| Miniproposals | ||||||||||
|
| Operators | |
| Session leader(s): | Amanda Hubbard |
| Physics operator(s): | Joseph Snipes |
| Engineering operator(s): | Frank Silva |
| Engineering Operator Run Comment |
| h mode snipes |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:15:023PM |
| Author: To Be Determined |
From: LEADER::HUBBARD Date: 26-JAN-1996 17:35:23 Subj: Session Leader's Summary, 960126 Run summary for 960126 MP137 "Edge Threshold for H-mode" Run Plan: This run plans to do a controlled scan of density and current, with RF powers stepped up gradually so as to find the global and local H-mode thresholds. We are looking for well diagnosed conditions at the threshold, not necessarily long or record-breaking H-modes. All going well, the run will proceed as follows: a) Density scan at 800 kA, from lower density threshold to upper density limit. b) Repeat at 600 kA, with fewer densities. c) Repeat scan at 1.1 MA (or 1 MA if we have operational trouble). d) Several reproducible shots at 800 kA, 10^20 m-2, to scan ECE grating and other diagnostics to get detailed profiles. Try to get scanning probe in too. How it really went: Overall, the run was quite successful. The main accompishments were a) and d). We got a nice density scan at fixed 800 kA equilibrium. (shots 3-19) A quick analysis confirms that Te at the 95% surface is always close to 200 eV at the L-H transition, with density varying over a factor of two. The behaviour at the H-L threshold is less clear. One of the most interesting aspects is that we managed to 'catch' the low density limit on Shot 8 - the power threshold climbs steeply for nel= 6e19. Shortly before the transition, the radiated power started dropping and edge Te rose to the threshold. Shots 7 and 11 were similar but did not enter H-mode. These may shed some light on the causes of the low density limit. We experienced a lot of difficulty getting 600 kA discharges for the low current scan (see physop summary). After some time we decided to skip this and go to 1.1 MA. These ran well - we only had time for points at 1.0 and 1.15 e20 m-2. (Shots 26-28) It does seem that the edge temperature at threshold is higher at this Ip. Returning to 800 kA, we repeated shot 4 twice more (29, 31). Brian succeeded in getting probe scans both in H-mode and just before the transition. We also moved the GPC channels to get more profile points. With a bit of luck and analysis we should be able to match up our Te and ne profiles for the first time on ICRF shots. Shot 1: Disrupts 200 ms - EFC problem. Shot 2: Good fiducial - no moly monitor. Shot 3: Good shot. 800 kA, 10^20 m-2. Not quite the right outer gap. Shot 4: Good threshold shot at 800 kA, 10^20. Hmode transition at 745 ms, 750 kW. 1st shot of scan. Shot 5: Good threshold point at 800 kA, 9 x 10^19m-2 Transition at 754 ms, 750 kW. Shot 6: Good threshold point at 800 kA, 7 x 10^19m-2 Transition at 768 ms, 1.2 MW. Also an ohmic H-mode at 349 ms. Shot 7: Nel 6e19 m-2. No H-mode with 1.5 MW. Must be below low ne limit. Shot 8: Ne; 6e19 m-2. Goes to H-mode at 952 ms, with 1.8 MW. We must be on the upwards curve of the low ne threshold. Interesting shot, in that Prad decreases and edge Te increases shortly BEFORE the transition. Shot 9: Disrupts 280 ms. Shot 10 Fizzle. Shot 11: nel 5.6 e19. No H-mode with 1.75 MW RF. Shot 12: Fizzle Shot 14: 1.2 e 20 m-2. RF tuning poor - no H-mode. Shot 15: Fizzle. Shot 16: Vertical disruption 0.4 secs. Shot 17: Good transition at 1.3 e20 m-2, 1.5 MW (827 ms). Shot 18: Good shot. 1.5 e20 m-2. No H-mode with 1.5 MW. Shot 19: Good shot. 1.5 e20 m-2. No H-mode with 1.9 MW. Since this is about the maximum power available today, declare the 800 kA density scan complete. Shot 20: Attempt 600 kA, 10^20 m-2. Disrupts ~250 ms. Shot 21: Similar. Shot 22: Another disruption, with an injection. Shot 23: Fiducial - ran well. Shot 24: Fizzle Shot 25: Disrupts 260 ms. Shot 26: 1.1 MA, 1.0 e20. Nice H-mode threshold (but bad disruption) Shot 27: Repeat with changes in outer gap and GPC position. Good threshold point (and nice rampdown) Shot 28: 1.1 MA, 1.15e20. Good transition, but getting cutoff as ne rises. Shot 29: Repeat shot 4, 800 kA, 1e20. Brian got probe in just after RF pulse (ELMy H-mode) Shot 30: Disrupts 0.3 sec. Shot 31: Repeat again. Probe inserted 0.7 s, just before L-H transition. |
| Physics Operator Summaries |
| Entered: Jul 7 2004 04:36:55:927PM |
| Author: To Be Determined |
| MP 137 H-mode edge Te threshold 960126 Session Leader: Amanda Hubbard Physics Operator: Joseph Snipes Engineer in Charge: Frank Silva Overnight discharge cleaning in helium. Run plan: Start with the engineering setup from shot 960124024, for an initial fiducial shot. Then, perform a density scan at 5.3 T and 0.8 MA with (0.5 MW) steps in the RF power to determine the H-mode edge Te threshold at various densities. Then, we will go down to 0.6 MA and do a short density scan, then up to 1.1 MA and do a final short density scan. The run went reasonably well at higher current. There were many H-modes with clear threshold values. Preliminary indications are that the H-L edge temperatures were higher than the L-H temperatures this time around. But, the L-H temperature thresholds were rather consistent at about 200 eV. We had great difficulty getting 600 kA plasmas. We had vertical instabilities at about 0.2 sec on many shots, even some that were intended to go to 800 kA. So, we did not succeed in getting any data at 600 kA. Then, we went to 1.1 MA and had no problems. The first shot was copied from 960125021 and it disrupted just after the current turned over, leading to one strike. I then changed the rampdown and succeeded in getting decent rampdowns at 1.1 MA. We then returned to 800 kA so that LaBombard could insert the FSP to get H-mode profiles of the edge and we succeeded in getting good data by notching the RF power. Scorecard: 31 shots, 27 plasmas, 4 fizzles Shot 1: Copied shot 960124024 for a fiducial. Disrupted at 0.19 sec. Problem with EFC. Shot 2: Repeat. Good fiducial shot. H-modes from 0.78 to 1.05 sec. Moly monitor gate valve failed to open. Shot 3: Moved RCUR out by 5 mm to reduce outer gap for RF coupling. Increased flattop duration of Ip to 1.1 sec. Good shot, but the RF is rather choppy before the H-mode. Shot 4: Moved RCUR back in by 2 mm to 0.669 m to increase the outer gap a bit. Good shot. H-mode from 0.74 - 1.01 sec. Shot 5: Density reduced to nl = 7.5 x 10^19 m^-2. Ar gas puff enabled with 19 msec duration at 0.28 sec. H-modes from 0.74 - 1.01. Shot 6: Density reduced to nl = 6 x 10^19 m^-2. Good shot. Ohmic H-mode from 0.34 sec to 0.67 sec, then dithering until 0.82 sec, then ICRF H-modes from 0.82 to 1.02 sec. Shot 7: Turned off pre-programmed gas puffing after 0.2 sec. Good shot. No H-mode. Density around 6 x 10^19 m^-2. Shot 8: Increased RCUR by 2 mm to 0.671 m. Good shot. Short H-mode from 0.95 to 1 sec at 1.8 MW of RF power. Shot 9: Disrupted at 0.3 sec. Vertical instability when the plasma goes diverted early. Shot 10: Reduced initial ramp of CLEARIN from 0.1 to 0.2 sec instead of 0.1 to 0.16 sec as before. Fizzle! Shot 11: Repeat. Good shot. Density had some problems. No H-mode. Shot 12: Increased pre-programmed gas during segment 2 to get the programmed density. Fizzle! Shot 13: Increased pre-puff by 2 msec to 14 msec duration. Increased nl to 1.25 x 10^20 m^-2. Good shot. RF coupling poor. Shot 14: Repeat to tune RF. Good shot. Only 0.6 MW of RF for 50 msec. Shot 15: Increased ZXL and reduced CLEARIN, RCUR, and ZXU to try to improve the ramp down. One more time for tuning. Fizzle! Shot 16: Reduced pre-puff by 1 msec to 13 msec duration. Reduced Br offset by 0.5 mT to 5.9 mT. Disrupted at 0.41 sec. Shot 17: Reduced rate of rise of the density around 0.2 sec. Good shot. H-mode from 0.83 to 1.02 sec. RF steps up from 1 to 1.5 MW at 0.8 sec. Shot 18: Raised nl to 1.5 x 10^20 m^-2 and increased pre-programmed gas feed in segment 2 to 45 V from 0.4 to 1 sec. Good shot. No H-mode. RF power up to 1.3 MW. Shot 19: Reduced ZXU and increased ZXL after 1.1 sec to reduce the plasma elongation during the rampdown. Good shot. No H-mode. RF up to 1.9 MW. No more RF available today, so we will go to 0.6 MA. Shot 20: Reduced Ip to 0.6 MA, nl to 1 x 10^20 m^-2. Reduced pre-programmed gas in segment 2 to 30 V until 0.4 sec, then 0 V. Disrupted at 0.2 sec. Vertical instability. Shot 21: Moved crowbars on OH1 and OH2 from 0.2 sec to 0.1 sec to slow down the current rise. Disrupted at 0.2 sec. Shot 22: Set Ip to reach 0.6 MA at 0.2 sec. Reduced the rate of rise of the density so that it should reach 5 x 10^19 m^-2 by 0.2 sec. Overcurrent on OH2U by 40 kA. Disrupted at 0.19 sec. Shot 23: Returning to shot 960124024 to do a fiducial. Good shot. H-mode from 0.79 to 1.01 sec. Shot 24: Reduced Ip to 0.6 MA, copied RCUR from shot 960126022. Reduced rate of rise of the density. Fizzle! Shot 25: Reduced Br offset by 0.5 mT to 5.9 mT. Increased pre-puff by 1 msec to 13 msec flattop. Returned to density from 960126023 and kept the same rate of rise until 0.05 sec, then reduced the rate of rise until 0.4 sec. Disrupted at 0.25 sec. Shot 26: Punt. Copied shot 960125021 with Ip = 1.1 MA. Reduced Br offset by 0.5 mT to 5.9 mT. Good shot. Disrupted at 1.2 sec. Shot 27: Start rampdown of Ip at 1.1 sec. Moved RCUR out by 1 mm during the flattop to 0.67 m. Moved RCUR in by 1 mm during the rampdown. Ramped CLEARIN faster during the rampdown. Good shot. H-mode from 0.65 to 1.02 sec. Shot 28: Raised nl to 1.2 x 10^20 m^-2 and raised pre-programmed gas puffing to 40 V from 0.4 to 0.97 sec. Good shot. H-mode from 0.79 to 1.02 sec. Shot 29: Returned to shot 960126004 to insert the FSP. Good shot. H-mode from 0.76 to 0.98 sec. Shot 30: Reduced Br offset by 0.5 mT to 5.9 mT. Disrupted at 0.3 sec. Vertical instability. Shot 31: Reduced the rate of rise of the density. Good shot. H-mode from 0.75 to 0.99 sec. |
| Session Leader Comments | |||
| Jan 26 1996 08:42:10:940AM | Amanda Hubbard | This run plans to do a controlled scan of density and current, with RF powers
stepped up gradually so as to find the global and local H-mode thresholds. We are looking for well diagnosed conditions at the threshold, not necessarily long or record-breaking H-modes. All going well, the run will proceed as follows: a) Density scan at 800 kA, from lower density threshold to upper density limit. b) Repeat at 600 kA, with fewer densities. c) Repeat scan at 1.1 MA (or 1 MA if we have operational trouble). d) Several reproducible shots at 800 kA, 10^20 m-2, to scan ECE grating and other diagnostics to get detailed profiles. Try to get scanning probe in too. | |
| Jan 26 1996 08:51:23:520AM | 960126001 | Amanda Hubbard | Disrupts at 200 ms - chopper problems?
