Emission of radiation by particles in media with inhomogeneities and coherent bremsstrahlung

A theoretical investigation is reported of coherent bremsstrahlung generated by a relativistic particle together with noncoherent Bethe–Heitler radiation in a medium characterized by macroscopic density inhomogeneities. These inhomogeneities may be due to the structure of the medium or due to fluctuations excited in an initially macroscopically homogeneous medium. The conditions for the observation of the coherent bremsstrahlung in various systems (plasma channel, pile of plates) are considered. The relationship between the coherent bremsstrahlung and some already known effects (inverse Compton eifect involving Langmuir oscillations and transition radiation in media with inhomogeneities) is considered.