Alcator C-Mod Weekly Highlights March 2, 2009 FY2009 weeks of research operations: Target: TBD Completed: 0 weeks Operations ---------- Installation of the TF arm to leg spring-plates continued last week. Low insertion force measurements on some of the spring-plate slots required reworking of the spring-plates that span the gaps between the TF magnets and the outer support blocks. C-Mod cryostat components have been returned from storage and are being prepared for installation. Our vendor completed smoothing and polishing operations on the turbine end of the alternator rotor bore last week. We continued analysis of collector end ring samples, and are preparing the turbine end samples to undergo a similar testing procedure. Lower Hybrid System ------------------- We continued fabrication and design of components for the new lower hybrid launcher including 4-way splitters, waveguide and waveguide vacuum windows, rf probes, and transmission line hardware, as well as control system upgrades. ICRF Systems ------------ The installation of all FMIT#3 intermediate power amplifier wiring is complete. Testings of this new system is proceeding. We are designing a test stand which will be used to investigate breakdown phenomena in rf antenna systems. The current design uses a well matched ridged waveguide capable of generating high rf electric fields with relatively low input powers. A design review of this new test facility was held last Friday. The design appears good for short pulses (< 1 s), but thermal issues arising during long pulses (~5 s) will have to be evaluated before construction. Diagnostics ----------- The microwave electronics for the ICRF antenna and lower hybrid launcher reflectometers arrived from ORNL last week. Plans were made for the placement of the microwave electronics in the cell and for the external waveguide run from C-port to the diagnostic laboratory. Communication with the digitizer was established enabling calibration and testing of the microwave electronics to begin this week. Travel and Visits ----------------- Paul Allaire, Tim Diamond, and Jawad Chaudhry, all from the University of Virginia Rotating Machinery and Controls Laboratory (ROMAC), visited on 2/24 to discuss the MIT Alternator and collect information on its operation and design. They are experts in rotating machinery dynamics. Codes they have developed will be used to evaluate changes in rotor dynamics that could result from possible modifications to the rotor bore that are under consideration. Tuong Hoang and Alain Becoulet, CEA Cadarache, France, visited on Thursday and gave a presentation on the plans for lower hybrid on ITER. They had extensive discussions with Ron Parker, Amanda Hubbard, and the rest of the lower hybrid group. Bruce Lipschultz traveled to Cadarache, France to participate in a Fusion for Energy meeting from February 16 to 17 on ITER operation with an all-tungsten divertor. Bruce presented the C-Mod experience with an all high-Z machine. Topics included startup, both at the beginning of a campaign, and during ramp-up and ramp-down for each discharge, the role of molybdenum in affecting core transport, the role of ICRF in eroding molybdenum surfaces, and the effect on the core plasma of melted divertor tile edges. Stewart Zweben, PPPL, was at C-Mod to work on completing the GEMR comparison paper. He brought a PSI-5 ultrafast camera for testing, which can be used for gas puff imaging experiments at 500,000 frames/sec. He also worked on other preparations for the next run campaign. Greg Hanson, ORNL, visited last week to inspect the microwave electronics recently shipped from ORNL, and to finalize details of the vacuum waveguide run. John Rice gave the Columbia University Plasma Physics Colloquium on 'Spontaneous and RF Driven Rotation' on February 27th. Nakanishi Hideya, National Institute for Fusion Science, Nagoya, is visiting for two weeks to collaborate with Joshua Stillerman and Tom Fredian on high latency network performance. _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly