The relativistic theory of fluctuation electromagnetic interactions of moving neutral particles with a flat surface

Abstract

The problem concerning the fluctuation electromagnetic interaction of a neutral particle moving parallel to the boundary of a semi-infinite homogeneous isotropic medium characterized by a permittivity and permeability dependent on the frequency is considered in terms of the fluctuation electrodynamic theory within the relativistic formalism. It is assumed that, in the general case, the particle and the medium have different temperatures. Within the proposed approach, general expressions are derived both for conservative (normal to the boundary of the medium) and nonconservative (tangential) forces of the interaction between the particle and the medium and for the thermal heating (cooling) rate of the particle. In the nonrelativistic limit (c → ∞), the derived relationships coincide with nonrelativistic analogs available in the literature. It is demonstrated that the tangential force acting on the particle can be either accelerating or decelerating. There can occur a situation when the hot moving particle will be heated and the cold medium will be cooled. The interaction of the high-conductivity medium with a high-conductivity particle is analyzed numerically. The asymptotics of the radiative contributions to the heat flux and the tangential force is investigated. It is shown that the inclusion of the relativistic effects leads to a substantial increase in the tangential force and the heat flux at distances greater than 1 µm (as compared to the nonrelativistic case); however, the corresponding dependences exhibit a monotonic decreasing behavior over the entire range of studied distances (from zero to several hundreds of microns).