| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Amanda Hubbard |
| Physics operator(s): | Unknown |
| Engineering operator(s): | Unknown |
| Engineering Operator Run Comment |
| Ohmic Transport studies; Te and Ti profiles |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:08:540PM |
| Author: To Be Determined |
| Plan for 930818 - MP 010 (Ohmic Confinement) Part C Kappa Scan at constant Ip Objectives: 1) Scan Kappa in plasmas limited on the inner wall, between 1.2 and 1.6 Parameters Ip = 400 kA, flat top to 400 ms Av ne = 10^20 (nel 5 x 10 ^ 19 at k = 1.2, increasing with k). Good measurements of Te, Ti, Prad, ne, Zeff etc. 2) Make diverted plasma as similar as possible to highest elongation limiter plasma, and compare bulk parameters. Probes may wish to piggyback on this part to compare edge parameters. Plan: 1) Start with discharge similar to yesterdays (930817). Lower EF1 to keep elongation at 1.2, instead of rising during discharge. Plasma centered at midplane. Tweak gas puffing and argon to get steady ne trace and good HIREX statistics during flat-top. This will probably require several discharges. 2) Adjust EF1 to increase elongation to 1.4. Adjust gas as necessary for constant average density. 2-3 similar shots. 3) Repeat for elongation 1.6. 4) Shift plasma down to Z=-2 cm and try to divert. Adjust gas to correct for any changes in density. 5) If time, go back to low elongation (k = 1.0?). Attempt to raise density to nel = 6-8 x 10^19. Summary of Run: The changes made to yesterday's plasmas (ie vertical position at midplane, lower elongation via EF1 and other tweaks) worked well and we had no problem producing a series of similar plasmas. The main difficulty, which occupied much of the first ten shots, was achieving a constant density. We reproved the recent observation that there is a very small window in gas puffing between marginally non-thermal shots (eg 001, 007) and radiation 'events' similar to a shark fin when ne and Prad rise, Te cools sharply and the rest of the discharge appears disruptive. (eg shots 006, 009). A number of adjustments in EF1 programming were also required to get the steady, low elongation we required. We did succeed in getting a steady nel of around 4 e19 during at least part of the current flat-top window, and three stable elongation values of 1.2, 1.3 and 1.44. The best of these discharges, which have been selected for further confinement analysis, are as follows: Kappa Shot Nel(ch 4) Time period 1.2 016(best)3.8-4.0 260-330 ms 011 3.9-4.2 200-300 ms 015 3.6-4.0 230-300 ms 1.3 022 3.7 240-330 ms 023(best) 4.0-4.1 250-400 ms 1.44 025 3.7-3.9 220-260 ms 026 3.6-3.8 220-320 ms 027(best)4.5-4.0 230-390 ms 028 4.9-4.0 230-330 ms The higher density set of shots at k=1.44 are to compensate for the increased path length (53 vs 49 cm) and should give approximately constant average density. Attempts to further raise the elongation (shot 30) resulted in a nice demonstration of the vertical stability limit. Probably because of impurities following this disruption, the subsequent shots (31, 32) were also disruptive although we went back to previously successful parameters. Data system problems on what was supposed to be shot 33 ended the run. John Rice has already done a preliminary analysis of the above shots and reports good HIREX statistics for Ti profiles throughout (thanks to earlier introduction of argon). No problems with fizzles were found - in fact we did not have any fizzles today. Scorecard: 26 'good' discharges 5 disruptions 1 power supply fault ------------------- 32 shots |
| Physics Operator Summaries |
| Session Leader Comments | |||
| Aug 18 1993 08:51:05:680AM | Amanda Hubbard | Plan for 930818 - MP 010 (Ohmic Confinement)
Part C Kappa Scan at constant Ip Objectives: 1) Scan Kappa in plasmas limited on the inner wall, between 1.2 and 1.6 Parameters Ip = 400 kA, flat top to 400 ms Av ne = 10^20 (nel 5 x 10 ^ 19 at k = 1.2, increasing with k). Good measurements of Te, Ti, Prad, ne, Zeff etc. 2) Make diverted plasma as similar as possible to highest elongation limiter plasma, and compare bulk parameters. Probes may wish to piggyback on this part to compare edge parameters. Plan: 1) Start with discharge similar to yesterdays (930817). Lower EF1 to keep elongation at 1.2, instead of rising during discharge. Plasma centered at midplane. Tweak gas puffing and argon to get steady ne trace and good HIREX statistics during flat-top. This will probably require several discharges. 2) Adjust EF1 to increase elongation to 1.4. Adjust gas as necessary for constant average density. 2-3 similar shots. 3) Repeat for elongation 1.6. 4) Shift plasma down to Z=-2 cm and try to divert. Adjust gas to correct for any changes in density. 5) If time, go back to low elongation (k = 1.0?). Attempt to raise density to nel = 6-8 x 10^19. | |
| Aug 18 1993 09:13:11:590AM | 930818001 | Amanda Hubbard | Good, long shot. Density a little low, decreasing during shot. There are some non-thermals.
Also, kappa increases during shot, and may become diverted. Nice flat current trace, Ip = 370 kA. For next shot, increase the gas. |
| Aug 18 1993 09:25:20:370AM | 930818002 | Amanda Hubbard | Density still low, decreasing during shot. Thermal this time. Add more gas for next shot.
Also, will tweak EF1 at 400 ms at avoid kappa increasing. Centroids worked this time. Z is nicely centered at the midplane. There is an unexplained increase in radiation around 240 ms. |
| Aug 18 1993 09:34:50:050AM | 930818003 | Amanda Hubbard | Disruptive, high radiation shot. Ends at 330 ms. Probably too much gas - will back off
for next shot. |
| Aug 18 1993 09:57:43:290AM | 930818004 | Amanda Hubbard | A long, steady shot. Density gets to a reasonable level (nel 4.5 e 10 19) at 200 ms,
but then decreases. For shot 5, increase gas after 150 ms. Kappa still going up (to 1.4), but less than previous shots. Tweak EF1 some more. |
| Aug 18 1993 10:12:28:350AM | 930818005 | Amanda Hubbard | Minor disruption at 300 ms, loses about 50 kA. Looks like too much gas.
For next shot, reduce gas after 8 ms. Also tweak EF3 to try and remove oscillation in R0. |
| Aug 18 1993 10:30:00:970AM | 930818006 | Amanda Hubbard | Shark fin leading to minor disruption (and major cooling an Prad) at 300 ms.
Major disruption at 470 ms. Go back to gas from shot 4. |
| Aug 18 1993 10:47:01:050AM | 930818007 | Amanda Hubbard | Succeeded in getting back long, non-disruptive shot, but at the cost of low density
(3.4 x 10 19 nel). On the threshold of non-thermals - 1 V of hards and spikes on ECE. Kappa is reasonable, but still drifts up to 1.4 by 400 ms. FFIT shows brief diversion on top at 440 ms. For next shot, increase gas slightly and also increase gain on Rcur feedback. |
| Aug 18 1993 11:02:25:720AM | 930818008 | Amanda Hubbard | The gas increase didn't seem to bring up the density significantly. Still dropping after
300 ms. Try a bit more gas next shot. The change in Rcur gain seems to have helped, although R is still larger than demand. For next shot, try more tweaks in EF1 to keep kappa down. |
| Aug 18 1993 11:17:23:030AM | 930818009 | Amanda Hubbard | The minor gas tweak resulted in a shark fin type 'event' starting at 250 ms. This
cools the plasma from 1.5 to 1.1 keV, increases radiation, and takes a 100 kA chunk out of the current. We don't seem to have any room to manuever! For next shot, go back to Pulse gas A programming from yesterday to get another density knob. Also increase Rcur gain. Kappa went higher on this shot, probably due to current drop. |
| Aug 18 1993 11:32:09:370AM | 930818010 | Amanda Hubbard | Going to yesterday's gas programming resulted in a non-thermal discharge.
Not what we wanted!. Also got less current (360 kA, then dropping after 200 ms). Try going back to shot 008 gas on B side upper, adding A-side pulse at 180 ms. Kappa is still increasing after 300 ms, but HIREX apparently has good enough signal before this time to get Ti profiles. |
| Aug 18 1993 11:46:05:040AM | 930818011 | Amanda Hubbard | This one was more like it. Density gets to 4 e 19 at 210 ms, but droops after 250 ms,
causing temperatures to rise. Current stays in range 370 to 390 ms. For next shot, extend fast gas puff to try and keep ne up longer. |
| Aug 18 1993 11:51:22:890AM | 930818012 | Amanda Hubbard | Fizzle caused by power supply problems. No EF3.
|
| Aug 18 1993 12:12:36:950PM | 930818013 | Amanda Hubbard | Good shot, but we have another 'shark fin' cooling event and ne excursion starting
200 ms. The gas up to this point should have been the same as shot 11, which did not have this problem. |
| Aug 18 1993 12:26:19:290PM | 930818014 | Amanda Hubbard | Very similar 'event' to shot 013. Reduce gas for next shot.
