Alcator C-Mod Weekly Highlights May 31, 2005 FY2005 weeks of research operations Planned: 17 weeks Completed: 7.5 weeks Operations ---------- Plasma operations continued at Alcator C-Mod last week. Four run days were scheduled and completed. A total of 111 plasma discharges were produced, with an overall reliability of 82%. The runs were dedicated to continued machine and ICRF antenna conditioning, following the recent vent. 1MA discharges were run in lower single null, upper single null, and inboard limiter configurations in order to clean all plasma contact surfaces in the vessel. The J-port antenna conditioned up to 3MW, its nominal power level, fairly quickly. The E-port dipole antenna operated up to 1.5 MW, with some faulting. The D-port antenna, which is closest to the lower hybrid launcher location and was observed to have the most dust on and inside the Faraday screen in the in-vessel photos taken during the vent, was limited to powers of order 0.5MW by the end of the week. Dust injections were observed on video views, coming both from the D-port antenna and from the divertor. Plasma operations are scheduled to continue this week. Lower Hybrid ------------ A video-conferenced meeting was held on May 23 to continue the discussion and planning for the Lower Hybrid coupler repair. Concepts based on earlier designs used on both PLT and Alcator-C were discussed, as were some new ideas. PPPL is pursuing the use of a copper sleeve brazed to the alumina window that could then be brazed to stainless steel flanges. In parallel, MIT is looking at brazing stainless steel wave guides that could be welded into stainless flanges. MIT has also completed a promising first 3-window prototype braze test of a stainless coupler using a molydenum frame to restrain the growth of the stainless steel during the brazing process. Long Pulse Diagnostic Neutral Beam ---------------------------------- The DNB operated for much of the week. The beam is being conditioned and has not been not been brought to its optimum operating conditions. The lower beam current leads to a diffuse beam with a lower main energy component. Ron Bravenec and Bill Rowan acquired data for beam width and for CXRS. The beam was verified to be broad. CXRS data are being analyzed as a measure of boron density. The MSE diagnostic also observed their first signals from the new beam during operation last week. Travel, Visitors, Remote Collaborations --------------------------------------- Bob Ellis, Joel Hosea, Doug Loesser, Gerd Schilling, and Randy Wilson attended by videoconference the Lower Hybrid meeting on 5/23 . _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly