Electromagnetic analysis by finite elements of electron guns for traveling wave tubes

Abstract

Electron guns are used as electron beam source in a wide variety of devices including traveling wave tubes (TWT), klystrons and particle accelerators. Usage of more complex geometries and insertion of control grid allow the designer to obtain a better performance but it requires specialized 3D numerical simulators to carry out the design process. In this paper we present the COLLGUN simulator, a 3D tool for the design of TWT's electron gun. The complete simulator consists of three main modules: a dedicated fully 3D Finite Element mesh generator, a 3D FE Vlasov solver, including space-charge effects, with an integrated electron trajectory tracer and a graphic post-processing module for result restitution. Several examples of 3D simulation of electron guns have been analyzed to test the simulator.