Experimental investigation of radiation from the interaction of an electron beam and a conducting grating

Recent experimental results on the radiation generated from an electron beam passing closely over a conducting grating are presented. The most striking results are that the output power is 4 orders of magnitude more intense than that predicted by the Smith-Purcell explanation and that the output power increases exponentially with the beam thickness until it saturates at a thickness of a 1000 times the grating period. The recent theoretical model of Chang and McDaniel [Phys. Rev. Lett. 63, 1066 (1989); J. Opt. Soc. Am. B 7, 239 (1990)] is shown to compare favorably with these results.