Waveguide modes in a relativistic electron beam with an axial magnetic field

Abstract

Dispersion relations (DRs) for the azimuthally symmetric waves in a cylindrical metallic waveguide completely filled with a magnetized relativistic electron beam are investigated within the framework of cold-fluid description. The defocusing effect of self-fields is counteracted by considering a rotating electron beam. Both electrostatic and electromagnetic waves are investigated by a general electromagnetic analysis. As an approximation, waves are separated into transverse magnetic (TM) and transverse electric (TE) waves with the field components taken as the field components of waves in an empty waveguide. The DRs are solved numerically to study the wave-mode properties. The justification for separating the waves into TM and TE modes is presented and errors that are so introduced are given. It is shown that the TE DR gives only one legitimate high frequency electromagnetic TE mode and the other two are not physically acceptable modes.

Instability of electromagnetic waves with radial polarization in a rotating relativistic electron beam guided by ion channel

“…The stability of rotating relativistic electron beam in a uniform magnetic field was studied by Han [20]. Dispersion relations for the azimuthally symmetric waves in a cylindrical metallic waveguide completely filled with a rotating magnetized relativistic electron beam were investigated within the framework of cold-fluid description [21]. Rouhani et al [22] found high-frequency eigenmodes of a cylindrical metallic waveguide partially filled with a relativistic electron beam guiding by the ion channel.…”