| Miniproposals | ||||||||||||
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| Operators | |
| Session leader(s): | Jerry Hughes,Phil Snyder |
| Physics operator(s): | David Pace |
| Engineering operator(s): | Andy Pfeiffer,Bill Parkin,Gary Dekow |
| Engineering Operator Run Comment |
| MP578 EPED pedestal prediction in ELMy H-Mode SL: Snyder, Hughes PO: Pac |
| Session Leader Plans |
| Entered: Nov 16 2010 04:39:00:057PM |
| Author: Jerry Hughes |
| SL Plan for 1101117.
MP578: "Experimental tests of EPED pedestal prediction in ELMy H-Mode" SL: Snyder, Hughes PO: Pace Overnight boronization, followed by ECDC in He, as specified in PO plan. Need ICRF, DNB Diagnostics requested: TS, ECE's, CXRS, H-alpha, Ly-alpha, bolos, TCI, PCI, core and SOL reflectometers Goal: Make some progress on the shaping portion of MP578, and if time allows, get more data in the extended Ip-scan which was started on 1101026. Shot plan::: A. Boronization recovery and shape development. (5--8 shots) -Load from 1101026015. (5.4T, 900kA, nl04~5e19, JFT2M shape, kappa=1.45) -Extend Ip flattop out to 1.5s. -Request flat 2MW ICRF from 0.8 to 1.1s, 3MW from 1.1 to 1.5s. Begin boronization recovery. While recovering, make changes to equilibrium shot-by-shot as follows: (1) Run equilibrium as described above. (2) Try to move RXL to 51.6cm earlier than 0.8s. Getting it to its target position by 0.6s or earlier is desired for increasing the useful flattop time. (3) Change elongation, while keeping RXL, ZXL, right and left gaps all fixed. This will best be done by increasing (decreasing) the ZCUR demand to increase (decrease) kappa. Attempt kappa values of 1.3, 1.5, 1.6 and 1.7. Try to implement these changes to elongation dynamically, with ramps from 1.0 to 1.2s. B. Ip=1MA. (2--3shots) Using the baseline equilibrium with kappa=1.45 developed in A(2) above, raise Ip to 1MA and run with same power steps as in part A. Vary target nl04 as needed to get a range in pedestal and ELM behavior. C. ELMs with Elongation scan. (6--8 shots) Return to the baseline 900kA case. Assess pedestal, confinement, and ELM behavior at fixed input power (choose something between 2 and 3MW), and varied elongation, with the kappa scan determined by the results in step A. If ELMs cannot be immediately accessed at kappa>1.5, then load a good ELMing shot at kappa=1.5 and raise kappa during the H-mode phase at ~1.1s. C(2). Ip scan at higher elongation (? shots) If an interesting operating point with ELMs has been obtained at higher elongation, then perform a current scan. Try Ip=1MA, 0.8MA and 0.6MA. D. Triangularity scan. (6--8 shots) Identify a base case from the exercise above, with good ELMy H-mode. Repeat, with RXL increasing shot-by-shot to give a delta_L scan of 0.7, 0.6, 0.5. In so doing, keep the shape of the plasma crown as fixed as possible. If ELMs cannot be immediately accessed at delta_L<0.75, then load a good ELMing shot at delta_L=0.75 and increase RXL during the H-mode phase at ~1.1s. E. Supplemental (? shots) With any remaining time, get more data for the original current scan. This may include 1MA points or possibly 0.5MA points to fill in the beta_pol scan. Hold shape fixed in the original elongation, X-point position. At Prf=2MW, scan nl04 from 4e19 to 8e19 in steps of 2e19. Increase Prf to 3MW and repeat density scan. |
| Physics Operators Plans |
| Entered: Nov 17 2010 08:27:16:790AM |
| Author: David Pace |
| ---------------------------------------------------
Engineering Setup for Wednesday, November 17, 2010 --------------------------------------------------- MP578: Experimental Tests of EPED1 Pedestal Prediction in ELMy H-mode Run begins at 09:00 and ends at 17:00 Power systems as on: 1101026 (LSN) * Please ensure that the fizzle detector OFF time is 2.1 s * Acoil: +Dtop -Dbot -Jtop +Jbot (standard) Hybrid Enabled Gas setup: Fill B-Top with 6 psi D2 Hybrid enabled (PG4) fill B-side lower with 1 psi Ar Hybrid DISABLED (PG1) leave B-side upper as is Hybrid DISABLED (PG2) fill B-main (C-side) with 40 psi D2 Hybrid enabled (PG3) fill NINJA with 10 psi D2 DISABLED Enable gate-valves and shutters: ECE, VUV, HiREX Sr, Xeus Leave z-bolo shutter as is (should be open) Torvac gatevalve toggle (yes/no): no Boronization(yes/no): yes Overnight ECDC (yes/no): yes ICRF(yes/no): yes LH(yes/no): no Cryopump (yes/no): NO DNB (yes/no): yes Vessel temperature: 35/35/35 ----------------------------- Boronization and ECDC Details ----------------------------- Overnight boronization (NOTE optimized sweep parameters): dP=120 psi ** optimized sweep parameters ** rmin/rdwell/rmax: 44/75/80 cm tdwell/tsweep: 60/120 s Zero EF4 current Pulser 0.7 on 0.3 off Post boronization ECDC * Note: using He only * ---------------------- 1st Gas Setup Gas: He sweep: 44/45/103 cm scan: 20/120 s Pressure: 5e-5 Torr Duration: 3 hrs ------- PO Plan ------- PO Scratch Directory = /home/pace/pcs_scratch/ First Shot -- As directed by SL, shot 1101026015 has been edited to extend the current flattop to 1.5 s. The nl04 of that shot is 4e19, which is close enough to the SL request of 5e19, and we know from the previous post-boronization run of this MP that lower nl04 requests are better. The first section of the SL Plan is implemented as: A1) program described above is saved in scratch as shot 1101117399 A2) the actual requested value of RXL in the program was -0.049, so I created two possible shots. One keeps RXL = -0.049 and sets it by 0.6 s and is saved in scratch as shot 1101117400. The other uses RXL = -0.0516 as stated in the SL Plan and also tries to reach that value by t = 0.6 s. This is saved in scratch as shot 1101117401. A3) it remains to be determined which shot program will serve as the basis for this early elongation scan. Since the SL requests that the midplane gaps and lower X-point settings remain fixed, a range of ZCUR has been calculated for the scna. If those other parameters are fixed, then ZCUR needs to be adjusted by 1/2 the desired relative change in kappa. The kappa change is roughly 20%, therefore a range of 10% in ZCUR has been determined. kappa ~ 1.3 at ZCUR = -0.028; kappa ~ 1.7 at ZCUR = -0.016. If the SL decides to allow adjustment of the inner (left) gap, then that will be the backup plan for achieving the SL's requested elongation values. B) This section of the SL Plan requires changes that can be implemented in between shots. C) This section of the SL Plan requires determination of the most successful elongation programming. Since it is based on the I_p = 900 kA shot, it should be capable of being adjusted quickly between shots. D) Adjusting RXL to modify the lower triangularity is straightforward. If the SL determines that the plasma crown (i.e., top of the plasma) has deviated too much from the reference shot, then we will try to remedy this by adjusting RXU and ZXU. E) This shot program depends on what the SL determines to be the most desirable missing conditions. If the I_p = 1.0 MA case is preferred, then this is a minor change from the other shots. |
| Session Leader Summaries |
| Entered: Nov 17 2010 05:34:46:770PM |
| Author: Jerry Hughes |
| Today we made reasonably good progress on our run plan. We set out (1) to fill
in some ELMy H-mode data for EPED comparisons at 1MA and (2) to extend studies of ELMy H-mode to more typical values of plasma elongation. Referring to the components of the SL_PLAN, we progressed well through parts A, B, C and C(2). Boronization recovery was fairly swift, and by shot 9 ICRF was performing very well. We routinely operated most shots in the latter half of the day with 3MW of ICRF, and had relatively few faults. Pedestal data in ELMy H-modes and EDA with small ELMs were obtained at 900kA and 1MA in the conventional JFT2M shape (kappa=1.45) and at a shape with matched X-point position and increased elongation (kappa=1.54). In the modified shape, we also obtained H-modes at 650, 700 and 800kA, which may be compared with prior data at those Ip in the kappa=1.45 shape. The last shot of the day ramped elongation dynamically from higher to lower during an ELMy H-mode plasma. Some periods of impressive performance were obtained today, with neutron rates approaching 10^14 at times, and H98 as high as 1.47. These tended to be very transient however, as the ELMs were generally not able to regulate the pedestal and impurity accummulation sufficiently well. Somewhat poorer performance was generally observed in the steadier ELMing cases. Nonetheless we gained some hope that the ELMy regime might be extended to more typical plasma shapes (kappa>1.5) and this should improve our ability to test EPED and other models for ELMy H-mode pedestals. |
| Physics Operator Summaries |
| Entered: Nov 17 2010 05:35:45:817PM |
| Author: David Pace |
| Startup Notes --
The first few shots of the day were programmed with very low NL04 request and a reduced PG3 puff to account for the density increase due to boronization recovery and ICRF. The failure of shot 1 is attributed to the PG3 puff being too large, even after the initial attempt to reduce it. Beginning with shot 13, however, the breakdown gas programming was so low that we produced a large runaway electron population and DPCS_XJUMP aborted both shots 13 and 14. Increasing the PG3 puff to typical values improved breakdown in shot 15, and this programming was used for the rest of the day. The value of B_z0 slowly increased during the day. Shots 23 and 24 fizzled, and this was attributed to a non-zero value of B_z0 ~ 0.002. Wolfe suggested a 10 A increase (further negative, resulting in a reduction in B_z0) in the EF4 coils to force B_z0 back to zero. The following shot, 25, produced an ideal breakdown and ran to full length. This does not appear to be related to the magnetic coil offset warnings, as they were fluctuating between 1 and 1.2e-2 throughout the day. Injections, Wall Conditions, etc. -- Multiple shots disrupted near 1.0 s. In shot 18, Reinke identified an injection of Fe, which occurred during the ohmic phase of the discharge. In some shots, including 16, injections may be seen originating from the divertor as shown in the lower-left region of the WIDE2 camera. After shot 28, we noticed that the K-limiter status board displayed orange coloring indicative of ~20 MJ/m^2 energy deposition. This is likely due to the low current operation employed at that time in conjunction with high power ICRF. Following shot 28, we began increasing the current and the K-limiter status returned to preferred values at or below 10 MJ/m^2. Delays -- There was an approximately 20 min delay prior to shot 9 due to an issue with the alternator. The Alternator Team dealt with the issue and it did not cause any delays the rest of the day. A slightly slower cooling of the EF3L coil occasionally caused a very short delay before the next shot. This was never more than 4 minutes (based on the assumption that there was nothing else preventing a shot every 10 minutes). Other -- There were a few instances in which the PO workstation (cmodws50) experienced a reduction in responsiveness. Viewing the load on the workstation using the TOP command, it appears as though other accounts were logged in and using it to perform calculations. This did not cause any delays because the PCS remained responsive. EFIT and DWSCOPE review slowed noticeably, which contributes to a longer time for the PO to determine shot programming. These shots may be of particular use to anyone interested in achieving elongation scans without changing the lower half of the plasma. As ZCUR is changed enough (through a linear scan during the shot), the lower x-point begins to move. We used the R_XL and Z_XL outputs from EFIT to attempt to correct for this motion by implementing a corresponding scan in the PCS variables RXL and ZXL. It took more than one shot to get the desired behavior. |
| Session Leader Comments | |||
| Nov 17 2010 09:08:30:273AM | 1101117001 | Jerry Hughes | Shot 1.
Fizzle |
| Nov 17 2010 09:21:51:007AM | 1101117002 | Jerry Hughes | Shot 2.
Attempt: Reproduce equilibrium from 1101026015. Start bringing up RF. Result: Flattop to 1.5s, decent E-port, D and J are struggling. EDA H-modes. |
| Nov 17 2010 09:39:18:633AM | 1101117003 | Jerry Hughes | Shot 3
Attempt: PO will bring X-point inboard sooner. RF will continue to condition. Result: Target RXL is obtained by about 0.65s. Long EDA H-mode. Some injections, in the H-mode phases. |
| Nov 17 2010 09:59:52:280AM | 1101117004 | Jerry Hughes | Shot 4.
Attempt: Speed up RXL shift a little more, try to raise elongation in the last half of flattop Result: RXL is at its target by ~0.6s. Kappa rises from 1.45 to 1.49 after 1s. |
| Nov 17 2010 10:01:57:207AM | 1101117005 | Jerry Hughes | Shot 5.
Attempt: More aggressive scan of kappa. Result: Kappa from 1.45 to 1.54. Injections from 0.7 to 0.9s. Are these from the divertor? |
| Nov 17 2010 10:03:40:447AM | 1101117005 | Elongation ramp from ~1.45 - ~ 1.54. This degree of change should make a significant difference to peeling-ballooning stability.
Working on getting density down to move into ELMing regime. Large injection at t~.73s. | |
| Nov 17 2010 10:03:41:707AM | 1101117005 | Phil Snyder | Elongation ramp from ~1.45 - ~ 1.54. This degree of change should make a significant difference to peeling-ballooning stability.
Working on getting density down to move into ELMing regime. Large injection at t~.73s. |
| Nov 17 2010 10:23:23:577AM | 1101117006 | Jerry Hughes | Shot 6.
Attempt: More aggressive increase of elongation Delay RF onset to 0.8s Result: Still some injections between 0.6 and 0.8s, though not too severe. Kappa sweep after 1.0s causes dome trouble. Kappa goes from 1.45 to 1.6, but (1) H-mode density ramps at 1s and (2) Rampant injections start at 1.15s. lower X-point is not well controlled during the ramp and the strike point is hitting the EF1 pocket. |
| Nov 17 2010 10:58:40:320AM | 1101117007 | Jerry Hughes | Shot 7
Attempt: Get back the kappa scan of shot 5 and get lower X-point drift compensated. Result: X-point drift compensation was imperfect. Kappa also went a bit higher than on 005. |
| Nov 17 2010 11:03:07:730AM | 1101117008 | Jerry Hughes | Shot 8.
Attempt: More X-point drift compensation. Result: RF seems to be meeting demands reasonably well. Not a lot of ELM activity early. Density rises substantially after 1s. Is this promoted by the kappa scan?? Edge TS localization will now admit a scan of kappa from about 1.45 to 1.55 and still provide pedestal coverage. We will probably keep this positioning for the remainder of the run. I feel like part A is reasonably well completed. |
| Nov 17 2010 10:57:46:970AM | 1101117009 |
For shot 9, go back to fixed shape, but raise current to 1MA. Want to complete current scan by getting more data at high current, then move on to elongation scan. | |
| Nov 17 2010 11:37:03:660AM | 1101117009 | For shot 9, go back to fixed shape, but raise current to 1MA. Want to complete current scan by getting more data at high current, then move on to elongation scan.
Result: Pedestal high with ELMs ~0.85-0.92s, but drops thereafter, presumably related to low RF power. Retry same shot and try for increased power. | |
| Nov 17 2010 11:37:04:790AM | 1101117009 | Phil Snyder | For shot 9, go back to fixed shape, but raise current to 1MA. Want to complete current scan by getting more data at high current, then move on to elongation scan.
Result: Pedestal high with ELMs ~0.85-0.92s, but drops thereafter, presumably related to low RF power. Retry same shot and try for increased power. |
| Nov 17 2010 11:37:41:133AM | 1101117009 | Jerry Hughes | Shot 9.
Move on the part B of SL_PLAN. Reload shot 4 and remove kappa scan. Raise Ip demand to 1MA. Result: Long delay imposed by the alternator house. Some ELMs. RF needs to re-tune for this Ip. |
| Nov 17 2010 11:54:29:957AM | 1101117010 | Jerry Hughes | Shot 10.
Attempt: retry ELMy H-mode at 1MA with steadier RF. Result: Improved RF, but the big ELMs seem to knock out D and E pretty reliably Also they don't do much for the density rise. Options to improve include (1) lowering density (which we have little control over) and increasing power (2) increasing power (which we also have little good control over) |
| Nov 17 2010 12:02:49:653PM | 1101117011 | Jerry Hughes | Shot 11.
Attempt: Reduced starting density. Steadier RF power. Result: More or less imporved. 2 distinct H-modes. First is clearly ELMy, with increasing Prad and density. Second is EDA-like, with steadier Prad, but still rising density. |
| Nov 17 2010 12:08:07:600PM | 1101117011 | Phil Snyder | Repeat with lower target density request.
Result: Achieved nice ELMing period from ~0.95-1.15s. Pedestal looks fairly robust during that perdiod (except for small windows perhaps related to RF dropout). High radiation leads to back-transition around 1.24s. It is starting to appear that the ELMs have more trouble controlling the density and impurity accumulation at 1MA than they do at lower currents. |
| Nov 17 2010 12:39:42:477PM | 1101117012 | Jerry Hughes | Shot 12.
Attempt: Try to come on harder with RF. 3MW from the beginning. Result: Nice ELmy phase, prior to big injections. Starting after 1s, these lead to a flattop disruption. But, the ELMy phase from about 0.9 to 1.0s seems to have some good data. |
| Nov 17 2010 12:41:07:183PM | 1101117013 | Jerry Hughes | Shot 13.
Attempt: Recover the 900kA baseline ELMy case Result: Early runaways, shot aborted by DPCS. |
| Nov 17 2010 12:41:30:450PM | 1101117014 | Jerry Hughes | Shot 14.
Attempt: Recover the 900kA baseline ELMy case Result: Again, early runaways, shot aborted by DPCS. Need more gas! |
| Nov 17 2010 12:56:36:867PM | 1101117015 | Jerry Hughes | Shot 15.
Attempt: Recover the 900kA baseline ELMy case Result: Runaways problem solved, but disrupts early still. The density drop at crossover is interesting. It's really obvious in this shot with the autoscale turned on in the dwscope. Looks like a pretty significant Te pedestal at around 0.3s. |
| Nov 17 2010 01:11:46:757PM | 1101117016 | Jerry Hughes | Shot 16.
Attempt: Recover the 900kA baseline ELMy case Result: RF performs well, but the density may be too low to allow easy H-mode access. Also we are heating up something in the divertor slot something awful. Big injection kills this one. Let's try to remedy both problems by raising the nl04 demand for next shot. |
| Nov 17 2010 01:25:46:077PM | 1101117017 | Jerry Hughes | Shot 17.
Attempt: Recover the 900kA baseline ELMy case Result: Fizzle |
| Nov 17 2010 01:41:04:090PM | 1101117018 | Jerry Hughes | Shot 18:
Attempt: Recover the 900kA baseline ELMy case Result: Disruption in Ohmic phase at 0.65s caused by a Fe injection. Not obvious where this injection came from. |
| Nov 17 2010 01:46:45:290PM | 1101117019 | Phil Snyder | Nice ELMing shot at 900kA and fixed shape.
There's a large injection at ~1s, but the plasma recovers nicely, and there's a fairly steady ELMing period from ~1.15-1.45s. |
| Nov 17 2010 01:49:50:530PM | 1101117019 | Jerry Hughes | Shot 19.
Attempt: Recover the 900kA baseline ELMy case. Target nl04 raised to 5e19. Result: Sweet! Several distinct H-mode phases, with numerous ELMs. Pedestal and core performance _increases_ throughout discharge. There is a big injection at about 1s, but it's not a shot killer. |
| Nov 17 2010 02:01:08:600PM | 1101117020 | Phil Snyder | Reasonably good shot with ELMs at high power. However, not much change in the elongation. Try again with higher elongation programmed from the beginning. |
| Nov 17 2010 02:04:47:673PM | 1101117020 | Jerry Hughes | Shot 20
Attempt: 3MW constant RF, with kappa scan after 1.1s Result: ELMs throughout most of discharge RF has a few faults, with successful retries. Increased radiation throughout discharge. The ZCUR ramp, coupled with the X-point drift, results in only a minor kappa increase, combined with a net upward movement of the plasma centroid. |
| Nov 17 2010 02:24:53:103PM | 1101117021 | Jerry Hughes | Shot 21
Attempt: Increased elongation from the beginning of flattop. Result: H-modes with some QCM activity. But no good pedestal/Prad regulation. No big ELMs. X-point has drifted as a result of the ZCUR change. |
| Nov 17 2010 02:38:23:657PM | 1101117022 | Jerry Hughes | Shot 22.
Attempt: Get the higher elongation point with corrected X-point position. Result: ELM-free H-mode with a beefy pedestal. High Prad and a big injection, likely has something to do with the strike point hitting the EF1 pocket. X-point did not move the way it was supposed to!! It went in instead of out. |
| Nov 17 2010 02:52:41:463PM | 1101117022 | Phil Snyder | The period slightly before the disruption is interesting (high pedestal, high global pressure), but without clear ELMs. |
| Nov 17 2010 02:40:14:900PM | 1101117023 | Jerry Hughes | Shot 23
Attempt: fix X-point and relax increase in plasma height. Result: Fizzle |
| Nov 17 2010 02:52:44:310PM | 1101117024 | Jerry Hughes | Shot 24
Attempt: Retry Result: Fizzle |
| Nov 17 2010 03:14:08:613PM | 1101117025 | Phil Snyder | Very interesting shot. ELMing at increased elongation ~1.55. High pedestal pressure ELMing period from about 0.87-0.93. Later ELMing phase at lower pedestal. |
| Nov 17 2010 03:23:47:010PM | 1101117025 | Jerry Hughes | Shot 25.
Attempt: Retry Result: Good shot. Fairly steady RF at 3MW, continuous H-mode. First phase is high-performing, with Te,ped~1keV, with ELMs. H-mode endures Prad rise, then settles down into a steady ELMing H-mode at reduced performance. until 1.5s. This is at kappa>1.5, so a good result. |
| Nov 17 2010 03:33:41:853PM | 1101117026 | Phil Snyder | Reduce current to 700kA. Interesting period from t~0.9-1.04s with very small ELMs and high pedestal, before disruption. |
| Nov 17 2010 03:35:08:047PM | 1101117026 | Jerry Hughes | Shot 26
Attempt: Given the difficulty accessing higher elongations, let's do a current scan. Lower Ip demand to 700kA. Result: Weak QCM with some small ELMs. H-mode looks reasonably good until Prad increases sharply at 1.05s. Disruption shortly after. |
| Nov 17 2010 03:43:43:277PM | 1101117027 | Phil Snyder | Current down to 650kA. Very small high frequency ELMs. Two interesting timeslices on either side of a back-transition at about 1.25s. t~0.9-1s and t~1.35-1.45s both have high performance, betaN_global~1.4. |
| Nov 17 2010 03:50:28:400PM | 1101117027 | Jerry Hughes | Shot 27
Attempt: Reduce Ip to 650kA to try to match some of our earlier ELMy cases at lower elongation. Result: 2 distinct H-modes with lowish density, H98=1.37 ! Small hashy ELMs on top of QCM A good Ip/density match to 1090914018--021. |
| Nov 17 2010 04:04:08:207PM | 1101117028 | Jerry Hughes | Shot 28
Attempt: Reduce nl04 Result: More radiative, but transiently, H98 hits 1.45. Again, small hashy ELMs in the high confinement phase. K-limiter is getting hot. |
| Nov 17 2010 04:06:22:590PM | 1101117028 | Phil Snyder | Repeat current of 650kA at lower density. ELMs are more distinct. There are again multiple periods of high performance H-mode, but radiated power is rising until back-transitions. Most interesting time window is probably the early window at t~0.9-0.98s. |
| Nov 17 2010 04:19:59:043PM | 1101117029 | Jerry Hughes | Shot 29.
Attempt: 800kA Result: Multiple H-mode phases, with some small ELMs. In the high-confinement phase the ELMs don't do much Prad regulation. Regular ELMs from 1.23 onward seem to keep things under control, although the global performance is kind of weak. |
| Nov 17 2010 04:23:54:130PM | 1101117030 | Jerry Hughes | Shot 30:
Attempt: 1MA Result: More ELMs. This gives us a fairly broad current scan at the increased elongation. |
| Nov 17 2010 04:26:11:050PM | 1101117030 | Phil Snyder | Current up to 1MA. Again there is an early phase with high pedestal pressure before ~1s. The shot settles into a steady ELMing H-mode from t~1.1-1.5, at fairly low pedestal. Are these Type III ELMs (resistive ballooning?) or small Type I (ballooning, with bootstrap current suppressed by collisionality) ELMs?
Try a power increase to discern ELM type. |
| Nov 17 2010 04:42:13:667PM | 1101117031 | Jerry Hughes | Shot 31
Attempt: Try to put in 4MW at 1.3s Result: Didn't make it to the power increase. Disrupted at 1.19s. Transient H-mode is briefly quite hot, and has a short patch of small ELMs from 0.89 to 0.9s. |
| Nov 17 2010 05:17:03:317PM | 1101117032 | Jerry Hughes | Shot 32.
