Afterglow Plasma Diagnostics with a Microwave Sampling Radiometer

Abstract

A simple waveguide arrangement has been developed for the study of microwave absorption and emission from a magnetized afterglow plasma column. The time and frequency resolved measurements are performed by a sampling radiometer. A comparison and null technique permits the direct measurement of the electron temperature. Continuous plots of the temperature vs frequency, magnetic field, and afterglow time are made possible by means of a servoloop. The width of the emission or absorption spectrum in the range of upper hybrid frequencies is used to derive the electron density which, together with the temperature measurement, allows a more complete analysis of the plasma decay.