| Miniproposals | ||||||||||
|
| Operators | |
| Session leader(s): | Amanda Hubbard |
| Physics operator(s): | Robert Granetz |
| Engineering operator(s): | Andy Pfeiffer,Ed Fitzgerald |
| Engineering Operator Run Comment |
| MP#448 Small ELM regime and possibly MP#404a Alfven damping Session lea |
| Session Leader Plans |
| Entered: May 11 2006 04:04:37:197PM |
| Author: Amanda Hubbard |
| Run Plan for of 1060512, MP 448, Comparison of Small ELM regimes on C-Mod, MAST and NSTX
Session Leaders: Rajesh Maingi (PPPL) , Amanda Hubbard RF operator (and co-leader): Yijun Lin Physics Operator: Bob Granetz Goals: A. Optimize techniques for obtaining high power (3.5-4 MW) ICRF in combination with good machine conditions. B . Complete C-Mod part of Small ELM pedestal comparisons by going to high power, nu* scan This run follows previous runs on 1060407 and 1060504, in which suitable target plasmas were demontrated but it was found (particularly on 1060504) that conditioning J-port following overnight boronization was a challenge. This run will therefore explore an alternate procedure; we will NOT boronize before the run, but use between-shot boronization following RF conditioning. Before the run, the RF group will use multipactor conditioning of J-port - Steve and Yijun to prescribe time and voltage etc; see RF entry 1) Load and repeat shot 1060407033 ; 5.45 T, 708 kA. (same shape etc as successful RF conditioning pulses eg 1060505013). 2) Take several shots to condition RF antennas, bring up power. Minimum needed is 3 MW; target is 4 MW. Plasma target may be modified to aid conditioning (eg, raising target density to 9e19 m-2). 3) Assuming that H-mode conditions indicate the need for it (which is very likely after 3 run days, 2 at low ne), use between-shot boronization - see procedure used 1060510 by Jim Terry. 4) Repeat H-mode discharges. Assess coupled power and H-mode quality. If all looks OK, do 5) Density scan: Keeping power, and hopefully beta, in its upper range, scan target density shot to shot to vary nped, Tped and thus n*. Use two power levels per shot, selected based on results of step two. Start by raising target nel (9x 1019 m-2, 1.1x 1020 m-2, 1.3x1020 m-2, 1.5x1020 m-2. Upper limit will probably be set by neutral pressure limit of J-port, or if we are lucky, a transition to Type III ELMs. Then scan downwards, 7x 1019 m-2 ,6x 1019 m-2. The limit in this case will be losing EDA and getting either transient ELM-free H-modes or, more interestingly, discrete Type I ELMs. Stop for between-shot boronization as needed. 6) Current scan: If pedestal beta is too low, try raising Ip to increase odds of getting into small ELM regime. May slightly increase Bt at this point; there will be a tradeoff in terms of moving RF off-axis. We will assess progress around 1pm in terms of RF and machine performance. Standby MP in case we decide we aren't likely to meet goal A is Joe Snipes Active MHD expt. |
| Physics Operators Plans |
| Entered: May 11 2006 04:17:42:990PM |
| Author: Robert Granetz |
Engineering setup for Friday 12 May 2006
MP#448 Small ELM regime (50-100% of the run day)
and possibly
MP#404a Alfven damping (0-50% of the run day)
Session leaders: A. Hubbard (MP#448), and possibly J. Snipes (MP#404a)
Physics operator: R. Granetz
Overnight ECDC in deuterium; bake at 60 C.
BE PREPARED TO DO BETWEEN-SHOT BORONIZATION.
The run will start at 09:00 and end at 17:00.
Power systems as on 1060407033 (5.45 T, 0.71 MA)
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, edge Thomson, ECE
-------------------------------------------------------------------------------
ICRF Setup: All transmitters in run-on by 08:00, after doing the
multipactor thing.
