A high power microwave vircator with an enhanced efficiency

A radially extracted vircator (virtual-cathode oscillator) with two identical opposite output ports is presented. The microwave modes propagating inside the WR650 output rectangular waveguide are determined by the calibrated E-probes lined up in the direction perpendicular to the axis of the WR650 waveguide. Velvet-covered cathodes are used to emit electrons. Several diameters of velvet are chosen to see how the emitting area effects microwave generation. Evidence of virtual cathode formation, onset of electron reflexing, and simultaneous microwave emission are discussed. This vircator is found to have the capability of generating a maximum 1.4 GW microwave pulse with the dominant frequency at 8.2 GHz. The radiation pattern is dominated by the TE/sub 10/ mode and the instantaneous efficiency for producing this microwave pulse is around 6+or-0.8%. Simple E-probes are applied to pick up the microwave signals inside the WR650 output rectangular waveguide.>