X1-Experiment : Smith-Purcell Radiation (SP)






Smith-Purcell radiation, generated when a beam of charged particles passes close to the surface of a diffraction grating, has been studied in the visible spectral range at wavelengths of 360 nm and 546 nm with the low emittance 855 MeV electron beam of the Mainz Microtron MAMI. The beam focused to a spot size of 4 µm (FWHM) passed over optical diffraction gratings of echelle profiles with blaze angles 0.8, 17.27 and grating periods of 0.833 µm and 9.09 µm. Taking advantage of the specific emission characteristics of Smith-Purcell radiation a clear separation from background components, such as diffracted synchrotron radiation from upstream beam optical elements and transition radiation, was possible. The intensity scales with a modified Bessel function of the first kind as function of the distance between electron beam and grating surface. Experimental radiation factors have been determined and compared with theoretical predictions [12].

Production Mechanism

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