Numerical simulation of high power microwave sources

Electromagnetic fully relativistic particle-in-cell codes are a powerful tool for modeling and designing components of high power microwave sources and accelerator systems. This paper reviews the principles and properties of numerical simulation codes as applied to problems of microwave generation. The important aspects which can be treated with such codes are, improved representation of microwave circuits in complicated geometries, proper treatment of nonlinear particle wave interaction in the body of a device, inclusion of self-consistent self-field effects, and treatment of surface properties such as emission, secondary particles, and surface breakdown. Examples of application of two- and three-dimensional codes to specific devices such as gyrotrons, magnetrons, and klystrons is presented. The information obtained from large numerical simulation codes provides both detailed insight into source physics as well as the basis for improved design technology