Attempt: Go back to flat 3MW ICRF program, 900kA, and try to ramp elongation from 1.55 to 1.45 during shot. Basically morph from shot 25 to shot 19. Result: H-mode with an early disruption. Never makes it to the elongation scan. Weird little clusters of ELMs occur when there are dips in edge Te, and then stop when the sawtooth heat pulse arrives. (between 0.96 and 1.1s) |
| Nov 17 2010 05:20:01:080PM | 1101117033 | Jerry Hughes | Shot 33
Retry Result: Not a bad one to finish off with. We get the elongation ramp, and the crown drops from the nominal shot 25 position, almost down to the shot 19 position. ELMs persist throughout, perhaps becoming more distinct at the lower kappa. Also the intrinsic H-mode density may be lower at the lower kappa. EOR |
| Physics Operator Comments | |||
| Nov 17 2010 09:07:47:883AM | 1101117001 | David Pace | Shot 1 Plan:
Begin with shot 1101026015 (900 kA at 5.4 T) and then make the following changes: - extend current flattop to 1.5 s (reload shot 1101117399 from /home/pace/pcs_scratch) Shot 1 Actuality: Late breakdown and large H-alpha signal near 22 ms. Suspect that breakdown gas programming is too large, will reduce for next shot. |
| Nov 17 2010 09:16:21:487AM | 1101117002 | David Pace | Shot 2 Plan:
Begin with shot 1 and then make the following changes: - reduce segment 1 PG3 peak to 40.0 (was 50.0) Shot 2 Actuality: Full length shot, small adjustment to PG3 appears to have worked. Current flattop extends to 1.5 s as requested. |
| Nov 17 2010 09:33:18:440AM | 1101117003 | David Pace | Shot 3 Plan:
Begin with shot 2 and then make the following changes: - bring RXL to steady position (-0.049 cm) by 0.6 s, this is ~150 ms earlier than in shot 2 Shot 3 Actuality: Full length shot. From EFIT, steady RXL was achieved by 0.66 s. |
| Nov 17 2010 09:44:59:340AM | 1101117004 | David Pace | Shot 4 Plan:
Begin with shot 3 and then make the following changes: - bring RXL to steady position (-0.049 cm) by 0.55 s, this is ~50 ms earlier than in shot 3 and the target is to realize the position by 0.6 s - increase elongation between 1.0-1.2 s: add linear increase in ZCUR from -0.025 to -0.016 in that time window, then hold ZCUR fixed at -0.016 until 1.5 s Shot 4 Actuality: Full length shot. From EFIT, the elongation reached a peak close to 1.5, so the next shot should plan on a more aggressive increase to meet the SL's request. The steady position of RXL is reached near 0.6 s as desired. |
| Nov 17 2010 10:04:39:187AM | 1101117005 | David Pace | Shot 5 Plan:
Begin with shot 4 and then make the following changes: - increase elongation between 1.0-1.2 s: add linear increase in ZCUR from -0.025 to 0.0 in that time window, then hold ZCUR fixed at 0.0 until 1.5 s (in shot 4 the change in elongation was very small, increasing from 1.45 to 1.50, so this is a more aggressive scan in ZCUR) Other: we are getting messages concerning the bp11_jk coil offset. This is reaching -1.1e-2, which also happened in the previous run from this MP and did not lead to any problems. Shot 5 Actuality: Full length shot. A few peaks in the 2pi bolometer near 730 and 760 ms, no clear injection at those times on the LH, WIDE2, or G_H_LIM cameras. Elongation reached ~1.55, though the plasma is running well enough that we have room to try still larger values. |
| Nov 17 2010 10:17:05:613AM | 1101117006 | David Pace | Shot 6 Plan:
Begin with shot 6 and then make the following change to achieve larger elongation: - increase elongation between 1.0-1.2 s: add linear increase in ZCUR from -0.025 to 0.02 in that time window, then hold ZCUR fixed at 0.02 until 1.5 s (in shot 5 the change in elongation was from 1.45 to ~1.55, so this is a more aggressive scan in ZCUR) Shot 6 Actuality: Full length shot. Reached maximum elongation near 1.6. As this peak elongation is approached (~1.15 s), our neutron rate drops and the ICRF suffers many faults. This may be the result of the plasma reaching new areas of the limiter due to the stretched shape. |
| Nov 17 2010 10:35:41:050AM | 1101117007 | David Pace | Shot 7 Plan:
Load segment 2 from shot 5 (into seg. 2). Try to compensate for the change in the lower strike point as the elongation scan takes place. From EFIT, it looks like ZXL moves up by ~1 cm during the elongation scan between 1.0-1.2 s. Add a 1 cm decreasing ramp during this time to compensate. The RXL change is smaller, so add a 3 mm ramp (increase to -0.046 from -0.049) to keep it out as necessary. Shot 7 Actuality: Full length shot. The compensating control on the lower strike point did not hold it steady during the elongation ramp. SL is adjusting the Thomson diagnostic in a cell access and will then determine the desired programming for the next portion of the shot plan. |
| Nov 17 2010 10:52:59:077AM | 1101117008 | David Pace | Shot 8 Plan:
Repeat shot 7. Add 3 mm to RXL in compensation for elongation scan: reach -0.043 at 1.2 s and hole until 1.5 s (was -0.046). Shot 8 Actuality: Full length shot. Plenty of injections, better density control leading to the ICRF turn-on, but then a steady increase. Elongation may be contributing to the density rise after 1.2 s due to plasma-surface interactions. |
| Nov 17 2010 11:29:53:743AM | 1101117009 | David Pace | Shot 9 Plan:
Begin with shot 4, then make the following changes: - remove the elongation ramp - increase current to 1.0 MA - extend magnetic field flattop to 1.4 s (was 1.5 s) * all of the preceding shots feature a flattop current through 1.5 s, but the magnetic field begins decreasing at 1.4 s * Shot 9 Actuality: Delay (~20 min) before the shot due to an issue with the alternator. The Alternator Team reports the problem is related to river-water (details in their notes). Full length shot with a disruption in ramp-down. |
| Nov 17 2010 11:48:29:893AM | 1101117010 | David Pace | Shot 10 Plan:
Repeat shot 9. Shot 10 Actuality: Full length shot. |
| Nov 17 2010 11:55:14:197AM | 1101117011 | David Pace | Shot 11 Plan:
Begin with shot 10 and attempt to reduce the density. - reduce flattop NL04 to 3e19 (was 4e19) Shot 11 Actuality: Full length shot. Achieved the relative reduction of ~20% in pre-ICRF density. SL reports better pedestal behavior. |
| Nov 17 2010 12:13:09:677PM | 1101117012 | David Pace | Shot 12 Plan:
Repeat shot 11, only ICRF changes are requested. Shot 12 Actuality: Disruption near 1.04 s with preceding jump in H-alpha. |
| Nov 17 2010 12:29:10:747PM | 1101117013 | David Pace | Shot 13 Plan:
Begin with shot 12, then lower the current to 900 kA (was 1.0 MA). Shot 13 Actuality: Disruption at 0.224 s, possibly related to remnants from previous shot. Hard x-ray is large before 0.1 s, which is behavior similar to a shot from yesterday's run. Will treat this as a disruption recovery shot and try one more time (with gas increase planned if 14 fails). |
| Nov 17 2010 12:38:33:820PM | 1101117014 | David Pace | Shot 14 Plan:
Repeat shot 13. Shot 14 Actuality: Another XJUMP aborted shot. Possible that density has reduced enough that our early reduction in PG3 is now too low. |
| Nov 17 2010 12:54:57:433PM | 1101117015 | David Pace | Shot 15 Plan:
Repeat shot 14 with increase in early gas puff. PG3 peak increased to 80.0 (was 50.0) and flattop increased to 50.0 (was 20.0). By design, this may be slightly above what is necessary to achieve a good breakdown, which will allow for the following shot to be optimized. Shot 15 Actuality: Disruption arrived a little later (~0.38 s) compared to 14. Hard x-ray signal is significantly reduced during early time, so the PG3 programming will likely carry over to the next shot. |
| Nov 17 2010 01:09:47:030PM | 1101117016 | David Pace | Shot 16 Plan:
Begin with shot 15 and then increase gas across transition from segment 1 to segment 2 by increasing NL04 request to 4e19 until 0.25 s (was 3e19). Shot 16 Actuality: Disruption at 1.04 s. WIDE2 camera shows injection (lower left corner) preceding disruption. Will try to remedy with density increase to reach H-mode and move away from this sensitive region. |
| Nov 17 2010 01:26:30:840PM | 1101117017 | David Pace | Shot 17 Plan:
Begin with shot 16 and increase density in attempt to reach H-mode. Increase NL04 flattop to 4e19 (was 3e19). Shot 17 Actuality: Fizzle, large CII trace at 0.1 s marks end of current increase. No changes planned for next shot. |
| Nov 17 2010 01:34:46:187PM | 1101117018 | David Pace | Shot 18 Plan:
Repeat shot 17. Shot 18 Actuality: Disruption at ~0.64 s. May need to consider adjustment to shape or X-point in order to avoid the injection source. |
| Nov 17 2010 01:44:40:723PM | 1101117019 | David Pace | Shot 19 Plan:
Begin with shot 18, then increase NL04 flattop to 5e19 (was 4e19). Shot 19 Actuality: Full length shot. Injection at 1.009 s, completely acceptable performance. |
| Nov 17 2010 01:58:24:950PM | 1101117020 | David Pace | Shot 20 Plan:
Begin with shot 19, then increase elongation beginning at 1.1 s and ending at 1.3 s. Will increase ZCUR from -0.025 to -0.015 during this time window to achieve a maximum elongation just over 1.5. Shot 20 Actuality: Full length shot. Elongation increase is minimal. From shot 5, a value of ZCUR = 0.0 should produce a maximum elongation near 1.55. |
| Nov 17 2010 02:11:34:237PM | 1101117021 | David Pace | Shot 21 Plan:
Begin with shot 20 and reach an elongation of 1.55 before ICRF turn on at 0.8 s. Will program ZCUR to 0.0 flattop. Shot 21 Actuality: Full length shot. Elongation generally > 1.5. Large neutron signal and we have reached the notification level for total neutron production. Not enough ELMs to satisfy SL requirements. |
| Nov 17 2010 02:31:21:973PM | 1101117022 | David Pace | Shot 22 Plan:
Begin with shot 21 then slightly reduce elongation and move X-point to match SL reference condition. - increase RXL to -0.045 (was -0.049) - reduce ZXL to 0.007 (was 0.020) --> these two changes in the X-point will affect the elongation, so no change has been made to ZCUR Shot 22 Actuality: Disruption at 1.02 s. X-point did not settle at large enough radial position. Need to make further adjustment on next shot. |
| Nov 17 2010 02:40:51:570PM | 1101117023 | David Pace | Shot 23 Plan:
Begin with shot 22 then slightly reduce the crown to improve Thomson diagnostic coverage and move X-point to match SL reference condition. - reduce ZCUR to -0.01 (was 0.0) - increase RXL to -0.041 (was -0.045) Shot 23 Actuality: Fizzle. Attributed to post-disruption recovery. |
| Nov 17 2010 03:04:36:290PM | 1101117024 | David Pace | Shot 24 Plan:
Repeat shot 23. Shot 24 Actuality: Fizzle. Bz0 is positive during breakdown, will implement Wolfe suggestion of reducing Bz0 using the EF4 coil: IC_EFU4 changed to -1290.0 leading up to t = 0 s, was -1280 in previous shot. |
| Nov 17 2010 03:13:11:387PM | 1101117025 | David Pace | Shot 25 Plan:
Repeat shot 23. IC_EFU4 changed to -1290.0 leading up to t = 0 s, was -1280 in previous shot. Shot 25 Actuality: Full length shot. Bz0 reduced by 50% or more compared to fizzle shot. |
| Nov 17 2010 03:28:43:147PM | 1101117026 | David Pace | Shot 26 Plan:
Repeat shot 25, then reduce current to 700 kA. Shot 26 Actuality: Disruption before 1.1 s. Steady increase in bolometer leading to disruption. Decent ELM behavior for SL prior to end of shot. |
| Nov 17 2010 03:42:31:093PM | 1101117027 | David Pace | Shot 27 Plan:
Begin with shot 26, then reduce current to 650 kA. Shot 27 Actuality: Full length shot. Plasma may be displaced 1 cm lower than previous shot. Will determine whether this needs to be remedied according to SL preference. |
| Nov 17 2010 03:57:15:477PM | 1101117028 | David Pace | Shot 28 Plan:
Begin with shot 27, then reduce density. Change NL04 to 4e19 (was 5e19). Shot 28 Actuality: Full length shot. SL reports density reduction in relevant portion of discharge. |
| Nov 17 2010 04:09:38:240PM | 1101117029 | David Pace | Shot 29 Plan:
Begin with shot 28, then increase current to 800 kA. After shot 28, the K-limiter display indicated loads near 20 MJ/m^2. This motivated an increase in current as we assume the power to the limiter is due to ion losses produced in the low-current/high-power ICRF discharges. Shot 29 Actuality: Full length shot with excellent 3 MW ICRF input. |
| Nov 17 2010 04:22:36:923PM | 1101117030 | David Pace | Shot 30 Plan:
Begin with shot 29, then increase current to 1.0 MA Shot 30 Actuality: Full length shot. Control system behaves normally at 1 MA, no indication of desire for further current increase. |
| Nov 17 2010 04:38:11:583PM | 1101117031 | David Pace | Shot 31 Plan:
Repeat shot 30, only ICRF changes requested by SL. Shot 31 Actuality: Disruption at ~1.19 s. Injections throughout the shot, including streakers on the LH camera early (t < 0.2 s). |
| Nov 17 2010 04:45:43:490PM | 1101117032 | David Pace | Shot 32 Plan:
Begin with shot 25 (900 kA), then scan elongation between 1.1 and 1.3 s. This elongation scan will be performed as a reduction (it was increasing in the earlier scans). - ZCUR ramps from -0.01 to -0.025 between 1.1 and 1.3 s Shot 32 Actuality: Disruption at ~1.1 s. This is similar to the timing of the disruption from the previous shot, and the beginning of the elongation scan. |
| Nov 17 2010 04:59:12:237PM | 1101117033 | David Pace | Shot 33 Plan:
Begin with shot 32, then move x-point radially out by 6 mm to better match reference shape. - change flattop RXL to -0.035 (was -0.041) Shot 33 Actuality: Full length shot. Final plasma shot of the day. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 08:58:57:427AM | Plasma | Ok | |
| 2 | 09:11:39:957AM | Plasma | Ok | |
| 3 | 09:27:04:553AM | Plasma | Ok | |
| 4 | 09:39:28:527AM | Plasma | Ok | |
| 5 | 09:55:21:537AM | Plasma | Ok | |
| 6 | 10:08:36:050AM | Plasma | Ok | |
| 7 | 10:26:12:117AM | Plasma | Ok | |
| 8 | 10:46:40:757AM | Plasma | Ok | |
| 9 | 11:24:26:380AM | Plasma | Ok | |
| 10 | 11:37:25:100AM | Plasma | Ok | |
| 11 | 11:51:30:690AM | Plasma | Ok | |
| 12 | 12:06:04:550PM | Plasma | Ok | |
| 13 | 12:19:39:527PM | Plasma | Ok | |
| 14 | 12:32:35:623PM | Plasma | Ok | |
| 15 | 12:45:39:337PM | Plasma | Ok | |
| 16 | 01:01:40:733PM | Plasma | Ok | |
| 17 | 01:14:12:847PM | Plasma | Ok | |
| 18 | 01:26:42:957PM | Plasma | Ok | |
| 19 | 01:39:43:157PM | Plasma | Ok | |
| 20 | 01:52:30:693PM | Plasma | Ok | |
| 21 | 02:05:20:353PM | Plasma | Ok | |
| 22 | 02:21:51:717PM | Plasma | Ok | |
| 23 | 02:37:41:593PM | Plasma | Ok | |
| 24 | 02:50:16:173PM | Plasma | Ok | |
| 25 | 03:04:09:323PM | Plasma | Ok | |
| 26 | 03:22:22:270PM | Plasma | Ok | |
| 27 | 03:34:53:000PM | Plasma | Ok | |
| 28 | 03:49:15:723PM | Plasma | Ok | |
| 29 | 04:03:25:007PM | Plasma | Ok | |
| 30 | 04:15:56:543PM | Plasma | Ok | |
| 31 | 04:28:44:960PM | Plasma | Ok | |
| 32 | 04:42:46:717PM | Plasma | Ok | |
| 33 | 04:55:31:560PM | Plasma | Ok | |
| System Availability | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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