Abstract: Based on the finite difference method and the statistical theory of thermal electron emission, a set of computing and plotting programs using to computer aided design of electron beam device for electron guns and image tubes has been written in FARTRAN77 running on MV/8000 digital computer, and a good agreement between calculated result and that measured or given in ref has been obtained, This paper presents some numerical methods, such as optimization of Lagrange's interpolation function, determination of the optimum image plane using the statistical radius of the Airy disk, the tracing methods of equipotential lines and ion trajectories and so on. and some examples of the practical application, such as calculation and design for guns and image tubes, and analysis of the ion feedback in image tubes has been given.

Key words: electron optics, electron gun, image tube, computer aided design