A diode design study of the virtual cathode oscillator with ring-type reflector

Summary form only given, as follows. A numerical simulation study of the high power microwave generation from the virtual cathode oscillator (vircator) is carried out for various diode configurations by a 3 dimensional particle-in-cell (PIC) code called MAGIC. The coaxial vircator has a cylindrical cathode, cylindrical anode-mesh, and reflector, in order to enlarge the active interaction region in the virtual cathode space. The simulation results show that the output microwave frequency has a narrow bandwidth and its output microwave power depends sensitively on the position and width of ring-type reflector. The maximum microwave output power is obtained with a reflector 10mm in width and 40mm in distance from the intense relativistic electron beam. Output microwave mode without the ring-type reflector was mixture of the TM mode, however, it is found to be dominantly TM/sub 01/ mode with a resonance frequency of 22 GHz with the ring-type reflector.