PHOTOCATHODE ENHANCEMENT BY SURFACE MODIFICATION

MODERN APPLICATIONS OF ACCELERATORS DEMAND RUGGED AND EFFICIENT PHOTOCATHODE SOURCES. WE ARE IMPROVING THE QUANTUM EFFICIENCY OF RUGGED PHOTOCATHODE MATERIALS USING SURFACE PLASMON EXCITATION. OUR SCHEME USES TWO LIGHT BEAMS, ONE TO EXCITE THE SURFACE PLASMONS ON A MODIFIED SURFACE OF THE MATERIAL AND ONE TO CREATE EXCITED ELECTRONS WHOSE PROBABILITY OF ESCAPING IS ENHANCED 10-30 TIMES BY THE PRESENCE OF THE SURFACE PLASMONS. SUCH AN ENHANCEMENT PLACES THE QUANTUM EFFICIENCY IN THE PERCENT RANGE, EQUAL TO THE EFFICIENCY OF THE FRAGILE CESIATED MATERIALS CURRENTLY BEING USED. THE USEFUL LIFETIME OF OUR NEW PHOTOCATHODE BOOSTS THE STATE OF THE ART FROM LESS THAN TEN HOURS TO THOUSANDS OF HOURS. ACCELERATORS BASED ON OUR LASER DRIVEN PHOTOCATHODE SYSTEM WILL BE USED FOR FREE ELECTRON LASERS, LITHOGRAPHY, AND NUCLEAR PHYSICS.