High-precision calculation of quasistatic field near a photocathode surface microrelief

In modern photoelectron devices, the problem of the impact of photocathode roughness on a photoelectron beam and the characteristics of the devices is extremely challenging. Through a three-dimensional (3D) field determination near a photocathode surface microrelief, the high-precision dynamics of photoelectrons from a photocathode can be determined and the influence of photocathode surface roughness on photoelectron beam characteristics can be investigated. The combined analytical–numerical method of field determination presented in this paper can be used in the investigations. In contrast with FEM method, the combined analytical–numerical method can calculate the field with a heightened accuracy and in a shorter time using a PC. The method can be applied to both arbitrary surfaces and a class of realistic microrelief surfaces. In the latter, it is possible to accelerate the speed of calculations through analytical developments of the method. For another class of microrelief surfaces, it is possible to formulate an analytical solution for field determination without numerical computations. Typical precisions and computation times of the written code were presented, comparison with a commercial code based on FEM method was done, and features of the method related to numerical instabilities of the code were discussed. A method of eliminating the instabilities was proposed.