A theoretical model of Cerenkov instability in the linear amplification regime of Plasma Cerenkov Masers has been improved. The novelty of the model consists in considering azimuthal dependence of the amplified electromagnetic field in the approach of finite thicknesses of annular electron beam and plasma in axial symmetric system. This assumption leads to a new topology of wave modes coupling and consequently, the spectrum of instability is found to be distributed over one or several frequency bands, according to initial parameters. This result gives the opportunity to foresee the emission spectrum for a giving experimental configuration. A special attention is paid to the field spatial dependence for different azimuthal modes.
Michel Birau, Michel Birau,
"Multimode linear analysis of plasma Cerenkov masers driven by relativistic electron beams", Proc. SPIE 2843, Intense Microwave Pulses IV, (28 October 1996); doi: 10.1117/12.255388; https://doi.org/10.1117/12.255388