Alcator C-Mod Weekly Highlights November 26, 2012 FY2013 weeks of research operations Target: tbd Completed: 0.53 weeks Plasma Shots: 61 Operations ---------- Routine maintenance of engineering systems continued last week. Another 24 hours of glow discharge cleaning was completed, aimed at the reduction heavy boron hydrides. C-Mod is now warming up to room temperature in preparation for venting to air. Advanced Outer Divertor ----------------------- Thermal modeling work to evaluate the required dome height continued last week. A brief meeting reviewing the results of two dome height cases was held, with recommendations for looking at still lower cases. Heater connector fabrication will begin following approval of the latest design updates. Work with the heater vendor continues as they fabricate our latest order. Development of a test program for this set of heaters with connectors is underway. Final components for the spherical bearing test assembly are being fabricated. Work on the design of the overall heater electrical system continues. This process includes measuring contact resistances between heater connectors, identifying feedthroughs and in-vessel cabling, and selecting power supplies. Diagnostic design and specification continues with efforts examining both physics and engineering needs. ICRF Systems ------------ FMIT#4 has been operated into a dummy load to investigate an anomalous driver anode current measurement. Using a spectrum analyzer, it was found that harmonics were not unusually high up to a power of 1.5 MW. Some improvement was made in re-tuning, but there was an inconsistency in the anode current over repeated identical test shots, suggesting the problem has not been eliminated. We will continue to investigate as we move both FMIT#3 and #4 to 53 MHz. FMIT#4's phase shifter push/pull rod has been repaired and is ready to be re-installed. An FFT unit that arrived from the vendor with manufacturing defects has been prepared for shipment back to the vendor for repairs under warranty. Lower Hybrid System ------------------- The LHCD system was made safe for personnel entry into the vacuum vessel. Short circuit plates were installed between the waveguide switches and jungle gym to provide a secondary safety break. The LH launcher remote position controller was disconnected and tagged out to prevent accidental movement of the launcher while personnel are in-vessel. Parts for an IQ demodulator circuit for the LH FFT control system have been assembled, and fabrication of the circuit has begun. A voltage variable attenuator and phase shifter in series with a short circuit termination will be used to provide a wide range of load conditions for low power dynamic testing of the FFT. The LH FFT development plan will focus on a high power compatible, double-stub system. High power test of ferrites with full edge and corner rounding without bonding will soon begin. Additional ferrite material will be procured for measuring the coefficient of thermal expansion, and the testing of various bonding approaches. Remote Participation, Travel, and Visitors ------------------------------------------ Syun'ichi Shiraiwa attended the 22nd International TOKI Conference (ITC) in Toki City, Japan last week where he presented a poster on LH modeling and experiments on C-Mod. _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly