Digital Computer Analysis of Axially Symmetric Solid-Beam Electron Guns

摘要

Digital programs written in the IBM 7090 FORTRAN programming system are described and then employed in the analysis of several electron guns. The digital programs employ relaxation techniques while alternately computing electric fields and trajectories. One cycle through the program consists of three parts. (1) Calculation of the voltages in the gun by solving Poisson's equation, in difference form, on a 7200 point matrix on which electrode potentials are laid out. (2) Calculations of new current densities along the cathode and the setting up of new trajectory starting points along the cathode. (3) Calculation of trajectories and comparison of the new beam with the previous one. Thermal effects and direct particle-particle interaction effects are ignored but space-charge effects, introduced through the field calculations tend to prevent excessive or unusual trajectory crossings. Execution time for the entire program is usually less than 10 minutes. Results produced by the programs are presented and compared with experimental and analytical results. (Author)