(The) effects of the perpendicular momentum distribution on the cyclotron cherenkov maser

Abstract

The formulation of the Vlasov-Maxwell equations is utilized to investigate the kinetic instabilities for the transverse-magnetic (TM) and transverse-electric (TE) modes of the cyclotron Cherenkov maser for a dielectric-loaded cylindrical waveguide system in the small signal limit. Using the orthogonality condition of the electromagnetic modes, the dispersion relation is derived for the dielectric-loaded waveguide system, along which the relativistic electron beam traverses under the constant guiding magnetic field. The growth rates of the Cherenkov and cyclotron Cherenkov instability for the azimuthally symmetric TM and TE modes are studied for the various perpendicular momentum distributions. We find that the cyclotron Cherenkov instability has a growth rate comparable to that of the Cherenkov instability for the finite perpendicular momentum distribution. The results shows that the amplification of an electromagnetic wave is possible in the range of millimeter to sub-millimeter using the electron cyclotron mode arising from the anomalous Doppler effect.