The influence of the azimuthal inhomogeneity of electron beam-microwave interaction on the operation regime of subterahertz gyrotrons

The investigation of operation regimes of CW/263 GHz/1kW gyrotron, developed at IAP RAS/GYCOM Ltd., was made by various numerical methods. The influence of the azimuthal inhomogeneity (such as electron beam radial misalignments and tilt) has been studied. The method of average equations and 3D PIC codes (CST Studio Suite and KARAT) were used. Results, achieved by different methods, are in agreement with experimental data. It is shown, that for feasible values of asymmetry, relative efficiency reduction can reach 40% from initial value. The possibility of future three-dimensional analysis of THz band gyrotrons with overside cavities and simultaneous azimuthal asymmetry of the electron beam and electrodynamics system by PIC codes has been demonstrated.