Terahertz radiation modes in Cherenkov generator with single-section slow-wave structure

The paper studies the interaction between the relativistic electron beam and electromagnetic resonances in the Cherenkov generator with the single-section slow-wave structure using the 2.5D hybrid particle-in-cell code. In numerical simulation, the tubular beam current of ≤ 25 kA and ≤ 490 keV energy are used to inject the electron beam into a homogeneous slow-wave structure of a diameter 40 mm with and without a diffraction reflector. The frequency range is 362 to 367 GHz. Parameter ranges are obtained for the stable radiation generation with synchronization of electromagnetic resonances by the electron beam and self-modulation of radiation power. With the diffraction reflector, the total power of stable radiation is 400 MW with the forward radiation power of 90%, regardless of power ohmic losses. Resonance magnification modes are detected for the radiation power in the narrow range of the electron energy, which match the radiation frequency near the third-order electromagnetic resonance with no electron beam.