Eigenmodes of a circular waveguide with a dielectric rod and magnetized plasma and plasma influence on cherenkov interaction in an antenna-amplifier

Summary form only given. Electrodynamics of a circular waveguide with a dielectric rod and magnetized plasma layer adjoining the rod surface has been considered. The dispersion relation has been derived for non-axisymmetric modes; the solutions of this equation corresponding to the structure modes have been numerically investigated both in cases of pure structure modes and hybrid modes, when the frequency is, respectively, higher or lower than the plasma frequency. In particular, the dependences of the fundamental HE₁₁ mode phase velocity on the plasma density and layer thickness were studied, and parameters of the plasma were identified that modified the mode dispersion to such a degree that prevents a Cherenkov interaction with an electron beam. RF field profiles and Poynting flux over the system cross-section were analyzed, and the plasma influence on the fundamental mode coupling impedance has been emphasized. From the standpoint of normal operation of an X-band antenna-amplifier device, it is important that when the annular electron beam propagates along the dielectric rod, the plasma formation at the rod surface is quite admissible while its density remains less than or of the order 10¹² cm^-3