Super-power W-band Free Electron Maser with Combined Two-mirror Resonator Consisting of 3D and 1D Bragg Reflectors

A spatially-extended planar free-electron maser (FEM) with a combined two-mirror resonator consisting of an up-stream (cathode-side) Bragg reflector of new type that implements three-dimensional distributed feedback, and a down-stream (collector-side) "conventional" Bragg reflector was studied. The possibility of creating an FEM of this type in the W-band based on the high-current explosive-emission accelerator "U-2" 1 MeV/140kA/10µs, which forms a sheet electron beam with a transverse size of 1cm × 140cm, was evaluated. It was shown that the use of the proposed two-mirror scheme can reduce Ohmic losses and increase the efficiency of electron-wave interaction in the generator. The possibility of establishment a stable narrow-band generation regime with an electron efficiency of 18–20% and a record output power of up to 20GW was demonstrated in the FEM under development.