Simulation and analysis of an axial vircator using PIC code

An axial virtual cathode oscillator (vircator) designed for a high pulsed power system has been simulated and analyzed to generate high power microwaves (HPM) in a three dimensional Particle-In-Cell (PIC) simulation code. Magic, which is based on Finite Difference Time Domain (FDTD) and PIC techniques, is an electromagnetic specific code involving space charge interactions. The intense relativistic electron beam (IREB) used is typically of 200kV, 100ns. With increasing anode-cathode (AK) gap, direct proportionality of HPM output frequency and inverse proportionality of HPM output power with AK gap was established. The dependency of space charge limited current on the IREB voltage was proved by changing the IREB voltage levels and observing its effect on the space charge limited current. Using different metals for the anode mesh, it was observed that copper is ideally suited for the anode mesh of an axial vircator. As the cathode radius was varied, the Child-Langmuir current was observed to vary as the square of the radius of the emitter area which is the same as the cathode top radius.