| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Martin Greenwald |
| Physics operator(s): | Ron Parker,Joseph Snipes |
| Engineering operator(s): | Unknown |
| Engineering Operator Run Comment |
| MP# 385 Edge Rotation and LH Treshold/Greenwald/Parker/&Friends |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:02:837PM |
| Author: Martin Greenwald |
| MP 385 Phys Op: Parker/Snipes Session Leader: Greenwald Plan: We want to extend studies which correlate flows and the L/H threshold to look at the effects of parameters which are observed to be important in the threshold scaling. The general approach will be similar to mp 375 but with PRF fixed at just above the power threshold with a very slow ramp and with SSEP varied from shot to shot. We need to give the plasma time to evolve before the transition to accurately determine threshold parameters. Discharges which transition promptly to H-mode are not very useful for these studies. Given previous results, we can choose the SSEP values to be -5, 0 and +5 mm (We won't have enough power to get an H-mode for upper null discharges at higher densities, so these cases will be skipped for now.). This experiment would then be repeated for different plasma conditions. The parameter scans to be performed would be roughly nebar = 1.2, 2.0, 3.0 , BT = 5.4 and Ip = 0.6, 0.9, 1.2 MA. Results: We were able to reproduce previous results at lower densities but did not have much luck at higher densities. The RF had the usual problems with neutral pressure at high densities. As we lowered the density to allow operation of the antennas at high power, the threshold dropped leading to prompt transitions. We were unable to find a combination of parameters which put us close to the threshold at densities much above 1.5 x 10^20. Shots for further analysis: target Shot SSEP Prf Vphi density Comment ---------------------------------------------------------------- 1040219002 -0.5 cm 0.8-1.2 0 km/s 1.5 No H-mode 1040219003 -0.5 1.0-1.4 0 1.4 No H-mode 1040219004 -0.8 1.0-1.4 0 1.4 No H-mode 1040219005 -1.2 1.0-1.4 0 -10 1.3 No H-mode 1040219006 -1.2 1.2-1.3 -20 0 1.4 Late H-mode 1040219008 +1.3 2.3-2.4 -20 0 1.1 H-mode 1040219009 +1.3 2.3-2.5 -25 0 1.2 No H-mode 1040219010 +1.3 2.6-3.0 -40 0 1.35 No H-mode (RF trips) 1040219011 +1.3 3.5-4.0 -35 -15 1.4 H-Modes 1040219013 -1.3 0.6-0.8 0 1.5 No H-mode 1040219015 -1.3 1.3-1.9 0 2.0 No H-mode (RF trips) 1040219020 -1.3 1.6-2.0 -15 0 1.9 No H-mode (RF trips) 1040219021 -1.2 1.9 0 1.9 Prompt H-mode 1040219022 -1.3 1.8-2.0 -20 -10 1.8 Prompt H-mode 1040219023 -1.3 1.7-2.8 -20 -10 1.8 Prompt H-mode 1040219024 -1.3 1.5-3.0 -20 -10 2.0 Prompt H-mode 1040219026 -1.3 1.2-2.0 0 1.8 No H-mode (RF trips) |
| Physics Operator Summaries |
| Entered: Jul 7 2004 04:36:49:020PM |
| Author: Joseph Snipes |
| ;; This buffer is for notes you don't want to save, and for Lisp evaluation. ;; If you want to create a file, visit that file with C-x C-f, ;; then enter the text in that file's own buffer. Physop Summary 1040219 This run featured switching back and forth between lower and upper null equilibria with variable ssep. The ssep control works very well and allows the PO to dial the desired configuration with ease. Due to Parker's teaching commitments and need to prepare PAC talk,, Joe Snipes took over as PO at 1:00 and finished the run. Until shot 15 the machine ran fairly well, with a few disruptions when the configuration was changed from lower to upper single null. After Joe took over,a data system problem developed