Surface-wave Oscillators with Advanced Bragg Reflectors as a Way to Increase Frequency Stability and Tuning

To ensure the radiation coherence in a surface-wave oscillator based on a single-periodic slow-wave structure with a high oversize factor, it is proposed to use an additional resonant Bragg reflector of an advanced type, providing coupling of paraxial and quasi-cutoff waves. In the framework of 3D PIC-simulations, a planar scheme of generators of this type, driven by an electron beam of a sheet configuration, was studied. It is shown that the use of the proposed resonant reflector makes it possible to provide a narrow-band generation regime with excitation of the fundamental mode of the slow-wave structure at the SWO oversize factor amounting to about 7–10 radiation wavelengths. An additional advantage of the considered planar SWO scheme is the possibility of precise mechanical frequency tuning when changing the resonator gap width. The parameters for the implementation of high-power W-band SWO based on the high-current accelerator complex "SINUKI" (IAP RAS) have been evaluated.