Dynamics of frequency of microwave generation of vircator without magnetic field with the interaction space filled with neutral gas

Results of study of physical processes in the electron beam with a virtual cathode in the interaction space of vircator filled with neutral gas are presented. The mathematical 2D model of self-consistent processes of electron and ion motion, and gas ionization is developed. The basic physical mechanism is defined; the vircator system dynamics in the presence of ions is described. This mechanism is determined by the ion acceleration in the electric field of a moving virtual cathode. With the help of this model the effect of increase of the frequency of microwave generation of the system with the virtual cathode in the case of the excess a certain critical value of gas pressure is observed.