| Miniproposals | ||||||||||
|
| Operators | |
| Session leader(s): | Jerry Hughes |
| Physics operator(s): | Joseph Snipes |
| Engineering operator(s): | Andy Pfeiffer,Bill Parkin |
| Engineering Operator Run Comment |
| MP452: Reversed field pedestal studies SL: Hughes PO: Snipes |
| Session Leader Plans |
| Entered: May 23 2006 05:27:15:610PM |
| Author: Jerry Hughes |
| Session leader run plan for 1060524
MP452: Reversed field pedestal studies SL: Hughes PO: Snipes The goal for this experiment is to acquire and characterize H-modes and pedestals with the direction of field and current reversed, in order to make a comparison with similar discharges in the normal configuration. We will attempt to run a range of currents and densities in this configuration, tracking pedestal parameters (both dimensional and dimensionless), confinement and edge fluctuations. How these quantities differ between forward and reversed field will be studied and analyzed. SETUP: *Required diagnostics: Edge and core Thomson, ECE diagnostics, CXRS, visible continuum, bolometer arrays, PCI, fast D-alpha diodes, Hirex, NeSoX. *Overnight boronization required, same prescription as before 1060509. *RF will require power room access by 06:00 in order to begin a boronization recovery recipe consisting of: 1.) vacuum tune, 2.) multipactor conditioning of J antenna, 3.) re-tune to vacuum and 4.) vacuum conditioning with RF pulses. A ~1-hour run delay is possible. *Gas: --NINJA plenum loaded with 10psi D2 --Argon/Neon puff: 50ms at 0.3s (Neon at 2psi, Argon at 1psi) Tentative shot sequence (subject to change, depending on how the run is going): 1. Begin by loading 1060519008 (5.4T, 0.8MA rev.; nl04~1e20). Start bringing up RF power, while increasing elongation of plasma from 1.55 to 1.65. (~3 shots) 2. When RF is working, and shape is matched, begin power end density scans: A. Apply RF power ramp from 2.5MW up to maximum available to find approximate power threshold. (1 shot with an H-mode) B. Use a staircase waveform for RF, stepping power up from just above the threshold power to the maximum available. This should give some collisionality variation at the given target. (~2 shots with good H-modes) 2. Repeat step 2 with a target nl04 of 1.3e20m^-2, then with nl04~0.7e20m^-2. (~6 shots) 3. Make Ip=1.2MA. Repeat step 2 with target nl04 of 1.7, 1.3 and 0.9e20m^-2. (~9 shots) 4. Make Ip=0.5MA. Repeat step 2 with target nl04 of 0.8, 0.6 and 0.4e10m^-2. (~9 shots) |
| Physics Operators Plans |
| Entered: May 23 2006 12:26:13:720PM |
| Author: Joseph Snipes |
| Physop plan and engineering setup for Wednesday, May 24 MP452: Reversed field pedestal studies SL: Hughes PO: Snipes Overnight boronization. ********************************************************* * NOTE: PEI Sweep limited to <80cm * ********************************************************* 20% B2D6 / 80% He 6L bottle. vessel temperature at 60/60/60. 60 psi to be deposited. PEI setting to 44/70/80 (Rmin/Rres/Rmax) with no pulser. Gas Pressures: TC3/TC6/TC9/TC6Request = [4 to 7]/150/95/150 Follow boronization with 4 hours ECDC in helium. RF will require power room access by 06:00 in order to begin a boronization recovery recipe consisting of: 1.) vacuum tune, 2.) multipactor conditioning of J antenna, 3.) re-tune to vacuum and 4.) vacuum conditioning with RF pulses. A ~1-hour run delay is possible. Engineering setup: ------------------- Power system setup as on 1060519008 Gas Setup: fill B-Top with 6 psi D2 Hybrid enabled (PG4) fill B-side lower with 1 psi Ar + 2 psi Ne Hybrid enabled (PG1) leave B-side upper with 15psi He3. Hybrid enabled (PG2) fill B-main with 40 psi D2 Hybrid enabled (PG3) fill NINJA with 10psi D2 (Disable) Enable the following gate valves and shutters, assuming no vacuum problems: ECE, VUV, Z-bolo shutters FMIT#1,2,3,4 in Run-on by 8:30AM; turn on earlier if requested by RF Run Plan: --------------------- Start from 1060519008, LSN with NL04=1.0 x 10^20 m^-2. The starting shot may change if a better shot is found on 1060523. Attempt to run a range of currents and densities at 5.4 T monitoring edge pedestals and looking for H-mode thresholds with the ion grad B drift direction away from the X point. See the Session Leader Run Plan for details. |
| Session Leader Summaries |
| Entered: May 24 2006 05:32:23:197PM |
| Author: Jerry Hughes |
| MP452: Reversed field pedestal studies
