| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Eric Edlund |
| Physics operator(s): | Robert Granetz |
| Engineering operator(s): | Bill Cochran,Gary Dekow |
| Engineering Operator Run Comment |
| MP#444b: Alfven Cascades during current ramp with ICRF heating |
| Session Leader Plans |
| Entered: Jul 3 2006 04:01:46:467PM |
| Author: Eric Edlund |
| SL: E. Edlund
PO: R. Granetz MP #444b Alfvén cascade studies during the current ramp-up with ICRF Heating The purpose of these experiments is to expand the database of Alfven cascades, specifically looking at the dependence of the initial frequency on temperature. Excitation of the cascade modes is induced by resonant interaction with the RF generated ion tail. Previous thresholds for activity were about 2.5 MW. It is expected that stong activity will be seen at 3 and 4 MW. A scan of RF power at 1 MW steps will be used to vary the bulk temperature. Setup: RF: all 4 transmitters run-on by 8:00 am use a waveform starting at 0.09 seconds with a ramp to full power by 0.10 seconds, run until 0.5 seconds. Begin with 0.75 MW D, 0.75MW E, and 0.5MW J. Diagnostics: PCI and magnetics are the principal diagnostics. ECE and Thomson are required for temperature and density profile measurements. Hirex and neutrons are requested to help monitor ion temperatures. Run Plan: Use a target plasma similar to 1060525007. Begin at 5.4 T, Ip = 800 kA, nl_04 = 0.5 10^19 in flattop. This will put the 80 MHz resonance on axis and the 70 MHz resonance to the LFS. Establish Alfven cascade activity and then proceed with power scan from 2MW to 5MW (if possible) in 1MW steps. Shots will be repeated to improve the RF matching, if necessary. Change to 5.0 T for symmetric resonance heating. Repeat the power scan. Change to 4.7 T for HFS resonance heating with 80 MHz and on-axis heating with 70 MHz. Repeat the power scan. |
| Physics Operators Plans |
| Entered: Jul 3 2006 05:50:43:070PM |
| Author: Robert Granetz |
Engineering setup for Wednesday 05 July 2006
MP#444b: Alfven Cascades during current ramp with ICRF heating
Session leaders: E. Edlund
Physics operator: R. Granetz
Overnight ECDC in deuterium; bake at 60 C.
The run will start at 10:00 and end at 17:00.
Power systems as on 1060525007
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: PCI (in high-k configuration), Mirnov coils, Thomson, and
ECE. Neutron rate and Hirex are also desirable.
-------------------------------------------------------------------------------
ICRF Setup: all transmitters (70 and 80 MHz) in run-on by 09:30
-------------------------------------------------------------------------------
Run plan: Load shot 1060525007 segment 2. Try increasing Ip ramp rate in
order to get 0.6 MA by 0.1 s, and 0.8 MA by 0.2 s. 5.4 T to start.
nl_04=0.7e20 m-2. Prf=3 MW. After establishing Alfven cascades,
do an ICRF power scan: 2.0, 3.0, 4.0 MW at 5.4 T.
Repeat this sequence at 4.7 T, then at 5.0 T.
|
| Session Leader Summaries |
| Entered: Jul 7 2006 10:24:33:930AM |
| Author: Eric Edlund |
| The morning started out with EF3 and RF problems. By the afternoon we were getting good shots. In particular, shot 012 (the first good shot of the day) showed strong cascade activity, revealing multiple base frequencies which can be seen to increase in time with T_e. The cascade activity decreased throughout the shots, likely due to a creep up in density. An attempt to decrase the density to the shot 012 level was made on the last shot (023) but with the opposite effect, causing the cascades to be completely washed out. It should be noted that Zeff was held at or below 3 for many shots, significantly better than the May experiments which showed a Zeff of 4 or greater.
The previously noted sawteeth related modes were seen again today, most notably on shot 017. During this shot numerous chirping modes were seen between the sawteeth, often with a non-chirping base. In one case it looks like there may be a down-chirping mode preceeding the flat frequency section and the subsequent up-chirping modes, spanning almost the whole sawtooth period. In summary, we did not get the data we had hoped for due to the short run day. It was shown that density is a key parameter for the development of cascades, with an nl_04 value of about 0.55 having produced strong cascades during shot 012, and nl_04 values of 0.65 and greater producing very weak cascades. We did not have a good opportunity to test the effect of the 70 MHz off-axis heating on the cascades because for those shots with decent J-port power the density had also increased. Shot 1060705012 could be used as a target plasma for future experiments. |
| Physics Operator Summaries |
| Entered: Jul 5 2006 05:14:51:320PM |
| Author: Robert Granetz |
Run summary for Tuesday 05 July 2006:
MP#444b: Alfven cascades during Ip rampup with ICRF.
Session leader: E. Edlund
Physics operator: R. Granetz
The run got off to a slow start because of a problem with EF3, which had a
breaker replaced in it last week. It took until 13:00 to get it working.
Shot 7 was our first plasma attempt. We immediately noticed some unusual
fields and power supply currents, which indicate that the OH1 internal
voltage feedback has changed for some reason (something which it has done
occasionally in the past). This led to an alternating series of fizzles
and plasmas, until I made enough tweaks to get a more reliable current
ramp. (After shot 17 the OH1 control was power cycled, and this returned
the power supply to its usual state.) We saw some good Alfven cascades
during the first few plasmas when J-port was NOT operating well. Later in
the run, when J-port was up to 1+ MW, the cascades were weak. So at the
end of the run we tried a shot with no J-port (shot 23), but the cascades
remained weak. Unlike the last Alfven cascades run, the Zeff today was
relatively clean, so that is not the explanation.
Scorecard: 13 plasmas
0 duds
5 fizzles
0 gas system tests
0 TF scanner tests
6 power supply tests (EF3-only)
0 no power MDS shot cycles
--------------
Total: 24 shot cycles
|
| Session Leader Comments | |||
| Jul 5 2006 02:36:58:010PM | 1060705012 | Eric Edlund | P_rf ~ 1.5 MW
very clear and clean cascades, a visual inspection of the base frequency shows good scaling with Te. Base frequencies slightly lower than usual, around 150 kHz. Chirping modes folloqing 300 ms. |
| Jul 5 2006 02:50:32:187PM | 1060705014 | Eric Edlund | P_rf ~ 1.5 MW
some cascade activity, not nearly as clean as for shot 012. sawteeth delayed until about 300ms, again some (faint) chirping modes seen with the sawteeth. |
| Jul 5 2006 03:43:35:753PM | 1060705017 | Eric Edlund | P_rf ~ 2 MW
weak cascade activity, tops but no bases. sawtooth modes with very clear base frequencies after 300 ms, slight evidence of preceeding down-chirping modes, suggestive of a slow increase of qmin. |
| Jul 5 2006 04:24:08:690PM | 1060705020 | Eric Edlund | P_rf ~ 2 MW
some cascades, intermittent but showing base frequencies no strong sawtooth modes |
| Jul 5 2006 04:40:24:050PM | 1060705021 | Eric Edlund | P_rf ~ 2.5 MW
no obvious cascades, increased power (x1.7) and increased radiated power (x1.5) compared to shot 012. Zeff about the same, though increases after about 250ms (compared to shot 012) and brings the sawteeth in sooner. |
| Jul 5 2006 04:45:47:880PM | 1060705022 | Eric Edlund | P_rf ~ 2.5 MW
somewhat stronger cascade signals than shot 021 no sawteeth modes apparent |
| Jul 5 2006 04:59:01:753PM | 1060705023 | Eric Edlund | P_rf ~ 2.5 MW
density seems to have creeped up, no cascades. bring target denisty back down and try again |
| Jul 5 2006 05:10:59:773PM | 1060705024 | Eric Edlund | Prf ~ 1.5 MW
density creeped up even more, cascades completely washed out |
| Physics Operator Comments | |||
| Jul 3 2006 05:49:02:523PM | Robert Granetz | I took the most recent shot (1060623017) for segments 1,3, and 4, and copied 1060525007 segment 2 into segment 2. This segment is from a reversed-field day (but after the F11 issue), so I flipped all the appropriate wires in the "All V" and "All P" screens. I also "call"ed the B21_PROJ wire and confirmed that it picked up the correct A-coil configuration. | |
| Jul 3 2006 06:21:01:960PM | Robert Granetz | Btor across segments 1 and 2 (i.e. at t=0.100 s) is continuous (150 kA). Eric mentioned something about a thrashing problem with Btor at the segment switch during his last run, but there's no problem with today's programming. | |
| Jul 3 2006 06:24:55:663PM | Robert Granetz | I increased the Ip ramp rate to try and get to 0.6 MA by t=0.10 s. | |
| Jul 5 2006 10:05:37:077AM | 1060705001 | Robert Granetz | Shot 01 -- Test of EF3 under PLC control (check new breaker installation). No EF3 current?? |
| Jul 5 2006 10:16:26:067AM | 1060705002 | Robert Granetz | Shot 02 -- Test. Another PLC-controlled attempt to test the new EF3 breaker. Still no current in EF3. |
| Jul 5 2006 11:24:38:467AM | 1060705003 | Robert Granetz | Shot 03 -- Test of EF3 control signals. |
| Jul 5 2006 11:35:35:597AM | 1060705004 | Robert Granetz | Shot 04 -- Test of EF3 control signals again. |
| Jul 5 2006 12:08:10:327PM | 1060705005 | Robert Granetz | Shot 05 -- Test of EF3 control signals again. |
| Jul 5 2006 12:50:44:080PM | 1060705006 | Robert Granetz | Shot 06 -- Test of EF3. This time we got current! The sparker is not
working, however. This could mean some duds today. |
| Jul 5 2006 01:12:43:697PM | 1060705007 | Robert Granetz | Shot 07 -- Fizzle. H-alpha signal is very high. Carbon signal is high too.
Bz0 at 10 ms is too positive. Next shot: subtract 15 amps from IC_EF4; reduce pre-fill by 2 ms. |
| Jul 5 2006 01:25:27:623PM | 1060705008 | Robert Granetz | Shot 08 -- Plasma, but very short. Lasted until 0.13 s, but we did get some
RF into it. Bad startup...Bz0 is still too positive, and the H-alpha signal is huge. The EFC vertical control is banging from rail-to-rail right from the start of the shot. Next shot: subtract another 15 amps from IC_EF4. |
| Jul 5 2006 01:38:37:377PM | 1060705009 | Robert Granetz | Shot 09 -- Fizzle. Bz0 doesn't seem to be responding at all to the IC_EF4 changes
that I've made over the last two startups. Next shot: Decrease RCUR offset in seg 1 to 1600 (from 2000) at Steve W's suggestion. Also decrease pre-fill puff by 4 ms (even though F-side pressure looks reasonable). |
| Jul 5 2006 01:53:44:773PM | 1060705010 | Robert Granetz | Shot 10 -- Plasma. Full length. 0.8 MA, 5.4 T. We got to 0.6 MA at t=0.106 s,
which is just about what Eric wanted. nl_04=0.65e20 m-2. Prf=1.3 MW. Next shot: no DPCS changes. |
| Jul 5 2006 02:01:39:403PM | 1060705011 | Robert Granetz | Shot 11 -- Fizzle.
Next shot: Add 0.5 mT to Br0. Change early RCUR programming out by 5 mm. |
| Jul 5 2006 02:21:53:533PM | 1060705012 | Robert Granetz | Shot 12 -- Plasma. Good full-length shot. Got 0.6 MA at about 0.11 s, and
1.4 MW of RF from D and E. Eric saw some nice cascades, but at this RF power he can't discern the starting frequency. Startup is still not so good. Next shot: no DPCS changes |
| Jul 5 2006 02:32:17:850PM | 1060705013 | Robert Granetz | Shot 13 -- Fizzle.
Next shot: reduce pre-fill another 2 ms. |
| Jul 5 2006 02:43:12:637PM | 1060705014 | Robert Granetz | Shot 14 -- Plasma. Good shot. Prf=1.4 MW.
Next shot: no DPCS changes. |
| Jul 5 2006 02:58:51:987PM | 1060705015 | Robert Granetz | Shot 15 -- Fizzle. We seem to be in an alternating pattern.
