The Effect of Degenerate Plasma on the Frequency Spectra of Slow Waves in Helix Traveling-Wave Tube

The dispersion relationship of electromagnetic waves in a helix traveling-wave tube consisting of a dielectric rod and a degenerate plasma layer was investigated and the presence of terahertz (THz) waves in this helix waveguide was shown. Furthermore, the permissible frequency region for the presence of slow waves in this helix waveguide was obtained. In addition to the effect of the dielectric radius, the plasma radius and the dielectric permittivity on the dispersion relationship were investigated. In the following, by injecting the electron beam in this helix waveguide, the electromagnetic waves were excited and the effect of geometric parameters on the growth rate of these THz waves was investigated.