SL: Hughes PO: Snipes The goal for this experiment was to acquire and characterize H-modes and pedestals with the direction of field and current reversed, in order to make a comparison with similar discharges in the normal configuration. A range of currents and densities was proposed, in which we would track pedestal parameters (both dimensional and dimensionless), confinement and edge fluctuations. This was only a half-day run, due to an alternator system repair, along with ECDC following a leak, as well as RF vacuum conditioning for boronization recovery. Oh, and there was a stuck gas valve. First plasma attempt was at 13:00. Time remaining allowed us to get through only steps 1 and 2 of the run plan. There were initially several fizzles, with a plasma mixed in, presumably as part of boronization recovery. Also, there were subtle difficulties with startup, and pesky MARFEs in the early phase of some discharges, of the type seen in reversed field configuration lately (in particular on 1060519). With some tweaks, the PO got a number of shots without MARFEs and matched the elongation of 1060523013 (a USN shot) and RF was brought up to full power. Later in the day, injections disrupted several plasmas. These occurred both with and without RF. H-mode access required >3MW of ICRF, which was hard to come by. Outgassing from the antennas was observed to fuel the plasma, further hindering L-H transitions via density rise. This effect was observed all day. H-modes were obtained on shots 14, 18, and 19. Most were not sustained, since the L-H transition tended to drop the RF out. The longest was on shot 19, and showed a hint of a fluctuation in the right frequency range to be the QCM. Radiated power, though rising in the H-mode, stayed relatively low. If we are able to keep RF on at the 2--3MW level during H-mode, we could likely produce useful results in this configuration. |
| Physics Operator Summaries |
| Entered: May 24 2006 05:08:11:337PM |
| Author: Joseph Snipes |
| The run started just after noon due to repairs on the alternator. Then, there were problems with the main gas valve that cost us another hour or so. Finally, when we did get running, there were a number of fizzles probably due mostly to too little gas, but some tweaks in Bz and Br also seemed to help. Once the startup was tuned up, we had reasonably good plasmas as the RF tuned its way up to 3.5 MW. There were a few brief H-modes so that some data toward the expected physics results of the MP were obtained, but longer duration H-modes are required to get good Thomson pedestal data. The last shot was perhaps the best with the longest H-mode, but there were runaways from the very beginning for some reason. The last five shots all disrupted in the flattop apparently due to moly injections. Attempts to raise the density slightly and increase the outer gap slightly did not seem to help much, though the disruptions were later in the last two shots near the end of the flattop. Shot,Duration(s),Ipmax(MA),Result Shot,Duration(s),Ipmax,Result | 01 0.000 0.002 Test | 02 0.000 0.002 Test | | 03 0.000 0.002 Test | 04 0.000 0.023 Fizzle | | 05 1.681 0.793 Plasma | 06 0.000 0.039 Fizzle | | 07 0.000 0.029 Fizzle | 08 0.000 0.023 Fizzle | | 09 1.853 0.809 Plasma | 10 1.872 0.819 Plasma | | 11 1.809 0.814 Plasma | 12 1.674 0.817 Plasma | | 13 1.735 0.821 Plasma | 14 1.788 0.832 Plasma | | 15 0.774 0.845 Plasma | 16 0.587 0.827 Plasma | | 17 0.788 0.887 Plasma | 18 1.451 0.835 Plasma | | 19 1.486 0.829 Plasma Date 1060524: 19 shots. 12 plasmas. 4 fizzles. 3 tests. 0 System Error. (Plasma = Ip gt 50.0 kA Dud = H_alpha lt 0.40 V) Total plasma duration: 17.50 s (exceeding 100 kA) |
| Session Leader Comments | |||
| May 24 2006 12:56:22:480PM | Jerry Hughes | Long delay today due to alternator repair. Then gas valve problmes, again.
Then RF conditioning. | |
| May 24 2006 01:18:24:883PM | 1060524004 | Jerry Hughes | Fizzle. |
| May 24 2006 01:29:05:370PM | 1060524005 | Jerry Hughes | Not a fizzle. The MARFE that has been starting around 400ms in these reversed
field shots (last week and this week) is sutained throughout most of the discharge. RF is not able to come up and blow it away as it did, for example, on 1060523014 or 1060519008. Joe will lower the gas on the next shot. |
| May 24 2006 01:40:40:197PM | 1060524006 | Jerry Hughes | Fizzle |
| May 24 2006 01:52:39:713PM | 1060524007 | Jerry Hughes | Fizzle |
| May 24 2006 02:07:59:557PM | 1060524008 | Jerry Hughes | Fizzle |
| May 24 2006 02:25:28:947PM | 1060524009 | Jerry Hughes | We got plasma. The MARFE rears its head, then dies after <100ms.
Shape match to the (reflected) USN shot 1060523013 is now quite good. Keep this target and try to bring RF up. |
| May 24 2006 02:50:00:603PM | 1060524011 | Jerry Hughes | Plasma. MARFE from 480--720ms, going away when RF comes on.
Getting RF power up, but still numerous faults in RF. Next shot: Repeat, try to get better RF. Joe is relaxing the programmed rate-of-rise on the density further. |
| May 24 2006 03:01:43:493PM | 1060524012 | Jerry Hughes | Plasma. A good non-MARFEing shot, with a cleaner RF trace.
RF ramps from 2--3MW, with some faults. No H-mode yet, though. Edge Te rises very little during RF, probably because there is a lot of fueling from the antennas. Next shot: RF will try for more power. |
| May 24 2006 03:45:07:620PM | 1060524013 | Jerry Hughes | Plasma. Higher RF power, with faults.
Cell access to pull back the LH grill, which is lighting up rather brightly at the probe tips. The glowing probes seem to have got brighter as we increased power into the plasma. The spectroscopists in the back report levels of Mn on the increase. Mn? Next shot: RF will try for more power. |
| May 24 2006 03:56:01:633PM | 1060524014 | Jerry Hughes | Plasma. Short H-modes. nl04 at the transition is about 1.3e20, sue to RF
outgassing. Having Joe lower the traget density for next shot to try to get this down. Next shot: Lower nl04. RF will try to get smoother power trace. |
| May 24 2006 04:12:26:307PM | 1060524015 | Jerry Hughes | Plasma, disrupting at 0.76s. Injection seems to have killed this one.
The nl04 trace looks pretty reasonable. Next shot: Repeat. |
| May 24 2006 04:25:01:620PM | 1060524016 | Jerry Hughes | Big disruption and spark shower, before RF fires. Not something you like to see.
Next shot: Retry, except Joe has tweaked nl04 program from 8 to 9e19. |
| May 24 2006 04:41:16:870PM | 1060524017 | Jerry Hughes | Another disruption, during RF.
Next shot: Have RF ramp up a little more gently. No idea whether this will help. |
| May 24 2006 04:49:34:213PM | 1060524018 | Jerry Hughes | Doesn't disrupt so early. H-mode from 0.81--0.90s. Unfortunately, the
RF is unhappy with the H-mode, and so we can't sustain it. Next shot: RF will improve their tune into H-mode on D+E. |
| May 24 2006 05:07:32:400PM | 1060524019 | Jerry Hughes | RF delivered what they promised: relatively clean D+E and loss of J during the
H-mode. But, the H-mode was sustained much longer. There is a hint of something QCM-like in freq. on the PCI from 0.92--0.96s. Last shot. |
| Physics Operator Comments | |||
| May 24 2006 09:13:03:500AM | Joseph Snipes | Alternator repair still underway. We expect to begin running around 12:30 pm. | |
| May 24 2006 12:03:10:540PM | 1060524001 | Joseph Snipes | Shot 1: Gas test shot. |
| May 24 2006 12:18:02:790PM | 1060524002 | Joseph Snipes | Shot 2: Gas test shot now with a proper test puff on PG3 B-side main at 100 V between -1 and -0.9 s with all other gas valves disabled and the DNB gate valve off. No gas. Need to get the valve to open. Cell access. |
| May 24 2006 12:34:20:120PM | 1060524003 | Joseph Snipes | Shot 3: Another gas test shot with PG3 only and 100 ms 100 V puff at -1 s. Got gas. The valve now works after Tommy Toland went in and zapped it with his power supply. |
| May 24 2006 01:05:43:820PM | 1060524004 | Joseph Snipes | Shot 4: Loaded shot 1060519008 and modified ZCUR to shift it up 2 mm at 0.5 s, the same at 0.9 s and down 2 mm at 1.5 s ramping from -0.007 to -0.013 cm between 0.5 and 1.5 s. Ramped ZXL down between 0.5 and 1.5 s from -.001 to -0.009 m to shift ZXL down 5 mm at 0.9 s. Changed nl04 to 1 x 10^20 m^-2. Fizzle. |
