Intense electromagnetic radiation from relativistic particles

Several mechanisms for emission of electromagnetic radiation by relativistic electrons in various media which are of interest for generating intense ultraviolet, x-ray, and $\gamma$ radiation are examined. Theoretical and experimental results on ultraviolet and x-ray Cherenkov radiation, quasi-Cherenkov radiation in artificial periodic structures, radiation from crystals which results from the diffraction of virtual photons, and radiation accompanying channeling are discussed.