Simulation of injection phase locking in relativistic backward wave oscillator

An relativistic backward wave oscillator (RBWO) with trapezium slow wave structure is studied. Properties of the RBWO are investigated and optimized by the 2.5-dimensional fully electromagnetic PIC software. An external microwave signal is injected into the RBWO from diode area. When the injected power is 50 kW, and the injected power ratio is －48.3 dB, the relative phase between the RBWO output microwave and the injected signal is less than 20. The formula that describes the relationship between the RBWO output microwave phase jitter and the injected power is given. When the injected power is increased to 120 MW, and the injected power ratio is increased to －14.5 dB, the frequency of the RBWO output microwave is locked.