An X-Band Relativistic Backward Wave Oscillator Driven by a Dual-Exponential Voltage Pulse

Available high power microwave (HPM) sources generally have strict requirements for a rectangular-shaped driving pulse, which needs complicated pulse forming types of equipment for the driving source. Here, we propose to use an easily accessible dual-exponential voltage pulse to drive an X-band relativistic backward wave oscillator (RBWO), in order to facilitate the driving source and lower the weight. Particle-in-cell (PIC) simulations were used in the design and optimization of the device. In particular, we demonstrate that when the guiding magnetic field strength is 0.5 T, a simulated microwave output with frequency at 11.67 GHz, output power at 0.95 GW, and power conversion efficiency at 29.5% can be obtained under the following conditions: a peak voltage of 500 kV, a pulse front edge of 8 ns, and a full width at half-maximum amplitude (FWHM) of 20 ns of the dual exponential pulse. In addition, we analyze the influence of different parameters of the dual exponential pulse on the output of the device, including peak voltage and FWHM.