Design of a sub-millimetric electron gun with analysis of thermomechanical effects on beam dynamics

This paper describes a particular design of a thermionic electron gun employable in Sub-millimetric waves vacuum tubes and for spatial environment applications. Design strategies are proposed by providing closed formulas and dimensioning techniques. A multiphysics approach has been employed for studying the effect of multiple physics influencing factors due to the cathode heating over the beam dynamics. Operating temperature, thermal expansion displacements and external environment effects have been considered. This paper would give the academic knowledge for developing electron sources with narrow dimension providing an analytical approach followed by numerical modeling technique for virtual prototypes, which foresee the global behavior of this kind of devices while operating. For this aim, several strategies have been adopted and described in detail to obtain a simple model, which shows clearly these effects and their relations. The proposed modeling can allow for the correct operation in this range of narrow dimensions, where the operation is extremely critical while the cathode heating effects are present. According to this study, the appropriate materials and geometrical shapes for the beam-forming electrodes can be chosen.