Radiation from an oscillator uniformly moving along the axis of a dielectric cylinder

TL;DR

This paper derives a formula for the radiation emitted by a charged oscillator moving inside a dielectric cylinder, revealing how the cylinder can significantly enhance radiation intensity under certain conditions.

Contribution

It provides a new spectral-angular distribution formula for radiation from a moving oscillator in a dielectric cylinder, including both continuous and discrete spectra, under Cherenkov conditions.

Findings

Radiation intensity can be significantly increased by the dielectric cylinder.

The formula accounts for both continuous and discrete spectral components.

Numerical results show the cylinder's influence on angular distribution of emitted quanta.

Abstract

The radiation generated by a charged longitudinal oscillator moving with a constant drift velocity along the axis of a dielectric cylinder immersed in a homogeneous medium is investigated. For an arbitrary oscillation law a formula is derived for the spectral-angular distribution of this radiation. Under the Cherenkov condition for the dielectric permittivity of the external medium and oscillator drift velocity this formula contains two summands. The first one corresponds to the radiation with a continuous spectrum which propagates at the Cherenkov angle of the external medium. The second one describes the radiation which has a discrete spectrum for a given angle of propagation. The corresponding frequencies are multiples of the Doppler-shifted oscillation frequency. The results of numerical calculations for the angular distribution of the radiated quanta are presented and they are compared with the corresponding quantities for the radiation in a homogeneous medium. It is shown that the presence of the cylinder can increase essentially the radiation intensity.