An Efficient X-Band Relativistic Backward Wave Oscillator Combining Single-Mode Structure With Overmoded Structure

A combined modes operation mechanism in a sectioned relativistic backward wave oscillator (RBWO) is presented. The RBWO consists of single-mode slow wave structure (SWS) and over-moded SWS. In the single-mode SWS, the electron beam interacts with TM01 mode synchronously; in the overmoded SWS, the operation mode is mainly TM02 mode. The microwave frequency is determined by the single-mode SWS, which alleviates the mode competition in the overmoded SWS. Moreover, the power capacity of the RBWO can be improved due to the employment of overmoded structure and TM02 mode operation. Particle-in-cell simulation results demonstrate that a microwave with a power of 2.5GW and a frequency of 9.18 GHz is generated with a 680 kV, 7.3 kA electron beam, corresponding to a beam-wave power conversion efficiency of 50%. Published by AIP Publishing.