Alcator C-Mod Weekly Highlights March 7, 2011 FY2011 weeks of research operations Target: 15 weeks Completed: 12.2 weeks Plasma Shots: 1447 Operations ----------- Last week was a scheduled maintenance week at Alcator C-Mod. No plasma operation was scheduled. Replating and reassembly of the TF bus in the power room was completed. A PLC control processor associated with the cryogenics system was replaced. Routine preventive maintenance was carried out on all subsystems. Plasma operation is planned to resume this week. PAC Meeting ----------- The Alcator C-Mod Program Advisory Committee met on Mar. 2-4 at MIT. PAC members attending included Rich Hawryluk (PPPL, Committee Chair), Troy Carter (UCLA), Steve Knowlton (Auburn), George McKee (U. Wisc.), Richard Fitzpatrick (IFS, U. Texas), Phil Snyder (GA), and Richard Pitts (ITER Organization). Mark Foster (OFES) also participated in the meeting. C-Mod personnel provided presentations on recent C-Mod results and plans; slides are available on the web at http://www.psfc.mit.edu/research/alcator/pubs/Cmod_PAC_2011.html . The PAC was asked to provide advice on our research and upgrade plans through FY2013. Rich Hawryluk presented a preliminary panel report at the end of the meeting. DoE-OFES representatives participated in the debriefing session by videoconference. ICRF Systems ------------ A series of tungsten vacuum plasma sprayed samples has been tested for their breakdown characteristics with the RF electric field parallel to the magnetic field. The preliminary data suggests the VPS tungsten performed as well or better than polished copper. This result is encouraging since the VPS process can be used on large structures. We plan to do more testing after the run campaign is completed to quantify the breakdown voltages for VPS tungsten, both as sprayed, and then after polishing. The last four TZM tiles for the ARRA-funded rotated antenna have been machined from their blocks and the radius cut has been completed on 12 of the 18 tiles. The center back plate has been cleaned and prepared for plating. The Z plate is nearing completion. Our vendor has begun machining the back plates. A process has been developed to polish and blend the bending marks from the 34 accepted bent Faraday rods. The marks must be removed and the rods threaded before they can be sent out for TiCN coating. Lower Hybrid System -------------------- The Lower Hybrid system was used at high power to test a prototype high power waveguide stub tuner. Breakdown in the stub occurred at 150kW. A new design which should have higher power handling capability, up to 250kW, is in progress. Progress on the new transmitter protection system (TPS) continued. Collector over temperature (COT) modules were fitted in the cell and are ready for connectors and fans to be installed. Phase and amplitude controllers for the 4th klystron cart were calibrated using a raster scan method. This calibration method will be compared with the results of the "orthogonal" method and existing vector modulators. Travel and Visitors ------------------- Bob Granetz participated in the ITPA MHD topical group meeting held in Ahmedabad, India. While in India he gave two presentations to the C-Mod PAC via remote conferencing tools. Weixing Ding, UCLA, visited all last week to work with Will Bergersen, also UCLA, and Peng Xu on the C-Mod Polarimeter. Good progress was made on understanding the effects on polarization caused by the wire mesh beam-splitters and wire grid polarizers. The installation of a second detector to monitor both the transmitted and reflected component of the return beam off the last polarizer was completed. Following his participation in the C-Mod PAC Meeting, Dr Richard Pitts (ITER Organization) engaged in discussions with C-Mod scientists, including Brian Labombard, Bruce Lipschultz, Earl Marmar, Matt Reinke, Jim Terry, and Steve Wolfe, on planning for C-Mod impurity seeding experiments in support of ITER, as well as other topics of mutual interest. He also presented a general PSFC Seminar entitled "Key physics and materials aspects of plasma-wall interactions in ITER." Graduate students Ted Golfinopoulos and Geoff Olynyk presented a poster on "Fusion energy and plasma physics research at the MIT Plasma Science & Fusion Center" at the MIT 2011 Energy Conference at the Westin Copley Place Hotel in Boston on Friday. Ted and Geoff also handed out literature and spoke to numerous visitors with diverse professional experiences. The PSFC presentation was one of more than 100 energy-themed displays from industry, academic, and government sources. _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly