Numerical simulation of low-frequency oscillations of the space charge and potential in the electron-optical system of a gyrotron

Abstract

We present the results of simulating magnetron-injection guns of gyrotrons using the PIC technique for large values of the pitch factor, in which case intense oscillations of the space charge cloud and the related oscillations of the potential in the beam are observed. Time dependences are found for the charge located in the adiabatic trap. The temporal evolution of the potential in different cross sections of the beam and the corresponding frequency spectra are calculated. The process of reflected-particle bombardment of the cathode and the role of the secondary electron emission in the process of particle accumulation in the trap are studied. The beam parameters for regimes with a great share of trapped particles are found and compared with those calculated within the framework of the static model. Time dependences of the current of the beam entering the operating space are analyzed and the electron energy distribution at the input of the gyrotron cavity is found.