psi Ne Hybrid DISABLED (PG1) leave B-side upper with whatever Hybrid disabled fill B-main (C-side) with 40 psi D2 Hybrid enabled (PG3) No NINJA for this run. Gas jet has been set up with argon at 70 bar. Torvac setup: unnecessary diagnostic gate valves (ECE) should be kept closed on all gas jet shots. Enable the following, assuming no vacuum problems: Z-bolo shutters only Necessary diagnostics: IR divertor camera Fast PSI camera on B-horizontal, if possible, starting at t=0.800 s, Ar+0 filter Thomson scattering, with timing set so that one profile is obtained at t=0.800 s and the other varies shot-to-shot from 0.804 to 0.810 s (subject to change) Bolometry AXUV array with reduced gain Halo current Rogowskis SX arrays with fast sampling window (t=0.795 to 0.820 s) Mirnov Bp fluctuations ------------------------------------------------------------------------------- ICRF Setup: We'll need 2-3 MW shortly after we begin this MP. ------------------------------------------------------------------------------- Run plan: Start with the specified shot and program ZCUR to turn off at a specified time (t=0.800 s is reasonable). Determine reproducibility of disruption timing and direction by firing 2-3 shots. If necessary, program in a ZCUR `kick' to ensure reproducibility (1-2 shots). These unmitigated VDEs will also provide baseline data for radiated power fractions, divertor heating, and halo currents. After a reliable VDE is set up, enable the argon gas jet to fire at an appropriate time (4-8 ms before the thermal quench), and measure the standard mitigation parameters. If there's enough time, try several gas jet trigger timings. If we end up getting most of the run day, and if the DPCS routine is installed and working, then for the second half of this MP, enable the DPCS trigger to the gas jet system (might require a quick access to interface room). Select a threshold for the ZCUR error based on results from the first half of this MP. (10 mm should be about right, based on previous analysis of a few `natural' VDEs.) Again, measure the standard mitigation parameters. If there's enough time, try several different threshold values of the ZCUR error. |
| Physics Operators Plans |
| Entered: Apr 13 2006 05:16:07:967PM |
| Author: Joseph Snipes |
| Physop Plan and engineering setup for Friday, April 14, 2006 MP#353 "Study of striations in Li Pellet ablation clouds" for first half day then MP#424 on VDE mitigation with the gas jet for the second half day. Note that MP#424 depends on work being done tonight and if that work is unsuccessful, we will switch to Plan B for the second half day: MP#404a Parametric Dependence of Moderate n Alfvén Eigenmode Damping Rates with ICRF Physics Operator: Joseph Snipes Session Leader(s): Brock Bose followed by either Robert Granetz or Jason Sears Overnight ECDC in deuterium prior to the run stopping by 7:30 am. Power systems as on 1060308026 (1.0 MA, 5.4 T, LSN fiducial but with Ip lowered to 0.8 MA) A-coil configuration: normal [+Dtop -Dbot -Jtop +Jbot] and enabled. C-coil Start=0.3sec, Invert=2.0sec D & E (1 & 2) ICRF systems in run-on by 8:30 am. Gas Setup: ---------- fill B-top 6psi D2 Hybrid enabled (PG4) fill B-side lower 1 psi Argon Hybrid Disabled (PG1) fill B-side Upper as is, Hybrid Disabled (PG2) fill B-main 40psi D2 Hybrid Enabled (PG3) No NINJA for this run. Gas jet has been set up with argon at 70 bar. Torvac setup: unnecessary diagnostic gate valves (ECE) should be kept closed on all gas jet shots. Enable the following, assuming no vacuum problems: ECE, Z-bolo shutters, VUV enabled for MP#353 and MP#404a but NOT for MP#424 Necessary diagnostics: IR divertor camera Fast PSI camera on B-horizontal, if possible, starting at t=0.800 s, Ar+0 filter Thomson scattering, with timing set so that one profile is obtained at t=0.800 s and the other varies shot-to-shot from 0.804 to 0.810 s (subject to change) Bolometry AXUV array with reduced gain Halo current Rogowskis SX arrays with fast sampling window (t=0.795 to 0.820 s) Mirnov Bp fluctuations ------------------------------------------------------------------------------- ICRF Setup: We'll need 2-3 MW shortly after we begin this MP. ------------------------------------------------------------------------------- Run plan for MP#353 Li Pellets: Three shots with Toroidal field: 5.4 T Plasma Current: 800 kA NL04=1*1020 Standard shape Next we would like 5 shots same parameters with an additional 2.5 MW of RF from D and E antennas from .7s to 1.0s. Li pellets will be injected into these plasmas. ------------------------------------------------------------------------------- Run plan for MP#424 Gas Jets: Start with the specified shot and program ZCUR to turn off at a specified time (t=0.800 s is reasonable). Determine reproducibility of disruption timing and direction by firing 2-3 shots. If necessary, program in a ZCUR `kick' to ensure reproducibility (1-2 shots). These unmitigated VDEs will also provide baseline data for radiated power fractions, divertor heating, and halo currents. After a reliable VDE is set up, enable the argon gas jet to fire at an appropriate time (4-8 ms before the thermal quench), and measure the standard mitigation parameters. If there's enough time, try several gas jet trigger timings. If we end up getting most of the run day, and if the DPCS routine is installed and working, then for the second half of this MP, enable the DPCS trigger to the gas jet system (might require a quick access to interface room). Select a threshold for the ZCUR error based on results from the first half of this MP. (10 mm should be about right, based on previous analysis of a few `natural' VDEs.) Again, measure the standard mitigation parameters. If there's enough time, try several different threshold values of the ZCUR error. _______________________________________________________________________________ Run Plan for MP#404a TAE Damping with ICRF Begin with 1060309020 inner wall limited moderate elongation plasmas with nl04 = 9 x 10^19 m^-2, Ip = 0.8 MA, and BT = 5.4 T. Reduce nl04 to 7 x 10^19 m^-2 Sweep the active MHD antennas through the calculated center of the gap TAE frequency multiple times throughout the discharge and look for resonances. From shot to shotslowly increase the ICRF power in steps of 0.25 MW from 0.5 to 1.5 s up to 2.5 MW or until unstable TAEs are observed. Measure the TAE damping rate for each ICRF power level. |
| Session Leader Summaries |
| Entered: Apr 14 2006 12:08:36:410PM |
| Author: Brock Bose |
| Mini proposal The objective of Mini Proposal #353 was to perform radial scan of the pellet ablation in a standard l-mode and h-mode plasma using the psi 4, high speed ccd camera. The timing for the exposures of the camera would be varied, to obtain the entire radial profile. Unfortunately, some problem has occured with the LPI and less than one pellet in nine attempted was actually injected into the plasma. In addition, the psi4 camera is either not triggering correctly so no images were taken of the few pellets that were injected. |
| Entered: Apr 14 2006 06:40:23:863PM |
| Author: Robert Granetz |
Run summary for Friday 14 Apr 2006: MP#449 Gas jet disruption mitigation of VDEs Session leader: R. Granetz Physics operator: J. Snipes This was a very successful day. We accomplished everything in the miniproposal and then some. We started with some baseline VDEs with no gas jet injection (shots 9,10,11,12). These were done by turning off the ZCUR feedback gains (P and D) in DPCS. The first two shots went upward, which was not desirable. So we gave a negative ZCUR 'kick' to all following shots (up through shot 19) before turning off the ZCUR feedback. This reliably produced