High resolution electron cyclotron emission temperature profile and fluctuation diagnostic for Alcator C-Mod

Abstract

A new second harmonic heterodyne electron cyclotron emission system with high spatial resolution (⩽15 mm) and a large number of channels (32) for dense profile coverage will be installed on Alcator C-Mod. The system will provide detailed radial electron temperature profiles and core temperature fluctuation measurements. The collection system is composed of elliptical and parabolic mirrors coupled to two overmoded waveguides to provide high poloidal spatial resolution necessary for T̃e measurements. Four radiometer sections cover the frequency range of 234–306 GHz, coupled to four optimized intermediate frequency modules with eight channels of detectors, amplifiers, dividers, and filters providing the profile information. A separate filter arrangement allows for temperature fluctuation measurements utilizing correlation techniques.