-------------------------------------------------------------------------------
Run plan: Don't do overnight boronization, in the hopes that J-port will
run better than it has after the previous overnight
boronizations. Instead, we will be doing between-shot
boronizations and RF vacuum conditioning. If we get good
H-modes, then we will do a density scan, and possibly a current
scan. If we don't get good H-modes or the RF is not performing
well, then we'll switch to the alternate miniproposal, MP#404a
Alfven damping, and load 1060309020 to begin with.
|
| Session Leader Summaries |
| Entered: May 12 2006 05:09:15:637PM |
| Author: Amanda Hubbard |
|
Mixed day. Started off much better than I expected RF -wise. J-port ran clean from shot 1 and Ptot was over 4 MW on several shots. Best shot of the day was shot 5, with clean RF up to 4.7 MW and H-mode performance that actually increased over the discharge (H ~ 1.6, despite no boronization since Monday night). High pedestal parameters though, somewhat surprisingly, no small ELMs. The run took a turn for the worse after shot 6, which had PS problems and a crowbar. (perhaps coincidence). Had many early disruptionss and fizzles. On the full plasmas , 13 and 19, it was clear that H-mode performance was degrading though RF power was still high. We followed shot 19 with 10 minutes between shot boronization. This was, unfortunately, followed by 6 fizzles. On the only remaining shot of the day, 26, we got a nice long H-mode, at slightly higher ne. D and E ran clean, J tripped early. Bottom line: - We have demonstrated that J-port, and other RF, can run at very high power following RF conditioning and some time after boronization. - At least on the first shot after boron, J still has trouble; we didn't get to test how many shots it would take to come back up. No 'magic bullet', but not yet cause to give up on this approach. - Got a few nice, fairly high pressure points for NSTX/MAST pedestal comparison. But not, alas, with small ELMs though we were likely close. |
| Physics Operator Summaries |
| Entered: May 12 2006 04:56:19:327PM |
| Author: Robert Granetz |
Run summary for Friday 12 May 2006:
MP#448 Small ELM regime
Session leader: A. Hubbard/R. Maingi
Physics operator: R. Granetz
Bad day, although the first few shots were very encouraging. Shot 5 is the
trophy shot, with nearly 4-5 MW of ICRF on steadily for 0.75 s, long EDA
H-mode, and good confinement. But then things went downhill. Many
fizzles and several very short discharges, with a between-shot boronization
thrown in. I have no idea why I was unable to recover plasma operation.
Scorecard: 12 plasmas
1 dud (EF4 didn't fire)
15 fizzles
0 gas system tests
0 TF scanner tests
0 power supply test (TF-only)
0 no power shot cycle
0 MDSplus cycle tests
--------------
Total: 28 shot cycles
|
| Session Leader Comments | |||
| May 12 2006 09:13:52:700AM | 1060512001 | Amanda Hubbard |
Good first shot. Got ramp up to 3.3 MW with just D+J. Target nel was lower than I expected, 5.5e19 m-2; will raise next shot. 2 H-modes. Te8 up to 600 eV. |
| May 12 2006 09:30:57:310AM | 1060512002 | Amanda Hubbard | ne tweak led to larger change than intended, perhaps causing J-port trips.
bel 0.8 to 1.3e20 m-2. Te8 530 eV, steady until injection. |
| May 12 2006 09:41:21:577AM | 1060512003 | Amanda Hubbard | Good full length shot. Full length, with long EDA, steady ne. target 7e19 m-2, H-mode 1.e20 m-2. First phase had Ptot 3.8 MW. Later, after some trips, got 4.2 MW. Radiation not as bad as I expected. Te8 700 eV, ETS 600 eV, ne95 1.6e20 m-2, pe95 9e22. Beta_N~ 1.1.
