Alcator C-Mod Weekly Highlights November 19th, 2007 FY2008 weeks of research operations: Target: TBD Completed: 0 weeks Physics ------- Four invited talked were given on C-Mod results at the 49th DPP APS meeting last week in Orlando, Florida. Paul Bonoli gave a talk on "Lower Hybrid Current Drive Experiments on Alcator C-Mod: Comparison Between Theory and Simulation", Brian LaBombard discussed "Critical Gradients and Plasma Flows in the Edge Plasma of Alcator C-Mod", Steve Wukitch talked on "ICRF Performance with Metallic Plasma Facing Components: Revenge of the Sheath", and Valerie Izzo, University of California, San Diego, gave a talk on "MHD Simulations of Disruption Mitigation on DIII-D and Alcator C-Mod". John Rice presented a talk on "Spontaneous Rotation in Tokamak Plasmas" at the Angular Momentum Mini-Conference associated with the meeting. These presentations, together with the contributed orals and posters may be found at http://www.psfc.mit.edu/research/alcator/pubs/APS/APS2007/orlando2007index.htm We are very happy to report that Jim Terry was named a Fellow of the APS at the meeting. Operations ---------- On Tuesday of last week the initial cool-down of Alcator C-Mod was begun with liquid nitrogen flowing over the superstructure. On Wednesday the magnets were cooled down to -25C, and a 120C bake of the vacuum vessel was begun. We continue to bake and electron cyclotron discharge clean C-Mod in preparation for first operation of the FY2008 campaign later this week. On Friday, the cell and power room were locked up, and the ACCESS control system was checked out successfully. In addition, the data system was run through machine cycle tests, and systems required for operation were brought back online including the Digital Plasma Control System, TCI (two color interferometer), the gas puff system, vacuum gauges, preionization system (sparker), magnetics digitizers, and the TF resistance scanner. The alternator has been brought up to full speed and is ready for operation. Hi-Pots of the magnets have been completed successfully. All magnet bus work and inspections have been completed. Lower Hybrid System ------------------- Phase and amplitude calibrations of the lower hybrid klystrons were completed this week at beam voltages of 40 and 50 kV. Work continued on the new remote launcher positioner. This new system will allow radial positioning of the launcher without entry into the cell. ICRF Systems ------------ We continued re-assembly of transmission line components, calibration of directional couplers, and work on the rf gate generator boards. Diagnostics ----------- The data acquisition system for the 152 channel soft x-ray tomography diagnostic has been upgraded from CAMAC-based 12-bit, 100 kHz digitizers to cPCI-based 16-bit, 250 kHz digitizers. Additionally, an edge viewing aperture has been re-installed on one of the arrays so that the diagnostic is configured to have: 76 core channels, 38 channels viewing the pedestal at the outboard mid-plane and 38 channels viewing the pedestal at the top of the plasma. These pedestal arrays will be used to further investigate flux surface asymmetries in x-ray emissivity previously observed in C-Mod H-modes. _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly