| Miniproposals | ||||||||||
|
| Operators | |
| Session leader(s): | Martin Greenwald |
| Physics operator(s): | Jim Irby |
| Engineering operator(s): | Bill Cochran,Bill Byford,Gary Dekow |
| Engineering Operator Run Comment |
| MP #400A -- High k, high frequency fluctuations in electrontransport dom |
| Session Leader Plans |
| Entered: Aug 19 2005 08:41:50:040AM |
| Author: Martin Greenwald |
| Background:
We want to look for changes in density fluctuations, particularly those at short wavelength and high frequency, in low density Ohmic regimes, where transport is known to be dominated by the electron channel. The goal is to correlate electron transport levels with fluctuations at scales that might correspond to predicted instabilities. Approach: Run a series of Ohmic plasmas starting above the "breakpoint" density between the neo- Alcator and L-mode regimes (see figure). To avoid spending time finding the appropriate discharge conditions, we will attempt to duplicate the shots from the 95-96 campaigns where the linear confinement regime was first studied on C-Mod. Several scans would be performed using different shapes, all limited on the inner wall and with lower than normal elongation. PCI is the primary fluctuation diagnostic, though it would be useful to be monitoring the reflectometer at the same time. PCI should be configured to look at high k. Standard profile diagnostics should be available to allow calculation of electron and ion power balance. The machine conditions are probably not critical, though it should be clean enough to allow operation at low density, where ZEFF tends to increase in any event. The A coils should be used to avoid locked modes. If an opportunity to get a few shots in H2 discharges occur, these would be useful to investigate the scaling of the k spectrum observed. The two equilibria and currents proposed correspond to scans performed in 95-96. Plan: Start with shot 1050818016 which was limited, raise the elongation to 1.5 and the current to 0.8. Start at nebar 1.5-2 and slowly lower to lowest density while monitoring fluctuations. When we finish that scan, repeat with elongation nearer 1. and same q. If time permits, do a scan with a diverted discharge... |
| Physics Operators Plans |
| Entered: Aug 18 2005 04:52:09:690PM |
| Author: Jim Irby |
| Engineering setup for Friday, Aug 19, 2005
MP #400A -- High k, high frequency fluctuations in electron transport dominated regimes Session leader: Greenwald/LLin Physics operator: Irby Overnight ECDC, D2, P=2e-4 torr gauge, and bake at 60 C. Run begins at 09:00 and ends at 17:00. Power systems as on 1050818024 A-coil configuration: normal [+Dtop -Dbot -Jtop +Jbot] and enabled. Gas Setup: fill B-Top with 6 psi D2 Hybrid enabled (PG4) fill B-side lower with 1 psi Ar plus 1 psi neon Hybrid DISABLED (PG1) leave B-side upper as is He3 Hybrid DISABLED (PG2) fill B-main (C-side) with 40 psi D2 Hybrid enabled (PG3) Enable the following gate valves and shutters: ECE, VUV, Z-bolo shutters |
| Session Leader Summaries |
| Entered: Aug 19 2005 05:27:48:867PM |
| Author: Martin Greenwald |
| Results:
We got some of what we were after. It was difficult to run the limited shots, especially at lower density (dust, moly?). There were a number of early disruptions, etc. We switched to diverted plasmas at shot 18 and completed one density scan. The last 3 shots (29-31) were limited again The high-frequency magnetic fluctuations that were seen previously during current rise and fall were seen through the limiter discharges. Their character changes, but the amplitude remains large. Suggests that the underlying phenomena is damped in divertor plasmas (Joe suggests edge magnetic shear). Some shots had dithering or Halpha oscillations. JANT videos showed strange wave-like phenomena on these shots. Shots for further analysis: Shot topology density ~tau_kin 01 limited 1.85 37 msec 02 limited 1.76 36 04 limited 1.74 36 06 limited 1.4 34 11 limited 1.2 32 12 limited 1.05 31 18 diverted 0.58 ? 19 diverted 0.6 33 20 diverted 0.4 27 21 diverted 0.4 27 22 diverted 0.66 29 24 diverted 0.8 35 25 diverted 1.0 34 26 diverted 1.4 36 27 diverted 1.6 35 28 diverted 1.8 31 29 limited 1.6 31 30 limited 1.3 28 31 limited 1.2 26 |
| Physics Operator Summaries |
| Entered: Aug 19 2005 05:32:45:790PM |
| Author: Jim Irby |
| We had some difficulty early in the run running low density inner wall limited shots. Injections (probably moly) affected the current rise and eventually caused the plasma to disrupt. We moved to low density diverted plasmas on shot 17, and after a fizzle, we were able to run full length shots again. Following a density scan, we returned to inner wall limited discharges on shot 29 without any serious injections and full length plasmas. Dropping the density was difficult since the wall had become loaded during the density scan.
Machine generally ran well today. We had some trouble rebooting one of the data acquisition computers, and one shot was lost when the ef3 breaker pulled before the shot. We had two fizzles that seemed to be related to drift in Bz0. A dud may have been fixed by an increase in prefill. no power 05,07,08 ef3 breaker 23 dud 03 fizzle 15,17 plasma 01,02,04,06,09,10,11,12,13,14 16,18,19,20,21,22,24,25,26,27, 28,29,30,31 |
| Session Leader Comments | |||
| Aug 19 2005 09:32:16:383AM | 1050819001 | Martin Greenwald | Good shot
nebar ~ 1.85 Ip = 0.8 Wmhd = 0.4 tau_mhd ~ 37 msec Wkin (TS had cooling water problem) H89 ~ 1 PCI data good |
| Aug 19 2005 09:56:01:040AM | 1050819002 | Martin Greenwald | Good shot - elongation still a little low 1.4 instead of 1.5
nebar ~ 1.76 Ip = 0.8 Wmhd = 0.39 tau_mhd = 36 msec Wkin = 0.39 tau_kin = 36 H89 ~ 1 PCI data good |
| Aug 19 2005 10:00:50:850AM | 1050819003 | Martin Greenwald | Dud
|
| Aug 19 2005 10:23:13:350AM | 1050819004 | Martin Greenwald | Good shot elongation at 1.5
nebar ~ 1.74 Ip = 0.8 Wmhd = 0.42 tau_mhd = 38 msec Wkin = 0.38 tau_kin = 36 H89 ~ 1 PCI data good |
| Aug 19 2005 10:49:27:053AM | 1050819006 | Martin Greenwald | Good shot elongation at 1.5
nebar ~ 1.4 Ip = 0.8 Wmhd = 0.42 tau_mhd = 38 msec Wkin = 0.38 tau_kin = 34 msec H89 ~ 1 PCI data good |
| Aug 19 2005 12:02:59:773PM | 1050819009 | Martin Greenwald | after delay for cpci problems - Early disruption |
| Aug 19 2005 12:28:08:710PM | 1050819010 | Martin Greenwald | Early disruption |
| Aug 19 2005 12:32:58:650PM | 1050819011 | Martin Greenwald | Good shot
nebar ~ 1.2 Ip = 0.8 Wmhd = 0.40 tau_mhd = 37 msec Wkin = 0.35 tau_kin = 32 msec H89 ~ 1 PCI data good |
| Aug 19 2005 12:45:03:007PM | 1050819012 | Martin Greenwald | Good shot
nebar ~ 1.05 Ip = 0.8 Wmhd = 0.38 tau_mhd = 35 msec Wkin = 0.33 tau_kin = 31 msec H89 ~ .9 PCI data good |
| Aug 19 2005 12:52:12:727PM | 1050819013 | Martin Greenwald | Early disruption again |
| Aug 19 2005 01:14:30:087PM | 1050819014 | Martin Greenwald | Early disruption
Lots of dust specs on the camera titanium? |
| Aug 19 2005 01:26:32:273PM | 1050819015 | Martin Greenwald | fizzle |
| Aug 19 2005 01:40:56:587PM | 1050819016 | Martin Greenwald | disrupts early |
| Aug 19 2005 01:56:19:807PM | 1050819017 | Martin Greenwald | fizzle |
| Aug 19 2005 02:19:50:587PM | 1050819018 | Martin Greenwald | Went to diverted configuration to avoid disruption problem
elongation to 1.66 Good shot nebar ~ .58 Ip = 0.8 Wmhd = 0.31 tau_mhd = 40 msec Wkin = laser problem tau_kin = H89 ~ .85 PCI data good |
| Aug 19 2005 02:38:50:727PM | 1050819019 | Martin Greenwald | Went to diverted configuration to avoid disruption problem
elongation to 1.66 Good shot nebar ~ .6 Ip = 0.8 Wmhd = .030 tau_mhd = 41 msec Wkin = .024 tau_kin = 33 msec H89 ~ .85 PCI data good |
| Aug 19 2005 02:48:44:010PM | 1050819020 | Martin Greenwald | Good shot
nebar ~ .4 Ip = 0.8 Wmhd = .020 tau_mhd = 30 msec Wkin = .018 tau_kin = 27 msec H89 ~ .7 PCI data good |
| Aug 19 2005 03:01:28:930PM | 1050819021 | Martin Greenwald | Good shot
nebar ~ .4 Ip = 0.8 Wmhd = .023 tau_mhd = 32 msec Wkin = .018 tau_kin = 27 msec H89 ~ .67 PCI data good |
| Aug 19 2005 03:09:34:697PM | 1050819022 | Martin Greenwald | Good shot
nebar ~ .66 Ip = 0.8 Wmhd = .026 tau_mhd = 38 msec Wkin = .023 tau_kin = 29 msec H89 ~ .78 PCI data good |
| Aug 19 2005 03:18:34:100PM | 1050819023 | Martin Greenwald | dud |
| Aug 19 2005 03:37:19:807PM | 1050819024 | Martin Greenwald | Good shot
nebar ~ .88 -> .72 Ip = 0.8 Wmhd = .034-.028 tau_mhd = 44-36 msec Wkin = .028-24 tau_kin = 38-35 msec H89 ~ .92 PCI data good |
| Aug 19 2005 03:57:30:820PM | 1050819025 | Martin Greenwald | Good shot - but dithering??
nebar ~ 1.1 -> .83 Ip = 0.8 Wmhd = .035-.030 tau_mhd = 35-31 msec Wkin = .034-30 tau_kin = 34-31 msec H89 ~ .85 PCI data good |
| Aug 19 2005 05:11:39:603PM | 1050819026 | Martin Greenwald | diverted
strange oscillations/dithering strange looking waves in JANT video Good shot nebar ~ 1.4 Ip = 0.8 Wmhd = .034 tau_mhd = 36 msec Wkin = .034 tau_kin = 36 msec H89 ~ .87 PCI data good |
| Aug 19 2005 04:22:26:023PM | 1050819027 | Martin Greenwald | Good shot - but dithering??
nebar ~ 1.6 Ip = 0.8 Wmhd = .036 tau_mhd = 35 msec Wkin = .034 tau_kin = 35 msec H89 ~ .72 PCI data good |
| Aug 19 2005 04:30:06:023PM | 1050819028 | Martin Greenwald | Good shot
nebar ~ 1.8 Ip = 0.8 Wmhd = .034 tau_mhd = 31 msec Wkin = .034 tau_kin = 31 msec H89 ~ .72 PCI data good |
| Aug 19 2005 04:43:33:243PM | 1050819029 | Martin Greenwald | limited again
Good shot nebar ~ 1.6 Ip = 0.8 Wmhd = .037 tau_mhd = 31 msec Wkin = .034 tau_kin = 31 msec H89 ~ .72 PCI data good |
| Aug 19 2005 04:54:55:710PM | 1050819030 | Martin Greenwald | limited again
Good shot nebar ~ 1.3 Ip = 0.8 Wmhd = .036 tau_mhd = 31 msec Wkin = .032 tau_kin = 28 msec H89 ~ .85 PCI data good |
| Aug 19 2005 05:07:48:993PM | 1050819031 | Martin Greenwald | limited again
Good shot nebar ~ 1.2 Ip = 0.8 Wmhd = .034 tau_mhd = 30 msec Wkin = .030 tau_kin = 26 msec H89 ~ .87 PCI data good |
| Physics Operator Comments | |||
| Aug 19 2005 09:25:05:010AM | 1050819001 | Jim Irby | loaded shot 1050818016
increased Ip to 800 kA from 600 kA A-Coils under feedback control try to start with a little more elongation: decreased ZXL by .01 m (-.01 to -.02) prefill to 33 ms plasma into rampdown --- good startup pressure .056 at t=0 |
| Aug 19 2005 09:57:48:320AM | 1050819002 | Jim Irby | clearin from -0.047 to -0.040 m
plasma into rampdown --- elongation 1.4; better but still not 1.5 |
| Aug 19 2005 10:07:29:960AM | 1050819003 | Jim Irby | clearin from -.04 to -.03 m
dud --- pressure was actually higher than on shot 1 or 2. |
| Aug 19 2005 10:21:39:960AM | 1050819004 | Jim Irby | increased prefill to 35 ms from 33 --- last shot was a dud
plasma into rampdown --- got elongation 1.5 |
| Aug 19 2005 10:35:20:290AM | 1050819005 | Jim Irby | nl_04 request from 8.0 to 4.75e20 /m^2
no power shot --- computer problem |
| Aug 19 2005 10:59:56:180AM | 1050819006 | Jim Irby | try again with power
plasma into rampdown --- lower density --- good startup |
| Aug 19 2005 11:16:41:490AM | 1050819007 | Jim Irby | no power --- computer problem |
| Aug 19 2005 11:41:18:663AM | 1050819008 | Jim Irby | no power |
| Aug 19 2005 11:59:28:243AM | 1050819009 | Jim Irby | Tom rebooted daq computer
enabled LPI gatevalve disruption at 0.394 s PF breaker pulled --- oh2l out by 0.393 s stop to check fuses, etc |
| Aug 19 2005 12:23:40:587PM | 1050819010 | Jim Irby | try again --- no problems found with oh2l supply
disruption at 0.557 s very unclear what the cause of the disruption |
| Aug 19 2005 12:30:50:790PM | 1050819011 | Jim Irby | try again --- saw a few injections on the last shot
plasma into rampdown --- startup looks good |
| Aug 19 2005 12:44:32:570PM | 1050819012 | Jim Irby | removed pg3 puff around 0.1 s --- may have caused density to be higher than requested.
dropped density request from 4.0e19 to 3.8e19 / m^2 plasma into rampdown --- density still too high |
| Aug 19 2005 12:59:48:087PM | 1050819013 | Jim Irby | dropped early density request --- flattop density still 3.8e19 / m^2
disruption at 0.545 s got lower density but also much more radiation starting around 0.1 s see injections on j-port camera |
| Aug 19 2005 01:14:44:633PM | 1050819014 | Jim Irby | put early density request rise back
disruption at 0.378 s --- pulled breaker injections early delay current rise frame 6 of the j-port view is a classic: min/max/gamma 0/4714/-32 |
| Aug 19 2005 01:27:48:273PM | 1050819015 | Jim Irby | dropped early density request
fizzle Bz0 high, pressure looks okay |
| Aug 19 2005 01:48:21:350PM | 1050819016 | Jim Irby | repeat
disruption at 0.63 s --- still had early injections affecting current rise |
| Aug 19 2005 02:00:21:900PM | 1050819017 | Jim Irby | load seg 2 from 1050818026 --- go diverted but keep density low
nl_04 request to 0.4e20/m^2 Ip request to 800 kA fizzle --- |
| Aug 19 2005 02:15:47:883PM | 1050819018 | Jim Irby | ef4 from -1325 to -1300 A
prefill from 35 to 34 ms plasma into rampdown |
| Aug 19 2005 02:36:50:290PM | 1050819019 | Jim Irby | ef4 from -1300 to =1320 A
plasma into rampdown --- density still too high |
| Aug 19 2005 02:48:36:117PM | 1050819020 | Jim Irby | density request from 4 to 3e19 /m^2
plasma for 1.68 s --- 4e19/m^2 at 1.0 s |
| Aug 19 2005 02:57:55:290PM | 1050819021 | Jim Irby | added 2 ms to prefill to account for DNB gatevalve
plasma into rampdown |
| Aug 19 2005 03:11:17:007PM | 1050819022 | Jim Irby | nl_04 request to 4.5e19/m^2
