Comparison of Smith-Purcell radiation models and criteria for their verification

The paper presents the analysis of the angular distributions of the incoherent Smith-Purcell radiation (SPR) generated by a charged particle passing over a periodic conducting structure (grating). The calculations were carried out for a grating which consists of conducting strips separated by vacuum gaps and a lamellar grating with the use of three models of this radiation: van den Berg's model, the surface current model, and the resonant diffraction radiation model. The two last models predict sufficiently close results for different geometries, while the results obtained with van den Berg's model predict primarily the SPR intensity which is by a few orders of magnitude lower for the electron energy approximate to 6 MeV. The authors propose simple criteria to verify the SPR models by comparing the SPR yields between the volume (with the thickness comparable with a grating period) and flat (with the thickness which is much less than that of a period) gratings; by comparing the azimuth dependencies of the SPR intensities from the flat gratings; by comparing the dependencies of the SPR intensity on the Lorentz factor of a particle.