Simple laser-driven, metal photocathodes as cold, high-current electron sources

Recent developments in excimer laser design have made near ultraviolet light intensities of several MWcm2 possible in unfocused beams. These advances and recent experiments indicate that high-current, simple-metal photoemissive electron guns are now feasible. Producing more than 50 Acm2 of illuminated cathode surface, the guns could operate at vacuums of 10-6 torr with no complicated system components inside the vacuum enclosure. The electron beam produced by such photoemission guns would have very low emittance and high brightness. This beam would also closely follow the temporal characteristics of the laser pulse, making fast risetime, ultrashort electron beam pulses possible