Superheterodyne frequency-modulated radiometer for studying the evolution of the microwave spectrum from a plasma

In order to study the evolution of the microwave frequency spectrum from a plasma a superheterodyne frequency-modulated radiometer has been developed which uses a raster to record nine components of the spectrum simultaneously on an oscilloscope screen. Sawtooth voltages from two generators with multiple frequencies are used to image the electron beam and the frequency modulation of the heterodyne. This results in a simplification of the circuit and a decrease in the response time of the radiometer compared with devices that use square frequency-modulated voltage pulses, control pulses, and image pulses of a more complicated form. The parameters of the radiometer circuit are given. The results of experiments using the radiometer on the Tuman-3 tokamak are described. 6 refs., 4 figs