Keep this target, retry RF. |
| May 12 2006 10:39:23:607AM | 1060512004 | Amanda Hubbard | Very good shot. RF up to 4.4 MW. H ~ 1.6, beta_N1.2 steady EDA
Pe95 9e22. |
| May 12 2006 10:36:17:263AM | 1060512005 | Amanda Hubbard |
"Trophy/viewgraph shot". Got clean RF, slow ramp up to 4.7 MW. 129 kJ, Pe95~ 1.2e23 m-3. Looks like steady EDA, no evident ELMs but a nice pedestal comparison point. beta_N ~ 1.3, H ~1.6, John says record Moly, but Prad is at least steady at ~2.5 MW. We will square up RF pulse and try some density scanning on subsequent shots (assuming power supplies OK after shot 6). |
| May 12 2006 10:40:04:077AM | 1060512006 | Amanda Hubbard | DUD - power supply problems |
| May 12 2006 11:16:21:437AM | 1060512007 | Amanda Hubbard | Early (0.2 s) disruption |
| May 12 2006 11:16:34:873AM | 1060512008 | Amanda Hubbard | Another early (0.2 s) disruption |
| May 12 2006 11:54:46:187AM | 1060512010 | Amanda Hubbard | disrupts before RF |
| May 12 2006 11:54:27:873AM | 1060512011 | Amanda Hubbard | Fizzle |
| May 12 2006 12:03:40:077PM | 1060512012 | Amanda Hubbard | fizzle |
| May 12 2006 01:01:58:343PM | 1060512013 | Amanda Hubbard |
Plasma, disrupts 0.95 secs. Nominally repeat of shot 5, with RF 'squared up' - 4.1 MW early. But, Prad starts rising and edge cooling ~ 0.75 secs. (this is well before the first RF trip). Prad gets to 3.7 MW. May be soon time to boronize... |
| May 12 2006 01:35:33:970PM | 1060512014 | Amanda Hubbard |
Fizzle |
| May 12 2006 01:35:49:640PM | 1060512015 | Amanda Hubbard | Fizzle |
| May 12 2006 01:36:23:810PM | 1060512016 | Amanda Hubbard | PS Dud |
| May 12 2006 01:25:51:110PM | 1060512017 | Amanda Hubbard | Yet another fizzle. Try between-shot ECDC to clean things up.
For next plasma attempt, raise Ip to 800 kA and nel target to 7e19 m-3. |
| May 12 2006 01:52:16:700PM | 1060512018 | Amanda Hubbard | Another fizzle.... can't win. |
| May 12 2006 02:32:12:513PM | 1060512019 | Amanda Hubbard | Full length. 800 kA, 0.7-1.6E19 M-2. Long H-mode, 3-4 MW RF (J works well, E is unhappy). But, Prad is rising - to 3.8 MW) and Tedge eroding from ~ 0.75 secs. H decreases to ~ 1.1 late in H-mode (vs 1.6 on shot 5). Plasma is telling us it is time to boronize. Start with 10 minutes before shot 20.
pped 8 to 6e22 m-3 eV, lower than shot 5 despite higher Ip. |
| May 12 2006 03:24:47:277PM | 1060512020 | Amanda Hubbard | post-boronization fizzle |
| May 12 2006 03:24:34:870PM | 1060512021 | Amanda Hubbard | second post-boronization fizzle |
| May 12 2006 04:44:10:870PM | 1060512026 | Amanda Hubbard | Finally, a plasma. Pretty good in fact, long EDA H-mode. Higher ne - target was 8.5 e29 m-2, H-mode got to 1.7e20 m-3.
