A coaxial Ku-band transit radiation oscillator without an external guiding magnetic field

A coaxial transit radiation oscillator without an external guiding magnetic field is designed to generate high power microwave at Ku-band. By using a coaxial structure, the space-charge limiting current can be increased significantly. In order to reduce the system´s volume, weight and the consumption of the energy, a Pierce-like cathode is proposed to realize the transmission of the intense relativistic annular electron beam without the guiding magnetic field. By contrast with conventional relativistic microwave generators, such a kind of device has the advantages of high stability, non-guiding magnetic field, low impedance and high efficiency. Moreover, with such a design it is possible to improve power capacity by increasing the radial dimension of the Ku-band device. With a 550 kV, 7.5 kA beam, a 1.25 GW microwave pulse at 12.08 GHz has been obtained in the simulation. The power conversion efficiency is about 30%.