Dielectric-Loaded Plasma Filled Helix Traveling Wave Tube Analysis Based on the Linearized Field Theory

Abstract

A linear relativistic field theory of a plasma-loaded helix traveling wave tube is presented. The configuration consist of a solid electron beam propagating through a tape helix enclosed within a loss-free wall in which the gap between the helix and the outer wall is filled with a dielectric. The dispersion relation is derived for azimuthally symmetric modes. The effects of dielectric constant, plasma density, axial guide field, and electron beam density on the phase velocity and growth rate were considered numerically. Numerical results indicate that the phase velocity and growth rate increase in the presence of the plasma. Further the growth rate and frequency are maximum at the special value of the dielectric constant. The growth rate increases with axial guide field and remains relatively constant at strong magnetic field, however the growth rate increases considerably by incrementing the electron beam density.