Large-Signal Field Analysis of a Linear Beam Traveling Wave Amplifier for a Sheath-Helix Model of the Slow-Wave Structure Supported by Dielectric Rods. Part 1: Theory

Abstract

A rigorous field-theoretic method of analyzing the large-signal behavior of a linear beam traveling wave tube amplifier (TWTA) with slow-wave structure modeled to be a dielectric-loaded sheath helix is presented. The key step in the analysis is a representation of the field components as nonlinear functionals of the electron arrival time through a Green's function sequence for the slow-wave circuit. Substitution of this functional representation for the axial electric field component into the electron ballistic equation casts the latter into a fixed point format for a nonlinear operator in an appropriate function space. The fixed point, and therefore the solution for the electron-arrival time and hence the solution for the electromagnetic field components, can be obtained by standard successive approximation techniques. The calculations of the gain, the efficiency and the other amplifier parameters, comparison of the results of the present theory with experimental results etc., on the basis of such a successive approximation solution for the field components, will be presented in the second part of this paper.