downward-going VDEs. After getting good baseline shots (halo currents about 185-190 kA), we chose 11 mm as the threshold ZCUR error at which to fire the gas jet, and used the baseline shots to determine the timing for the pre-programmed (i.e. synchronous) gas jet trigger. This worked very well (shots 13,14,15,16,17), and clearly mitigated the halo current (110-140 kA) and the maximum vertical displacement (6-8 cm vs 20 cm). We have bolometry data and IR camera data which we need to analyze for Prad fraction and for divertor temperatures to see if these also showed mitigation. We then tried a pair of shots (18,19) with the gas jet timing delayed by 5 ms, corresponding to a ZCUR error of 20 mm (instead of 11 mm). Halo currents for these was intermediate between unmitigated and well-mitigated. This completed the first half of the MP. The second half of the miniproposal was devoted to having DPCS do real-time detection of the VDE, using a routine written and implemented by Steve Wolfe, and then firing the gas jet when the ZCUR error exceeded a given threshold value (i.e. asynchronous). This is the first time that this has ever been tried on C-Mod, and it was very successful (shots 20,21). (Steve and I had previously verified that all the hardware and software components were working properly, so maybe I shouldn't have been so elated.) We started with a threshold of 11000 A-m (corresponding to 11 mm for today's 1 MA plasmas), and got very similar mitigation results to the corresponding synchronous dataset. The latency time of the DPCS/gas jet system was found to be only 100 microseconds. We then finished up the MP by getting a couple more baseline (i.e. no gas injection) shots (22,23) for additional Thomson profiles. Since we still had another hour of run time remaining, we tried making VDEs by ramping up the elongation during the shot, while keeping the normal ZCUR feedback on, and again using DPCS to detect the VDE in real-time and fire the gas jet. This worked very well, although we found the these high elongation shots (kappa=1.8) moved faster, and therefore were more difficult to mitigate, at least in terms of their maximum displacement (shot 24). We tried decreasing the threshold to 8000 A-m or 8 mm (shot 25), and this fired the gas jet during the last oscillation before the position was lost, resulting in good mitigation (110 kA halo current, 7 cm max displacement). Shot 26 was a no-gas-jet baseline shot for comparison. For the final two shots of the day (27,28) we set the threshold at an intermediate value of 9500 A-m (9.5 mm). Both went upwards, so they weren't optimal. An attempt for one more shot to try for a downward VDE was scrubbed due to hardware problems with the Torvac PLC. There were no 'false positives' from the DPCS with the threshold settings we used today. Based on these results, it is conceivable that the DPCS/gas jet system could be used in normal C-Mod operation, particularly when there is an enhanced risk of VDEs. |
| Physics Operator Summaries |
| Entered: Apr 14 2006 05:11:03:753PM |
| Author: Joseph Snipes |
| The run began attemping lithium pellet injections with limited success. Shot 6 was the only no plasma shot due to a computer problem in INIT. Shots 2 and 8 had Li pellets just after 0.8 s. However, there were problems with the pellet viewing camera. So, the run was then turned over to gas jet mitigation of disruptions. That part of the run went very well. Every shot for this part of the run had plasma and disrupted between 0.8 and 1 s depending on the gas jet control scheme. The gas jet disruption mitigation system worked well as well as the DPCS control of the gas puff depending on the plasma vertical position. There were three delays during the day that slowed down the run and reduced the overall number of pulses for ICRF, the TF scanner, and TORVAC. Despite these delays, the gas jet disruption mitigation run went quite well and produced very good results. Shot,Duration(s),Ipmax(MA),Result Shot,Duration(s),Ipmax,Result | 01 1.950 0.806 Plasma | 02 1.929 0.811 Plasma | | 03 1.738 0.805 Plasma | 04 1.784 0.811 Plasma | | 05 1.845 0.814 Plasma | 06 0.000 0.002 System Error | | 07 1.717 0.821 Plasma | 08 1.756 0.820 Plasma | | 09 0.845 1.036 Plasma | 10 0.847 1.031 Plasma | | 11 0.811 1.016 Plasma | 12 0.811 1.016 Plasma | | 13 0.804 1.081 Plasma | 14 0.804 1.051 Plasma | | 15 0.805 1.062 Plasma | 16 0.804 1.058 Plasma | | 17 0.804 1.067 Plasma | 18 0.810 1.040 Plasma | | 19 0.810 1.052 Plasma | 20 0.805 1.066 Plasma | | 21 0.808 1.047 Plasma | 22 0.809 1.016 Plasma | | 23 0.812 1.017 Plasma | 24 1.002 1.096 Plasma | | 25 0.945 1.088 Plasma | 26 0.978 1.018 Plasma | | 27 1.001 1.075 Plasma | 28 1.008 1.073 Plasma | Date 1060414: 28 shots. 27 plasmas. 0 fizzles. 0 duds. 1 System Error. (Plasma = Ip gt 50.0 kA Dud = H_alpha lt 0.40 V) Total plasma duration: 29.85 s (exceeding -80 kA) |
| Session Leader Comments | |||
| Apr 14 2006 11:27:41:583AM | 1060414009 | Robert Granetz | Gas jet VDE mitigation run will begin on shot 9. Argon gas jet. Standard 1 MA, 5.4 T, 1.0e20 m-2, SNL. RF will turn on at t=0.6 s. Gas jet will fire at t=0.800 s, although we will take a few shots first with no gas jet in order to determine timing and reproducibility of the VDE. ZCUR feedback will turn off at t=0.800 s. |
| Apr 14 2006 11:47:18:863AM | 1060414009 | Robert Granetz | Shot 9 -- Baseline VDE. Fast ZCUR feedback (P,D) turned off at t=0.800 s. Plasma moved downwards, reaching -30 mm after 20 ms, but then turned around and became an upward VDE. Unfortunately the upper halo Rogowski is not working, so I really want these VDEs to go downward so that I can get a good baseline. Next shot: try turning off the slow ZCUR gain also. (Maybe it was the slow ZCUR that caused the plasma to turn around.) |
| Apr 14 2006 12:04:45:647PM | 1060414010 | Robert Granetz | Shot 10 -- Went up again, this time with no oscillitory behavior. Next shot: give the plasma a downwards kick before letting it go. Program a -5 cm excursion in ZCUR from t=0.78 to 0.80 s, and then turn off the feedback at t=0.80 s. |
| Apr 14 2006 12:57:08:193PM | 1060414010 | Robert Granetz | Shot 10 -- The IR camera was not going for this shot or the previous shot. Glen Wurden restarted the camera after this shot, so it should be there for the next one. |
| Apr 14 2006 01:09:04:100PM | 1060414011 | Robert Granetz | Shot 11 -- Plasma. Good downward VDE...much faster than the previous two upward VDEs. Got good IR camera data, good 2pi diode data, good halo current (186 kA). At 0.800 s the ZCUR error is -16 mm, and at 0.804 s it is 50 mm. It's 10 mm at t=0.7976 s. Next shot: one repeat, just to check reproducibility. |
| Apr 14 2006 01:20:26:427PM | 1060414012 | Robert Granetz | Shot 12 -- Plasma. Good downward VDE. Position vs time is shifted about 3.5 ms earlier than the previous shot. So that tells us something about the reproducibility. I_halo=188 kA. Note: these are in H-mode because the RF is giving 2 MW. IR camera didn't work this shot. Glen will monitor it for the next few shots. Also, the IR camera gain is reduced by ~2 today compared to previous days. Next shot: turn on gas jet at t=0.795 s (at about ZCUR error = 10 mm). |
| Apr 14 2006 01:34:12:740PM | 1060414013 | Robert Granetz | Shot 13 -- Good shot. Argon gas jet fired at t=0.795 s, when the ZCUR error was 11 mm. Maximum plasma excursion is about 6 cm. Very clear mitigation. IR camera worked. Btor = 5.4 T. Current quench starts at t=0.801 s. Current quench duration is about 1 ms. I_halo=110 kA. Prf=2.0 MW (ohmic) Wth=105 kJ. Plenum gas: argon Pulse length (ms): 2.0 Plenum pre -pulse pressure (bar): 71 Plenum post-pulse pressure (bar): 66 Plenum change in pressure (bar): 5 |
| Apr 14 2006 01:47:52:520PM | 1060414014 | Robert Granetz | Shot 14 -- Good shot. Argon gas jet fired at t=0.795 s, when the ZCUR error was 11 mm. Maximum plasma excursion is about 7 cm. Very obvious mitigation. Got IR camera data. Thomson time is being changed from shot-to-shot. Btor = 5.4 T. Current quench starts at t=0.801 s. Current quench duration is about 1 ms. I_halo=110 kA Prf=2.0 MW (ohmic) Wth=101 kJ. Plenum gas: argon Pulse length (ms): 2.0 Plenum pre -pulse pressure (bar): 71 Plenum post-pulse pressure (bar): 66 Plenum change in pressure (bar): 6 |
| Apr 14 2006 01:59:36:113PM | 1060414015 | Robert Granetz | Shot 15 -- Good shot. Argon gas jet fired at t=0.795 s, when the ZCUR error was 11 mm. Maximum plasma excursion is about 8.5 cm. Very obvious mitigation. Got IR camera data. Btor = 5.4 T. Current quench starts at t=0.8015 s. Current quench duration is about 1 ms. I_halo=141 kA Prf=2.0 MW (ohmic) Wth=99 kJ. Plenum gas: argon Pulse length (ms): 2.0 Plenum pre -pulse pressure (bar): 71 Plenum post-pulse pressure (bar): 66 Plenum change in pressure (bar): 5 |
| Apr 14 2006 05:56:52:647PM | 1060414015 | Robert Granetz | Next shot: fire gas jet pulse at t=0.800 s (instead of 0.795). Note: It turns out that I didn't properly APPLY the change to the trigger timing, so shots 16 and 17 were still at 0.795 s. |
| Apr 14 2006 02:41:14:177PM | 1060414016 | Robert Granetz | Shot 16 -- Good shot. Argon gas jet fired at t=0.795 s (although I wanted it to go at 0.800, but I didn't load it properly), when the ZCUR error was 33 mm. Maximum plasma excursion is about 8 cm. Got IR camera data. Btor = 5.4 T. Current quench starts at t=0.801 s. Current quench duration is about 1 ms. I_halo=130 kA Prf=2.0 MW (ohmic) Wth=104 kJ. Plenum gas: argon Pulse length (ms): 2.0 Plenum pre -pulse pressure (bar): 71 Plenum post-pulse pressure (bar): 66 Plenum change in pressure (bar): 5 |
| Apr 14 2006 02:40:16:630PM | 1060414018 | Robert Granetz | Shot 18 -- Good shot. Argon gas jet fired at t=0.800 s (really), when the ZCUR error was 20 mm. Maximum plasma excursion is about 8 cm. Got IR camera data. Btor = 5.4 T. Current quench starts at t=0.806 s, which is 5 ms later than the previous shots, as expected. Current quench duration is about 1 ms. I_halo=152 kA Prf=2.0 MW (ohmic) Wth=100 kJ. Plenum gas: argon Pulse length (ms): 2.0 Plenum pre -pulse pressure (bar): 66 Plenum post-pulse pressure (bar): 61 Plenum change in pressure (bar): 5 |
| Apr 14 2006 02:52:50:503PM | 1060414019 | Robert Granetz | Shot 19 -- similar to 18 (it's supposed to be, anyway) |
| Apr 14 2006 02:54:10:753PM | 1060414020 | Robert Granetz | This shot will be the first one on which we will try letting DPCS fire the gas jet, based on a threshold value of 11000 A-m for the ZCUR error (corresponding to 11 mm for these 1 MA plasmas. Note: I have turned off the gas jet node in the xtomo tree, so only the DPCS trigger can fire the gas jet. |
| Apr 14 2006 03:03:34:177PM | 1060414020 | Robert Granetz | First attempt at real-time DPCS triggering of the gas jet. Threshold is set 11000 A-m (11 mm). It worked!! Shot 20 -- Good shot. Argon gas jet fired at t=0.795 s, when the ZCUR error was 11 mm. Maximum plasma excursion is about 6 cm. Got IR camera data. Btor = 5.4 T. Current quench starts at t=0.802 s. Current quench duration is about 1 ms. I_halo=124 kA Prf=2.0 MW (ohmic) Wth=105 kJ. Plenum gas: argon Pulse length (ms): 2.0 Plenum pre -pulse pressure (bar): 66 Plenum post-pulse pressure (bar): 60 Plenum change in pressure (bar): 6 |
| Apr 14 2006 03:47:20:147PM | 1060414021 | Robert Granetz | This shot and the next one will not have any gas jet injection, in order to get some more background Thomson profiles on these VDEs. |
