Alcator C-Mod Weekly Highlights October 29, 2012 FY2013 weeks of research operations Target: tbd Completed: 0.53 weeks Plasma Shots: 61 Advanced Divertor Preliminary Design Review ------------------------------------------- On Monday, October 22nd, a committee consisting of Phi Heitzenroeder (chair), Larry Dudek, Irv Katz, Steve Raftopoulos, PPPL, Arnie Kellman and Chris Murphy, GA, and Rui Vieira and Soren Harrison, MIT, met via teleconference for a Preliminary Design Review of the C-Mod Advanced Divertor. The morning session began with a welcome by Earl Marmar. Bruce Lipschultz gave a presentation on the physics and operational issues motivating the new design. Soren Harrison gave an overview of the design, Jeff Doody described the electro-magnetic analysis, and Han Zhang, PPPL, described the thermal analysis of the divertor during 600 C operation. In the afternoon session Rui Vieira presented the schedule and budget. Details of the design were presented by Soren Harrison, Lihua Zhou, and Bob Ellis, PPPL, These included analysis work done on the components which will mount the divertor to the chamber while allowing several millimeters of radial movement during thermal cycling, and the current shunts that are designed to provide thermal isolation while controlling the path of halo currents. Off-normal events and remediation ideas were also discussed. A review of the installation procedure of the divertor by Soren Harrison was the final technical presentation. Also participating in the review were Peter Titus, at PPPL, and Jim Irby, Bill Beck, Dan Karnes, Brian LaBombard, Bob Granetz, and Sam Pierson, at MIT. The committee met again on Wednesday, October 24th, for a detailed presentation by Rui Vieira on the budget and effort estimates, and to go over the chits generated during the review. We greatly appreciate the time spent, and the excellent advice and suggestions given, by the committee during this process. Operations ---------- Routine maintenance of engineering systems continued last week. Work in the Hi-Yard has been completed and high power engineering systems can now be brought back on-line when needed. ICRF Systems ------------ The cause of faulting in the J-Port antenna transmission line is still unidentified. Hi-Pots and TDR measurements have thus far been inconclusive. Tests into a dummy load and vacuum are being planned. Improvements to the rf demodulators are being incorporated into the existing design. Lower Hybrid System ------------------- Work continues on the 4th cart. Measurements were made for fiber lengths for the filament power supplies inside the cart. Work has started on fiber routing and adding connectors to the fibers. Two ± 2 A, 100 V supplies have been borrowed from the VTF experiment for testing of the LH FFT double stub tuner. The 50 us rise time of the supplies is sufficient for control of the FFT, but the current limits will not allow the FFT to be tested over its full range. Diagnostic Neutral Beam Systems ------------------------------- Faulting of the DNB power supply at the end of the last run campaign has been tracked down to failed MOV and high voltage diode components. Repairs are in progress. Diagnostic Systems ------------------ The LLNL intensified CID imaging system recorded first data of 550.6nm Mo I emission and 549nm continuum emission in similar discharges. In continuum images, a bright ring observed on the GH limiter during operation of the non-field aligned (D & E) antennas, but not during the field aligned (J) antenna, exceeds the intensity of even the divertor strike points. A chord on the Chromex spectrometer co-incident with the bright ring reveals a Planck type spectrum, believed to result from heating due to fast ion impact with the limiter. Remote Participation, Travel, and Visitors ------------------------------------------ Jan Coenen, JET, visited MIT on October 24 and 25. He gave two presentations - one on the status of tungsten melt studies at AUG, Textor, C-Mod and JET as well as the status of PWI studies on JET. The other talk was on CXRS measurements of the C+5 density, velocity and temperature profiles (with resultant Er and shearing frequency) as a function of radius on Textor and their dependence on changes in particle transport during ergodic divertor experiments on Textor. Dr. Coenen also met with a number of C-Mod staff to discuss C-Mod results. Thomas Sunn Pedersen, Max-Planck Institute of Plasma Physics, visited MIT on October 26. He had discussions with Miklos Porkolab, Bruce Lipschultz, Bob Granetz, and Jim Terry. He also gave the PSFC seminar on "The Status and challenges for the development of diagnostics for W7-X". _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly