Advances in modeling and simulation of vacuum electronic devices

Recent advances in the modeling and simulation of vacuum electronic devices are reviewed. Design of these devices makes use of a variety of physical m odels and numerical code types. Progress in the development of these models and codes is outlined and illustrated With specific examples. The state of the art in device simulation is evolving to the point such that devices ca n be designed on the computer, thereby eliminating many trial and error fab rication and test steps. The role of numerical simulation in the design pro cess can be expected to grow further in the future.