Kappa finally came down a bit between 0.3 and 0.4 s. Take EF1 down a bit more for next shot. |
| Aug 18 1993 12:44:17:080PM | 930818015 | Amanda Hubbard | Pretty good low elongation shot. Density still varies aomewhat, but no sudden 'event'
|
| Aug 18 1993 01:05:59:760PM | 930818016 | Amanda Hubbard | A good shot. This will be our reference pulse for low kappa (nominal 1.2)
The most steady period for ne is 260-330 ms. nel (ch 4) is 3.8 -4.0 e 10 19. Ip is .375 to .365 in this period. FFIT kappa 1.15 to 1.18. ECE temperature 1.4 keV. For next shots, we will be increasing kappa (leave gas alone for next shot). |
| Aug 18 1993 01:16:36:310PM | 930818017 | Amanda Hubbard | Good shot, quite similar to 016. However, kappa only increased slightly in response to
EF1 changes. For next shot, try bigger changes. We are aiming towards kappa = 1.4. |
| Aug 18 1993 01:40:36:250PM | 930818018 | Amanda Hubbard | Kappa is higher, but still ramping steadily. At 280 ms (the density flat-top), it is 1.3
Te is 1.4 keV, the same as shot 16. |
| Aug 18 1993 01:43:04:220PM | 930818019 | Amanda Hubbard | EF1 changed. Kappa loses its wild excursion on FFIT. Still around 1.3 at 300 ms.
For shot 20, try shifting R in to 66 cm (from 68 cm). |
| Aug 18 1993 02:04:38:780PM | 930818020 | Amanda Hubbard | The change in R0 seems to have worked (ie moved in 2 cm to 67-68 cm)
Kappa is still around 1.3 at 300 ms, 1.45 at 400 ms. Tweak gas on next shot. |
| Aug 18 1993 02:13:30:980PM | 930818021 | Amanda Hubbard | EF1 was teaked but kappa pretty unresponsive.
Getting flat ne of 3.5 e 19 from 250 to 350 ms . |
| Aug 18 1993 02:26:51:080PM | 930818022 | Amanda Hubbard | Good shot. Kappa stays steady at 1.3 from 250-375 ms, and doesn't change much after
that. Density is 3.7 e 19 m-2, steady from 240 -330 ms. This will be a 'reference shot'. Repeat for shot 23 to get better HIREX profile. |
| Aug 18 1993 02:38:22:970PM | 930818023 | Amanda Hubbard | Repeat of last shot. A second nominal refernce at kappa = 1.3.
Density very steady, slightly higher at 4.0-4.1 e 19 in period 250 - 400 ms. This is in fact closer to the density on shot 12, and will help us extract the ne dependence of Te, Ti. |
| Aug 18 1993 02:53:12:150PM | 930818024 | Amanda Hubbard | Good shot. Kappa is 1.4 at 300 ms, but still ramping slowly in time.
Try tweaking a bit more. Density dropping a bit, 3.9-3.6 e 19 |
| Aug 18 1993 03:06:41:790PM | 930818025 | Amanda Hubbard | Good shot with steady kappa 1.44 to 1.48 in range 250 - 380 ms.
This will be a reference shot. The density is a little lower than before, ne = 3.8-3.3, causing slight variation in Te. Repeat on next shot, for Ti profiles. |
| Aug 18 1993 03:28:45:340PM | 930818026 | Amanda Hubbard | Repeat of 025. Another good one.
