Cherenkov and parametric (quasi-Cherenkov) radiation from relativistic charged particles moving in crystals formed by metallic wires

摘要

Until recently, the interaction of electromagnetic waves with crystals builtfrom parallel metallic wires (wire media) was analyzed in the approximation ofisotropic scattering of the electromagnetic wave by a single wire. However, ifthe wires are thick (kR~1), electromagnetic wave scattering by a wire isanisotropic, i.e., the scattering amplitude depends on the scattering angle. Inthis work, we derive the equations that describe diffraction of electromagneticwaves and spontaneous emission of charged particles in wire media, and takeinto account the angular dependence of scattering amplitude. Numericalsolutions of these equations show that the radiation intensity increases as thewire radius is increased and achieves its maximal value in the range kR~1. Thecase when the condition kR~1 is fulfilled in the THz frequency range isconsidered in detail. The calculations show that the instantaneous power ofCherenkov and parametric (quasi-Cherenkov) radiations from electron bunches inthe crystal can be tens--hundreds megawatts, i.e., high enough to allowexperimental observation as well as possible practical applications.