A High-Power Planar W-Band Čerenkov Maser with Two-Dimensional Distributed Feedback: Design Elements and Modeling Results

The project of a high-power, spatially developed, planar surface-wave W-band generator with two-dimensional distributed feedback is developed jointly by the Institute of Applied Physics of the Russian Academy of Sciences and the Institute of Nuclear Physics of the Russian Academy of Sciences on the basis of the ELMI accelerator (an electron beam with a particle energy of 1 MeV, a current of 2–5 kA, and a pulse duration of 5 μs). The electrodynamic system of the generator is based on the use of a two-dimensional Bragg structure that combines the properties of a slow-wave system, which ensures efficient ˇ Cerenkov interaction with a rectilinear ribbon electron beam, and a high-Q cavity, which ensures selective excitation of the operating mode in the conditions of a significant value of the oversize parameter. The paper discusses design elements and parameters of the generator and presents the modeling results that demonstrate the possibility to achieve a stable narrow-band generation regime with a gigawatt level of the output radiation power. To ensure a mainly one-directional output of the radiation, a planar Bragg reflector was designed, which is installed in the channel for transportation of the relativistic ribbon electron beam on the cathode side of the interaction space.