|
| Physics Operator Comments | |||
| Jan 26 1996 08:54:46:620AM | Joseph Snipes | MP 137 H-mode edge Te threshold 960126
Session Leader: Amanda Hubbard Physics Operator: Joseph Snipes Engineer in Charge: Frank Silva Overnight discharge cleaning in helium. Run plan: Start with the engineering setup from shot 960124024, for an initial fiducial shot. Then, perform a density scan at 5.3 T and 0.8 MA with (0.5 MW) steps in the RF power to determine the H-mode edge Te threshold at various densities. Then, we will go down to 0.6 MA and do a short density scan, then up to 1.1 MA and do a final short density scan. | |
| Jan 26 1996 08:55:17:260AM | 960126001 | Joseph Snipes | Shot 1: Copied shot 960124024 for a fiducial. Disrupted at 0.19 sec.
Problem with EFC. |
| Jan 26 1996 09:14:00:160AM | 960126002 | Joseph Snipes | Shot 2: Repeat. Good fiducial shot. H-modes from 0.78 to 1.05 sec.
Moly monitor gate valve failed to open. |
| Jan 26 1996 09:22:43:170AM | 960126003 | Joseph Snipes | Shot 3: Moved RCUR out by 5 mm to reduce outer gap for RF coupling.
Increased flattop duration of Ip to 1.1 sec. Good shot, but the RF is rather choppy before the H-mode. |
| Jan 26 1996 09:51:30:090AM | 960126004 | Joseph Snipes | Shot 4: Moved RCUR back out by 2 mm to 0.669 m to increase the outer
gap a bit. Good shot. H-mode from 0.74 - 1.01 sec. |
| Jan 26 1996 10:03:21:890AM | 960126005 | Joseph Snipes | Shot 5: Density reduced to nl = 7.5 x 10^19 m^-2. Ar gas puff enabled
with 19 msec duration at 0.28 sec. H-modes from 0.74 - 1.01. |
| Jan 26 1996 10:25:33:020AM | 960126006 | Joseph Snipes | Shot 6: Density reduced to nl = 6 x 10^19 m^-2. Good shot. Ohmic H-mode
from 0.34 sec to 0.67 sec, then dithering until 0.82 sec, then ICRF H-modes from 0.82 to 1.02 sec. |
| Jan 26 1996 10:35:13:100AM | 960126007 | Joseph Snipes | Shot 7: Turned off pre-programmed gas puffing after 0.2 sec. Good shot.
No H-mode. Density around 6 x 10^19 m^-2. |
| Jan 26 1996 11:06:46:020AM | 960126008 | Joseph Snipes | Shot 8: Increased RCUR by 2 mm to 0.671 m. Good shot. Short H-mode from
0.95 to 1 sec at 1.8 MW of RF power. |
| Jan 26 1996 11:07:26:420AM | 960126009 | Joseph Snipes | Shot 9: Disrupted at 0.3 sec. Vertical instability when the plasma goes
diverted early. |
| Jan 26 1996 11:07:43:850AM | 960126009 | Joseph Snipes | Shot 10: Reduced initial ramp of CLEARIN from 0.1 to 0.2 sec instead of 0.1
to 0.16 sec as before. Fizzle! |
| Jan 26 1996 11:39:59:930AM | 960126010 | Joseph Snipes | Shot 10: Reduced initial ramp of CLEARIN from 0.1 to 0.2 sec instead of 0.1
to 0.16 sec as before. Fizzle! |
| Jan 26 1996 11:40:18:920AM | 960126011 | Joseph Snipes | Shot 11: Repeat. Good shot. Density had some problems. No H-mode.
|
| Jan 26 1996 11:40:40:790AM | 960126012 | Joseph Snipes | Shot 12: Increased pre-programmed gas during segment 2 to get the
programmed density. Fizzle! |
| Jan 26 1996 11:58:34:450AM | 960126013 | Joseph Snipes | Shot 13: Increased pre-puff by 2 msec to 14 msec duration. Increased nl to
1.25 x 10^20 m^-2. Good shot. RF coupling poor. |
| Jan 26 1996 11:58:49:140AM | 960126014 | Joseph Snipes | Shot 14: Repeat to tune RF. Good shot. Only 0.6 MW of RF for 50 msec.
|
| Jan 26 1996 12:17:59:560PM | 960126015 | Joseph Snipes | Shot 15: Increased ZXL and reduced CLEARIN, RCUR, and ZXU to try to improve
the ramp down. One more time for tuning. Fizzle! |
| Jan 26 1996 12:41:20:180PM | 960126016 | Joseph Snipes | Shot 16: Reduced pre-puff by 1 msec to 13 msec duration. Reduced Br offset
by 0.5 mT to 5.9 mT. Disrupted at 0.41 sec. |
| Jan 26 1996 12:41:37:650PM | 960126017 | Joseph Snipes | Shot 17: Reduced rate of rise of the density around 0.2 sec. Good shot.
H-mode from 0.83 to 1.02 sec. RF steps up from 1 to 1.5 MW at 0.8 sec. |
| Jan 26 1996 01:08:06:220PM | 960126018 | Joseph Snipes | Shot 18: Raised nl to 1.5 x 10^20 m^-2 and increased pre-programmed gas
feed in segment 2 to 45 V from 0.4 to 1 sec. Good shot. No H-mode. RF power up to 1.3 MW. |
| Jan 26 1996 01:21:17:860PM | 960126019 | Joseph Snipes | Shot 19: Reduced ZXU and increased ZXL after 1.1 sec to reduce the plasma
elongation during the rampdown. Good shot. |
| Jan 26 1996 01:23:18:060PM | 960126019 | Joseph Snipes | Shot 19: Reduced ZXU and increased ZXL after 1.1 sec to reduce the plasma
elongation during the rampdown. Good shot. No H-mode. RF up to 1.9 MW. No more RF available today, so we will go to 0.6 MA. |
| Jan 26 1996 02:49:02:420PM | 960126020 | Joseph Snipes | Shot 20: Reduced Ip to 0.6 MA, nl to 1 x 10^20 m^-2. Reduced
pre-programmed gas in segment 2 to 30 V until 0.4 sec, then 0 V. Disrupted at 0.2 sec. Vertical instability. |
| Jan 26 1996 02:49:17:820PM | 960126021 | Joseph Snipes | Shot 21: Moved crowbars on OH1 and OH2 from 0.2 sec to 0.1 sec to slow down
the current rise. Disrupted at 0.2 sec. |
| Jan 26 1996 02:49:35:410PM | 960126022 | Joseph Snipes | Shot 22: Set Ip to reach 0.6 MA at 0.2 sec. Reduced the rate of rise of
the density so that it should reach 5 x 10^19 m^-2 by 0.2 sec. Overcurrent on OH2U by 40 kA. Disrupted at 0.19 sec. |
| Jan 26 1996 02:49:51:530PM | 960126023 | Joseph Snipes | Shot 23: Returning to shot 960124024 to do a fiducial. Good shot.
H-mode from 0.79 to 1.01 sec. |
| Jan 26 1996 04:27:27:330PM | 960126024 | Joseph Snipes | Shot 24: Reduced Ip to 0.6 MA, copied RCUR from shot 960126022. Reduced
rate of rise of the density. Fizzle! |
| Jan 26 1996 04:27:45:160PM | 960126025 | Joseph Snipes | Shot 25: Reduced Br offset by 0.5 mT to 5.9 mT. Increased pre-puff by 1
msec to 13 msec flattop. Returned to density from 960126023 and kept the same rate of rise until 0.05 sec, then reduced the rate of rise until 0.4 sec. Disrupted at 0.25 sec. |
| Jan 26 1996 04:28:11:390PM | 960126026 | Joseph Snipes | Shot 26: Punt. Copied shot 960125021 with Ip = 1.1 MA. Reduced Br offset by
0.5 mT to 5.9 mT. Good shot. Disrupted at 1.2 sec. |
| Jan 26 1996 04:28:34:280PM | 960126027 | Joseph Snipes | Shot 27: Start rampdown of Ip at 1.1 sec. Moved RCUR out by 1 mm during
the flattop to 0.67 m. Moved RCUR in by 1 mm during the rampdown. Ramped CLEARIN faster during the rampdown. Good shot. |
| Jan 26 1996 04:28:53:290PM | 960126028 | Joseph Snipes | Shot 28: Raised nl to 1.2 x 10^20 m^-2 and raised pre-programmed gas
puffing to 40 V from 0.4 to 0.97 sec. Good shot. |
| Jan 26 1996 04:36:54:230PM | 960126028 | Joseph Snipes | Shot 28: Raised nl to 1.2 x 10^20 m^-2 and raised pre-programmed gas
puffing to 40 V from 0.4 to 0.97 sec. Good shot. H-mode from 0.79 to 1.02 sec. |
| Jan 26 1996 04:37:08:510PM | 960126029 | Joseph Snipes | Shot 29: Returned to shot 960126004 to insert the FSP. Good shot. H-mode
from 0.76 to 0.98 sec. |
| Jan 26 1996 05:19:08:150PM | 960126030 | Joseph Snipes | Shot 30: Reduced Br offset by 0.5 mT to 5.9 mT. Disrupted at 0.3 sec.
Vertical instability. |
| Jan 26 1996 05:19:22:470PM | 960126031 | Joseph Snipes | Shot 31: Reduced the rate of rise of the density. Good shot. H-mode from
0.75 to 0.99 sec. |
| Jan 26 1996 05:20:01:550PM | 960126031 | Joseph Snipes | The run went reasonably well at higher current. There were many H-modes
with clear threshold values. Preliminary indications are that the H-L edge temperatures were higher than the L-H temperatures this time around. But, the L-H temperature thresholds were rather consistent at about 200 eV. We had great difficulty getting 600 kA plasmas. We had vertical instabilities at about 0.2 sec on many shots, even some that were intended to go to 800 kA. So, we did not succeed in getting any data at 600 kA. Then, we went to 1.1 MA and had no problems. The first shot was copied from 960125021 and it disrupted just after the current turned over, leading to one strike. I then changed the rampdown and succeeded in getting decent rampdowns at 1.1 MA. We then returned to 800 kA so that LaBombard could insert the FSP to get H-mode profiles of the edge and we succeeded in getting good data by notching the RF power. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 08:28:40:510AM | Plasma | Ok | oh2 selfpower, no efc |
| 2 | 08:53:59:810AM | Plasma | Ok | fiducial |
| 3 | 09:14:42:870AM | Plasma | Ok | |
| 4 | 09:31:32:580AM | Plasma | Ok | |
| 5 | 09:50:54:040AM | Plasma | Ok | |
| 6 | 10:08:46:330AM | Plasma | Ok | |
| 7 | 10:22:58:340AM | Plasma | Ok | |
| 8 | 10:37:25:720AM | Plasma | Ok | no faults |
| 9 | 10:51:02:930AM | Plasma | Ok | |
| 10 | 11:04:34:560AM | Plasma | Ok | |
| 11 | 11:14:22:060AM | Plasma | Ok | |
| 12 | 11:27:21:040AM | Plasma | Ok | |
| 13 | 11:40:44:170AM | Plasma | Ok | |
| 14 | 11:52:37:780AM | Plasma | Ok | |
| 15 | 12:07:47:420PM | Plasma | Ok | |
| 16 | 12:19:00:470PM | Plasma | Ok | oh2u bypass comm fault |
| 17 | 12:34:37:450PM | Plasma | Ok | |
| 18 | 12:48:44:240PM | Plasma | Ok | |
| 19 | 01:04:45:690PM | Plasma | Ok | |
| 20 | 01:23:22:010PM | Plasma | Ok | |
| 21 | 01:40:57:860PM | Plasma | Ok | Self powered fired OH1 & OH2U [bypass] |
| 22 | 02:00:07:880PM | Plasma | Ok | oh2U IOC & Self powered fired [bypass] |
| 23 | 02:32:10:910PM | Plasma | Ok | |
| 24 | 02:50:00:230PM | Plasma | Ok | |
| 25 | 03:02:45:880PM | Plasma | Ok | |
| 26 | 03:17:22:880PM | Plasma | Ok | |
| 27 | 03:48:01:070PM | Plasma | Ok | |
| 28 | 04:06:50:560PM | Plasma | Ok | |
| 29 | 04:25:39:750PM | Plasma | Ok | |
| 30 | 04:41:18:380PM | Plasma | Ok | |
| 31 | 04:52:19:760PM | Plasma | Ok | |