Design and characterization of radiometer system for electron cyclotron measurements at Aditya-Upgrade tokamak

Abstract

Instrumentation and characterization techniques have been developed for a 16-channel radiometer system to obtain localized electron cyclotron emission (ECE) measurements at Aditya-Upgrade tokamak. Inverse dependence of the EC radiation on the toroidal magnetic field constrains the hardware for measurements at a fixed radial location. This results in having costly and complex sweep systems or use of multiple receiver units dedicated to a specific toroidal magnetic field. A simple, cost effective solution to this issue could be using a fixed frequency wideband intermediate frequency (IF) receiver. This multiple channel hardware unit can do localized measurements at fixed as well as different magnetic fields thereby improving the measurement range. Designed system provides a spatial resolution of 1.2 cm and a temporal resolution of 10 μs.Noise figure of the system varies from 15–22 dB while the sensitivity is 0.1 × 106 V/W. The manuscript provides an insight over the characterization techniques followed for the design of the radiometer system. A brief overview of the calibration technique is discussed. First measurements obtained from the system are also presented.