Experimental investigations of Smith–Purcell radiation

We present experimental investigations of Smith–Purcell radiation and Salisbury’s model and emphasize the amplification mechanism and efforts to build a resonator operating in the visible wavelength region. The first experiment demonstrated that electrons can be reflected from a rough surface owing to crystal-lattice diffraction. The second experiment showed that the radiation output increases exponentially as the beam thickness increases, indicating a possible occurrence of lasing action; the results were consistent with Salisbury’s model. The last experiment yielded inconclusive results; the use of a more stable electron beam and a blazed grating is suggested for future experiments.