| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Martin Greenwald,Brock Bose |
| Physics operator(s): | Robert Granetz |
| Engineering operator(s): | Bill Cochran,Bill Byford,Bill Parkin |
| Engineering Operator Run Comment |
| C-Mod/JET rho* Scan MP 423 |
| Session Leader Plans |
| Entered: Apr 24 2006 03:23:35:607PM |
| Author: Martin Greenwald |
| Plan for 1060425 C-Mod/JET rho* Scan MP 423
The goal is to get the low-field portion of a rho* "dimensionless" scan. This will also serve as the C-Mod part of a multi-machine rho* scan. Today's plan is to get the "low-field" C-Mod data, The parameters we are aiming for are: Bt = 2.6 T Ip = 0.68 MA n = 1.2e20 Pin at least 2.3 MW Shape will be as 1010731008 (As an practical approach, Steve W. has recommended starting with 1050726036 and making minor changes in shaping.) To get the easiest, best match with JET we need to run at high power, but the internal C-Mod rho* scan, is limited by power available for the 5.3 T discharges. Since we do not know what the 2nd harmonic heating efficiency will be, a power scan is appropriate. Achieving the low density required may be a challenge. Our previous 2nd harmonic H-mode experiments, on 960118016, had a density of 1.4e20. (Note: this was a difficult run) Plan: 1. Achieve shape at desired current and field, target density 1e20 LINE AVERAGED 2. RF pulse steady through Bt 2.6 T flat-top, precise timing to be determined 3. Raise RF power gradually, avoid trips and drop-outs - target is beta_N of 1.5 4. Adjust target density as appropriate to achieve required final density. As time permits, run shots with same shape but at 5.3 T, 1.1 MA, with RF power up to 5 MW. (match beta_N from low field discharge). Adjust density to match low-field nu*. |
| Physics Operators Plans |
| Entered: Apr 24 2006 05:37:15:740PM |
| Author: Robert Granetz |
Engineering setup for Tuesday 25 Apr 2006
MP#423 C-Mod/ET rho* scan (2.6 T)
Session leaders: M. Greenwald
Physics operator: R. Granetz
Overnight boronization, followed by 4 hours of ECDC in helium.
The run will start at 09:00 and end at 17:00.
Power systems as on 1050726036
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 + 2 psi Ne Hybrid DISABLED (PG1)
leave B-side upper as is Hybrid DISABLED (PG2)
fill B-main (C-side) with 40 psi D2 Hybrid enabled (PG3)
leave NINJA as is DISABLED
Enable the following gate valves and shutters, assuming no vacuum problems:
ECE, VUV, Z-bolo shutters
Torvac setup: Gate valves open
Key diagnostics: core confinement; edge fluctuation measurements
-------------------------------------------------------------------------------
ICRF Setup: All transmitters in run-on by 08:00
-------------------------------------------------------------------------------
Run plan: Low end of a rho* scan with match to JET shape; 2.6 T, 0.68 MA,
low density, high beta_N (2.3+ MW of ICRF).
|
| Session Leader Summaries |
| Entered: Apr 25 2006 06:05:50:413PM |
| Author: Martin Greenwald |
| While we did get respectable heating via 2nd harmonic at 2.6 T, we were not successful in getting the dimensionless match we were looking for.
During the early part of the run, there was significant outgassing. Even with low target densities, the H-mode density was about a factor too high. beta_N of 1.5 was achieved, but the collisionality was 6-7 times too high. see shot 008. Assuming H=1 for the L-mode portion of this and other similar discharges, I'd estimate that about 50% launched power was absorbed. As the run progressed, the walls unloaded and we regained some density control. However, the low density shots were plagued with run-aways and high levels of radiation. Lowering the current to raise q95 helped, but not enough. It is possible that with the cryopump we may be able to puff and pump - keeping the edge cool enough. We may have more success with the 5.3 T part of this run - as the heating efficiency should be higher. We will be able to run higher density target plasmas, which should hold down run-aways. Still this will be a challenge. |
| Entered: Apr 27 2006 05:32:14:403PM |
| Author: Brock Bose |
| The work on MP#353 demonstrated that the LPI is now working reliably, we managed to inject 12 pellets in 11 attempts Unfortunately, the images on the PSI-4 camera continued to be over exposed. In addition, the ablating pellets were barely on the image. This indicates that either the lens on the fiber which interfaces with the camera is misaligned, or that the lenses on the b-port windows are misaligned. |
| Physics Operator Summaries |
| Entered: Apr 25 2006 04:55:50:337PM |
| Author: Robert Granetz |
Run summary for Tuesday 25 Apr 2006:
MP#423 C-Mod/JET rho* scan (2.6 T)
MP#353 Li pellet striations
Session leader: M. Greenwald (MP 423), Brock Bose (MP 353)
Physics operator: R. Granetz
Most of the day was devoted to MP 423, which involved running a particular
shape at 2.65 T and 0.54 MA. The joint experiment with JET required us to
be in H-mode, and also to run with very low density (nebar=1.2e20 m-3)
during the H-mode. Although the tokamak was running very reliably, it was
not possible to keep the density as low as desired and still be in H-mode.
See the session leader's report for the best shots to look at. As the run
continued, we tried to achieve low H-mode densities by starting with
extremely low target densities. After about 10 shots, we had unloaded the
walls to the point where we were obtaining target densities of
nl_04=0.12e20 m-2. But this was below the H-mode density threshold and so
these shots did not obtain H-modes. Also, putting 2-3 MW of ICRF power
into these very low density plasmas produced large runaway populations, and
also strongly heated the K-limiter. (It's glowing reflection was observable
on several camera views). It also caused most shots to disrupt during the
RF. So this experiment was stopped after shot 26.
The latter part of the day was devoted to MP 353, which involved firing
multiple lithium pellets into standard 0.8 MA, 5.4 T plasmas. Most of
these shots were good full-length plasmas. The lithium pellet injector
worked very well, firing 3 pellets in rapid succession into each of the
shots. Camera images were also obtained, and camera settings were
optimized.
Scorecard: 32 plasmas
0 duds
0 fizzles
0 gas system tests
0 TF scanner tests
1 power supply test (TF-only)
0 no power shot cycle
0 MDSplus cycle tests
--------------
Total: 33 shot cycles
|
| Session Leader Comments | |||
| Apr 25 2006 09:24:41:603AM | 1060425002 | Martin Greenwald | First plasma shot
~1 MW - no H-mode |
| Apr 25 2006 10:00:38:727AM | 1060425003 | Martin Greenwald | H-mode
Bt = 2.65 Ip = 0.54 nebar = 2.63 Ptot = 1.6 (assumes 50% abs) Wmhd = 0.053 betaN = 1.3 nu* = 1.0 rho* = .005 |
| Apr 25 2006 10:00:28:350AM | 1060425004 | Martin Greenwald | H-mode
Bt = 2.65 Ip = 0.54 nebar = 2.4 Ptot = 1.3 (assumes 50% abs) Wmhd = 0.040 betaN = 1.05 nu* = 1.0 rho* = .005 |
| Apr 25 2006 10:13:55:507AM | 1060425005 | Martin Greenwald | H-mode
Bt = 2.65 Ip = 0.52 nebar = 1.98 Ptot = 1.25 (assumes 50% abs) Wmhd = 0.04 betaN = 1.1 nu* = 1.0 rho* = .005 |
| Apr 25 2006 10:27:35:837AM | 1060425006 | Martin Greenwald | H-mode
Bt = 2.65 Ip = 0.52 nebar = 2.1 Ptot = 1.2 (assumes 50% abs) Wmhd = 0.04 betaN = 1.1 |
| Apr 25 2006 10:41:06:600AM | 1060425007 | Martin Greenwald | H-mode - disrupts early
Bt = 2.65 Ip = 0.52 nebar = 2.1 Ptot = 1.7 (assumes 50% abs) Wmhd = 0.44 betaN = 1.2 |
| Apr 25 2006 10:56:05:930AM | 1060425008 | Martin Greenwald | H-mode - disrupts early
Bt = 2.65 Ip = 0.52 nebar = 2.2 Ptot = 1.5 (assumes 50% abs) Wmhd = 0.054 betaN = 1.46 |
| Apr 25 2006 11:04:03:960AM | 1060425009 | Martin Greenwald | H-mode - disrupts v. early
Bt = 2.65 Ip = 0.52 nebar = Ptot = (assumes 50% abs) Wmhd = 0.0 betaN = |
| Apr 25 2006 11:23:50:833AM | 1060425010 | Martin Greenwald | No H-mode - disrupts early
serious radiation problem - starts about 80 mse after RF turns on |
| Apr 25 2006 11:34:05:650AM | 1060425011 | Martin Greenwald | Early disruption
Lots of radiation |
| Apr 25 2006 11:45:13:773AM | 1060425012 | Martin Greenwald | RF turned off for one shot
v low density, lots of runaways, early disruption |
| Apr 25 2006 11:56:28:350AM | 1060425013 | Martin Greenwald | RF turned off
still early disruption, runaways, radiation |
| Apr 25 2006 12:08:47:023PM | 1060425014 | Martin Greenwald | RF still off, but no disruption
density bumped up a bit |
| Apr 25 2006 12:20:42:680PM | 1060425015 | Martin Greenwald | RF on - D port
lots of runaways - more density early on next shot |
| Apr 25 2006 12:35:55:023PM | 1060425016 | Martin Greenwald | Prf held to 1 MW
No disruption No H-mode |
| Apr 25 2006 01:03:44:257PM | 1060425017 | Martin Greenwald | V. early disruption |
| Apr 25 2006 01:37:33:600PM | 1060425018 | Martin Greenwald | Disrupts at 1.18 sec
lots of RF power, but no H-mode unusual cyclic fluctuations at about 1.15 seconds on magnetics - near 900 kHz modulated by sawteeth? |
| Apr 25 2006 01:19:48:617PM | 1060425019 | Martin Greenwald | H-mode - lost due to radiation |
| Apr 25 2006 01:36:16:053PM | 1060425020 | Martin Greenwald | somewhat lower density 0.5e20
just barely an h-mode |
| Apr 25 2006 01:51:51:400PM | 1060425021 | Martin Greenwald | slightly higher density than 20, similar result |
| Apr 25 2006 02:00:48:553PM | 1060425022 | Martin Greenwald | similar to 21
disruption and radiation |
| Apr 25 2006 02:27:56:883PM | 1060425023 | Martin Greenwald | slightly higher densities - target nebar at 0.7e20
a few brief h-modes |
| Apr 25 2006 02:54:43:740PM | 1060425024 | Martin Greenwald | higher density still - 0.95
got series of h-modes for about 0.5 seconds |
| Apr 25 2006 02:53:34:680PM | 1060425025 | Martin Greenwald | lowered current to 0.45 MA
first h-mode lasted a bit longer, but still radiation problems density going too high |
| Physics Operator Comments | |||
| Apr 24 2006 06:35:30:503PM | Robert Granetz | Loaded segments 1,3, and 4 from most recent shot. Loaded segment 2 from segment 2 of 1050726036, and then: Dropped Ip to 540 kA (from 600 kA) Dropped Bt to 2.6 T (from 2.7 T) Dropped nl_04 to 0.6e20 m-2 (nebar=1.0e20 m-3) Increased RXL by 5 mm Moved ZXL down by 1 cm Increased CLEARIN by 5 mm Moved RCUR out by 2.5 mm (to keep outer gap the same with the increased CLEARIN) These changes should match the desired shape, nu*, and rho*, assuming the ICRF heating works well. | |
| Apr 25 2006 08:51:04:167AM | Robert Granetz | The first shot will be a TF-only test under PLC control. This is needed because some work has been done inside the TF cabinets since last Friday's run. | |
| Apr 25 2006 09:08:34:230AM | 1060425001 | Robert Granetz | Shot 01 -- TF test under PLC control. 50 kA. Good. Next shot: go for plasma |
| Apr 25 2006 09:32:49:993AM | 1060425002 | Robert Granetz | Shot 02 -- Plasma. Good shot. Btor=2.65 T (after t=1.0 s), Ip=532 kA, nl_04=0.72e20 m-2, kappa=1.67, delta_U=0.32-0.34, delta_L=0.48. Prf=1 MW (from E). Next shot: move ZXL down by 7 mm, RXL in by 3 mm, ZXU up by 5 mm. |
| Apr 25 2006 10:05:08:647AM | 1060425003 | Robert Granetz | Shot 03 -- Plasma. Good shot. Prf=2 MW (D+E). Got an H-mode, which raises the density well above the desired H-mode value. Somewhat better startup, but it had a bounce. Shape is close to the desired one, except that the upper part of the plasma needs to come down. Next shot: raise ZXU by 1 cm. Turn off finite density starting at t=0.8 s |
| Apr 25 2006 10:05:40:850AM | 1060425004 | Robert Granetz | Shot 04 -- Plasma. Good shot. Prf=1 MW (D). EDA H-mode. Target density is good, but H-mode density is too high. Need a cryopump. Upper edge of plasma is still needs to come down another 1-2 cm. Next shot: raise ZXU by 2 cm. Program target density to 3e19 m-2. Decrease Ip by 30 kA. |
| Apr 25 2006 10:16:30:803AM | 1060425005 | Robert Granetz | Shot 05 -- Plasma. Good shot. Getting closer on the shape match (according to Steve Wolfe). Prf=1 MW (D). H-modes. Next shot: move RXU in by 1-2 cm. |
| Apr 25 2006 10:33:40:930AM | 1060425006 | Robert Granetz | Shot 06 -- Plasma. Good shot. Prf=mostly 1 MW (D) Next shot: no PCS changes. |
| Apr 25 2006 10:43:20:833AM | 1060425007 | Robert Granetz | Shot 07 -- Plasma. Disrupted at t=1.29 s. I think it was an impurity injection. Next shot: decrease pre-programmed gas puff in segment 1 after t=0.050 s. |
| Apr 25 2006 11:00:28:803AM | 1060425008 | Robert Granetz | Shot 08 -- Plasma. Good shot. Disrupted at t=1.41 s. Prf=1.7 MW (1.0 from D, 0.7 from J). Very low target density, but of course the H-mode density is too high. Next shot: decrease early gas puffing some more. Also change EF2-by-EF4 from -2000 to -1500 during the relevant portion of the discharge (suggested by S. Wolfe). |
| Apr 25 2006 11:09:24:180AM | 1060425009 | Robert Granetz | Shot 09 -- Plasma. Disrupted at t=1.12 s. Still looks like an injection. Prf=2.8 Mw for a short time. Next shot: decrease nl_04 before t=0.8 s again to avoid brief turn-ons of PG4. |
| Apr 25 2006 11:27:05:257AM | 1060425010 | Robert Granetz | Shot 10 -- Plasma. Disrupts at t=1.39 s. Prf=2.8 MW, then 2.0-2.8 MW. Lots of radiated power on the 2pi diode. Doesn't look like we got an H-mode on this one. Next shot: no PCS changes. |
| Apr 25 2006 11:30:46:163AM | 1060425011 | Robert Granetz | Shot 11 -- Plasma. Disrupts at t=1.19 s. High Prad when the RF is one. Next shot: try a shot without RF to see if the disruption goes away. |
| Apr 25 2006 11:47:14:850AM | 1060425012 | Robert Granetz | Shot 12 -- Plasma. Very low density (nl_04=0.12e19 m-2) and lots of runaways...maybe this density is too low. Disrupted at t=1.13 s. Ohmic shot; no ICRF. Next shot: raise nl_04 to 0.22e20 m-2. Keep the RF off again. |
| Apr 25 2006 11:57:45:400AM | 1060425013 | Robert Granetz | Shot 13 -- Plasma. Disrupted at t=0.87 s. Still lots of runaways. Next shot: increase early gas puffing (but still less than normal). No RF. |
| Apr 25 2006 12:12:18:337PM | 1060425014 | Robert Granetz | Shot 14 -- Plasma. Full-length ohmic shot. Still have hard x-rays, although not extrememly high. Very low radiated power. Next shot: turn on 1 MW (D-port) of ICRF. |
| Apr 25 2006 12:21:37:227PM | 1060425015 | Robert Granetz | Shot 15 -- Plasma. Disrupted at t=1.15 s. Lots of runaways again. Next shot: raise early gas programming and nl_04 to 3e19 m-2. |
| Apr 25 2006 12:41:00:070PM | 1060425016 | Robert Granetz | Shot 16 -- Plasma. Good shot. Full-length. Still huge hard x-ray signal. Shape could still use a little more tweaking. Next shot: change EF2-by-EF4 to go 500 amps in the opposite direction compared to the change I made earlier in the run. Increase Prf to 2.5 MW. |
| Apr 25 2006 12:53:37:540PM | 1060425017 | Robert Granetz | Shot 17 -- Plasma. Disrupted at t=0.59 s. Lots of hard x-rays. Next shot: Pre-program 20 volts on PG3 gas valve in segment 2. |
| Apr 25 2006 01:03:42:180PM | 1060425018 | Robert Granetz | Shot 18 -- Plasma. Longer, but still disrupted at t=1.18 s. Hard x-rays and radiated power start upwards when the RF turns on. Prf=2.8 MW (from all three antennas). Next shot: increase nl_04 to 4e19 m-2. |
| Apr 25 2006 01:18:18:193PM | 1060425019 | Robert Granetz | Shot 19 -- Plasma. Disrupted at t=1.29 s. Prf=2+ MW. Got an H-mode. Next shot: reduce nl_04 a bit to 3.6e19 m-2. |
| Apr 25 2006 01:39:14:647PM | 1060425020 | Robert Granetz | Shot 20 -- Plasma. Disrupted at t=1.16 s. Looks like these shots get the K-limiter hot when the RF turns on. We see reflections of the glowing K-limiter on a number of camera views. Next shot: tweak nl_04 to 3.8e19 m-2. Move RCUR in by 2 mm to increase outer gap by 4 mm. |
| Apr 25 2006 01:52:08:633PM | 1060425021 | Robert Granetz | Shot 21 -- Plasma. Disrupted at t=1.17 s. Good density. Outer gap did indeed increase, but we're still heating K-limiter to glowing. Next shot: tweak nl_04 up to 0.40e20 m-2. |
| Apr 25 2006 02:07:20:350PM | 1060425022 | Robert Granetz | Shot 22 -- Plasma. Disrupted at t=1.18 s. Prf=2.9 MW. Next shot: raise nl_04 to 0.5e20 m-2 |
| Apr 25 2006 02:22:24:680PM | 1060425023 | Robert Granetz | Shot 23 -- Plasma. Disrupted at t=1.35 s. K-limiter glows for severals tenths of a second. Prf=2.9 MW for 0.35 s. Next shot: raise nl_04 to 0.6e20 m-2. |
| Apr 25 2006 02:41:41:773PM | 1060425024 | Robert Granetz | Shot 24 -- Plasma. Good shot. Disrupted at t=1.40 s. Prf=2.9 MW. H-modes, since the density is a little higher. Next shot: lower Ip to 450 kA. |
