Alcator C-Mod Weekly Highlights November 2, 2009 FY2010 weeks of research operations Base Target: tbd ARRA Target: 5 weeks Completed: 2.3 weeks Operations ----------- Last week was a scheduled maintenance week at Alcator C-Mod. No plasma operations were planned. A clean vent (up-to-helium) was carried out on Wednesday in order to replace or reposition several gate valves and windows, and to perform an in-vessel inspection using a camera on a boom inserted through a 2 3/4" flange. The inspection confirmed the presence of a broken outer divertor tungsten lamella tile and exposed leading edge, in the vicinity of B-port, as had been suspected based on operational and spectroscopic observations. We also identified a missing molybdenum tile on the lower "EF1 shelf". We were also able to assess the condition of the boron-coated molybdenum tiles on the outboard limiters and upper part of the outer divertor structure; most of these appear to be intact, with a few exhibiting some evidence of delamination. Following the inspection and installations, the vessel has been pumped down and will undergo bakeout and ECDC (electron cyclotron discharge cleaning) in preparation for resuming C-Mod operation following the APS DPP meeting this week. This week is a planned maintenance week, and no plasma operations are scheduled. ICRF Systems ------------ A new final power amplifier (FPA) tube was installed in the FMIT#4 transmitter, and we have begun installation of a new FPA tube in FMIT#2. The FMIT#4 FPA had failed in service after 3508 filament hours, and the FMIT#2 tube has accumulated over 3300 filament hours and is therefore likely near the end of its useful life. With these replacements all four transmitters will have tubes with less than 400 filament hours of operation. An order has been placed for two addtional FPA tubes made possible by the ARRA funding increments. A leaking 9" coax elbow in the J-port antenna transmission line has been repaired and re-installed. The J antenna coax has been changed to 50 MHz current drive configuration in preparation for upcoming experiments. The FMIT#3 and #4 transmitters are being re-tuned to 50 MHz operation. Lower Hybrid System ------------------- Sixteen waveguides have been e-beam welded (EBW) and leak checked. One weld was found to have a small, easily repairable, leak. All 16 four-way splitters are ready for stacking and alignment testing. A purchase order for three new klystrons has been generated under ARRA funding. Travel and Visitors ------------------- Steve Wukitch participated in ASDEX Upgrade Programme Seminar (Tegernsee, Germany) last week. Josh Stillerman visited NIFS (Toki, Japan) on a three week JSPS fellowship, working with Dr. Nakanishi on remote data system performance. In addition he provided MDSplus support to Dr. Takashi from the CHS experiment, and presented talks on the C-Mod data acquisition and control systems. Dr. Boyd Blackwell of U. Canberra visited the PSFC Thursday, October 15. He held discussions with a number of personnel including Bruce Lipschultz, Bob Granetz and Earl Marmar. The discussions with Bruce Lipschultz covered divertor physics and plasma surface interactions generally as he and the Canberra group are planning a more generalized emphasis on those subjects on their campus. They have started collaborations with materials scientists on campus for example to look at working together on improved plasma facing component materials. _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly