| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Amanda Hubbard |
| Physics operator(s): | Joseph Snipes |
| Engineering operator(s): | Unknown |
| Engineering Operator Run Comment |
| Snipes/Silva |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:19:553PM |
| Author: To Be Determined |
| Session Leader's Summary for 990225 MP137B, Local Edge Threshold for H-mode Session Leader: Amanda Hubbard Physics Operator: Joe Snipes The purpose of the run was to carefully measure conditions just before the LH threshold in a range of conditions. We started with the standard 800 kA, 1.0e20 discharge for a reference (shots 2,3). Both scanning probe data and Bt sweeps were obtained shortly before the transition. A current scan was carried out at fixed density, up to 1.2 MA. This took several shots as we optimized the RF steps at each current. The RF behaved very well at the moderate powers required, following programmed step waveform. The LH threshold was at 1.2 MW RF at 1.0 MA (shots 4,5) and only 560 kW at 1.2 MW (shots 5-9). Again, L-mode Te profiles were obtained close to threshold. It appears there is a most a weak Ip dependence of the Te threshold. We will have to look more closely at this, since sawteeth have a significant effect. The remainder of the run consisted of a density scan at 1.2 MA. We got several high density points, up to nel=1.5 e20. A surprise was that even a small density increase, to 1.2e20, caused a large increase in the RF power required (to 1.75 MW from 0.5). This may have been related to the large gas fuelling required, and high neutral pressures. The threshold temperatures seemed quite constant with density. 2.2 MW was needed at the highest density (Shot 18). The RF delivered power well even at these levels, though more tuning would be required to couple through the very high density ELM-free H-modes which were obtained under these conditions (nel up to 3.1e20, nebar to 5e20!). We then attempted to explore the low density limit. However, shots 19 and 20 were fizzles, and shot 21 had higher density than requested (back to 1.0e20). Shot 22 had the lowest density, 0.8e20 for the first H-mode, and threshold power (350 kW). We evidently did not reach the low density limit, which will be a priority for future runs. Data were obtained on several edge diagnostics, including the soft x-rays and edge Thomson scattering, in both L and H-modes, which I haven't yet had the time or expertise to look at. We should have succeeded in obtaining some good L-H datasets. Given the ELM-free nature of the H-modes, H-L studies were not as systematic, but we did do power stepdowns and obtained plenty of back- transitions. All in all a fairly successful day, considering the late start. Many thanks to all those who braved the snow! Amanda |
| Physics Operator Summaries |
| Entered: Jul 7 2004 04:37:00:300PM |
| Author: To Be Determined |
| Engineering Setup for Thursday, 990225: 2 hours ECDC in D_2 shut off one hour before the run Power supply settings should be taken from 990224028 TF under hybrid control Gas setup - fill B-top with 6 psi of D2 Hybrid enabled fill B-side lower with 1 psi of Ar Hybrid enabled fill C-side with 30 psi of D2 Hybrid enabled The following gate valves should be enabled, assuming no vacuum problems: ECE Run plan We will start with a standard H-mode plasma at 0.8 MA, 5.3 T, and nl04 = 1 x 10^20 m^-2 with 2 MW of ICRF if available. Then, we will increase the current to 1.1 MA and then 1.2 MA. If decent H-modes are obtained, we will perform a density scan from a target density nl04 of 0.6 - 1.5 x 10^20 m^-2. The ICRF power will be stepped up in 0.25 MW steps lasting at least 75 msec each to look for the L-H transition, then the power will be stepped down in the same way to look for the H-L transition and determine the forward and back H-mode threshold powers. Detailed edge pedestal measurements will be made with ECE, soft x ray, and fast scanning probe diagnostics. Physop Summary Despite a slow start due to the alternator coming up late, the run went quite well. The machine ran very well with 20 good shots out of 22. The 2 fizzles were probably due to having too much gas in the machine after running a number of shots at relatively high density. One H-mode reached nebar = 5 x 10^20 m^-3 with gas puffing only. Not all of the miniproposal was achieved, but significant progress was made with a decent density scan at 1.2 MA. Lower and higher density points would be helpful to extend the range, but more RF power would be necessary for higher density and we needed more time to get the low density points. Edge Thomson data looked good according to Dmitri and so we can expect some good results from this run for pedestals and L-H and H-L transitions. Shot 1: Copied shot 990224028 then took out the TF blip for the ECE sweep and changed the density to nl04 = 1 x 10^20 m^-2. Delay due to snow this morning. Alternator is not up to speed. Delay probably till 10:00 am. Nice plasma. No RF. It seems they did not think that we wanted RF on that shot. Power room access for the RF to fix something. Shot 2: Repeat with RF. Good shot with H-modes. Shot 3: Ramped ZXL down by 1 cm from 0.5 to 1.22 sec to compensate for its apparent drift. Put in Bt tweak from 0.57 to 0.7 sec by 7 kA for ECE sweep. Removed Pulse Gas 5 gas puff even though the valve should be disabled. Good shot with H-modes. Shot 4: Raise Ip to 1 MA (programmed to 0.95 MA). Good shot with H-modes. There are several CAMAC problems on the GKA5 highway causing very strange mixups of signals including the main gas programming as well as the probes and the 2 pi bolometer. Short cell access to try to solve the CAMAC problems. Shot 5: Moved CLEARIN from -0.008 to -0.003 m from 0.4 to 0.52 sec to avoid hitting the inner wall at OH1 crossover. Removed Bt tweak for ECE. Extended Ip out to 1.2 sec at 1 MA. Good shot with H-modes. Shot 6: Extended Bt flattop out to 1.3 sec. Moved RCUR in by 2 mm from 0.6 to 1.2 sec. Moved CLEARIN in by 2 mm at the same time to increase the outer gap for the RF. Increased Ip to 1.2 MA. Good shot with H-modes. Shot 7: Increased CLEARIN by 3 mm throughout the flattop to increase both the inner and outer gaps. Took 5 msec off the Ar puff at Rice's request. Removed RCUR ramp and set the flattop value to 0.667 m. Good shot with several H-modes. Shot 8: Moved all waveforms out to 1.3 sec. Several had been left out of the previous flattop extension including RCUR, CLEARIN, and nl04. Also increased the rate of rise of the current early to try to reach 1.2 MA by at least 0.5 sec. Short cell access for diagnostics. Good shot with H-modes. Shot 9: Increased CLEARIN by 3 mm at OH1 crossover to try to avoid touching the inner wall between 0.4 and 0.5 sec. Good shot with 2 H-modes. Shot 10: Put in Bt tweak by 7 kA between 0.65 and 0.76 sec. Increased RCUR by 2 mm during the flattop and increased CLEARIN as well to decrease the outer gap for the RF. Good shot with several H-modes. Shot 11: Short cell access for diagnostics before this shot. nl04 raised to 1.2 x 10^20 m^-2. Good shot. No H-modes. Need more RF power. Shot 12: Repeat with more RF power. Good shot. Still not enough RF power to get the H-mode. Shot 13: Repeat with more RF power. Removed Bt tweak. Good shot. Several H-modes. Shot 14: Repeat with 7 kA Bt tweak from 0.57 to 0.76 sec. Good shot with several H-modes. Shot 15: Increase nl04 to 1.4 x 10^20 m^-2. Good shot. RF tripped. No H-modes. Shot 16: Reduced flattop to 1.2 sec on Ip and Bt. Put in a small upward ramp in Ip to keep the current flat at 1.2 MA. Good shot. H-mode in the ramp down. Shot 17: Repeat with more RF power. Good shot. H-mode. Shot 18: Raised nl04 to 1.6 x 10^20 m^-2. Moved ZCUR up by 4 mm during the flattop for Dmitri to check the edge Thomson data. Good shot. H-mode. Shot 19: Dropping nl04 to 0.8 x 10^20 m^-2. Fizzle! Shot 20: Reduced pre-puff by 3 msec to 16 msec. Reduced Bz by 15 A to -1295 A on EF4. Fizzle! Shot 21: Put the EF4 tweak back to -1280 A and put the gas back to 19 msec. Try again. Miklos left. Good shot. H-modes. Shot 22: Reduced nl04 to 6 x 10^19 m^-2 and reduced the gas preprogramming during the shot as well to get low density. Good shot. H-modes. Scorecard 22 shots 20 good plasmas 2 fizzles |
| Session Leader Comments | |||
| Feb 25 1999 10:37:07:390AM | 990225002 | Amanda Hubbard | Good threshold shot. RF 0.8, 1.0 and 1.2 MW, as requested. L-H at 1.0 MW, 0.68 secs. ELM-free H-modes. Next shot, repeat with probe scan and Bt sweep in L-mode phase, slightly higher RF in last step. |
| Feb 25 1999 11:00:24:793AM | 990225003 | Amanda Hubbard | Good threshold shot. RF 0.8, 1.0 and 1.4 MW, as requested. L-H came later, at 1.4 MW. ELM-free H-modes. Got two good L-mode Bt sweeps. Not sure about probe, it has CAMAC problems. |
| Feb 25 1999 11:25:25:107AM | 990225004 | Amanda Hubbard | 1 MA Good threshold shot. RF 0.8, 1.0 and 1.2 MW, as requested. L-H came later, at 1.2 MW. ELM-free H-modes. Got two good L-mode Bt sweeps. |
| Feb 25 1999 11:40:48:123AM | 990225005 | Amanda Hubbard | 1 MA Good threshold shot. RF 0 1.0, 1.2 and 1.5 MW. L-H came early in 1.2 MW step again. ELM-free H-modes. No Bt sweeps. Got F-port probe, still CAMAC problems on A-port. Next shot, going to 1.2 MW. |
| Feb 25 1999 12:28:41:357PM | 990225006 | Amanda Hubbard | 1.2 MA LH transition at first RF step, 1.0 MW. Lower RF to 800 kW for next shot. Outer gap rather small, Rsep 90.0 cm. Increasing gap for next shot. |
| Feb 25 1999 12:27:46:403PM | 990225007 | Amanda Hubbard | 1.2 MA LH transition at first RF step, 0.8 MW. Lower RF to 600 kW for next shot. 4 H-modes, apparently ELM-free or small ELMs. |
| Feb 25 1999 01:15:41:967PM | 990225008 | Amanda Hubbard | 1.2 MA Good shot. L-H transition still at first RF step, 650 kW. Lower further on next shot. |
| Feb 25 1999 01:12:03:140PM | 990225009 | Amanda Hubbard | 1.2 MA Got a nice threshold point this time, L-H at 0.56 MW RF. Next shot, repeat with Bt sweep added. |
| Feb 25 1999 01:28:05:483PM | 990225010 | Amanda Hubbard | 1.2 MA Good shot. L-H transition a little later, at 740 kW. Got 2 good L-mode Bt sweeps. Time to start the density scan. Next shot, 1.2e20 m-3 |
| Feb 25 1999 01:53:11:827PM | 990225011 | Amanda Hubbard | 1.2 MA, nel 1.15e20. Good shot., but requested RF of 700 kW was below threshold. Retune and increase to 1.4 MW for next shot. |
