| Miniproposals | ||||||||||
|
| Operators | |
| Session leader(s): | Brian Labombard |
| Physics operator(s): | Ron Parker |
| Engineering operator(s): | Unknown |
| Engineering Operator Run Comment |
| MP 267 Dependence of SOL Fluctuations and Particle Transport on Collisio |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:25:150PM |
| Author: To Be Determined |
| MP#267 - reversed field "Dependence of SOL Fluctuations and Particle Transport on Collisionality" - reversed field, Day 1 Session Leader - B. LaBombard Phys Op - R. Parker ============================================================================== Overall objectives of MP#267: "The purpose of these experiments is to explore the dependence of SOL fluctuation characteristics and attendant cross-field particle transport on the collisionality of the SOL." Reason for today's run: Reversed field/current allows some important measurements to be made on particle transport in the SOL and the associated levels of plasma turbulence. From a series of shots over ~2 run days we hope to do the following: (1) get data on SOL particle transport (using Ly-alpha diag.) in reversed field. Does the field direction affect the 'scaling' of Deff with collisionality? (2) get data on in-out asymmetries. The outer divertor conditions should change in reversed B. This may impact (1) through changes in the sheath conditions at the divertor plate (e.g., affecting the propagation velocity of the 'blobs' if they somehow involve the 'sheath impedance' via a theory such as that outlined recently by S. Krasheninnikov) (3) get data on field-reversed C2D4 plumes. ExB should now carry the plume away from the probe shaft, resulting in plumes that may be easier to interpret. The 'reversed flows' associated with low collisionality near the separatrix should now become 'normal flows' with reversed B. This should be interesting for the plumes. The magnitude of Er in reversed B is of interest also. (4) get fluctuation data from scanning probe and fast diodes systems. Is the SOL plasma fluctuation character the same in reversed B? Today's run was to cover the Day 1 plan outlined in MP#267: Day 1 (today): Fine density scan at fixed plasma current (0.8 MA) and toroidal field (5.3 tesla). Results: This was another head-banging day for the Phys. Op. We only got 9 usable plasmas today, but of these only the last 4 shots had good probe targeting with reasonable data. But, the machine seems to be coming back on line and we hope to get a good run day tomorrow. We managed to get a very rough density scan: NL04 ~1.0, ~.8, ~.6 In-out divertor asymmetries showed the usual reversal in the lower density plasmas. Parallel flows (mach probes) also showed the expected reversal. Sanjay's plumes seemed to reverse also on some shots but the reversal was not as clean as expected and suggests that the probe shaft may be interfering with the ExB flows and the resultant impurity dispersal. The East probe (or its coaxial cable) on the ASP appears to be failing. The probe often exhibited an intermittent short-circuit behavior in the high g-force time of the scan. This artifact will complicate the analysis for sure. Shot notes: FSP setup: N, S in Vf mode, E-W in double probe sweep mode ASP setup: N, S in Vf mode, E,W in single probe sweep mode FSP and ASP always scanning at .7, .95 and 1.2 sec Shot 1 - Inner limited plasma, no probes scanning Shot 2 - Diverted plasma. NL04 ~ 1e20 Note: intermittent shorts seen on ASP East probe - this could be a problem today. Shot 4 - Diverted plasma. NL04 ~ 1e20 Still see shorts on ASP Shot 11 - NL04 ~ 1e20 C2D4 on on this shots and for the remainder of the run to generate 