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

TL;DR

This paper investigates Cherenkov and parametric radiation from relativistic charged particles in metallic wire media, accounting for anisotropic scattering when wire radius is comparable to wavelength, and finds potential for high-power radiation in the THz range.

Contribution

It develops new equations for electromagnetic diffraction and emission in wire media considering anisotropic scattering, extending previous isotropic models.

Findings

Radiation intensity increases with wire radius, peaking at kR~1.

Power of emitted radiation can reach tens to hundreds of megawatts.

High-power THz radiation from electron bunches is feasible for experiments and applications.

Abstract

Until recently, the interaction of electromagnetic waves with crystals built from parallel metallic wires (wire media) was analyzed in the approximation of isotropic scattering of the electromagnetic wave by a single wire. However, if the wires are thick (kR~1), electromagnetic wave scattering by a wire is anisotropic, i.e., the scattering amplitude depends on the scattering angle. In this work, we derive the equations that describe diffraction of electromagnetic waves and spontaneous emission of charged particles in wire media, and take into account the angular dependence of scattering amplitude. Numerical solutions of these equations show that the radiation intensity increases as the wire radius is increased and achieves its maximal value in the range kR~1. The case when the condition kR~1 is fulfilled in the THz frequency range is considered in detail. The calculations show that the instantaneous power of Cherenkov and parametric (quasi-Cherenkov) radiations from electron bunches in the crystal can be tens--hundreds megawatts, i.e., high enough to allow experimental observation as well as possible practical applications.