| Feb 25 1999 02:36:20:653PM | 990225012 | Amanda Hubbard | 1.2 MA, nel 1.2 e20. Good shot., but requested RF of 1.4 MW was still below threshold. Increase to 2 MW for next shot. |
| Feb 25 1999 02:37:02:793PM | 990225013 | Amanda Hubbard | 1.2 MA, nel 1.2 e20. Got H-mode at 1.7 MW. Lots of trips once in H-mode. Retune and try again. |
| Feb 25 1999 02:47:26:873PM | 990225014 | Amanda Hubbard | 1.2 MA, nel 1.2 e20. Got H-mode at 1.3 MW (earlier). Still tripping in H-mode. Very high H-mode densities are causing cutoff on ECE late in H-mode. |
| Feb 25 1999 03:47:03:733PM | 990225016 | Amanda Hubbard | 1.2 MA, nel 1.35 e20. No H-mode until Bt rampdown, despite 1.75 MW RF. Threshold seems high, note we are puffing D hard. Neutrals?? |
| Feb 25 1999 03:44:16:450PM | 990225017 | Amanda Hubbard | 1.2 MA, nel 1.35 e20. Good threshold point, L-H at 0.93 secs, 1.75 MW. Steve thinks he can do even more, so raising density and power again for next shot. |
| Feb 25 1999 03:47:39:763PM | 990225017 | Amanda Hubbard | 1.2 MA, nel 1.35 e20. Good threshold point, L-H at 0.93 secs, 2.2 MW. Steve thinks he can do even more, so raising density and power again for next shot. |
| Feb 25 1999 04:28:12:153PM | 990225018 | Amanda Hubbard | 1.2 MA, nel 1.5 e20. Good threshold point at 1.08 s 2.2 MW. H-mode gets to very high densities, nel 3.1 e20, neber 5e20. ECE is, of course, cut off. For next shots we will scan DOWN in density, towards low ne limit. |
| Feb 25 1999 04:50:42:687PM | 990225021 | Amanda Hubbard | 1.2 MA, wanted nel=0.8e20, got nel 1.0 e20. Good threshold point at 0.55 MW. Try for lower density on next shot |
| Feb 25 1999 05:01:43:060PM | 990225022 | Amanda Hubbard | Density 0.8-1.0e20, several transitions, earliest at 350 kW. Must be the minimum of the density curve. |
| Physics Operator Comments | |||
| Feb 25 1999 08:20:25:170AM | Joseph Snipes | Engineering Setup for Thursday, 990225: 2 hours ECDC in D_2 shut off one hour before the run Power supply settings should be taken from 990224028 TF under hybrid control Gas setup - fill B-top with 6 psi of D2 Hybrid enabled fill B-side lower with 1 psi of Ar Hybrid enabled fill C-side with 30 psi of D2 Hybrid enabled The following gate valves should be enabled, assuming no vacuum problems: ECE Run plan We will start with a standard H-mode plasma at 0.8 MA, 5.3 T, and nl04 = 1 x 10^20 m^-2 with 2 MW of ICRF if available. Then, we will increase the current to 1.1 MA and then 1.2 MA. If decent H-modes are obtained, we will perform a density scan from a target density nl04 of 0.6 - 1.5 x 10^20 m^-2. The ICRF power will be stepped up in 0.25 MW steps lasting at least 75 msec each to look for the L-H transition, then the power will be stepped down in the same way to look for the H-L transition and determine the forward and back H-mode threshold powers. Detailed edge pedestal measurements will be made with ECE, soft x ray, and fast scanning probe diagnostics. | |
| Feb 25 1999 08:22:35:513AM | 990225001 | Joseph Snipes | Shot 1: Copied shot 990224028 then took out the TF blip for the ECE sweep and changed the density to nl04 = 1 x 10^20 m^-2. Physop is ready, but there is a delay due to snow?! according to Frank Silva. |
| Feb 25 1999 08:25:09:500AM | 990225001 | Joseph Snipes | Shot 1: Copied shot 990224028 then took out the TF blip for the ECE sweep and changed the density to nl04 = 1 x 10^20 m^-2. Alternator is not up to speed. Delay probably till 10:00 am. |
| Feb 25 1999 10:02:42:623AM | 990225001 | Joseph Snipes | Shot 1: Copied shot 990224028 then took out the TF blip for the ECE sweep and changed the density to nl04 = 1 x 10^20 m^-2. Alternator is not up to speed. Delay probably till 10:00 am. Nice plasma. No RF. It seems they did not think that we wanted RF on that shot. Power room access for the RF to fix something. |
| Feb 25 1999 10:29:55:983AM | 990225002 | Joseph Snipes | Shot 2: Repeat with RF. Good shot with H-modes. |
| Feb 25 1999 10:42:44:483AM | 990225003 | Joseph Snipes | Shot 3: Ramped ZXL down by 1 cm from 0.5 to 1.22 sec to compensate for its apparent drift. Put in Bt tweak from 0.57 to 0.7 sec by 7 kA for ECE sweep. Removed Pulse Gas 5 gas puff even though the valve should be disabled. Good shot with H-modes. |
| Feb 25 1999 11:04:47:373AM | 990225004 | Joseph Snipes | Shot 4: Raise Ip to 1 MA (programmed to 0.95 MA). Good shot with H-modes. There are several CAMAC problems on the GKA5 highway causing very strange mixups of signals including the main gas programming as well as the probes and the 2 pi bolometer. Short cell access to try to solve the CAMAC problems. |
| Feb 25 1999 11:28:25:013AM | 990225005 | Joseph Snipes | Shot 5: Moved CLEARIN from -0.008 to -0.003 m from 0.4 to 0.52 sec to avoid hitting the inner wall at OH1 crossover. Removed Bt tweak for ECE. Extended Ip out to 1.2 sec at 1 MA. Good shot with H-modes. |
| Feb 25 1999 11:56:52:170AM | 990225006 | Joseph Snipes | Shot 6: Extended Bt flattop out to 1.3 sec. Moved RCUR in by 2 mm from 0.6 to 1.2 sec. Moved CLEARIN in by 2 mm at the same time to increase the outer gap for the RF. Increased Ip to 1.2 MA. Good shot with H-modes. |
| Feb 25 1999 12:08:06:857PM | 990225007 | Joseph Snipes | Shot 7: Increased CLEARIN by 3 mm throughout the flattop to increase both the inner and outer gaps. Took 5 msec off the Ar puff at Rice's request. Removed RCUR ramp and set the flattop value to 0.667 m. Good shot with several H-modes. |
| Feb 25 1999 12:37:51:030PM | 990225008 | Joseph Snipes | Shot 8: Moved all waveforms out to 1.3 sec. Several had been left out of the previous flattop extension including RCUR, CLEARIN, and nl04. Also increased the rate of rise of the current early to try to reach 1.2 MA by at least 0.5 sec. Short cell access for diagnostics. Good shot with H-modes. |
| Feb 25 1999 01:04:55:780PM | 990225009 | Joseph Snipes | Shot 9: Increased CLEARIN by 3 mm at OH1 crossover to try to avoid touching the inner wall between 0.4 and 0.5 sec. Good shot with 2 H-modes. |
| Feb 25 1999 01:17:00:123PM | 990225010 | Joseph Snipes | Shot 10: Put in Bt tweak by 7 kA between 0.65 and 0.76 sec. Increased RCUR by 2 mm during the flattop and increased CLEARIN as well to decrease the outer gap for the RF. Good shot with several H-modes. |
| Feb 25 1999 01:43:08:077PM | 990225011 | Joseph Snipes | Shot 11: Short cell access for diagnostics before this shot. nl04 raised to 1.2 x 10^20 m^-2. Good shot. No H-modes. Need more RF power. |
| Feb 25 1999 02:09:57:763PM | 990225012 | Joseph Snipes | Shot 12: Repeat with more RF power. Good shot. Still not enough RF power to get the H-mode. |
| Feb 25 1999 02:23:24:560PM | 990225013 | Joseph Snipes | Shot 13: Repeat with more RF power. Removed Bt tweak. Good shot. Several H-modes. |
| Feb 25 1999 02:38:22:153PM | 990225014 | Joseph Snipes | Shot 14: Repeat with 7 kA Bt tweak from 0.57 to 0.76 sec. Good shot with several H-modes. |
