Performance report for ''a visible tunable source''

Progress has been made both in the theoretical understanding of the Salisbury-Smith-Purcell (SSP) radiation which arises when electrons scatter off of a conducting diffraction grating, and in the experimental verification of the theory. The model consists of two parts. In the first part, the radiation is assumed to arise from currents induced by the incident electron beam in the conducting grating itself. In the second part, this induced conductor current radiation is assumed to be amplified by the electron beam as it passes through the slow wave structure formed by the periodic space charge sheets above the grating. It is this amplification mechanism in the space above the grating which we feel can explain why distant electrons contribute, and also why the scattering of a well collimated beam from the grating is so important. Experimental verification includes a measure of the degree of coherence of the radiation, a measure of radiator output with beam divergence, number of reflected electrons, and beam thickness, and the construction of a resonator and subsequent measurement of resonance enhancement of the radiation output