Ridge Loaded Radial Staggered Double Vane SWS for W-Band Backward Wave Oscillator

Backward wave oscillators (BWOs) play a crucial role in generating millimeter waves in the W-band frequency range. This paper presents a ridge-loaded radial staggered double vane (RL-RSDV) slow-wave structure (SWS) for a W-band BWO utilizing a diverging radial sheet electron beam (RSEB). The proposed radial configuration addresses the limitations of traditional axial BWOs by providing a larger interaction area and reducing space-charge effects. This eliminates the need for an external guiding magnetic field, thereby simplifying the electro-optic system. The dispersion characteristics of the SWS are numerically analyzed, and Particle-in-Cell (PIC) simulations are conducted without a magnetic field. The BWO operates at a beam voltage of 25 kV and a beam current of 15 A, achieving an average power of 26.9 kW, and an efficiency of 7.19%. FFT analysis confirms a generated signal frequency of 91.2 GHz. These results validate the proposed BWO as a high-efficiency source for millimeter-waves.