For next shot, try and raise ne to get average ne up. |
| Aug 18 1993 03:32:42:040PM | 930818027 | Amanda Hubbard | Kappa still 1.45. Ne up to 4.5 e 19 at 230 ms, drops to 4.0 after 300 ms.
|
| Aug 18 1993 03:47:57:380PM | 930818028 | Amanda Hubbard | Kappa still 1.45. Ne up to 5.0 e 19 at 230 ms, drops slowly.
|
| Aug 18 1993 03:57:35:890PM | 930818029 | Amanda Hubbard | Kappa still 1.45. Attempted to put in more gas earlier. This caused a disruptive
discharge, indicating we can't push ne much more. For next shot, go back to gas from shot 27, move R0 in 1 cm, and try to push kappa up higher. |
| Aug 18 1993 04:15:41:160PM | 930818030 | Amanda Hubbard | Went to kappa = 1.64 but then went vertically unstable and disrupted at 250 ms.
Go back to settings from shot 27 (k = 1.45) and move the radius out. Will probably go diverted. |
| Aug 18 1993 04:28:54:020PM | 930818031 | Amanda Hubbard | Tried for divertor shot but disrupted early.
Go back to shot 23 settings (k = 1.3, limiter) |
| Aug 18 1993 04:39:17:340PM | 930818032 | Amanda Hubbard | Using shot 23 settings (k = 1.3, limiter). Position is stable but plasma is dirty - get a
'shark fin' followed by a disruption. Take off pulse gas A sid for next shot. |
| Aug 18 1993 05:01:59:570PM | 930818032 | Amanda Hubbard | The supposed shot 33:
1) never updated shot number. 2) Was a dud according to camera - possible commutation problems?? 3) appears to have overwritten data from shot 32 due to data system problems. |
| Physics Operator Comments |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 08:54:08:840AM | Plasma | Ok | Good flat-top for 250 msec |
| 2 | 09:09:42:260AM | Plasma | Ok | no faults -- over 700msec plasma, 410ka |
| 3 | 09:24:56:420AM | Plasma | Ok | Disruption at 200 ka |
| 4 | 09:38:43:330AM | Plasma | Ok | Better |
| 5 | 09:53:25:690AM | Plasma | Ok | Disruptive |
| 6 | 10:14:34:030AM | Plasma | Ok | Nasty Disruption |
| 7 | 10:31:43:360AM | Plasma | Ok | Better; still disrupting at 150 kA |
| 8 | 10:46:43:180AM | Plasma | Ok | Same as last shot |
| 9 | 11:02:31:680AM | Plasma | Ok | Plasma Current quite variable |
| 10 | 11:18:45:700AM | Plasma | Ok | no faults |
| 11 | 11:32:29:700AM | Plasma | Ok | no faults |
| 12 | 11:46:13:670AM | Plasma | Bad | ef3 did not fire |
| 13 | 11:58:41:400AM | Plasma | Ok | ef3 ok now -- suspect master reset did not get to ef3 over paragon netwo |
| 14 | 12:14:16:410PM | Plasma | Ok | no faults |
| 15 | 12:29:50:630PM | Plasma | Ok | no faults |
| 16 | 12:46:10:840PM | Plasma | Ok | All OK |
| 17 | 01:01:21:150PM | Plasma | Ok | Same |
| 18 | 01:16:02:180PM | Plasma | Ok | Better flat-top |
| 19 | 01:31:49:800PM | Plasma | Ok | Better flat-top. Impurity injection gate valve opened without notifying |
| 20 | 01:44:58:020PM | Plasma | Ok | Better flat-top |
| 21 | 01:57:47:720PM | Plasma | Ok | no faults |
| 22 | 02:11:21:980PM | Plasma | Ok | no faults |
| 23 | 02:25:03:830PM | Plasma | Ok | no faults |
| 24 | 02:39:00:610PM | Plasma | Ok | no faults |
| 25 | 02:52:12:960PM | Plasma | Ok | no faults |
| 26 | 03:06:25:760PM | Plasma | Ok | no faults |
| 27 | 03:19:55:460PM | Plasma | Ok | no faults |
| 28 | 03:34:22:730PM | Plasma | Ok | no faults |
| 29 | 03:49:29:250PM | Plasma | Ok | no faults |
| 30 | 04:04:11:720PM | Plasma | Ok | no faults |
| 31 | 04:17:42:690PM | Plasma | Ok | no faults |
| 32 | 04:30:23:310PM | Plasma | Ok | no faults |
| 34 | 05:03:57:550PM | Test | Ok | data system ok now -- problem was with the dispatcher.....per T Fredian |