'plumes' Not as many shorts on ASP - running with reduced bias voltage. Shot 15 - NL04 ~ 1e20 ASP - running with reduced bias voltage. Got some data on FSP and ASP. Still they appear to be outside separatrix. Shot 17 - NL04 ~ 1e20 ASP - running with reduced bias voltage. Got some good data on FSP and ASP. Still some shorts on the east probe. SSEP is now around 2 cm and E-top pressures are now below 0.7 mtorr. Shot 18 - NL04 ~ 0.7e20 ASP - running with reduced bias voltage. Got some good data on FSP and ASP. Many shorts on the ASP east probe. Shot 19 - NL04 ~ 0.8e20 ASP - running with reduced bias voltage. Got some good data on FSP and ASP. Some shorts on the ASP east probe. Shot 20 - NL04 ~ 0.6 ramping to 0.7 ASP - running with reduced bias voltage. Got some good data on FSP and ASP. Again, shorts on the ASP east probe. |
| Physics Operator Summaries |
| Entered: Jul 7 2004 04:37:12:583PM |
| Author: To Be Determined |
| RUN PLAN: SL LaBombard PO Parker MP 267 Dependence of SOL Fluctuations and Particle Transport on Collisionality now with reversed (positive) toroidal field and plasma current overnight discharge cleaning in D_2, stopping 2 hours before the run. Run begins at 9:00 and ends at 17:00. Cell will close at 7:30AM Power system setup as on 1001012017 Gas setup - fill B-top with 6 psi of D2 Hybrid enabled fill B-side lower with 1 psi of Ar Hybrid enabled fill B-side upper with 35 psi of D2 Hybrid DISABLED (for ECDC) fill C-side with 30 psi of D2 Hybrid enabled leave J-bottom as is Hybrid DISABLED The following gate valves should be enabled, assuming no vacuum problems: ECE, VUV, NPA (aka Beast) This will be an ohmic run; RF is not required though it may do coupling studies The purpose of these experiments is to explore the dependence of SOL fluctuation characteristics and attendent cross-field particle transport on the collisionality of the SOL. The key diagnostics which must be operational for this study are: (a) A-port and F-port scanning probes operated in a fluctuation mode (The A-port probe will be used in both a spatially scanning and a fixed position mode.), (b) divertor probes operated in a fluctuation mode, (c) fast visible diodes viewing helium puffed from the A/B limiter capillary, (d) tangential Ly-alpha diode array, (e) limiter particle flux probes, and (f) edge thomson scattering. Day 1: Fine density scan at fixed plasma current (0.8 MA) and toroidal field (5.3 T). Start with a reload of 1001012017. Shot 1-3 NL01 = 1 x 10^20 m^-2 Setup equilibrium and FSP/ASP target Begin density scan with two shots at each density. Alternate between A-port probe in scanning and fixed location modes Shot 4,5 NL01 = 1.0 6,7 NL01 = 0.9 8,9 NL01 = 0.8 10,11 NL01 = 0.7 12,13 NL01 = 0.6 14,15,16 NL01 = 1.1 17,18 NL01 = 1.2 19,20 NL01 = 1.3 21,22 NL01 = 1.4 repeat shots as needed to get good diagnostic data. RUN SUMMARY The run continued the attempts of the previous day to establish Reversed Field discharges. These attempts had failed as all shots had either fizzled or were duds. Therefore expectations were not high for this run. Remarkably, the first two shots succeeded even though the last unsuccessful shot of the previous run had been loaded (with a minor tweak of Br suggested by IHH). The next shot fizzled, but the 4th shot ran so it seemed that the reversed field shots were on track. However, this turned out not to be the case as there then followed six shots which were either duds or fizzles. The tuning of the startup phase became unstable and the PO decided to return to what had worked, namely shot 2. The shot (11) ran OK but we were not out of the woods as the next 3 shots fizzled. ECH cleaning was done in between shots for these fizzles, but in view of the fact that the shots were unsuccessful, it was decided to abandon it. Shot 15 then ran, shot 16 fizzled, but then came a string of successful shots, namely 17-20. Finally, the last shot of the day, shot 21, fizzled. Nevertheless it appears that the machine is cleaning up and hopefully will run well in the reversed field mode tomorrow (1001103). Two problems did develop during the run: a nitrogen leak at F-Port (Hor) and a slow rep rate apparently caused by slowing the cooling (in deference to control- ling the leak) and possibly by instrumentation. Post run, the F-Port flange was torqued and the leak rate reduced by a factor of 5. So overall, not a great day, better than yesterday but hopefully not as good as tomorrow will be. |
| Session Leader Comments | |||
| Nov 2 2000 09:39:03:360AM | Brian Labombard | MP#267 - reversed field "Dependence of SOL Fluctuations and Particle Transport on Collisionality" - reversed field, Day 1 Session Leader - B. LaBombard Phys Op - R. Parker ============================================================================== Overall objectives of MP#267: "The purpose of these experiments is to explore the dependence of SOL fluctuation characteristics and attendant cross-field particle transport on the collisionality of the SOL." Reason for today's run: Reversed field/current allows some important measurements to be made on particle transport in the SOL and the associated levels of plasma turbulence. From a series of shots over ~2 run days we hope to do the following: (1) get data on SOL particle transport (using Ly-alpha diag.) in reversed field. Does the field direction affect the 'scaling' of Deff with collisionality? (2) get data on in-out asymmetries. The outer divertor conditions should change in reversed B. This may impact (1) through changes in the sheath conditions at the divertor plate (e.g., affecting the propagation velocity of the 'blobs' if they somehow involve the 'sheath impedance' via a theory such as that outlined recently by S. Krasheninnikov) (3) get data on field-reversed C2D4 plumes. ExB should now carry the plume away from the probe shaft, resulting in plumes that may be easier to interpret. The 'reversed flows' associated with low collisionality near the separatrix should now become 'normal flows' with reversed B. This should be interesting for the plumes. The magnitude of Er in reversed B is of interest also. (4) get fluctuation data from scanning probe and fast diodes systems. Is the SOL plasma fluctuation character the same in reversed B? Today's run was to cover the Day 1 plan outlined in MP#267: Day 1 (today): Fine density scan at fixed plasma current (0.8 MA) and toroidal field (5.3 tesla). | |
| Nov 2 2000 09:35:22:090AM | 1001102001 | Brian Labombard | Shot 1 - Inner limited plasma, no probes scanning Next shot - get diverted plasma and scan probes into far SOL to test systems. |
| Nov 2 2000 10:53:39:607AM | 1001102002 | Brian Labombard | Shot 2 - Diverted plasma. NL04 ~ 1e20 FSP setup: N, S in Vf mode, E-W in double probe sweep mode ASP setup: N, S in Vf mode, E,W in single probe sweep mode FSP and ASP scanning at .7, .95 and 1.2 sec in FAR sol Note: intermittant shorts seen on ASP East probe - this could be a problem today. Next shot - decrease outer gap, lower x-point by 5 mm and increase negative ramp on ZXL by 5 mm, also scan probes deeper |
| Nov 2 2000 10:55:29:860AM | 1001102004 | Brian Labombard | Shot 4 - Diverted plasma. NL04 ~ 1e20 FSP and ASP scanning at .7, .95 and 1.2 sec in FAR sol Still see shorts on ASP Next shot - lower x-point again by 5 mm and also in by 5 mm Turn C2D4 on for 'plumes' |
| Nov 2 2000 01:10:01:437PM | 1001102011 | Brian Labombard | Shot 11 - NL04 ~ 1e20 FSP and ASP scanning at .7, .95 and 1.2 sec in FAR sol Not as many shorts on ASP - running with reduced bias voltage. Next shot - repeat with plumes and deeper ASP/FSP insertion also try to increase SSEP by moving upper x-point up |
| Nov 2 2000 04:30:34:217PM | 1001102015 | Brian Labombard | Shot 15 - NL04 ~ 1e20 FSP and ASP scanning at .7, .95 and 1.2 sec ASP - running with reduced bias voltage. Got some data on FSP and ASP. Still they appear to be outside separatrix. Next shot - repeat with plumes and deeper ASP/FSP insertion again try to increase SSEP by moving upper x-point up |
| Nov 2 2000 04:30:17:077PM | 1001102017 | Brian Labombard | Shot 17 - NL04 ~ 1e20 FSP and ASP scanning at .7, .95 and 1.2 sec ASP - running with reduced bias voltage. Got some good data on FSP and ASP. Still some shorts on the east probe. SSEP is now around 2 cm and E-top pressures are now below 0.7 mtorr. Next shot - go to NL04 ~ 0.7 otherwise the same. |
| Nov 2 2000 04:29:55:170PM | 1001102018 | Brian Labombard | Shot 18 - NL04 ~ 0.7e20 FSP and ASP scanning at .7, .95 and 1.2 sec ASP - running with reduced bias voltage. Got some good data on FSP and ASP. Many shorts on the ASP east probe. Next shot - repeat with FSP in far SOL |
| Nov 2 2000 04:29:32:920PM | 1001102019 | Brian Labombard | Shot 19 - NL04 ~ 0.8e20 FSP and ASP scanning at .7, .95 and 1.2 sec ASP - running with reduced bias voltage. Got some good data on FSP and ASP. Some shorts on the ASP east probe. Next shot - go to NL04 ~ 0.5 |
| Nov 2 2000 04:57:19:640PM | 1001102020 | Brian Labombard | Shot 20 - NL04 ~ 0.6 ramping to 0.7 FSP and ASP scanning at .7, .95 and 1.2 sec ASP - running with reduced bias voltage. Got some good data on FSP and ASP. Again, shorts on the ASP east probe. Next shot - repeat with FSP scanning ~10 mm outside LCFS |
| Nov 2 2000 05:14:10:780PM | 1001102021 | Brian Labombard | Shot 21 - Fizzle |
| Physics Operator Comments | |||
| Nov 2 2000 09:21:11:123AM | 1001102001 | Ron Parker | We are attempting to run with reversed field and starting with conditions similar to shot 1001101034. For the first shot, the Br will be increased by 0.5 mT. Remarkably, the shot ran, presumably due to the presence and/or suggestions of of IHH. |
| Nov 2 2000 09:35:46:390AM | 1001102001 | Ron Parker | Next shot will have similar startup conditions, except the fill pressure will be lowered to .06 mT. The offset for clearin has been chnged in sign, from -12700 to 12700 to bring the discharge off the inner wall. |
| Nov 2 2000 10:08:16:390AM | 1001102002 | Ron Parker | Shot 2 ran well. Fill pressure was not reduced significantly. Next shot: Outer gap decreased by 5 mm and X-point lowered by 5 mm. No change in startup settings. |
| Nov 2 2000 10:25:02:860AM | 1001102003 | Ron Parker | Shot 3 fizzled for no apparent reason. For next shot, the fill will be lowered. |
| Nov 2 2000 05:48:30:077PM | 1001102004 | Ron Parker | Shot 4 ran OK, although with a hesitation on the current rise. |
| Nov 2 2000 05:53:03:543PM | 1001102004 | Ron Parker | |
| Nov 2 2000 11:13:09:717AM | 1001102005 | Ron Parker | Shot 5 had minor tweaks set for shape and position, but fizzled. IHH Takes over for RP as PO for ~ 1 hour. |
| Nov 2 2000 11:32:19:780AM | 1001102006 | Ian Hutchinson | Fizzle. Lower EF4 to 1315 from 1325A. Br offset to .0017 from .0012 Load. Shut down Parker's PCS. Start my own. Implement between shots ECDC. |
| Nov 2 2000 12:28:05:483PM | 1001102007 | Ian Hutchinson | Fizzle. Load seg 1 from 1000330026. Call RCUR and ZCUR predictors. Load. |
