Anomalous Doppler resonance of electrons with a one-dimensional monochromatic electromagnetic wave

A kinetic and hydrodynamic theory of emission from electron beams in a finite magnetic field under conditions of anomalous Doppler resonance with a one-dimensional monochromatic electromagnetic wave is developed. The transition from the hydrodynamic to the kinetic regime is investigated. The instability suppression mechanisms and the evolution of the distribution function of the emitting electrons are described. Analytic solutions of the problem of emission from the beam under conditions of the anomalous Doppler effect are obtained in the purely hydrodynamic and kinetic limits. It is shown that the physics of the kinetic instabilities under the conditions of the anomalous Doppler effect differ substantially from the physics of kinetic instabilities due to inverse collisional Landau damping