| Apr 14 2006 03:47:31:350PM | 1060414021 | Robert Granetz | Shot 21 -- Good shot. Argon gas jet fired at t=0.798 s, when the ZCUR error was 11 mm. Maximum plasma excursion is about 6 cm. Very obvious mitigation. Got IR camera data. Btor = 5.4 T. Current quench starts at t=0.805 s. Current quench duration is about 1.5 ms. I_halo=143 kA Prf=2.0 MW (ohmic) Wth=87 kJ (dropped out of H-mode just before VDE) Plenum gas: argon Pulse length (ms): 2.0 Plenum pre -pulse pressure (bar): 71 Plenum post-pulse pressure (bar): 65 Plenum change in pressure (bar): 6 |
| Apr 14 2006 03:46:03:147PM | 1060414022 | Robert Granetz | Shot 22 -- VDE, but gas jet is turned off. Current quench was at t=0.806 s. Ihalo=180 kA. Got the IR camera data. Maximum ZCUR error is 150 mm (much higher than the mitigated cases). Next shot: same thing...VDE, but no gas jet. The Thomson laser time will be moved again. |
| Apr 14 2006 03:46:32:973PM | 1060414023 | Robert Granetz | Shot 23 -- Good shot. VDE, but no gas jet injection. Ihalo=190 kA. Current quench started at t=0.808 s. Got the IR data. |
| Apr 14 2006 03:50:37:973PM | 1060414024 | Robert Granetz | For this shot, we will try to make the plasma vertically unstable by programming a kappa ramp (using CLEARIN). Steve has turned on the DPCS node to run the ZCUR gas jet program. Threshold is still at 11000 A-m, with the gate from 0.5 to 1.5 s. (The J221 trigger node is still off also.) |
| Apr 14 2006 06:23:40:333PM | 1060414024 | Robert Granetz | Shot 24 -- Good shot. Plasma went upwards after a few oscillations. Argon gas jet fired at t=0.992 s, when the ZCUR error was 11 mm. Maximum ZCUR error is about 20 cm. Got IR camera data. Btor = 5.4 T. Current quench starts at t=0.9987 s. Current quench duration is about 2 ms. I_halo is unknown because the upper halo Rogowski is not working. Prf=0 MW (ohmic) Wth=47 kJ (RF had turned off). Plenum gas: argon Pulse length (ms): 2.0 Plenum pre -pulse pressure (bar): 71 Plenum post-pulse pressure (bar): 66 Plenum change in pressure (bar): 5 |
| Apr 14 2006 04:05:46:503PM | 1060414025 | Robert Granetz | For this shot, decrease the ZCUR error threshold to 8000 A-m (instead of 11000) to try and fire the gas jet about 3.5 ms earlier. |
| Apr 14 2006 04:18:29:677PM | 1060414025 | Robert Granetz | Shot 25 -- Good shot. Argon gas jet fired at t=0.9355 s, when the ZCUR error was 11 mm. Maximum plasma excursion is about 7 cm. Very obvious mitigation. Got IR camera data. Btor = 5.4 T. Current quench starts at t=0.801 s. Current quench duration is about 1 ms. I_halo=110 kA Prf=2.0 MW (ohmic) Wth=80-90 kJ. Plenum gas: argon Pulse length (ms): 2.0 Plenum pre -pulse pressure (bar): 71 Plenum post-pulse pressure (bar): 66 Plenum change in pressure (bar): 5 |
| Apr 14 2006 04:32:11:287PM | 1060414026 | Robert Granetz | Shot 26 -- Good shot. No gas jet injection, for baseline comparison. Went downwards. Ihalo=145 kA. Got the IR camera data. |
| Apr 14 2006 06:27:24:740PM | 1060414027 | Robert Granetz | For this shot, continue doing the elongation ramp, and enable the DPCS gas jet trigger, but set the threshold at 9500 A-m (midway between 8000 and 11000). Shot -- Good shot, but it went up. Argon gas jet fired at t=0.991 s. Maximum plasma excursion is about 10 cm. Got IR camera data. Btor = 5.4 T. Current quench starts at t=0.998 s. Current quench duration is about 1 ms. I_halo=unknown, since the VDE went upwards Prf=1.0 MW Wth=69 kJ or less. Plenum gas: argon Pulse length (ms): 2.0 Plenum pre -pulse pressure (bar): 71 Plenum post-pulse pressure (bar): 66 Plenum change in pressure (bar): 5 |
| Apr 14 2006 04:39:58:003PM | 1060414028 | Robert Granetz | For this shot. repeat shot 27 in hopes of getting a downward-going VDE. |
| Apr 14 2006 04:50:58:350PM | 1060414028 | Robert Granetz | Shot 28 -- VDE went upwards again. DPCS gas jet threshold was 9500 A-m again. Maximum excursion was 20 cm, so we didn't seem to mitigate this one. Next shot: Drop equilibrium ZCUR position by 1 cm, in hopes of getting a downward VDE. This will be the last shot today. |
| Apr 14 2006 05:16:47:253PM | 1060414028 | Robert Granetz | Couldn't get shot 29 because of a hardware problem with the TORVAC plc or workstation. |
| Physics Operator Comments | |||
| Apr 14 2006 09:00:08:267AM | 1060414001 | Joseph Snipes | Shot 1: Reloaded shot 1060413031 for the startup and then loaded segment 2 from shot 1060405001 as a 1 MA fiducial. Reduced Ip to 0.8 MA. nl04 set to 1 x 10^20 m^-2. |
| Apr 14 2006 09:03:03:563AM | 1060414001 | Joseph Snipes | Short delay for power room access for the ICRF. |
| Apr 14 2006 09:39:40:063AM | 1060414001 | Joseph Snipes | Shot 1: Good shot. No pellet. There should also have been a NINJA deuterium puff just after the pellet, but if so, it also was not visible on the density, 2PI bolometer, or Z-meter. |
| Apr 14 2006 09:56:33:033AM | 1060414002 | Joseph Snipes | Shot 2: Good shot. Got a pellet at 0.8 s as expected. There is also an event at 1 s that quickly pumps out the increased density from the pellet. There is a very brief very low frequency oscillation on the magnetic pick-up coils at that time. NINJA should be puffing at 1.15 s, but it is not visible on the density. |
| Apr 14 2006 10:04:50:397AM | 1060414003 | Joseph Snipes | Shot 3: Good shot. No pellet. |
| Apr 14 2006 10:18:27:660AM | 1060414004 | Joseph Snipes | Shot 4: Reduced CLEARIN after 1.5 s to -0.01 m by 1.87 s to attempt to improve the rampdown. Good shot. No pellet. Ramp down is about the same. |
| Apr 14 2006 10:32:19:943AM | 1060414005 | Joseph Snipes | Shot 5: Reduced CLEARIN a bit more after 1.5 s to see if it will improve the rampdown. Good shot. NO pellet. Rampdown has improved. |
| Apr 14 2006 10:43:14:443AM | 1060414006 | Joseph Snipes | Shot 6: Reduced CLEARIN a bit more after 1.5 s to see if the plasma can ramp all the way down. No power shot due to a computer problem in INIT. |
| Apr 14 2006 11:01:31:973AM | 1060414007 | Joseph Snipes | Shot 7: Try again. Good shot. Now with 2 MW of ICRF from 0.7 to 1.0 s. No pellet. Good test for active MHD TAE resonances with ICRF. Rampdown is no better. |
| Apr 14 2006 11:13:17:363AM | 1060414008 | Joseph Snipes | Shot 8: Try again with a pellet. Good shot. There appears to be a pellet at 0.874 s rather than 0.8 as I expected. |
| Apr 14 2006 11:38:06:800AM | 1060414008 | Joseph Snipes | Shot 9: Changing to Granetz' MP424 gas jet disruption mitigation. Loaded segment 2 from shot 1060308026. Changed Ip to 1.0 MA. Derivative and proportional gain on wire 3 ZCUR set to 0 at 0.8 s. Changed nl04 to 1 x 10^20 m^-2. |
| Apr 14 2006 11:41:37:287AM | 1060414009 | Joseph Snipes | Shot 9: Changing to Granetz' MP424 gas jet disruption mitigation. Loaded segment 2 from shot 1060308026. Changed Ip to 1.0 MA. Derivative and proportional gain on wire 3 ZCUR set to 0 at 0.8 s. Changed nl04 to 1 x 10^20 m^-2. Gas jet disabled for the first shot. Disrupted at 0.84 s due to the loss of vertical control. |
| Apr 14 2006 11:58:38:457AM | 1060414010 | Joseph Snipes | Shot 10: Set wire 2 ZCUR gains to zero at 0.8 s as well as the integrator gain. Granetz wants to ensure a downward going disruption as a baseline before he attempts gas jet mitigation. Try again with no gas jet. Again, the plasma disrupted upward. |
| Apr 14 2006 12:03:35:753PM | 1060414010 | Joseph Snipes | Delay for cell access to fix the TF scanner temperature measurements. |
| Apr 14 2006 12:57:25:943PM | 1060414011 | Joseph Snipes | Shot 11: Programmed ZCUR to drop from -0.009 m to -0.045 m between 0.78 and 0.8 s to ensure a downward disruption. Good shot. Disrupted at 0.8 s. |
| Apr 14 2006 01:10:18:333PM | 1060414012 | Joseph Snipes | Shot 12: Repeat to check reproducibility of the downward going disruption. Disrupted at 0.8 s as in shot 11. |
| Apr 14 2006 01:23:51:397PM | 1060414013 | Joseph Snipes | Shot 13: Begin mitigation with the gas jet. Disrupted at 0.8 s. |
| Apr 14 2006 01:37:04:317PM | 1060414014 | Joseph Snipes | Shot 14: Repeat for reproducibility. Disrupted again at 0.8 s as expected. |
| Apr 14 2006 01:51:35:473PM | 1060414015 | Joseph Snipes | Shot 15: Repeat for reproducibility. Disrupted again at 0.8 s as expected. |
| Apr 14 2006 02:02:36:740PM | 1060414015 | Joseph Snipes | Shot 15: Repeat for reproducibility. Disrupted again at 0.8 s as expected. |
| Apr 14 2006 02:09:26:083PM | 1060414016 | Joseph Snipes | Shot 16: Repeat. Disrupted again at 0.8 s as expected. |
| Apr 14 2006 02:19:22:800PM | 1060414017 | Joseph Snipes | Shot 17: Repeat. Disrupted again at 0.8 s as expected. |
| Apr 14 2006 02:36:29:973PM | 1060414018 | Joseph Snipes | Shot 18: Repeat. Disrupted again at 0.8 s as expected. This time in L-mode. |
| Apr 14 2006 02:45:40:300PM | 1060414019 | Joseph Snipes | Shot 19: Repeat. Disrupted again at 0.8 s. This time in H-mode again. |
| Apr 14 2006 02:59:05:817PM | 1060414020 | Joseph Snipes | Shot 20: Repeat with DPCS control of the gas jet trigger. Disrupted again at 0.8 s. |
| Apr 14 2006 03:15:01:943PM | 1060414021 | Joseph Snipes | Shot 21: Repeat. Disrupted again at 0.8 s in L-mode. |
| Apr 14 2006 03:28:13:850PM | 1060414022 | Joseph Snipes | Shot 22: Repeat. Disrupted again at 0.8 s in H-mode. |
| Apr 14 2006 03:45:03:957PM | 1060414023 | Joseph Snipes | Shot 23: Repeat. Disrupted again at 0.8 s in H-mode. |
| Apr 14 2006 03:53:56:300PM | 1060414024 | Joseph Snipes | Shot 24: Put ZCUR back to its usual programming and returned the gains and integrator to 2.0 s. Instead, CLEARIN is ramped from 0.001 m at 0.7 s to 0.05 m at 1.5 s to increase the elongation until the plasma becomes vertically unstable. Disrupted at 1.0 s. |
| Apr 14 2006 04:07:46:677PM | 1060414025 | Joseph Snipes | Shot 25: Repeat with lower threshold for the DPCS gas puff trigger. Disrupted at 0.939 s. |
| Apr 14 2006 04:20:40:600PM | 1060414026 | Joseph Snipes | Shot 26: Repeat with DPCS gas puff trigger turned off as a control. No gas jet. Disrupted at 0.974 s because it was vertically unstable. |
| Apr 14 2006 04:33:56:147PM | 1060414027 | Joseph Snipes | Shot 27: Repeat with DPCS gas puff trigger turned on with an intermediate trigger threshold. Disrupted at 0.995 s. |
| Apr 14 2006 04:47:10:300PM | 1060414028 | Joseph Snipes | Shot 28: Repeat to get a downward going disruption. Disrupted at 1 s but still went up. |
| Apr 14 2006 05:08:18:253PM | 1060414028 | Joseph Snipes | We did not manage to get shot 29 because of a TORVAC failure apparently due to the gas jet from shot 28. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 09:35:17:983AM | Plasma | Ok | |
| 2 | 09:48:20:983AM | Plasma | Ok | |
| 3 | 10:01:23:943AM | Plasma | Ok | |
| 4 | 10:15:04:537AM | Plasma | Ok | |
| 5 | 10:27:59:240AM | Plasma | Ok | |
| 6 | 10:40:59:380AM | Plasma | Bad | Igor Failure in Init |
| 7 | 10:54:24:083AM | Plasma | Ok | |
| 8 | 11:07:05:503AM | Plasma | Ok | |
| 9 | 11:38:43:863AM | Plasma | Ok | |
| 10 | 11:51:16:457AM | Plasma | Ok | |
| 11 | 12:55:09:397PM | Plasma | Ok | |
| 12 | 01:08:07:817PM | Plasma | Ok | |
| 13 | 01:21:54:333PM | Plasma | Ok | |
| 14 | 01:34:58:240PM | Plasma | Ok | |
| 15 | 01:49:05:550PM | Plasma | Ok | |
| 16 | 02:04:21:473PM | Plasma | Ok | |
| 17 | 02:17:50:193PM | Plasma | Ok | |
| 18 | 02:30:34:740PM | Plasma | Ok | |
| 19 | 02:43:01:503PM | Plasma | Ok | |
| 20 | 02:55:46:753PM | Plasma | Ok | |
| 21 | 03:09:42:647PM | Plasma | Ok | |
| 22 | 03:25:07:113PM | Plasma | Ok | |
| 23 | 03:37:42:973PM | Plasma | Ok | |
| 24 | 03:50:33:207PM | Plasma | Ok | |
| 25 | 04:05:18:443PM | Plasma | Ok | |
| 26 | 04:17:45:630PM | Plasma | Ok | |
| 27 | 04:30:16:503PM | Plasma | Ok | |
| 28 | 04:42:41:443PM | Plasma | Ok | |