Alcator C-Mod Weekly Highlights October 18, 2004 FY 2005 weeks of operation planned: 14 weeks, completed: 0 weeks. We are currently up-to-air with the primary goal of installing the lower hybrid launcher. In addition, a large number of in-vessel activities are ongoing in support of ICRF and diagnostic systems. Maintenance and upgrades to diagnostic and power systems are also in progress. Physics ------- The CY2005 Alcator C-Mod Ideas Forum will be held on December 2-3, 2004. The purpose of the Forum is to solicit proposals for experiments on the C-Mod tokamak for the upcoming run campaign, with research operation scheduled to commence in January, 2005. The Forum is open to all interested parties, including current collaborators and potential future collaborators. We actively solicit proposals from the entire fusion community. Operations ---------- All tungsten brush tiles, including the tiles for outer divertor module edge locations, are now in-house. The tiles are in various stages of cleaning, baking, and installation. Upgrades of the engineering PC to PLC interface software continue. The torus vacuum control station, TORVAC, is currently being upgraded. We continued upgrades and maintenance on MIT Alternator systems. A review will be held on October 26 at MIT to consider proposed changes to the alternator stator neutral grounding system. John Lacenere, PPPL, Bill Cary, General Atomics, and Steve Fairfax, MTechnology, will serve on the committee. Lower Hybrid System ------------------- Test samples are being brazed to qualify a procedure for filling voids in the #3 PPPL coupler. Preparations for brazing the #4 PPPL coupler continued. Cleanup of the #5 PPPL coupler, already successfully brazed, was completed. The #5 PPPL coupler will replace the #3 PPPL coupler if required. Simulations of the rf probes for the rwg have continued. The latest design indicates a small asymmetric modification to the output coupler can make a large improvement to the directivity of the probes. A prototype board will be available for tests soon. Work on CPLD (complex programmable logic device) and PIC (peripheral interface controller) programs needed for the lower hybrid interlock system is underway. This system takes signals from many sources such as plasma current Rogowski, stray rf levels in the cell, and broken fiber indicators, and uses the information for lower hybrid system interlock control. Calibration of the vector modulators continued. Mapping coefficients from operator set-points to lookup tables to microwave output are being updated. ICRF System ----------- The crowbar trigger chassis assemblies for FMIT#3 and FMIT#4 have been modified, repackaged and are ready for installation. The supports on the crowbar cabinets will be modified this week. These systems will be extensively tested before the replacement of the FMIT#3 FPA tube. The two new 2 MW FPA tubes have been tested to EIMAC specifications and are ready for installation. One will be installed in FMIT#3 and the other in FMIT#1 (operated during the last campaign with a 1 MW tube). The rf bypass capacitor rails have been successfully welded. Machining of the rails and soldering of the copper braids to the tab assemblies are in process. Long Pulse DNB -------------- Dexter Beals and Robert Granetz were at the Budker Institute of Nuclear Physics in Novosibirsk to participate in the initial commissioning tests of the new C-Mod long pulse diagnostic neutral beam. They brought with them a compact optical spectrometer for measuring the energy component fractions of the beam. The spectrometer worked well, and H-alpha spectra were obtained. The initial operation was at low beam current and voltage, and it is expected that several weeks of conditioning by the Budker team will be required to reach full performance. Issues concerning the siting of the new beam and associated power electronics in the C-Mod cell were resolved, and a 3-week modification to the original shipping and installation schedule was agreed upon. Work continued on the design and documentation of the hardwired control system for the DNB AC power system. Drawings for the remote auxiliary control stations are being developed. Additional fuse protection and grounding methods that are required for the DNB 480 VAC power system are being specified. Diagnostics ----------- The MSE in-vessel shutter is being modified to allow a new position with a polariser to be switched into the optical path. Fit-up of the components in-vessel is ongoing. We have completed the design and testing phases of the polarimeter limiter amplifiers and have begun to work on the packaging of the boards and procurement of parts. The design of the Bragg cell driver electronics continues. The CAMAC crate has been installed in the electronics rack for the polarimeter along with phase demodulator modules and power distribution panels and fans. The vacuum bake of the poloidal b-dot coils for Alfven cascade studies has been successfully completed. The in-vessel cable runs are being layed out and mounting hardware is being designed and procured. Travel and Visits ----------------- David Mikkelsen, PPPL, spent last week at MIT learning what has been done to test theoretical expectations for transport in C-Mod ITB plasmas, and discussing what could be done to test the theory further. Several experimental approaches are promising and will be proposed at the Ideas Forum in December. Earl Marmar and Amanda Hubbard were in Denver, Colorado on Thursday and Friday of last week at the FESAC Priorities Panel Meeting. _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly