Microwave generators: Oscillating virtual cathodes and reflexing electrons

Simulation of the generation of a relativistic electron beam in a foil diode configuration and of the subsequent intense microwave generation resulting from the formation of the virtual cathode is presented. The oscillating virtual cathode and the trapped beam electrons between the real and the virtual cathodes were found to generate microwaves. Generation of high-power microwaves with about 10% efficiency might be reasonably expected from such a virtual-cathode configuration.