The deformable relaxation mesh technique for solution of electron optics problems

Abstract

This paper describes the principles of a method for the solution of electron optics problems which has led to significant design improvements in traveling wave tubes over the past few years. In contrast to Conventional procedures which solve Poisson's equation on square meshes, the space within the problem boundaries is filled with a network of irregular triangles resembling a stretched fishnet laid out by the computer itself. The technique has found its greatest use in the design of high-performance electron guns. The high accuracy and resolution of this method has enabled numerous better guns. The approach has also been used to analyze beam focussing arrangements, multistage depressed collectors, CRT guns and lenses, and problems obeying Laplace's equation. The procedure can be used for calculation of ion beam optics as well.