Influence of the Beam Self-Fields on the Dispersion Characteristics of EM Waves in a Dielectric Waveguide Filled with Plasma

Considering the self-fields of relativistic electron beam (REB), the electron beam injected in plasma will form an ion-channel, which can stably guide REB transmitted in plasma. Based on the effect of ion-channel, the EM dispersion characteristics in a dielectric waveguide filled with plasmas is studied by using linear electromagnetic (EM) hydrodynamics perturbation theory. Both the TM mode dispersion equation and the dispersion relation are derived. After that, a discussion on the conditions of Cherenkov radiation in this system is given. It was found that the betatron oscillation of the REB is one of the important factors for the slow-wave EM instability in this system. The dispersion relation is of the form of electromagnetic-electrostatic (EM-ES) hybrid mode, which is different from the case where the effect of the ion channel is neglected.