Alcator C-Mod Weekly Highlights September 25, 2006 FY2006 weeks of research operations: JOULE target: 14 weeks Completed: 16.7 weeks Major Facilities Review ----------------------- Earl Marmar, Martin Greenwald and Bruce Lipschultz traveled to Germantown for the C-Mod portion of the DoE Midpoint review of major facilities, held Wednesday, September 20. Many other members of the C-Mod team participated by video-conference from MIT. Viewgraphs of the presentations to the review panel can be found at http://www.psfc.mit.edu/research/alcator/pubs/midpoint/5_year_midpoint_review_presentations.html Physics ------- Graham Wright, University of Wisconsin-Madison, working with Dennis Whyte, has made important measurements of the retention of deuterium in molybdenum. Examining both the total retention rates in the first five microns and the deuterium depth profiles demonstrate that diffusion plays an important role in determining the retention rate. Plasma exposures at Mo temperatures of 400 K and ion energies of 100 eV demonstrate a linear retention rate up to deuterium concentrations of ~0.25 % D/Mo, achieving results similar to the retention rates seen in Alcator C-Mod during the "bare Mo" campaign. Future work will determine the importance of boron on the surface, the effects of dynamically changing temperature, and if similar behavior is seen in tungsten. These results could have important implications for tritium retention in ITER. Operations ---------- On Monday and Tuesday of last week General Electric Energy Division successfully completed an inspection of the MIT generator. After an extensive check of all the instrumentation, both the rotor and the stator passed all resistance, megger, polarization index, and hi-pot tests. A limited visual inspection through small access ports of the stator windings also indicated the stator is in excellent condition. Lower Hybrid System ------------------- Work on klystron refurbishment continued last week with a visit by C-Mod engineers to the vendor brazing the new cathode assemblies. An inspection of the ceramics was done, and an acceptable cathode stack assembly was picked and approved for brazing. ICRF Systems ------------ Work continued on the protection and control systems for the fast ferrite real-time tuners. Power, water cooling, and support systems are also being developed for the FFT in the C-Mod cell. As part of the preventative maintenance program for the transmitter high voltage power supply system a diode stack has been removed from the supply oil tank and brought into the rf lab for testing. These tests will continue this week. Long Pulse Diagnostic Neutral Beam ---------------------------------- Diagnostics attached to the F-Hor flange are being removed following calibrations and documentation. The F-Hor flange will be replaced with a new flange that will allow for a seven degree toroidal rotation of the DNB. A meeting was held last week to discuss changes needed to the flange to retain or improve diagnostic access to the flange with the new DNB beam path taken into account. Visitors and Travel ------------------- Roddy Vann of the University of York visited last week and gave a seminar on his research on nonlinear effects of Alfven eigenmodes. Dennis Whyte presented a talk on "Science and Technology Requirements Required for Fusion Energy," on invitation of the Netherlands Royal Academy of Science at a symposium on "Research Priorities on Renewable Energy," in Amsterdam, Sept 22, 2006. _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly