Alcator C-Mod Weekly Highlights June 14, 2004 We continued work invessel last week. Work also continued on the Lower Hybrid, ICRF, and power systems. Upgrades and calibrations to diagnostics proceeded. Alcator C-Mod Status -------------------- We are currently up-to-air with the primary goal of installing the lower hybrid launcher. In addition, a large number of invessel activities are ongoing in support of ICRF and diagnostic systems. Maintenance and upgrades to diagnostic and power systems are also in progress. Prior to stopping operations in May, we completed 18.9 weeks of research operation (75.5 days) in FY2004, satisfying the C-Mod portion of the JOULE target SC7-6a, "Achieve facility total operating weeks as planned for FY2004: C-Mod, 18 weeks." Operations ---------- Installation of the new HVAC unit for the power room began last week. The installation of the water cooling lines to supply the HVAC units has been an ongoing project by the contractor for the last few weeks. This MIT funded project will allow extended operation of C-Mod during very hot weather and generally improve conditions in the power room for both equipment and personnel. We began repairs and upgrades to the LN2 duct work. Upgrades to the magnet resistance instrumentation were also begun. Changes to this system will include an increase in the applied current used for the 4-wire voltage measurements, and improvements to the plating on the relays. The work on the alternator auto cooling valves, breakers, and oil filtration system has been completed. Maintenance and inspection of the C-Mod Hi-Yard equipment was also finished. The main breaker for supplying power to C-Mod was found to close inconsistently and will be replaced with the spare unit before we resume operation. Lower Hybrid Project -------------------- Ceramic window brazing tests and alumina window procurement continued at MIT last week. Tests of the window plating braze wetting and shear strength indicated excellent performance of the plating. We have released the vendor to perform the production run needed to supply windows for all five lower hybrid couplers (four plus one spare). Because of problems at one of its distribution sites, our power utility was unable to restore 13.8 kV primary power to the C-Mod site until Sunday night. High power tests of the launcher assembly can now resume. Electromagnetic and mechanical analysis of the external discharge developed during high power testing of the launcher assembly indicated that properly placed reinforcing bars along the waveguide channel plates should eliminate the discharge. Fabrication of the required parts was completed last week, and installation of the components has begun. We continued installation work on the new klystron vac-ion pump controllers. The remaining two solenoid power supplies are being installed following successful testing of the first one. Work continues on the Coupler Protection System (CPS). ICRF Systems ------------ Final calibrations this week of the digital tuning indicators will complete this upgrade. The coaxial lines between the drivers and the FPAs on FMIT#3 and #4 were removed last week to continue the investigation into tuning issues at 50 MHz. Tests on these systems can resume now that 13.8 kV power is restored. We continued general maintenance and documentation verification on all ICRF transmitters. Diagnostics ----------- A internal design review of the new B-Hor flange was held last week. The new flange will accommodate diagnostics moving from C-Hor to make room for the lower hybrid launcher. The flange design has been released for fabrication. The HIREX diagnostic has been temporarily removed from B-Hor in preparation for the new flange. This diagnostic system will be modified to allow more space for the new diagnostics and easier access to the port when required. A representative from our Thomson scattering laser vendor worked with MIT personnel last week to service and align our two YAG lasers. Both lasers are now in working condition. The availability of two lasers will allow us to improve by a factor of two the time resolution of the Thomson scattering system during the next run campaign. Approximately 30% of the invessel calibration of the C-Mod MSE diagnostic has been completed. A boron coating on the collection lens has been left in place so that conditions at the end of the run campaign can be documented. Another calibration with the boron coating removed will provide a calibration for the next run campaign. Travel and Visits ----------------- Martha Redi, PPPL, visited the MIT Plasma Science Fusion Center on June 7 and 8th. She met with Catherine Fiore, John Rice, Steve Wukitch and Martin Greenwald to discuss analysis of the off-axis RF internal transport barrier experiments, and their paper for the upcoming EPS conference. Stewart Zweben, PPPL, visited C-Mod last week to help upgrade the Gas Puff Imaging hardware, to work on a paper on the Edge Minority Heating experiment, and to discuss the new joint NSTX/C-Mod experiment on edge flows vs. magnetic topology led by Ted Biewer at NSTX.