| Feb 25 1999 02:55:47:623PM | 990225015 | Joseph Snipes | Shot 15: Increase nl04 to 1.4 x 10^20 m^-2. Good shot. RF tripped. No H-modes. |
| Feb 25 1999 03:13:16:513PM | 990225016 | Joseph Snipes | Shot 16: Reduced flattop to 1.2 sec on Ip and Bt. Put in a small upward ramp in Ip to keep the current flat at 1.2 MA. Good shot. H-mode in the ramp down. |
| Feb 25 1999 03:34:16:187PM | 990225017 | Joseph Snipes | Shot 17: Repeat with more RF power. Good shot. H-mode. |
| Feb 25 1999 03:49:32:013PM | 990225018 | Joseph Snipes | Shot 18: Raised nl04 to 1.6 x 10^20 m^-2. Moved ZCUR up by 4 mm during the flattop for Dmitri to check the edge Thomson data. Good shot. H-mode. |
| Feb 25 1999 04:17:14:763PM | 990225019 | Joseph Snipes | Shot 19: Dropping nl04 to 0.8 x 10^20 m^-2. Fizzle! |
| Feb 25 1999 04:47:50:107PM | 990225020 | Joseph Snipes | Shot 20: Reduced pre-puff by 3 msec to 16 msec. Reduced Bz by 15 A to -1295 A on EF4. Fizzle! |
| Feb 25 1999 04:39:43:217PM | 990225021 | Joseph Snipes | Shot 21: Put the EF4 tweak back to -1280 A and put the gas back to 19 msec. Try again. Miklos left. Good shot. H-modes. |
| Feb 25 1999 04:57:57:780PM | 990225022 | Joseph Snipes | Shot 22: Reduced nl04 to 6 x 10^19 m^-2 and reduced the gas preprogramming during the shot as well to get low density. Good shot. H-modes. |
| Feb 25 1999 05:07:43:420PM | 990225022 | Joseph Snipes | Physop Summary Despite a slow start due to the alternator coming up late, the run went quite well. The machine ran very well with 20 good shots out of 22. The 2 fizzles were probably due to having too much gas in the machine after running a number of shots at relatively high density. One H-mode reached nebar = 5 x 10^20 m^-3 with gas puffing only. Not all of the miniproposal was achieved, but significant progress was made with a decent density scan at 1.2 MA. Lower and higher density points would be helpful to extend the range, but more RF power would be necessary for higher density and we needed more time to get the low density points. Edge Thomson data looked good according to Dmitri and so we can expect some good results from this run for pedestals and L-H and H-L transitions. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 09:56:00:013AM | Plasma | Ok | no faults/plasma |
| 2 | 10:19:37:577AM | Plasma | Ok | no faults/plasma |
| 3 | 10:37:04:233AM | Plasma | Ok | no faults/plasma |
| 4 | 10:57:23:840AM | Plasma | Ok | no faults/plasma |
| 5 | 11:26:47:670AM | Plasma | Ok | no faults/plasma |
| 6 | 11:47:45:513AM | Plasma | Ok | no faults/plasma |
| 7 | 12:06:34:903PM | Plasma | Ok | No Faults / Plasma |
| 8 | 12:34:39:543PM | Plasma | Ok | No Faults / Plasma |
| 9 | 12:52:43:060PM | Plasma | Ok | No Faults / Plasma |
| 10 | 01:15:31:030PM | Plasma | Ok | No Faults / Plasma |
| 11 | 01:37:20:920PM | Plasma | Ok | No Faults / Plasma |
| 12 | 02:02:44:950PM | Plasma | Ok | No Faults / Plasma |
| 13 | 02:21:23:717PM | Plasma | Ok | No Faults / Plasma |
| 14 | 02:36:15:357PM | Plasma | Ok | No Faults / Plasma |
| 15 | 02:50:24:983PM | Plasma | Ok | No Faults / Plasma |
| 16 | 03:08:20:827PM | Plasma | Ok | No Faults / Plasma |
| 17 | 03:30:32:293PM | Plasma | Ok | No Faults / Plasma |
| 18 | 03:46:23:763PM | Plasma | Ok | No Faults / Plasma |
| 19 | 04:07:13:077PM | Plasma | Ok | No Faults / Plasma |
| 20 | 04:22:53:030PM | Plasma | Ok | No Faults / Plasma |
| 21 | 04:37:46:763PM | Plasma | Ok | No Faults / Plasma |
| 22 | 04:51:27:373PM | Plasma | Ok | No Faults / Plasma |