DNB gatevalve disabled --- prefill decreased by 1 ms to 35 ms plasma into rampdown --- nebar around 0.68e20/m^3 at 1 s startup not as good as on 21 |
| Aug 19 2005 03:36:11:760PM | 1050819023 | Jim Irby | nl_04 request to 5.4e19/m^2 (about 8.5e19 nebar)
dud --- ef3 breaker pulled before shot |
| Aug 19 2005 03:42:23:320PM | 1050819024 | Jim Irby | repeat with ef3
plasma into rampdown --- nebar 8.6e19/m^3 |
| Aug 19 2005 03:55:51:133PM | 1050819025 | Jim Irby | nl04 request to 6.7e19/m^2
plasma into rampdown, but very late breakdown |
| Aug 19 2005 04:06:16:617PM | 1050819026 | Jim Irby | increased prefill by 1 ms
density request to 7.5e19, extended density request to 1.5 s plasma into rampdown --- startup better, but breakdown still late |
| Aug 19 2005 04:18:50:587PM | 1050819027 | Jim Irby | nl_04 request to 9e19/m^2
plasma into rampdown --- got density request |
| Aug 19 2005 04:28:58:443PM | 1050819028 | Jim Irby | nl_04 request to 10.2e19/m^2
plasma into rampdown |
| Aug 19 2005 04:47:58:850PM | 1050819029 | Jim Irby | load seg 2 from shot 1050819016 into seg 2 --- try limited plasma again
nl_04 request to 6.4e19/m^2 plasma into rampdown --- density high from wall fueling |
| Aug 19 2005 04:57:36:337PM | 1050819030 | Jim Irby | reduced early density request
density into rampdown |
| Aug 19 2005 05:07:05:337PM | 1050819031 | Jim Irby | dropped early density request again --- also flattop request
plasma into rampdown --- slight drop in density all done |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 09:10:57:523AM | Plasma | Ok | |
| 2 | 09:44:05:040AM | Plasma | Ok | |
| 3 | 09:57:48:133AM | Plasma | Ok | |
| 4 | 10:13:57:523AM | Plasma | Ok | |
| 6 | 10:41:23:837AM | Plasma | Ok | |
| 7 | 10:54:39:697AM | Plasma | Bad | shot cycle problem |
| 8 | 11:16:33:850AM | Plasma | Bad | shot cycle problem |
| 9 | 11:46:00:367AM | Plasma | Bad | OH2L type 1 flt |
| 10 | 12:08:33:867PM | Plasma | Ok | |
| 11 | 12:24:28:650PM | Plasma | Ok | |
| 12 | 12:37:14:820PM | Plasma | Ok | |
| 13 | 12:49:58:867PM | Plasma | Ok | |
| 14 | 01:03:00:540PM | Plasma | Ok | |
| 15 | 01:21:43:290PM | Plasma | Ok | |
| 16 | 01:35:10:617PM | Plasma | Ok | |
| 17 | 01:54:39:210PM | Plasma | Ok | |
| 18 | 02:07:54:790PM | Plasma | Ok | |
| 19 | 02:24:58:663PM | Plasma | Ok | |
| 20 | 02:37:43:320PM | Plasma | Ok | |
| 21 | 02:51:27:540PM | Plasma | Ok | |
| 22 | 03:03:54:603PM | Plasma | Ok | |
| 23 | 03:16:54:367PM | Plasma | Bad | EF3 Didn't Fire, Breaker Pulled Prior to shot |
| 24 | 03:30:35:367PM | Plasma | Ok | |
| 25 | 03:43:31:603PM | Plasma | Ok | |
| 26 | 03:57:32:507PM | Plasma | Ok | |
| 27 | 04:12:03:507PM | Plasma | Ok | |
| 28 | 04:24:23:337PM | Plasma | Ok | |
| 29 | 04:38:32:180PM | Plasma | Ok | |
| 30 | 04:51:01:163PM | Plasma | Ok | |
| 31 | 05:03:31:540PM | Plasma | Ok | |