Pulse Stimulated Radiation from a Plasma at Harmonics of the Gyrofrequency

Abstract

A magneto-plasma excited by two short pulses at the gyrofrequency or a multiple thereof, is considered in the single particle approach. After the second pulse radiation maxima arise at the gyrofrequency and its harmonics. In a situation where the time separation of these maxima is τ* (in the simplest case τ* = τ) at the fundamental, it is τ*/n at the n-th harmonic. As the resonances at the harmonics are a finite Larmor radius effect, excitation at these frequencies requires an initial energy. As an example, the case is studied where the first pulse has the gyrofrequency while the second has the frequency 2ω_c. In this case radiation maxima arise with 2ω_c at times t_ℓ = ℓτ (ℓ = 1, 2, 3 . . .) after the second pulse. At the fundamental the maxima arise at times t_ℓ = (2ℓ - 1)τ , where the maximum at the time τ is initially due to the nonlinearity during the second pulse.