Coherent X-Ray Radiation Generated by a Divergent Beam of Relativistic Electrons in a Single Crystal in the Beam-Axis Direction

A theory of coherent X-ray radiation generated by a beam of relativistic electrons in a single crystal in the direction close to the electron-beam axis is developed in the Laue scattering geometry. The theory takes into account asymmetry of the electron-field reflection with respect to the crystal surface and the electronbeam divergence. Expressions describing the spectral-angular densities of parametric X-ray radiation near the electron-velocity direction, of transition radiation, and their interference are obtained. The influence of the electron-beam divergence and asymmetry of the electron-field reflection with respect to the target surface on the spectral-angular radiation densities is studied.