Enhancement of Cyclotron Harmonics in a Homogeneous Magnetoplasma

Abstract

A theoretical investigation is made of the radiation from a point charge e gyrating in a plane almost perpendicular to a magnetic field. The perpendicular component of the velocity, v, of the charge is assumed to be non-relativistic but much larger than the thermal velocity v_T, lnv⁄v_T>>1. Under the conditions |ε₁|>>(sv_T⁄v)^4⁄3·s−2, ε₃>>(v_T⁄sv) and ω₀²<ω_r²=(sω_H)²<ω₀²+ω_H², the intensity of the s-th harmonic is enhanced and given by
\frac2e²ω_r²πsv\sqrt|ε₁ε₃|ln\fracvv_T.
Here ω₀ and ω_H are the plasma frequency and the electron cyclotron frequency, respectively, s is a positive integer larger than unity and ε₁=1−ω₀²⁄(ω_r²−ω_H²), ε₃=1−ω₀²⁄ω_r². A harmonic structure appears when ω_H or ω₀ is changed. It is pointed out that some features of the experiments on cyclotron harmonic waves can be explained by this theory.