Mixed news on RF front. D and E ran clean (2 MW total, slight programmed ramp). But, J-port tripped from the beginning. We'll see how it cleans up next shot. Pedestal starts off fairly hot, Te96 530 eV, when W=116 kJ, H ~ 1.8, ne_95~ 2e20m-3. But, all erode from ~0.9 secs, seems that Prad and ne rise from 0.98 secs, H drops to ~1.2 |
| Physics Operator Comments | |||
| May 12 2006 08:46:53:187AM | Robert Granetz | Loaded shot 1060407033, except loaded segment 1 from shot 20 of yesterday (1060511020). | |
| May 12 2006 09:16:28:093AM | 1060512001 | Robert Granetz | Shot 01 -- Plasma. Good shot. 0.71 MA, 5.47 T, target nl_04=0.5e20 m-2. Several longish H-modes. Prf = 2 -> 3 MW (ramped). No power from E-port. Next shot: raise target nl_04 to 0.7e20 m-2 |
| May 12 2006 09:24:44:467AM | 1060512002 | Robert Granetz | Shot 02 -- Plasma. Disrupted at t=0.88 s due to large injection. J-port did not do well, but E-port was on. Next shot: tweak nl_04 to 0.65e20 m-2. |
| May 12 2006 09:35:07:233AM | 1060512003 | Robert Granetz | Shot 03 -- Plasma. Goood shot. Very long, steady EDA H-mode. Prf=4 MW, then 2 MW. D and E look very good. J-port is struggling. Next shot: no PCS changes. |
| May 12 2006 09:50:20:763AM | 1060512004 | Robert Granetz | Shot 04 -- Plasma. Good shot. Very long, steady EDA H-mode. Prf=3.7 -> 4.5 MW (ramped), with 2+ MW coming from J-port. Some faulting, but much improved. Next shot: no DPCS changes. |
| May 12 2006 10:04:00:467AM | 1060512005 | Robert Granetz | Shot 05 -- Plasma. Good shot. Long, steady EDA H-mode. Great RF performance. Prf=3.7 -> 4.7 MW. Faultless RF for 0.75 s. Next shot: no DPCS changes |
| May 12 2006 10:44:01:047AM | 1060512006 | Robert Granetz | Shot 06 -- Fizzle, but it was due to a problem with the TF and the PFs. All coil currents were lagging in their rampup. It's as if the alternator was not supplying the power it should have. All TF and PF breakers tripped. TF crowbarred. Power room access to check fuses. All OK. Next shot: go for plasma, no DPCS changes |
| May 12 2006 10:54:05:327AM | 1060512007 | Robert Granetz | Shot 07 -- Plasma, but disrupted at t=0.2 s. Probably an injection, but I can't see it on the WIDE2 view. Next shot: try again, no changes. |
| May 12 2006 11:12:27:280AM | 1060512008 | Robert Granetz | Shot 08 -- Plasma, but again it disrupted at t=0.2 s. Next shot: try again. |
| May 12 2006 11:28:58:717AM | 1060512009 | Robert Granetz | Shot 09 -- Plasma, but disrupted at t=0.3 s. Is it an injection, or something under my control. Next shot: I blew away DPCS, restarted it, and reloaded shot 5. In principle, this should not have done anything. |
| May 12 2006 11:43:41:657AM | 1060512010 | Robert Granetz | Shot 10 -- Plasma. Went a little longer before disrupting at t=0.58 s. Next shot: no changes. |
| May 12 2006 11:58:38:310AM | 1060512011 | Robert Granetz | Shot 11 -- Fizzle. Next shot: drop Br0 offset by 0.3 mT |
| May 12 2006 12:03:26:593PM | 1060512012 | Robert Granetz | Shot 12 -- Fizzle again. Next shot: subtract 15 amps from IC_EF4 |
| May 12 2006 12:34:58:420PM | 1060512013 | Robert Granetz | Shot 13 -- Plasma. Halfway decent shot until a swarm of UFOs come in at t=0.91 and kill the plasma. Good view of them on the WIDE2 video camera view. Good startup, at least for now. Next shot: no DPCS changes |
| May 12 2006 12:40:13:640PM | 1060512014 | Robert Granetz | Shot 14 -- Fizzle. Next shot: tweak IC_EF4 and pre-fill puff. |
