Electrodynamics of plasma-filled diffraction generator

For determining the possibility of the creating beam-plasma generators in mm range the electrodynamic properties of the structure that consists of a sequence of metallic rings filled with plasma and surrounded by a metallic screen has been investigated. The excitation of HF-oscillations is produced by an electron beam. The dispersion characteristics, field topography, and HF-power flow distribution and their dependence on plasma density have been determined. The dispersion equation was obtained using the method of partial regions: I-inside of rings space, II-outside of rings up to metallic screen, and III-boundary region between them. Finding fields from Maxwell equations with permeability tensor and matching them at region III using the condition of Pointing vector continuity transcendental equation was derived for numerical analysis. Dispersion curves shifted with plasma density increase and allows to regulate the generated frequency. In the vacuum case, modes resonant with the e-beam have surface characteristics that result in low amplification coefficient. The ratio of power flow in region II to one in region I is 0.48 for the principle mode for the parameters considered. This demonstrates the possibility of such systems to take off the generated HF-power. Thus, plasma filling was considered as a tool for generation enhancement.