Gauss-Schell sources as models for synchrotron radiation

Gauss-Schell light sources are considered as models for synchrotron radiation. These sources can be viewed as random superpositions of coherent Gaussian beams. The relationships of the various widths that can be defined for the description of intensity and coherence, as related to the widths of the electron beam and the single-electron radiation (diffraction) pattern, are summarized. The description is also applied to the temporal coherence, which is of interest in the case of free-electron lasers.