Microwave Reflection by Magneto-Plasmas

Abstract

The microwave powers reflected by magneto-plasmas are examined experimentally and compared with theoretical values at resonances calculated under an approximation, in a range where ω_p²⁄ω² is close to unity and for small ω_c⁄ω, where ω_p is the plasma frequency, ω is the applied microwave frequency and ω_c is the electron cyclotron frequency. It is demonstrated that the reflection method adopted here is useful for detecting the electron resonances which appear approximately at 1−ω_p²⁄ω²=ω_c²⁄ω², in particular for small ω_c⁄ω. Moreover the collision frequency ν can be estimated from the relative value of the reflected power at resonance. The incident microwave power is most efficiently absorbed at a relatively small value of ω_c⁄ω, for instance, at ω_c⁄ω\simeq0.3 for ν⁄ω\simeq0.1×(ω_p²⁄ω²).