On the cyclotron maser instability in a waveguide

The cyclotron maser instability is conventionally treated as a pure electromagnetic instability⁽⁵⁾. Waveguide modes can'be equivalent to plane waves reflected slantingly upon the two sides of the waveguide. According to the principles of plasma physics(⁶) the electromagnetic and the electrostatic modes can't be decoupled when the wave vector isn't strictly perpendicular or parallel to the d-c magnetic field. Therefore the conventional treatment is incomplete and invalid in the case of intense beams.Vlasov kinetic theory of the cyclotron maser instability taking into account the space-charge wave is presented. It is found that the respective couplings between the negative-energy cyclotron mode and the RHCP waveguide mode as well as the fast space-charge mode are responsible for the wave-guide maser instability.