| Nov 2 2000 12:27:51:497PM | 1001102008 | Ian Hutchinson | Fizzle. Breakdown at 10ms Br was too negative by about 1.5mT Raise Br offset from -2.5 to -2mT. Fill puff to 20ms from 18. Load. Close PCS. |
| Nov 2 2000 12:23:01:297PM | 1001102009 | Steve Wolfe | Wolfe in for Hutch who was in for Parker. Shot#9 was loaded by hutch, with a Br and gas tweak on #8, which was reloaded (seg 1) from 1000330026. Note: IC_oh1=19000 IC_oh2=27500 IC_ef1=5800 IC_ef4=1310 Br0=-.001 (was -.0025) pg4 = 20msec (was 18) Result: dud? fields look ok. next shot: raise fill by 2 more msec. |
| Nov 2 2000 12:38:40:607PM | 1001102010 | Steve Wolfe | shot 10: another dud. Parker will now be back in the chair; he will reload seg 1 from shot #2 for shot 11 |
| Nov 2 2000 01:06:06:043PM | 1001102011 | Ron Parker | For some strange reason, the shot went breaking a string of fizzles and duds. We'll try this shot again. Also restart ECDC between shots. Note that RF is pigyybacking at the end of the shot, probably causing its disruptive end. |
| Nov 2 2000 01:38:41:437PM | 1001102012 | Ron Parker | Shot 12 fizzled, again for no apparent reson when the startup is compared to shot 11. I suspect the problem is with wall conditions and impurities during the startup phase. CII is a little higher during the early current ramp. Next shot: repeat of shot 12 setup conditions. We'll continue ECDC between shots. |
| Nov 2 2000 02:00:38:967PM | 1001102013 | Ron Parker | Shot 13 was another fizzle. ECDC doesn't seem to help. Next shot unchanged except for fill pressure -- pulse reduced by 2 msec. |
| Nov 2 2000 02:19:23:997PM | 1001102014 | Ron Parker | Shot 14 was a fizzle (again). ECDC will be stopped. Added 0.5 mT to BR offset. |
| Nov 2 2000 02:47:10:983PM | 1001102015 | Ron Parker | Shot 15 ran. Minor tweaks for next shot. Breakdown pressure for this shot was lower ~.05 mT. this presumably helps startup. Upper X-Point will be moved 5mm up for next shot. |
| Nov 2 2000 03:13:50:263PM | 1001102016 | Ron Parker | Shot 16 was a fizzle. No obvious problem except possibly during burnout. Try again on shot 17. |
| Nov 2 2000 03:35:24:170PM | 1001102017 | Ron Parker | Shot ran. Density ramp was slowed to reduce early MARFE. For next shot, density will be reduced to 0.7e14. |
| Nov 2 2000 04:05:10:810PM | 1001102018 | Ron Parker | Shot 18 ran--two in a row! We'll try again without changes. |
| Nov 2 2000 04:37:19:857PM | 1001102019 | Ron Parker | Shot ran as programmmed. Next shot: density lowered to 0.5e20. |
| Nov 2 2000 04:59:43:967PM | 1001102020 | Ron Parker | Shot ran well again. Density was a little higher than programmed. Next and last shot will be a repeat. |
| Nov 2 2000 05:18:15:763PM | 1001102021 | Ron Parker | Shot 21 fizzled. It could be that the BR offset was too high, perhaps by 0.5 mT. Suggest lowering it from 2 mT to 1.5 mT. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 09:18:33:077AM | Plasma | Ok | |
| 2 | 09:48:39:937AM | Plasma | Ok | |
| 3 | 10:10:08:403AM | Plasma | Ok | |
| 4 | 10:28:34:437AM | Plasma | Ok | |
| 5 | 10:54:30:543AM | Plasma | Ok | |
| 6 | 11:13:23:327AM | Plasma | Ok | |
| 7 | 11:33:25:343AM | Plasma | Ok | |
| 8 | 11:53:04:217AM | Plasma | Ok | |
| 9 | 12:13:12:997PM | Plasma | Ok | |
| 10 | 12:33:58:623PM | Plasma | Ok | |
| 11 | 12:53:55:997PM | Plasma | Ok | |
| 12 | 01:23:15:217PM | Plasma | Ok | |
| 13 | 01:45:33:670PM | Plasma | Ok | |
| 14 | 02:08:40:403PM | Plasma | Ok | |
| 15 | 02:30:28:373PM | Plasma | Ok | |
| 16 | 02:56:35:920PM | Plasma | Ok | |
| 17 | 03:23:22:280PM | Plasma | Ok | |
| 18 | 03:49:24:937PM | Plasma | Ok | |
| 19 | 04:15:37:890PM | Plasma | Ok | |
| 20 | 04:44:59:247PM | Plasma | Ok | |
| 21 | 05:11:08:013PM | Plasma | Ok | |