Modeling instabilities in the relativistic electronic stream in the medium CST Particle Studio

We report on the features of the development of the classic vircator model in the CST Particle Studio for the investigation of the physical mechanisms of the development, coexistence and interaction of Pierce/Bursian and diocotron instabilities in relativistic electron beam. The numerical analysis of such model with the help of CST Particle Studio was carried out. We have revealed the development of the numerical instability leading to the additional small-scale space charge density modulation in the electron beam during its motion in the system. We have found out the character time scale of the instability and identified its relation with a spatial mesh step. We have conducted the study of the instability and offered the method of its suppression by the CST Particle Studio tools. A few important notes concerning the development of models of microwave devices in CST Particle Studio are presented.