The Vavilov-Cherenkov effect produced by an electromagnetic pulse

Abstract

In this paper the Vavilov-Cherenkov radiation produced by an electromagnetic pulse propagating, unchanged in shape, inside a medium is analysed. The electromagnetic pulse induces a polarization charge which moves inside the medium with the group velocity. This polarization charge induces time-dependent elemental dipoles in the material medium. If the group velocity is greater than the phase velocity of light in such a medium there is a coherent superposition of the radiation emitted by each elemental dipole that gives rise to Vavilov-Cherenkov radiation. Two methods to obtain the energy spectrum are developed.