| Miniproposals | ||||||||||
|
| Operators | |
| Session leader(s): | Joseph Snipes |
| Physics operator(s): | Robert Granetz |
| Engineering operator(s): | Bill Cochran,Bill Parkin,Ed Fitzgerald |
| Engineering Operator Run Comment |
| MP 404a Parametric Dependence of Moderate n Alfven Eigenmode Damping Rat |
| Session Leader Plans |
| Entered: Aug 11 2005 05:08:20:337PM |
| Author: Joseph Snipes |
| Session Leader Run Plan for 1050812 MP 404a Parametric Dependence of Moderate n Alfven Eigenmode Damping Rates Session Leaders: J Snipes, A Fasoli Physics Operators: R Granetz, J Snipes This run will continue parameter scans with active MHD to measure the Alfven eigenmode damping rates vs plasma parameters. We will begin with 1050615011, which is an inner wall limited elongated plasma with kappa = 1.6 at 0.8 MA except we need to change the TF to be constant at 5.4 T (150 kA). The first three shots will be the same except for changing the q at which the TAEs will be driven from q=1.5, to q=1, to q=2. Next, we will change the triangularity from near 0 to 0.8 with both upper and lower triangularity changing together. Next, we will scan the toroidal field at constant flattop field from 2 T up to 7 or 8 T depending on the administrative limit and the results while maintaining constant q95 = 4.9 to scan rho*. Finally, time permitting, we will scan the density from nebar = 0.5 x 10^20 m^-3 to 4 x 10^20 m^-3 to scan nu*. In addition, we would like to swap the phase of one antenna with respect to the other antenna to drive the two out of phase to look at the effect of the change in poloidal mode structure on the signal and damping rate. ICRF will not be required for this run. Key diagnostics are magnetics, density, Zeff, and it would be interesting to check the PCI to see if it can measure the AEs. |
| Physics Operators Plans |
| Entered: Aug 12 2005 08:18:55:237AM |
| Author: Robert Granetz |
Engineering setup for Friday 12 Aug 2005 MP #404a Alfven damping Session leader: J. Snipes/A. Fasoli Physics operator: R. Granetz No overnight ECDC, but bake at 60 C. Run begins at 09:00 and ends at 17:00. Power systems as on 1050615011 (inner wall limited) but keep Btor constant at 5.4 T (150 kA). 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) fill B-side upper with 15 psi He3 Hybrid enabled (PG2) fill B-main (C-side) with 40 psi D2 Hybrid enabled (PG3) No NINJA Enable the following gate valves and shutters, assuming no vacuum problems: ECE, VUV, Z-bolo shutters No between-shot boronization. Important Diagnostics: PCI, Mirnov coils. ------------------------------------------------------------------------------- ICRF Setup: No ICRF needed today. ------------------------------------------------------------------------------- Run plan: See the session leader's detailed posting. |
| Session Leader Summaries |
| Entered: Aug 12 2005 06:04:47:540PM |
| Author: Joseph Snipes |
| The purpose of the run was to excite stable Alfven eigenmodes (AEs) and measure their damping rates as a function of plasma parameters. We varied triangularity, toroidal field, and the resonant q value of the center frequency. We began with 5.4 T inner wall limited plasmas with an elongation of 1.6 and triangularity of 0.35. We sweep the active MHD frequency several times throughout the discharge to look for AE resonances. The run started off with some difficulty including a few fizzles and duds and a problem with the DPCS f_TAE frequency control signal not getting to the amplifier. After that was resolved we then found that the demand for the frequency had a rather noisy signal. We removed the monitor signal as well as a second lower antenna current monitor to be able to close the door on the amplifier cabinet and that seemed to resolve most of the noise problem. Ian noted that there was pick-up of the active MHD signal on the 2pi foil bolometer. After resolving these issues, we did a triangularity scan down to 0.27 and up to 0.75 for both the upper and lower triangularities. Next, we did a toroidal field scan from 2 T up to 7 T at nearly constant q95 = 5. We also varied the q value of the excited TAE frequency from q = 1, to 1.5, to 2.0 for a few shots to scan for other resonances. For the last part of the run, we inverted the lower antenna signal to drive a different m spectrum and looked for the change in the measured mode structure and damping. A number of clear resonances were obtained, but more time is required to analyze determine the mode numbers. A typical damping rate of just over 2% was found in one case. Further analysis is required to determine if there is any scaling of the damping rate with these parameters. There was no time to do a density scan to determine damping as a function of collsionality and no attempt was made to do the RF part of the mini-proposal, which will need another run. |
| Physics Operator Summaries |
| Entered: Aug 12 2005 05:05:57:387PM |
| Author: Robert Granetz |
Physics operator summary for Friday 12 Aug 2005:
MP #404a Alfven damping
Session leader: J. Snipes/A. Fasoli
Physics operator: R. Granetz
The tokamak ran well today, although some initial tweaking of the startup
was required because this was the only run this week that we didn't do
between-shot boronization, so the wall conditioning was very different than
recent runs. We ran inner wall limited plasmas all day, and exercised
machine parameters quite a bit, including triangularity scans, and a
combined Btor scan (2.2-7.0 T) and Ip scan (0.28-1.03 MA) at fixed q95=5.
There were some difficulties with the active MHD amplifier signals early in
the run, but these were eventually solved.. See the session leader's
summary for TAE physics results.
Scorecard: 27 plasmas
2 duds
3 fizzles
1 computer-related aborts
0 cycle tests
--------------
Total: 33 shot cycles
|
| Session Leader Comments | |||
| Aug 12 2005 10:21:38:810AM | 1050812004 | Joseph Snipes | Problems with the fiber interface in the active MHD amplifier control box that did not permit the DPCS f_TAE signal from getting to the amplifier. They should now be resolved for shot 4. |
| Aug 12 2005 10:46:13:720AM | 1050812005 | Joseph Snipes | Got the q=1.5 discharge with frequency sweeping. However the demand for the frequency sweep is very noisy. |
| Aug 12 2005 10:51:47:927AM | 1050812006 | Joseph Snipes | Changed to q=1 for the f_TAE from DPCS. Still noisy. |
| Aug 12 2005 11:15:14:433AM | 1050812008 | Joseph Snipes | Removed the extra current monitor on the lower antenna I_GH_LOWER_X and removed the output of the amplifier control box for the DPCS f_TAE signal to the \MAGNETICS::TOP.ACTIVE_MHD.SIGNALS:F_AMHD to attempt to remove the noise on the frequency demand signal. |
| Aug 12 2005 11:30:11:700AM | 1050812008 | Joseph Snipes | Shot 8 is the control shot with deltal and deltau about 0.36 to 0.37. It is not as noisy as before, though there is more noise on the lower antenna current and upper antenna voltage. |
| Aug 12 2005 11:42:37:613AM | 1050812009 | Joseph Snipes | Shot 9 had lower triangularity of 0.28 and upper triangularity of 0.31. However, I had accidentally disconnected the lower antenna when I disconnected the I_GH_LOWER_X external current monitor. |
| Aug 12 2005 12:01:29:613PM | 1050812010 | Joseph Snipes | Shot 10 now has the lower antenna connected again but the I_GH_LOWER_X current monitor is still disconnected. Triangularity down to deltau = 0.29 and deltal = 0.27. |
| Aug 12 2005 12:05:08:877PM | 1050812011 | Joseph Snipes | Shot 11 going to lower triangularity and faster sweep rate at 1.5 MHz/s. Disrupted early. |
| Aug 12 2005 12:22:45:750PM | 1050812012 | Joseph Snipes | Shot 12 disrupted early again. So, we will go to higher triangularity for shot 13. |
| Aug 12 2005 12:39:28:543PM | 1050812013 | Joseph Snipes | Shot 13 to go to higher triangularity than shot 8. Fizzle |
| Aug 12 2005 12:52:34:000PM | 1050812014 | Joseph Snipes | Shot 14 Try again at higher triangularity. Got triangularities of about 0.5 each. |
| Aug 12 2005 01:04:18:850PM | 1050812015 | Joseph Snipes | Shot 15 Try again at still higher triangularity. Got triangularities of about 0.6 upper and 0.7 lower but the plasma is going diverted. |
| Aug 12 2005 01:32:15:837PM | 1050812016 | Joseph Snipes | Shot 16 pushed the plasma to the inner wall and reduce delta to 0.55 to 0.6. |
| Aug 12 2005 01:32:53:697PM | 1050812017 | Joseph Snipes | Try higher triangularity. Did not get it. |
| Aug 12 2005 01:39:05:163PM | 1050812018 | Joseph Snipes | Repeat with q=1 on f_TAE from DPCS. |
| Aug 12 2005 01:52:29:147PM | 1050812019 | Joseph Snipes | Repeat with q=2 on f_TAE from DPCS. |
| Aug 12 2005 02:11:00:647PM | 1050812020 | Joseph Snipes | Attempting 2 T at constant q95, which corresponds to 300 kA. Disrupted at 0.5 s. |
| Aug 12 2005 02:18:34:507PM | 1050812021 | Joseph Snipes | Need lower density and no Ar/Ne mixture to avoid disruptions. Asked for nl04 = 0.5 x 10^20 m-3. Start at 5.0 T to give a slightly longer time at 2 T. Fizzle! |
| Aug 12 2005 02:57:59:247PM | 1050812022 | Joseph Snipes | Try again at 5.2 T for startup and then ramp down to 2 T. Also changed to somewhat lower triangularity. |
| Aug 12 2005 02:58:36:340PM | 1050812023 | Joseph Snipes | Got 3 T and 300 kA at nl04 = 5 x 10^19 m^-2. |
| Aug 12 2005 02:59:12:793PM | 1050812024 | Joseph Snipes | Asked for 380 kA and 3 T. Got it, but q95 = 6.2 is too high. My mistake. Need 450 kA instead. |
| Aug 12 2005 03:09:12:917PM | 1050812025 | Joseph Snipes | Go to 450 kA and 3 T. Good shot. Got q95 = 5.3. |
| Aug 12 2005 03:33:12:917PM | 1050812026 | Joseph Snipes | Go to 650 kA and 4 T. Good shot. Got q95 = 4.8. |
| Aug 12 2005 03:33:48:010PM | 1050812027 | Joseph Snipes | Go to 750 kA and 5 T. Good shot. Got q95 = 5. |
| Aug 12 2005 03:46:26:853PM | 1050812028 | Joseph Snipes | Go to 900 kA and 6 T. Good shot. Got q95 = 5. |
| Aug 12 2005 04:09:10:323PM | 1050812029 | Joseph Snipes | Go to 1.03 MA and 7 T. Good shot. Got q95 = 5. |
| Aug 12 2005 04:19:30:417PM | 1050812030 | Joseph Snipes | Return to shot 14 at 5.4 T and 0.8 MA and 1 x 10^20 m^-2. Invert the lower antenna (upper amplifier in the cabinet). Good shot at q=1.5 for f_TAE from DPCS. |
| Aug 12 2005 04:33:10:760PM | 1050812031 | Joseph Snipes | Now, repeat at q=1 for f_TAE. Good shot. |
| Aug 12 2005 04:50:02:073PM | 1050812032 | Joseph Snipes | Now, repeat at q=2 for f_TAE. Good shot. |
| Aug 12 2005 04:58:27:183PM | 1050812033 | Joseph Snipes | Now, reload shot 27 at 5.0 T and 5 x 10^19 m^-2 with the inverted lower amplifier. Good shot. |
| Physics Operator Comments | |||
| Aug 12 2005 08:32:07:800AM | Robert Granetz | To set up the shot, I loaded 1050615011 (limited, but nearly double null) and changed Btor to be constant at 5.4 T (150 kA). I loaded in a startup from 1050802033 (recent run from before we did the between-shot boronization stuff this past week), but I decreased the pre-fill pulse to 30 ms. | |
| Aug 12 2005 09:12:12:787AM | 1050812001 | Robert Granetz | Fizzle. Next shot: reduce pre-fill to 24 ms. |
| Aug 12 2005 09:29:47:827AM | 1050812002 | Robert Granetz | Dud. Fields like fine. So does the gas for that matter. Next shot: add 3 ms (set to 27 ms) |
| Aug 12 2005 10:04:11:077AM | 1050812003 | Robert Granetz | Plasma. Good shot. Inner wall limited, but nearly double null. Delta_L=0.35, Delta_U=0.38. Kappa=1.6-1.7. Ip=0.8 MA, Btor=5.4 T. nl_04=1.0e20 m-2. There's a problem with the real-time drive signal to the active MHD antenna, which is requiring an extended access to the cell and the interface room. Next shot: increase argon/neon puff to 40 ms. |
| Aug 12 2005 10:24:52:123AM | 1050812004 | Robert Granetz | Dud. Next shot: add 3 ms to pre-fill (set at 30 ms) and set Br0 offset to -0.4 mT |
| Aug 12 2005 10:42:14:090AM | 1050812005 | Robert Granetz | Plasma. Good shot. Inner wall limited, high elongation, delta=0.35-0.38. MHD amplifier worked. Next shot: increase pre-fill another 1 ms (set to 31 ms). Also increase Ar/Ne puff to 50 ms. |
| Aug 12 2005 10:49:08:940AM | 1050812006 | Robert Granetz | Plasma. Good shot. The session leaders are scanning the drive frequency to changes the resonant q surface from shot-to-shot. Next shot: repeat, no changes |
| Aug 12 2005 11:03:48:987AM | 1050812007 | Robert Granetz | Plasma. Good shot. Startup bounced. Next shot: add 2 ms to pre-fill (set to 33 ms). |
