ﻻ يوجد ملخص باللغة العربية
We investigate the radiation from a charged particle moving outside a dielectric cylinder parallel to its axis. It is assumed that the cylinder is immersed into a homogeneous medium. The expressions are given for the vector potential and for the electric and magnetic fields. The spectral distributions are studied for three types of the radiations: (i) Cherenkov radiation (CR) in the exterior medium, (ii) radiation on the guided modes of the dielectric cylinder, and (iii) emission of surface polaritons. Unlike the first two types of radiations, there is no velocity threshold for the generation of surface polaritons. The corresponding radiation is present in the spectral range where the dielectric permittivities of the cylinder and surrounding medium have opposite signs. The spectral range of the emitted surface polaritons becomes narrower with decreasing energy of the particle. The general results are illustrated for a special case of the Drude model for dispersion of the dielectric permittivity of the cylinder. We show that the presence of the cylinder may lead to the appearance of strong narrow peaks in the spectral distribution of the CR in the exterior medium. The conditions are specified for the appearance of those peaks and the corresponding heights and widths are analytically estimated. The collective effects of particles in bunches are discussed.
It is generally accepted that the dynamics of relativistic particles in the lab frame can be described by taking into account the relativistic dependence of the particles momenta on the velocity, with no reference to Lorentz transformations. The elec
It is shown that in some special cases the Cherenkov radiation from a charged particle moving along the axis of cylindrical waveguide filled with a semi-infinite material consisting of dielectric plates alternated with vacuum gaps is many times stron
We propose a new type of axisymmetric dielectric target which effectively concentrates Cherenkov radiation (CR) generated in the bulk of the material into a small vicinity of focus point. It can be called the axicon-based concentrator for CR. A theor
We study the angular distribution of the radiation from a relativistic charged particle uniformly rotating along an equatorial orbit around a dielectric ball. Earlier it was shown that for some values of the problem parameters and in the case of weak
A problem of diffraction of a symmetrical transverse magnetic mode $ text{TM}_{0l} $ by an open-ended cylindrical waveguide corrugated inside is considered. A depth and a period of corrugations are supposed to be much less than the wavelength and the