Spectra of Electromagnetic Surface Waves on Plasma–Vacuum Interface Inside a Metallic Cylindrical Pipe

Abstract

A general nonlinear dispersion relation, for the spectra of electromagnetic surface waves on the interface separating an axially symmetric plasma and vacuum both enclosed in a resistive cylindrical pipe, have been derived and various limiting cases were discussed. The spectra were found to be similar to those ofelectrostatic surface wave modes existing at plasma–vacuum interface for cases such as thin plasma or a conducting wall far away from the plasma-vacuum interface. For moderate values of ka, where k is the wave number and ais the width of plasma, appreciable modifications of spectral curves have been observed. By including the surface impedance  Z_m of the pipe–wall, the dispersion relation of the electromagnetic surface waves becomes a function of the dispersive properties of the wall. Investigating the surface impedance shows no observable effect on the real part of the surface wave spectra, but it introduces an imaginary part into the frequency ω. The corresponding peak values have been obtained for various representative situations. When coupled to an external driver such as particle beams, surface wave fields can be excited, causing beam energy losses,
and thus affecting the beam dynamics.

Keywords: Electromagnetic Surface Waves, Surface Waves In Plasmas, Resistive Cylindrical Pipe.