This paper presents particle-in-cell simulation of the reflex triode with radially diverging magnetized electron beam. Dynamics of the electron beam and generation characteristics of the reflex triode are studied in the work. It is shown that two virtual cathodes are formed in it. It was calculated that the peak power of the microwave radiation reaches P=19 MW at the beam current I0=5 kA and potential of the cathode Uc=‒100 kV. There is a peak in the microwave radiation spectrum at the frequency ν = 5.2 GHz.
An analysis of the plane influence separating the interaction space from the electron beam-forming region is made by the particle-particle simulation method with the delay effect. During the simulation, it was shown that the boundary conditions on the surface have a significant effect on the electron beam dynamics in a longitudinal magnetic field and affect the time of formation of the virtual cathode and the particle velocity in the interaction space.