| Aug 12 2005 11:29:25:683AM | 1050812008 | Robert Granetz | Plasma. Good shot. Next shot: reduce upper and lower triangularity by 0.1 (move RXL and RXU out by about 0.1 x minor radius, or 0.022 m) |
| Aug 12 2005 11:42:00:220AM | 1050812009 | Robert Granetz | Plasma. Good shot. Upper and lower triangularities dropped by about 0.07 (was shooting for drop of 0.10). Elongation increased slightly to 1.66. Next shot: tweak ZXL down by 1 cm and ZXU up by 1 cm to try and get the elongation by to 1.6 |
| Aug 12 2005 12:02:51:113PM | 1050812010 | Robert Granetz | Plasma. Good shot. Elongation increased, rather than decreased. This one almost became diverted. Startup bounced. Next shot: try moving ZXL and ZXU 1 cm from earlier today, but this time in the opposite direction, i.e. in towards the plasma. Also increase pre-fill puff another 2 ms (set to 35 ms). Also, increase RXU and RXL by another 2 cm to decrease the triangularity further. |
| Aug 12 2005 12:10:46:810PM | 1050812011 | Robert Granetz | Plasma. Disrupted at t=0.47 s. Too much elongation? Next shot: Put ZXL and ZXU back to their values from earlier today. |
| Aug 12 2005 12:26:43:177PM | 1050812012 | Robert Granetz | Plasma. Disrupted at t=0.49 s. I think it's a problem with the equilibrium stability. Not sure I can fix it. Next shot: go for higher triangularity...subtract 3 cm from RXU and RXL. |
| Aug 12 2005 12:33:36:117PM | 1050812013 | Robert Granetz | Fizzle. Next shot: try reducing the pre-fill puff by 2 ms (set to 33 mm). |
| Aug 12 2005 12:55:43:940PM | 1050812014 | Robert Granetz | Plasma. Good shot. Got triangularities of 0.5 ... excellent. Kappa=1.6-1.65. Remained inner wall limited. Next shot: decrease RXL and RXU to go to even higher triangularity. |
| Aug 12 2005 01:04:36:253PM | 1050812015 | Robert Granetz | Plasma. Good shot. Triangularities reach 0.7 late in the flattop. Plasma is on the edge between being limited and being diverted. Next shot: reduce CLEARIN by 1 cm to try reducing the elongation. Also decrease RXL and RXU another 1 cm to increase triangularity some more. |
| Aug 12 2005 01:23:57:270PM | 1050812016 | Robert Granetz | Plasma. Good shot. This was much better limited, but the triangularity fell to 0.5-0.6 Next shot: decrease RXL and RXU another 2 cm to increase triangularity some more. |
| Aug 12 2005 01:29:16:277PM | 1050812017 | Robert Granetz | Plasma. Good shot. Slightly higher triangularity, but I don't think we can go much higher. Next shot: no DPCS changes |
| Aug 12 2005 01:38:41:477PM | 1050812018 | Robert Granetz | Plasma. Good repeat shot. Next shot: no DPCS changes. |
| Aug 12 2005 01:54:07:070PM | 1050812019 | Robert Granetz | Plasma. Good repeat shot. Next shot: reduce Btor to 2.0 T and Ip to 0.3 MA so that q95 remains the same as the 5.4 T, 0.8 MA plasmas. |
| Aug 12 2005 04:16:09:760PM | 1050812020 | Robert Granetz | Plasma. Decayed away around t=0.5 s when the plasma current got to 0.3 MA, possibly because we hit the density limit. Next shot: reduce nl_04 to 0.5e20 m-2. Also reduce initial Btor to 5.0 T (139 kA) so that we can get down to 2.0 T a little sooner. Also disable the Ar/Ne valve. |
| Aug 12 2005 02:29:14:790PM | 1050812021 | Robert Granetz | Fizzle. Next shot: try starting at 5.2 T instead of 5.0 T. Also increase RXL and RXU by 2 cm to decrease the triangularity (so that we won't have problems when we go to high current in a few shots). |
