Theoretical Mode-Gain in a Non-Intercepting Gridded Dual-Mode Broadband Helix TWT

Abstract

A theoretical analysis is developed to study the gain-frequency response of a dual-mode TWT consisting of a dual-perveance Hechtel and Hamak NIG gun, providing two solid electron beams, and a potentially dispersion-free slow-wave structure consisting of a helix supported by dielectric wedge bars in a metal shell provided with vanes projected radially inward. While both the pulse and the CW modes are found to be equally susceptible to the change in the vane dimension, the former are somewhat more so to the change in the beam filling factor. An alternative CW mode with a hollow beam obtainable from the same gun is found to have a potential for a higher gain as well as a wider bandwidth.