Studies of a Weakly Relativistic Oversized Backward Wave Oscillator with Disk Cathode and Rectangular Corrugation

Abstract

Studies of an oversized BWO with a novel cathode and a rectangular corrugation are presented. The beam voltage is weakly relativistic, less than 100 kV. We propose to use a disk cathode made of metal only. The disk cathode can generate a uniformly distributed annular electron beam even in the weakly relativistic case. By using the annular electron beam, a weakly relativistic oversized BWO consisting of rectangularly corrugated cylindrical waveguide is demonstrated. The oscillation starting energy is about 60 kV for a 10-period rectangular corrugation. The maximum output power is estimated about 200 kW. The operation mode between axisymmetric and nonaxisymmetric modes can be controlled by changing the end condition of BWO.