| Aug 12 2005 02:33:06:870PM | 1050812022 | Robert Granetz | No shot...ACK failure during pulse. Lots of data missing. |
| Aug 12 2005 02:48:00:603PM | 1050812023 | Robert Granetz | Plasma. Good shot. Got down to 2.2 T and 280 kA (q95=5.3) Next shot: raise Btor to 3.0 T and Ip to 380 kA. |
| Aug 12 2005 02:57:14:637PM | 1050812024 | Robert Granetz | Plasma. Good shot. Got 3.1 T and 380 kA, but that gave q95=6.1, which is higher than we wanted. Next shot: increase Ip to 450 kA. Also tweak Btor down to 3.0 T. |
| Aug 12 2005 03:11:00:997PM | 1050812025 | Robert Granetz | Plasma. Good shot. Btor=3.0 T, Ip=0.44 MA, q95=5.1-5.2. Next shot: Btor=4.0 T, Ip=0.65 MA. |
| Aug 12 2005 03:29:31:120PM | 1050812026 | Robert Granetz | Plasma. Good shot. Bt=4.0 T, Ip=0.65 MA, q95=4.8-4.9 Next shot: Btor=5.0 T, Ip=0.75 MA |
| Aug 12 2005 03:38:58:183PM | 1050812027 | Robert Granetz | Plasma. Good shot. Btor=5.0 T, Ip=0.75 MA, q95=5.0. Perfect Next shot: 6.0 T, Ip=0.90 MA |
| Aug 12 2005 03:57:12:543PM | 1050812028 | Robert Granetz | Plasma. Good shot. Btor= 5.9 T, Ip=0.90 MA, q95=5.0. Next shot: 7.0 T, 1.04 MA. |
| Aug 12 2005 04:10:13:730PM | 1050812029 | Robert Granetz | Plasma. Good shot. Disrupted during rampdown. Bt=7.0 T, Ip=1.03 MA, q95=5.0. End of B-field scan at constant q95. Next shot: reload segment 2 of shot 1050812014. Also increase pre-fill puff by 2 ms (set to 35 ms). |
| Aug 12 2005 04:25:21:167PM | 1050812030 | Robert Granetz | Plasma. Good repeat of shot 14. This one has higher elongation and lower triangularity than the recent B-field scan. Next shot: same equilibrium. Tweak IC_EF4 (add -10 A). |
| Aug 12 2005 04:35:24:450PM | 1050812031 | Robert Granetz | Plasma. Good repeat shot. Next shot: same equilibrium. Add 2 ms to pre-fill (set to 37 ms) |
| Aug 12 2005 04:50:19:043PM | 1050812032 | Robert Granetz | Plasma. Good repeat shot. Next shot: reload segment 2 from shot 27 (5 T shot of the B-field scan). |
| Aug 12 2005 04:59:48:807PM | 1050812033 | Robert Granetz | Plasma. Good shot. End of run. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 09:09:27:727AM | Plasma | Ok | |
| 2 | 09:23:15:750AM | Plasma | Ok | |
| 3 | 09:48:07:850AM | Plasma | Ok | |
| 4 | 10:20:44:620AM | Plasma | Ok | |
| 5 | 10:33:11:380AM | Plasma | Ok | |
| 6 | 10:46:21:703AM | Plasma | Ok | |
| 7 | 10:58:51:900AM | Plasma | Ok | |
| 8 | 11:14:31:760AM | Plasma | Ok | |
| 9 | 11:33:31:290AM | Plasma | Ok | |
| 10 | 11:46:24:593AM | Plasma | Ok | |
| 11 | 12:03:43:160PM | Plasma | Ok | |
| 12 | 12:18:37:223PM | Plasma | Ok | |
| 13 | 12:31:17:400PM | Plasma | Ok | |
| 14 | 12:43:51:793PM | Plasma | Ok | |
| 15 | 12:56:44:113PM | Plasma | Ok | |
| 16 | 01:11:38:040PM | Plasma | Ok | |
| 17 | 01:24:10:300PM | Plasma | Ok | |
| 18 | 01:37:06:210PM | Plasma | Ok | |
| 19 | 01:49:56:523PM | Plasma | Ok | |
| 20 | 02:02:38:053PM | Plasma | Ok | |
| 21 | 02:15:47:773PM | Plasma | Ok | |
| 22 | 02:29:28:837PM | Plasma | Bad | Ack Failure. No power shot |
| 23 | 02:39:28:293PM | Plasma | Ok | |
| 24 | 02:51:53:120PM | Plasma | Ok | |
| 25 | 03:05:31:073PM | Plasma | Ok | |
| 26 | 03:17:56:760PM | Plasma | Ok | |
| 27 | 03:30:42:433PM | Plasma | Ok | |
| 28 | 03:43:27:400PM | Plasma | Ok | |
| 29 | 03:59:07:793PM | Plasma | Ok | |
| 30 | 04:16:53:900PM | Plasma | Ok | |
| 31 | 04:31:22:090PM | Plasma | Ok | |
| 32 | 04:43:55:073PM | Plasma | Ok | |
| 33 | 04:56:11:870PM | Plasma | Ok | |