Determination of electrodes shapes for axially symmetric, gridded convergent pierce electron gun

The determination of electrode shapes for an axially symmteric gridded convergent Pierce electron gun involves solution of Laplace/Poisson's equations subject to specified boundary conditions. Finite element and iterative techniques are used for this purpose. The functional for this is calculated with the use of Laplace's equation in the form of two dimensional axially symmetric spherical co-ordinates. The electrode shapes are determined with the use of this functional and appropriate boundary conditions. A computer program is developed for this purpose and the resulting electrode shapes for a typical gridded electron gun are presented. The effects of variation of input parameters on the electrode shapes are also shown. (author). 9 refs., 4 figs