that delayed the run for 2 hours. The run resumed at approximately 3:00. In the remainder of the day, the shots went off as planned but often disrupted before full current rampdown. Scorecard: 26 Shots, 3 lost due to data system test or failure, 1 lost to eng operator error, 5 disruptions before rampdown, 2 fizzles and the rest (15) useful. Engineering Setup and Run Plan 1040219 Purpose: MP 385 Edge Rotation and LH Threshold - Dependence on Known Scaling Parameters Session leaders: Greenwald Physop: Parker and Friends Engineering Setup: ECDC Overnight in D2, stopping by 07:00 Run Begins at 09:00 and ends at 17:00 Power Supplies as on 1040123012 Gas System 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 C-side with 30 psi D2 Hybrid enabled (PG3) fill NINJA (lower cap) with 5 psi He All diagnostic valves (ECE, VUV, DNB) Enabled assuming no vacuum problems RF: Transmitters #1,2,3 and 4 in RUN-ON by 08:00 Run Plan 1. Start with: Ip = 0.8 MA, BT = 5.6 T (If we get HECE data, otherwise drop to 5.4 T nebar = 1.4e20 Prf = 0.8 to 1.0 MW (very slow ramp starting at 0.5 sec, going to 1.5 sec) Equilibrium from 1040123021 (ssep = -0.5 cm) 2. Then run 1040123021 (ssep = +0.3 cm) equilibrium Prf = 2.5 to 3.0 MW over same ramp time 3. Then nebar is increased to 2.2e20 and ssep set back to -0.5 cm Prf = 1.3 to 1.6 MW 4. Bring ssep back to +0.3 cm and Prf ramps from 3.5 to 4.0 MW We'll take stock of the situation at this point. If time, we'll repeat 1 & 2 but at 0.6 MA and then at 1.0 MA. |
| Session Leader Comments | |||
| Feb 19 2004 08:56:24:170AM | Martin Greenwald | MP 385 L-H scaling and rotation Session Leader - Greenwald Physop - Parker Background Recent work has revealed a connection between self-generated core and SOL flows, topology and the L/H threshold. The work has suggested a novel hypothesis for the dependence of the H-mode power threshold on the gradB drift direction. This 0$^{th}$ order effect, which roughly doubles the required power to acheve H-mode when the ion drift is in the direction away from a single null x-point, may be understood as the result of two rotation components which add or subtract depending on topology. The first is SOL flow which is driven in a direction determined by topology as parallel transport attempts to symmetrize poloidally asymmetric cross-field transport (ballooning) and which couples across the separatrix into the core plasma. The second is topology independent and increases (increments) monotonically in the co-current direction as the plasma pressure increases. The H-mode threshold could then be understood as a critical edge flow (or flow gradient) which requires very different input powers in the two cases. For the conditions studied, 0.8 MA, 5.4 T and 1.2-1.6 x 10$^{20}$, the transition occurs when core toroidal rotation reaches about 0 for USN, LSN and DN plasmas. (In contrast to input power or edge temperature which vary strongly with topology. [3]) To make a connection to the broader issues of the L/H threshold, we would like to determine if this picture holds for other plasma conditions and particularly to measure dependence on parameters which are known to be important for the L/H power threshold, namely n and B. Approach The general approach will be similar to mp 375 but with PRF fixed at just above the power threshold (or perhaps with a very slow ramp) and with SSEP varied from shot to shot. Given previous results, we can choose the SSEP values to be -5, 0 and +5 mm (We won't have enough power to get an H-mode for upper null discharges at higher densities, so these cases will be skipped for now.). This experiment would then be repeated for different plasma conditions. The parameter scans to be performed would be roughly nebar = 1.2, 2.0, 3.0 , BT = 5.7 and Ip = 0.6, 0.9, 1.2 MA. Plan 1. We want to start with: Ip = 0.8 Bt = 5.6 (If we are getting HECE data, otherwise we drop back to 5.4) nebar = 1.4 Prf = 0.8 -> 1.0 MW (very slow ramp starting at 0.5 sec going to 1.5 seconds) The equilibrium should be as 1040123012 (ssep = -0.5cm) ........................ 2. Then we go to equilibrium 1040123021 (ssep = +0.3cm) Prf = 2.5 -> 3.0 MW (same ramp times) ..................... 3. then nebar goes to 2.2 ssep = -0.5 Prf = 1.3 -> 1.6 MW ................ 4. then ssep goes back to +0.3 Prf = 3.5 -> 4.0 MW ............. We'll see where we are at that point. If there is time we will repeat steps 1 and 2 but at 0.6 MA then at 1.0 MA | |
| Feb 19 2004 05:59:42:380PM | Martin Greenwald | Results: We were able to reproduce previous results at lower densities but did not have much luck at higher densities. The RF had the usual problems with neutral pressure at high densities. As we lowered the density to allow operation of the antennas at high power, the threshold dropped leading to prompt transitions. We were unable to find a combination of parameters which put us close to the threshold at densities much above 1.5 x 10^20. Shots for further analysis: target Shot SSEP Prf Vphi density Comment ---------------------------------------------------------------- 1040219002 -0.5 cm 0.8-1.2 0 km/s 1.5 No H-mode 1040219003 -0.5 1.0-1.4 0 1.4 No H-mode 1040219004 -0.8 1.0-1.4 0 1.4 No H-mode 1040219005 -1.2 1.0-1.4 0 -10 1.3 No H-mode 1040219006 -1.2 1.2-1.3 -20 0 1.4 Late H-mode 1040219008 +1.3 2.3-2.4 -20 0 1.1 H-mode 1040219009 +1.3 2.3-2.5 -25 0 1.2 No H-mode 1040219010 +1.3 2.6-3.0 -40 0 1.35 No H-mode (RF trips) 1040219011 +1.3 3.5-4.0 -35 -15 1.4 H-Modes 1040219013 -1.3 0.6-0.8 0 1.5 No H-mode 1040219015 -1.3 1.3-1.9 0 2.0 No H-mode (RF trips) 1040219020 -1.3 1.6-2.0 -15 0 1.9 No H-mode (RF trips) 1040219021 -1.2 1.9 0 1.9 Prompt H-mode 1040219022 -1.3 1.8-2.0 -20 -10 1.8 Prompt H-mode 1040219023 -1.3 1.7-2.8 -20 -10 1.8 Prompt H-mode 1040219024 -1.3 1.5-3.0 -20 -10 2.0 Prompt H-mode 1040219026 -1.3 1.2-2.0 0 1.8 No H-mode (RF trips) | |
| Feb 19 2004 09:05:51:430AM | 1040219001 | Martin Greenwald | No TF |
| Feb 19 2004 09:21:40:960AM | 1040219002 | Martin Greenwald | Good shot, but no H-mode Prf .85 - 1.1 (raising by .15 for next shot) |
| Feb 19 2004 09:35:26:217AM | 1040219003 | Martin Greenwald | Good shot - but still no H-mode Prf to 1.05 - 1.35 SSep = -0.5 cm but probes show symmetric flows |
| Feb 19 2004 09:59:40:470AM | 1040219004 | Martin Greenwald | SSEP to -0.8 cm still no H-mode |
| Feb 19 2004 10:27:32:540AM | 1040219005 | Martin Greenwald | SSEP to -1.2 cm still no H-mode Edge temperature is pretty hot inner wall flows are small |
| Feb 19 2004 10:54:52:653AM | 1040219006 | Martin Greenwald | Got an H-mode late Prf at 1.3 MW Ptot to 1.9 at transition Core rotation starts -40 km/sec ramps to 0 at transition edge flow is somewhat counter to start tending to co with RF power |
| Feb 19 2004 10:55:05:390AM | 1040219007 | Martin Greenwald | Early disruption |
| Feb 19 2004 11:05:36:723AM | 1040219008 | Martin Greenwald | Disrupted early |
| Feb 19 2004 11:31:58:603AM | 1040219010 | Martin Greenwald | Plasma lasted full length no H-mode ssep +1.3 cm |
| Feb 19 2004 11:54:00:167AM | 1040219011 | Martin Greenwald | two h-modes ssep = +1.3cm Prf = 3.5 to 3.9 Got rotation data |
| Feb 19 2004 11:59:59:437AM | 1040219012 | Martin Greenwald | Fizzle |
| Feb 19 2004 12:15:49:827PM | 1040219013 | Martin Greenwald | Back to lower null ssep = -1.2 cm density to 1.8 RF tripped, only limited power |
| Feb 19 2004 12:28:01:897PM | 1040219014 | Martin Greenwald | fizzle |
| Feb 19 2004 12:45:00:830PM | 1040219015 | Martin Greenwald | Good shot - but no H-mode not enough power yet nebar to 2.1 |
| Feb 19 2004 01:35:09:870PM | 1040219016 | Martin Greenwald | no H-mode daq problems |
| Feb 19 2004 01:50:18:773PM | 1040219016 | Martin Greenwald | data system problems |
| Feb 19 2004 03:17:38:373PM | 1040219020 | Martin Greenwald | RF still tripping at this density no H-mode |
| Feb 19 2004 03:35:50:137PM | 1040219021 | Martin Greenwald | Got 2 brief h-modes early ssep = -1.2 cm Prf at 2 MW |
| Feb 19 2004 03:57:35:533PM | 1040219022 | Martin Greenwald | Another early H-mode followed by disruption |
| Feb 19 2004 04:24:31:420PM | 1040219023 | Martin Greenwald | Early H-mode |
| Feb 19 2004 04:34:17:747PM | 1040219024 | Martin Greenwald | Raised density to 2 - H-mode still early |
| Feb 19 2004 04:44:09:370PM | 1040219025 | Martin Greenwald | very early disruption |
| Feb 19 2004 04:58:41:957PM | 1040219026 | Martin Greenwald | no H-modes Prf = 1.2 to 1.8 then starts tripping |
| Physics Operator Comments | |||
| Feb 19 2004 09:33:37:717AM | 1040219001 | Ron Parker | For the first shot, shot 1040123012 is loaded Shot did not go -- TF was not enabled. |
| Feb 19 2004 09:33:21:543AM | 1040219002 | Ron Parker | Shot 2 ran well as programmed. |
| Feb 19 2004 09:35:24:170AM | 1040219003 | Ron Parker | Shot 3 ran well. Next shot: decrease ssep by 3-4 mm to ~-0.8 |
| Feb 19 2004 09:50:57:120AM | 1040219004 | Ron Parker | Shot 4 ran well with ssep decreased by 3 mm -- from -5 to -8 mm. Next shot: decrease ssep by 3 more mm. |
| Feb 19 2004 10:15:59:610AM | 1040219004 | Ron Parker | There is a delay to try to get Z-meter up. |
| Feb 19 2004 10:28:57:790AM | 1040219005 | Ron Parker | Delay was about 10 minutes. Shot ran well, with a glitch in current at 0.12 sec. Next: Same shot, higher RF power. |
| Feb 19 2004 10:41:41:567AM | 1040219006 | Ron Parker | Shot 6 ran well -- glitch went away as did injection. Next: ssep = +1 cm |
| Feb 19 2004 10:49:49:320AM | 1040219007 | Ron Parker | Shot disrupted, tried to make upper null equilibrium. Next: reload shot 1040123033 |
| Feb 19 2004 11:12:44:480AM | 1040219008 | Ron Parker | Shot 8 ran to 0.8 sec before disrupting. This is an upper null discharge -- impurity generation from top divertor? Next: Run shot again, raise density to 0.9, increase fill pulse by 2 ms |
| Feb 19 2004 11:24:28:253AM | 1040219009 | Ron Parker | Shot 9 also disrupted at 0.8 sec. Density was not increased as advertised. Next shot will have density increased to 0.9 on n_e.L(4) |
| Feb 19 2004 11:35:42:123AM | 1040219010 | Ron Parker | Success -- upper null discharge produced without disruption. Density was increased to 0.9e20. Next: Increase RF power. |
| Feb 19 2004 11:53:52:073AM | 1040219011 | Ron Parker | Shot 11 ran OK, but disrupted at 1.4 sec, late enough to get data. Next shot: Reload shot 1040219006, ssep -1.2 |
| Feb 19 2004 12:04:03:363PM | 1040219012 | Ron Parker | Shot 12 was a fizzle, possibly because of disruption late in shot 11. Next: Shot 1040219006 again loaded, density set for 1.2e20 and fill gas increased by 2 ms. |
| Feb 19 2004 12:24:05:753PM | 1040219013 | Ron Parker | Shot 13 ran OK, lower null. Disrupted on current fall. Next: Same as 13, with slightly higher desnity. |
| Feb 19 2004 12:30:10:617PM | 1040219014 | Ron Parker | Shot 14 fizzled, again probably due to disruption on rampdown in previous shot. Try again |
| Feb 19 2004 12:58:38:547PM | 1040219015 | Ron Parker | Shot 15 ran well, still disrupting on current rampdown. Moved density rampdown earlier for the next shot to attempt to reduce the density and avoid the disruption. |
| Feb 19 2004 01:07:12:083PM | 1040219016 | Ron Parker | Shot 16: Good shot though it disrupted in the rampdown again. There will be a 20 - 30 minute delay to resolve a computer problem. |
| Feb 19 2004 02:59:22:203PM | 1040219017 | Ron Parker | Shot 17: Reduced nl04 to 1.2 x 10^20 m^-2. Data system failed. |
| Feb 19 2004 03:00:20:923PM | 1040219018 | Ron Parker | Shot 18: Data system test. |
| Feb 19 2004 03:00:36:423PM | 1040219019 | Ron Parker | Shot 19: Another data system test. |
| Feb 19 2004 03:13:00:743PM | 1040219020 | Ron Parker | Shot 20: Good shot. Disrupted later in the rampdown due to the lower density. |
| Feb 19 2004 03:31:44:930PM | 1040219021 | Ron Parker | Shot 21: Reduced nl04 to 1.1 x 10^20 m^-2 and reduced pre-programmed gas puff at 0.3 s to attempt to reduce the neutral pressure to improve J-port operation. Also extended Ip out to 2.5 s and reduced the decay rate of Ip in the rampdown. Good shot. Disrupted later in the rampdown at about 1.84 s at 0.4 MA. |
| Feb 19 2004 03:53:25:573PM | 1040219022 | Ron Parker | Shot 22: Disrupted at 0.92 s in the middle of the H-mode. Appears that something fell into the plasma to cause the disruption. |
| Feb 19 2004 04:12:24:090PM | 1040219023 | Ron Parker | Shot 23: Good shot. Nice long H-mode throughout the RF pulse. |
| Feb 19 2004 04:26:21:377PM | 1040219024 | Ron Parker | Shot 24: Made RCUR ramp inward after 1.5 s to push the plasma against the inner wall to prevent the disruption in the rampdown. Increased nl04 to 1.2 x 10^20 m^-2. Good shot. Disrupted earlier in the rampdown at 1.77 s. |
| Feb 19 2004 04:49:56:507PM | 1040219025 | Ron Parker | Shot 25: Adjusted ZXU and ZXL to reduce the elongation in the rampdown and ramped RCUR and RXL in a bit faster as well. Disrupted at 0.36 s. Plasma started down at 0.32 s and the bolometer also increased at that time. Apparently something fell into the plasma again. |
| Feb 19 2004 04:59:06:207PM | 1040219026 | Ron Parker | Shot 26: Repeat. Good shot, though it remained in L-mode even with 1.9 MW of RF. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 09:01:11:100AM | Plasma | Ok | |
| 2 | 09:12:33:433AM | Plasma | Ok | |
| 3 | 09:28:24:260AM | Plasma | Ok | |
| 4 | 09:44:36:303AM | Plasma | Ok | |
| 5 | 10:17:45:127AM | Plasma | Ok | |
| 6 | 10:32:25:043AM | Plasma | Ok | |
| 7 | 10:46:32:397AM | Plasma | Ok | |
| 8 | 10:59:36:173AM | Plasma | Ok | |
| 9 | 11:13:43:450AM | Plasma | Ok | |
| 10 | 11:27:30:523AM | Plasma | Ok | |
| 11 | 11:41:16:737AM | Plasma | Ok | |
| 12 | 11:57:40:263AM | Plasma | Ok | |
| 13 | 12:10:17:930PM | Plasma | Ok | |
| 14 | 12:25:55:850PM | Plasma | Ok | |
| 15 | 12:39:00:420PM | Plasma | Ok | |
| 16 | 12:57:39:590PM | Test | Bad | |
| 19 | 02:54:34:087PM | Test | Ok | data system test |
| 20 | 03:09:19:540PM | Plasma | Ok | |
| 21 | 03:25:56:990PM | Plasma | Ok | |
| 22 | 03:45:36:437PM | Plasma | Ok | |
| 23 | 04:03:51:030PM | Plasma | Ok | |
| 24 | 04:22:13:493PM | Plasma | Ok | |
| 25 | 04:41:57:337PM | Plasma | Ok | |
| 26 | 04:54:43:433PM | Plasma | Ok | |