Next shot: at Steve W's suggestion, increase the proportional gain on the IC_OH1 wire to 4.0 (from 2.0). Maybe this will get the pre-breakdown OH1 current back to -19600 A instead of -20300 A. |
| Jul 5 2006 03:13:55:883PM | 1060705016 | Robert Granetz | Shot 16 -- Plasma, but very short. Looks like an injection around 0.12 s,
followed by a slowish decay. OH1 is closer to its programming, and the startup ramp looks a little better. Next shot: tweak Br0 offset a tiny amount (0.2 mT) |
| Jul 5 2006 03:23:44:963PM | 1060705017 | Robert Granetz | Shot 17 -- Plasma. Good shot. Prf=1.7-2.2 MW.
Next shot: no DPCS changes. |
| Jul 5 2006 03:41:13:360PM | 1060705018 | Robert Granetz | Shot 18 -- Plasma, but disrupted at 0.12 s. Looks like another injection.
Next shot: increase nl_04 gain. |
| Jul 5 2006 03:49:34:427PM | 1060705019 | Robert Granetz | Shot 19 -- Plasma, but another short one (0.12 s).
Next shot: no DPCS changes. |
| Jul 5 2006 04:16:51:843PM | 1060705020 | Robert Granetz | Shot 20 -- Plasma. Good shot. OH1 went back to its normal state, after the
engineers did a power cycle of the OH1 controls. We got some J-port power on this shot. Prf=2.3 MW briefly, then 1.6 MW. Next shot: add +15 A to IC_EF4 (I'm headed back towards a normal startup, now that OH1 is behaving like it used to.) |
| Jul 5 2006 04:33:11:070PM | 1060705021 | Robert Granetz | Shot 21 -- Plasma. Good shot. Prf=2.4 MW steady (1.0 MW from J-port). But the
cascades are not as strong as earlier today. Next shot: add 10 more amps to IC_EF4 |
| Jul 5 2006 04:48:07:097PM | 1060705022 | Robert Granetz | Shot 22 -- Plasma. Good shot. Prf=1.7-2.8 MW. Got some Alfven cascades, but
not as good as earlier today. Maybe the J-port power inhibits the cascades. Next shot: add 5 amps to IC_EF4 (to bring it back to where I started the day). Turn off J-port. |
| Jul 5 2006 04:59:04:440PM | 1060705023 | Robert Granetz | Shot 23 -- Plasma. Good shot. J-port was off (on purpose), but the cascades
were still weak. Next shot: lower the nl_04 density programming by 0.1 m-2. This will be the last shot of the run. |
| Jul 5 2006 05:14:07:850PM | 1060705024 | Robert Granetz | Shot 24 -- Plasma. Good shot. Prf=2.5 MW (D/E/J = 0.5/1.0/1.0 MW)
End of run. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 10:02:32:153AM | Test | Bad | EF3 PLC TEst |
| 2 | 10:13:51:080AM | Test | Bad | EF3 PLC Test |
| 3 | 11:21:30:420AM | Test | Ok | EF3 PLC no power |
| 4 | 11:32:54:253AM | Test | Ok | EF3 PLC no power |
| 5 | 11:43:55:803AM | Test | Ok | EF3 PLC no power |
| 6 | 12:46:45:153PM | Test | Ok | EF3 3KA 3KV |
| 7 | 01:04:52:147PM | Plasma | Ok | |
| 8 | 01:17:45:010PM | Plasma | Ok | |
| 9 | 01:31:09:593PM | Plasma | Ok | |
| 10 | 01:43:36:960PM | Plasma | Ok | |
| 11 | 01:57:15:370PM | Plasma | Ok | |
| 12 | 02:09:49:640PM | Plasma | Ok | |
| 13 | 02:25:49:193PM | Plasma | Ok | |
| 14 | 02:38:22:587PM | Plasma | Ok | |
| 15 | 02:50:57:953PM | Plasma | Ok | |
| 16 | 03:03:50:817PM | Plasma | Ok | |
| 17 | 03:16:13:713PM | Plasma | Ok | |
| 18 | 03:28:49:420PM | Plasma | Ok | |
| 19 | 03:43:31:207PM | Plasma | Ok | |
| 20 | 04:10:42:123PM | Plasma | Ok | |
| 21 | 04:24:33:490PM | Plasma | Ok | |
| 22 | 04:37:09:150PM | Plasma | Ok | |
| 23 | 04:50:35:550PM | Plasma | Ok | |
| 24 | 05:04:51:863PM | Plasma | Ok | |