The Plasma Background Effect on Time Growth Rate of Terahertz Hybrid Modes in an Elliptical Metallic Waveguide With Two Electron Beams as Energy Source

The dispersion relation of terahertz hybrid modes in a plasma waveguide made of dielectric tube surrounded by long cylindrical metallic wall with elliptic cross section is obtained. The plasma region has been placed on outer surface of dielectric tube. The waveguide mentioned earlier is considered instable by the injection of two electron beams with opposite velocities as source energy. The dispersion relation graph and its characteristics, such as its dependence to geometrical dimensions and characteristics of the electron beam, are presented. In addition, effects of relative permittivity constant of dielectric tube, geometrical dimensions, accelerating voltage and current density of electron beams on growth rate, and frequency spectra of waveguide will be investigated.