| Apr 25 2006 02:52:54:303PM | 1060425025 | Robert Granetz | Shot 25 -- Plasma. Ip=0.45 MA. Disrupted at t=1.28 s. Prad is less. Hard x-rays are less too. Next shot: lower Ip to 0.40 MA. |
| Apr 25 2006 03:17:57:210PM | 1060425026 | Robert Granetz | Shot 26 -- Plasma. 0.40 MA. Disrupted at t=1.31 s. H-modes. Prf=2-3 MW. End of MP 423. Next shot: load a standard 0.8 MA, 5.4 T, LSN for Brock Bose to try lithium pellet injection. This is MP 353. |
| Apr 25 2006 03:26:11:930PM | 1060425027 | Robert Granetz | Shot 27 -- Plasma. Good shot. 0.8 MA, 5.4 T. Got three lithium pellet at around t=0.85 s. This is for MP 353. Looks like the density feedback went beserk. Prf=1-2 MW. Next shot: turn off density feedback after t=0.8 s. Also zero the PG3 pre-programming after t=0.8 s as well. |
| Apr 25 2006 03:39:28:257PM | 1060425028 | Robert Granetz | Shot 28 -- Plasma. Full length. Got 3-4 Li pellets. Cell access made after this shot in order to change the settings on the LPI camera. Next shot: no PCS changes. |
| Apr 25 2006 04:02:48:837PM | 1060425029 | Robert Granetz | Shot 29 -- Plasma. Good full-length shot. 3 Li pellets. Prf=2 MW. Next shot: repeat, no PCS changes. |
| Apr 25 2006 04:23:22:773PM | 1060425030 | Robert Granetz | Shot 30 -- Plasma. Good full-length shot. 3 Li pellets. Prf=2 MW. Next shot: repeat, no PCS changes. |
| Apr 25 2006 04:35:34:430PM | 1060425031 | Robert Granetz | Shot 31 -- Plasma. Good full-length shot. 3 Li pellets. Prf=1-2 MW. Next shot: repeat, no PCS changes. |
| Apr 25 2006 04:48:36:570PM | 1060425032 | Robert Granetz | Shot 32 -- Plasma. Good full-length shot. 2 Li pellets. Prf=2 MW. Next shot: repeat, no PCS changes. |
| Apr 25 2006 04:56:37:570PM | 1060425033 | Robert Granetz | Shot 33 -- Plasma. Good full-length shot. 3 Li pellets. End of run. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 09:05:19:340AM | Test | Ok | TF 50kA PLC Test |
| 2 | 09:18:01:637AM | Plasma | Ok | |
| 3 | 09:33:04:417AM | Plasma | Ok | |
| 4 | 09:46:05:517AM | Test | Bad | |
| 5 | 10:07:47:507AM | Test | Bad | |
| 6 | 10:22:30:460AM | Plasma | Ok | |
| 7 | 10:35:07:990AM | Plasma | Ok | |
| 8 | 10:47:46:493AM | Plasma | Ok | |
| 9 | 11:01:24:867AM | Plasma | Bad | OH1 self powered circuit fired |
| 10 | 11:15:25:757AM | Plasma | Ok | |
| 11 | 11:28:02:367AM | Plasma | Ok | |
| 12 | 11:40:29:617AM | Plasma | Ok | |
| 13 | 11:53:00:197AM | Plasma | Ok | |
| 14 | 12:05:38:820PM | Plasma | Ok | |
| 15 | 12:18:09:883PM | Plasma | Ok | |
| 16 | 12:30:39:257PM | Plasma | Ok | |
| 17 | 12:43:07:727PM | Plasma | Ok | |
| 18 | 12:57:44:740PM | Plasma | Ok | |
| 19 | 01:10:24:257PM | Plasma | Ok | |
| 20 | 01:27:48:943PM | Plasma | Ok | |
| 21 | 01:42:44:273PM | Plasma | Ok | |
| 22 | 01:58:32:180PM | Plasma | Ok | |
| 23 | 02:13:23:367PM | Plasma | Ok | |
| 24 | 02:28:23:837PM | Plasma | Ok | |
| 25 | 02:46:41:460PM | Plasma | Ok | |
| 26 | 02:59:37:540PM | Plasma | Ok | |
| 27 | 03:17:42:350PM | Plasma | Ok | |
| 28 | 03:31:17:007PM | Plasma | Ok | |
| 29 | 03:55:46:867PM | Plasma | Ok | |
| 30 | 04:11:56:727PM | Plasma | Ok | |
| 31 | 04:25:48:273PM | Plasma | Ok | |
| 32 | 04:39:57:413PM | Plasma | Ok | |
| 33 | 04:53:10:430PM | Plasma | Ok | |