Spatially-Extended Sub-GW Surface-Wave Oscillators Operating from Ка- to W-Band for Powering Systems of Compton FELs

Spatially-extended high-power Cherenkov masers intended to be used in powering systems of Compton-type FELs are under development in IAP RAS (Nizhny Novgorod) at the "Sinus-6" accelerator 0.5 MeV / 5 kA / 20 ns. Electrodynamic systems of such oscillators are based on 2D periodical slow-wave structures realizing 2D distributed feedback mechanism, allowing for provision of stable narrow-band oscillation regime under conditions of substantial oversize. In the proof-of-principal experiments at the Ka-band under the transverse oversize (perimeter) of ~ 16 wavelength, narrow-band generation was obtained with ~ 0.2 - 0.3 MW output power level. Project to advance this oscillator into W-band with the oversized parameter of ~ 30 is in progress.