| May 24 2006 01:30:43:213PM | 1060524005 | Joseph Snipes | Shot 5: Increased prepuff by 5 ms to 22 ms duration. Good shot. MARFEing throughout. Too much gas. |
| May 24 2006 01:46:38:383PM | 1060524006 | Joseph Snipes | Shot 6: Fizzle. |
| May 24 2006 01:51:24:400PM | 1060524007 | Joseph Snipes | Shot 7: Reduced rate of rise of the density to attempt to eliminate the MARFE. Increased ramp rate of ZXL to decrease the bottom gap to compensate for the ramp in bottom gap. I also increased the ramp on ZCUR. Added 2 ms to the prepuff to make it 24 ms duration. Decreased EF4 current by 10 A to 1320 A. Fizzle. |
| May 24 2006 02:04:37:963PM | 1060524008 | Joseph Snipes | Shot 8: Reduced Br0 by 0.5 mT to -0.5 mT. Increased EF4 current by 20 A to 1340 A. Fizzle! |
| May 24 2006 02:18:39:667PM | 1060524009 | Joseph Snipes | Shot 9: Removed Br0 offset back to 0. Increased prepuff by 3 ms to 27 ms duration. Good shot. |
| May 24 2006 02:30:06:353PM | 1060524010 | Joseph Snipes | Shot 10: Repeat. Good shot. |
| May 24 2006 02:44:19:603PM | 1060524011 | Joseph Snipes | Shot 11: Reduced prepuff by 2 ms to 25 ms duration. Good shot. |
| May 24 2006 02:55:18:993PM | 1060524012 | Joseph Snipes | Shot 12: Reduced prepuff by 2 ms to 23 ms duration. Reduced rate of rise of the density to try to eliminate the MARFE. Good shot. |
| May 24 2006 03:33:16:197PM | 1060524013 | Joseph Snipes | Shot 13: Repeat. Good shot. LH grill is glowing after the shot and the glow duration increases with ICRF power. Brief cell access to pull the LH grill back to 1605 from 1585. |
| May 24 2006 03:46:41:260PM | 1060524014 | Joseph Snipes | Shot 14: Repeat. Good shot. |
| May 24 2006 04:13:51:090PM | 1060524015 | Joseph Snipes | Shot 15: Reduced nl04 to 8 x 10^19 m^-2. Disrupted at 0.74 s. Big Moly injection. |
| May 24 2006 04:18:15:197PM | 1060524016 | Joseph Snipes | Shot 16: Increased prepuff by 2 ms to 25 ms duration. Increased Br0 by 0.2 mT to 0.2 mT. Disrupted at 0.58 s. |
| May 24 2006 04:31:19:840PM | 1060524017 | Joseph Snipes | Shot 17: Raised nl04 to 9 x 10^19 m^-2. Disrupted at 0.78 s. This does not look good. |
| May 24 2006 04:48:52:103PM | 1060524018 | Joseph Snipes | Shot 18: Reduced RCUR by 1.5 mm to increase the outer gap. Disrupted at 1.44 s. |
| May 24 2006 04:59:34:180PM | 1060524019 | Joseph Snipes | Shot 19: Repeat. Lots of runaways from the getgo. Still, it was otherwise a decent shot with 2.5 MW of RF briefly then a long period of 2 MW. H-mode from 0.85 to 1.02 s. Disrupted at 1.48 s. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 12:03:31:447PM | Test | Bad | gas test |
| 2 | 12:15:07:697PM | Test | Bad | B Main gas |
| 3 | 12:29:41:993PM | Test | Ok | Gas B Main |
| 4 | 01:04:08:417PM | Test | Ok | |
| 5 | 01:17:20:353PM | Plasma | Ok | |
| 6 | 01:37:00:947PM | Plasma | Ok | |
| 7 | 01:49:52:930PM | Plasma | Ok | |
| 8 | 02:03:01:010PM | Plasma | Ok | |
| 9 | 02:15:43:760PM | Plasma | Ok | |
| 10 | 02:28:28:713PM | Plasma | Ok | |
| 11 | 02:40:55:680PM | Plasma | Ok | |
| 12 | 02:53:37:213PM | Plasma | Ok | |
| 13 | 03:13:18:993PM | Plasma | Ok | |
| 14 | 03:40:33:527PM | Plasma | Ok | |
| 15 | 04:00:25:087PM | Plasma | Ok | |
| 16 | 04:14:45:197PM | Plasma | Ok | |
| 17 | 04:28:33:697PM | Plasma | Ok | |
| 18 | 04:41:56:087PM | Plasma | Ok | |
| 19 | 04:54:51:307PM | Plasma | Ok | |