Projects of sub-GW/mm-wave Cherenkov Masers with 2D Slow-Wave Structures of Planar and Cylindrical Geometry intended for Powering Systems of Compton-type FELs

Original conception of Compton FEL-scattrons is under development at IAP RAS (N.Novgorod). For powering RF-undulators, project of sub-GW/Ka-band Cherenkov surface-wave oscillator of cylindrical geometry is elaborated at the “Sinus-6” accelerator 0.5 MeV/5 kA/20 ns. To ensure high-coherence of the radiation in a strongly oversized oscillator, we exploit the 2D distributed feedback mechanism. In the proof-of-principal experiments under the transverse oversize (perimeter) of ~16 wavelength, narrow-band generation was obtained with ~150 - 200 MW output power level. Project to advance this oscillator into W-band with the oversized parameter of ~30 is in progress.Project of powerful W-band Cherenkov maser with 2D distributed feedback of planar geometry is also under development in collaboration with BINP RAS (Novosibirsk) based on the “ELMI” accelerator 1 MeV/5 - 7 kA/3 μs. Design parameters of this project are discussed and results of the simulations are presented, which demonstrate possibility to achieve in this scheme stable narrow-band oscillation regime with output power of the GW-level under the transverse oversize parameter (width to the wavelength) of up to 50.