Many cathode ray tubes for color television now incorporate asymetrical electrodes. This thesis describes a numerical method which simulate a symetrical and asymetrical electron gun. The potentials and the space charge are calculated at the nodes of a pentahedron mesh. This mesh is automatically adjusted to fit the physical boundary and can be concentrated in critical high-field regions such as near the cathode.
The three-dimensional simulation uses a 180 degree wedge of the electron-gun. The potentials at nodes are caculated by the Finite Element Method using the conjugate gradient method. The current density at cathode is calculated by Child-Langmuir's law at 1 or 2 mesh unit from the cathode. The trajectory of electrons is carried out by the Runge-Gutta- Fehlberg method. The simulation may be divided into two or three sections. The performance is tested for $G_2$ thickness.
As a result, the potentials at nodes, the cathode current, and trajectory is obtained, but this results are somewhat different from the experimental data. This error can be improved by fitting the physical boundary more accurately with the expense of more computer memory and computer time. Without building an actual (electron) gun, the effect of varied electrode shape and grid voltage can be investigated.
The simulation program is coded in FORTRAN and implemented on a SUN 3/110 COMPUTER.
