Alcator C-Mod Weekly Highlights September 26, 2011 FY2011 weeks of research operations Target: 15 weeks Completed: 14.5 weeks Plasma Shots: 1706 Research -------- Amanda Hubbard has been appointed Deputy Director of the USBPO by the new BPO Director, Dr. Chuck Greenfield, and OFES, with input from the USBPO Council. Dr. Hubbard was a charter member of the USBPO Council and served as Chair of the Council from 2007 to 2010. G. Wallace was selected by the APS DPP Program Committee to give a post-deadline invited talk at the November meeting in Salt Lake City. The title of the talk will be "Lower hybrid current drive at high density in the multi-pass regime." Four new APS press releases have been posted describing research on C-Mod at http://www.psfc.mit.edu/research/alcator/pubs/research_highlights/index.html Ion temperature (T_i) profiles in I-mode plasmas (from run-day 1101209) made by combining He-like and H-like Ar x-ray Doppler measurements using inversions from HIREXSR were presented by Matt Reinke at the weekly Science Meeting. Analysis indicated that the time averaged T_i profile is close to the post-sawtooth T_e profile. Changes in the neutron rate during a sawtooth suggest only a few hundred eV increase in T_i and a significant difference, ~1 keV, develops between the ion and electron temperatures inside the sawtooth inversion radius. Ion-electron energy equilibration times were shown to be between 50 and 100 ms; much longer than the sawtooth period of 10 to 20 ms, supporting the hypothesis that equilibrium is not maintained between the two species. Further studies were proposed that will use HIREXSR with higher temporal resolution (1-2 ms) to measure profile evolution between sawtooth crashes. A summary of the recent ITPA and IAEA meetings on energetic particles (Sept. 7-13, Austin, TX) was given by David Pace during the C-Mod Weekly Science Meeting. The summary included updates on issues of particular concern for ITER, including the possibility of increased energetic ion heat flux on plasma facing tiles during operation of RMP coils for ELM suppression. Another area of concern is the possible presence of instabilities in runaway electron beams that occur after a disruption. These instabilities, if present, may cause added difficulty in safely dissipating such beams. It was suggested that C-Mod is well equipped to investigate this topic during disruption studies that are carried out by the MHD Topical Group. Operations ---------- In-vessel work last week included installation of new AXUV bolometers at five toroidal locations around the machine, installation of the new lower hybrid limiters, installation and alignment of the Correlation Electron Cyclotron Emission Diagnostic, installation of viewing dumps at A/B and B/C locations, and installation of TZM protection tiles around the polarimeter shutter assembly. The new G-Horizontal port extension has been installed and successfully leak-checked. The new extension provides improved access for personnel entry and exit to and from the vacuum vessel. ICRF Systems ------------ Our vendor has fabricated the fixture needed for the modification of the ARRA funded rotated antenna back plates. The plates have been installed on the fixture and measured and compared with the part models. After discussions with the vendor of the measurement results, machining of the plates was begun last week. Additional CMM measurements of the outer vessel wall at multiple locations between H and K ports were made to help refine the shim design. The shims will be used to position the antenna accurately relative to the plasma. Lower Hybrid Systems -------------------- Klystron drive amplifier assemblies have been assembled, tested, and installed on carts 1 to 3. All new TPS fiber cable lengths have been measured for ordering, fabrication, labeling and installation. Progress continues on the TPS controller board hardware, firmware, and testing. The new, movable LH limiter was installed in-vessel last week. This limiter moves with the launcher, maintaining a fixed distance between the coupler grill and the limiter. Diagnostics ----------- ITER has sent hardware components for the signal interface box needed for the ITER grounding scheme tests to be done on C-Mod. These components mount on the fast magnetics feedthrough flange. A test trial fit-up was done which indicated some minor modifications will be required. Remote Participation, Travel, and Visitors ------------------------------------------ Dennis Whyte traveled to U. Wisconsin-Madison to present a seminar "The 24/7 tokamak: The Vulcan Conceptual Design & the Future of Boundary Plasma Research." Nong Shiang, head of theory at China's IPP, visited the PSFC on Friday to discuss possible LHCD theory and simulation collaborations between the PSFC and IPP. He met with Ron Parker, Greg Wallace, Paul Bonoli, Syunichi Shiraiwa, Orso Meneghini, and John Wright. _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly