Interaction between the electron beam and the surface wave in a dielectric plate

A model of the traveling-wave tube (TWT) that includes a dielectric plate adjoining a perfectly conducting surface and a metal screen parallel to the plate is considered. The dispersion equation in the presence of a homogeneous electron beam filling the space between the plate and the screen is derived. The method of differentiation of the dispersion equation is used to obtain and calculate coefficients of the TWT characteristic equation and coupling and depression coefficients, i.e., coefficients determining the main properties of the TWT. The considered model is compared with an “impedance” comb structure and a cylindrical helix. Conclusions concerning the prospects of development of a “dielectric” TWT are drawn.