| May 12 2006 12:55:57:687PM | 1060512015 | Robert Granetz | Shot 15 -- Fizzle. Next shot: decrease IC_EF4 some more. |
| May 12 2006 01:11:48:157PM | 1060512016 | Robert Granetz | Shot 16 -- Dud. No EF4 Next shot: try again. |
| May 12 2006 01:25:35:610PM | 1060512017 | Robert Granetz | Shot 17 -- Fizzle. Do 15 minutes of ECDC before the next shot. Next shot: raise Ip to 0.8 MA, raise nl_04 to 0.7e20 m-2. |
| May 12 2006 01:52:36:513PM | 1060512018 | Robert Granetz | Shot 18 -- Fizzle. Pressure is much higher on this shot. Might be because of the between-shot ECDC. Next shot: reduce prefill pulse by 4 ms. |
| May 12 2006 02:27:53:623PM | 1060512019 | Robert Granetz | Shot 19 -- Plasma, finally. Good shot. 0.80 MA. Target nl_04=0.7e20 m-2. Long EDA H-mode. Prf=3.2-4 MW. Prad is up to 3 MW. We will now do 10 minutes of between-shot boronization. Next shot: no DPCS changes |
| May 12 2006 03:14:03:580PM | 1060512020 | Robert Granetz | Shot 20 -- Fizzle. Don't know what the pressure was because the ratiomatic was not turned back on. Next shot: tweak pre-fill down another 1 ms. |
| May 12 2006 03:24:35:573PM | 1060512021 | Robert Granetz | Shot 21 -- Fizzle again. Next shot: shorten pre-fill another 2 ms. |
| May 12 2006 03:43:55:730PM | 1060512022 | Robert Granetz | Shot 22 -- Fizzle. Fields and pressure look fine. Next shot: reload segment 1 from shot 03 today, except that I will take 5 ms off the pre-fill pulse. |
| May 12 2006 04:01:00:717PM | 1060512023 | Robert Granetz | Shot 23 -- Fizzle. This sucks. Next shot: on advice from Jim Irby, I will add more gas to the pre-fill. |
| May 12 2006 04:05:14:200PM | 1060512024 | Robert Granetz | Shot 24 -- Fizzle. Next shot: now try dropping pre-fill a lot. Also tweak Br0. |
| May 12 2006 04:20:14:327PM | 1060512025 | Robert Granetz | Shot 25 -- Fizzle. Next shot: shorten the pre-fill another 4 ms. |
| May 12 2006 04:34:09:120PM | 1060512026 | Robert Granetz | Shot 26 -- Plasma, finally. Good shot. J-port apparently doesn't like the 10 minute boronization. The steady 2 MW from D+E gave a long EDA H-mode. Next shot: no DPCS changes |
| May 12 2006 04:43:00:327PM | 1060512027 | Robert Granetz | Shot 27 -- Fizzle. Next shot: last shot coming up...no DPCS changes |
| May 12 2006 04:54:30:077PM | 1060512028 | Robert Granetz | Shot 28 -- Fizzle. Incredible. End of run. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 09:04:22:200AM | Plasma | Ok | |
| 2 | 09:17:06:530AM | Plasma | Ok | |
| 3 | 09:29:31:577AM | Plasma | Ok | |
| 4 | 09:42:04:153AM | Plasma | Ok | |
| 5 | 09:54:51:030AM | Plasma | Ok | |
| 6 | 10:07:22:920AM | Plasma | Bad | Excitation Fault |
| 7 | 10:47:18:670AM | Plasma | Ok | |
| 8 | 11:00:48:890AM | Plasma | Ok | |
| 9 | 11:19:04:797AM | Plasma | Ok | |
| 10 | 11:31:45:920AM | Plasma | Ok | |
| 11 | 11:44:32:280AM | Plasma | Ok | |
| 12 | 11:59:43:390AM | Plasma | Ok | |
| 13 | 12:19:37:467PM | Plasma | Ok | |
| 14 | 12:35:32:530PM | Plasma | Ok | |
| 15 | 12:48:52:780PM | Plasma | Ok | |
| 16 | 01:08:13:343PM | Plasma | Bad | EF4 |
| 17 | 01:21:36:623PM | Plasma | Ok | |
| 18 | 01:48:27:107PM | Plasma | Ok | |
| 19 | 02:02:12:030PM | Plasma | Ok | |
| 20 | 03:09:19:747PM | Plasma | Ok | |
| 21 | 03:22:05:963PM | Plasma | Ok | |
| 22 | 03:34:43:683PM | Plasma | Ok | |
| 23 | 03:47:22:607PM | Plasma | Ok | |
| 24 | 04:01:52:370PM | Plasma | Ok | |
| 25 | 04:14:27:980PM | Plasma | Ok | |
| 26 | 04:27:08:107PM | Plasma | Ok | |
| 27 | 04:39:46:700PM | Plasma | Ok | |
| 28 | 04:52:31:997PM | Plasma | Ok | |