Computer simulation of virtual cathode oscillations

Summary form only given. The dynamics of the relativistic electron beam and the oscillations of the virtual cathode in the vircator has been investigated with electrostatic particle-in-cell (PIC) computer simulations. In the diode region (cathode to anode) the solid electron beam is modeled by one-dimensional sheets for simplicity. In the drift tube region the potential at the center line is obtained by solving Poissons equation analytically in the radial direction and via PIC simulation in the axial direction. The electron beam in the drift tube region is modeled as a solid and uniform beam of constant radius equal to the cathode radius. The simulation results show that the potential minimum in the drift tube region oscillates at broadband frequencies with a dominant one at 10.4 GHz under the conditions of 7.3-kA beam current, 270-kV applied voltage. 1.25-cm-radius cathode 4.9-cm-radius drift tube, and 0.45-cm cathode-to-anode distance. The injected electron beam in the diode region was found to be modulated by the bunched reflex electrons