Alcator C-Mod Weekly Highlights August 1, 2011 FY2011 weeks of research operations Target: 15 weeks Completed: 14.5 weeks Plasma Shots: 1706 Physics ------- The impact of ICRH on parallel impurity transport has been further demonstrated using scans of the D(H) resonance layer. Accumulation of high-Z impurities on the HFS of a flux surface is thought to be linked to a poloidal potential variation due to magnetically trapped minority ions. First attempts to quantitatively model this effect show reasonable agreement to experimental measurements to within ~50%. C-Mode DoE Quarterly Review --------------------------- A C-Mod DoE quarterly review (FY11, Q3) was held by video-conference on Tuesday. Attendees from FES included Mark Foster, John Mandrekas, Nirmol Podder, and Steve Eckstrand. Presentations from the review can be downloaded at www.psfc.mit.edu/research/alcator/pubs/Q_Reviews/Q-Rev_July_2011/q-rev_july_26-2011.pdf. Operations ---------- The cleaning of in-vessel windows has begun. Preparations are being made to weld together the new G horizontal port extension components. Parts are being fabricated in our shop for the Fast Ion Loss diagnostic. In-vessel mirrors for the Correlation Electron Cyclotron Emission diagnostic are in-house and are being prepared for testing. ICRF Systems ------------ We continued to work with our vendor on the plating of components for the ARRA funded rotated antenna. Approximately 60% of the components have been plated. Polishing and baking of these components is ongoing. Installation of the studs in-vessel to support the antenna began last week and will continue this week. Work also continues on the Faraday rod components and boron carbide washers that provide the insulating support for the rods. The rods must be insulated from the rest of the antenna to reduce disruptions loads to acceptable levels. A conference call with our vendor regarding the schedule and status of the fast ferrite tuner fabrication was held last week. A delay in brazing of the center conductor was noted but is not expected to affect the overall schedule. We also had a visit from another of our vendors who discussed with us the status of the fast opening switch (crowbar replacement) for the ICRF transmitters. This work is being done as part of a Phase II SBIR. Lower Hybrid System ------------------- Work continues on the transmitter protection system (TPS) upgrade. Instrumentation for the Collector Over Temperature System (COTS) is being installed on the water cooling manifold to provide data on pressure, flow rate, and temperature. A lighter, more compact magnet yoke was manufactured for the LH FFT. Evaluation of the new yoke is ongoing. Molybdenum tiles for the new LH2 limiter were baked in preparation for installation. Machining of the limiter support plates is in progress. Remote Participation, Travel, and Visitors ------------------------------------------ On July 23rd, a group of nine scientists from the Chinese Academy of Scientists (CAS), led by Prof. Wenlong Zhan, Vice President of CAS, visited the MIT Plasma Science & Fusion Center to exchange information about the Chinese and PSFC fusion sciences programs. Miklos Porkolab gave an overview of the PSFC research activities, and Bruce Lipschultz gave an overview talk specifically about the C-Mod program. After a visit to the PSFC Nabisco laboratories, in particular C-Mod, Prof. Jiangang Li, Director General, IPP, CAS, gave on overview of the Chinese fusion program and its long range plans. Fruitful discussions were held that extended into a luncheon meeting attended by seven members of the PSFC, as well as the full Chinese delegation. Areas of overlap of the ASIPP EAST program and that of C-Mod were discussed, specifically in the areas of RF (Lower Hybrid current drive and ICRF heating) and plasma surface interactions. The Chinese were particularly interested in new developments in the C-Mod program including the rotated ICRF antenna and new SOL diagnostics aimed at understanding plasma-surface interactions as well as the role of the SOL in LH wave propagation and absorption, and the impact of ICRF power. There was significant interest in our point of view regarding next step projects and in particular, the Vulcan design, which was discussed by Dennis Whyte. After the general meeting between PSFC and CAS staff, Jiangang Li spent several hours discussing divertor and edge physics with Bruce Lipschultz and Dennis Whyte. He then spent time meeting with the Chinese graduate students at the PSFC. David Mikkelsen, PPPL, was at MIT all last week to discuss GYRO simulations of C-Mod plasmas, analysis of turbulence simulation sensitivities, and to install GYRO tools on the data analysis server. Jungpyo Lee, a C-Mod graduate student, was at the University of Oxford from 7/18 to 7/22 and met with Felix Parra and Michael Barns, U. Oxford, and Bill Dorland, U. Maryland. They discussed GS2 results pertaining to the radial flux of the toroidal angular momentum in C-Mod due to finite poloidal rhostar effects. Felix Parra and Peter Catto proposed that these effects may lead to broken symmetry that results in the intrinsic rotation. Martin Greenwald, Miklos Porkolab and Amanda Hubbard attended the FESAC meeting in Gaitersburg, MD last week (Martin is FESAC Chair, and Amanda is a member of the committee). _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly