Electron Density Dependence of Cyclotron Harmonic Radiation from a Plasma

Abstract

Simultaneous measurements of electron density and radiation emitted near harmonics of the electron cyclotron frequency have been made with a microwave cavity coaxial with a low-pressure argon discharge in a magnetic field. The dependence of the line position and width on electron density is in reasonable agreement with recent calculations made of the spectrum of electrostatic waves excited by fast electrons. The intensity of the radiation increased rapidly with electron density, and no radiation was observable unless the maximum hybrid frequency in the column was close to or greater than the frequency of observation. It is shown that axial variations in electron density account for nonuniform emission of radiation along the discharge.