NOVEL, ROBUST, HIGH REPETITION, HIGH BRIGHTNESS CATHODE

A LOW EMITTANCE, HIGH CURRENT DENSITY CATHODE FOR APPLICATIONS IN HIGH POWER ELECTRON AND ION ACCELERATORS IS PROPOSED. THE CATHODE IS BASED ON THE SUPER-EMISSIVE, SELF-HEATED CATHODE PRESENT IN THE BACK LIGHTED THYRATRON (BLT) AND PSEUDOSPARK SWITCHES. IT IS SIMPLE, AND HAS BEEN RECENTLY DEMONSTRATED TO BE A SOURCE OF EXTREMELY HIGH CURRENT ( 10KA) AND HIGH CURRENT DENSITY ( 10KAM2) ELECTRON BEAMS OF DURATION UP TO HUNDREDS OF NANOSECONDS. THE CATHODE HAS ALSO DEMONSTRATED LOW EMITTANCE (55 MM-MRAD)IN PRODUCING 1KA ELECTRON BEAMS. IT IS VERY ROBUST -- IT OPERATES IN THE PRESENCE OF BACKGROUND PLASMA WITHOUT THE "POISONING" PROBLEMS ASSOCIATED WITH THERMIONIC CATHODES. DAMAGE TO THE CATHODE IS NEGLIGIBLE EVEN AT VERY HIGH CURRENTS AND AT VERY HIGH REPETITION RATES, AND EROSION IS SLIGHT. THIS SIMPLE CATHODE IS A CANDIDATE TO REPLACE THERMIONIC AND FIELD EMISSION CATHODES CURRENTLY UNDER DEVELOPMENT, WILL PROVIDE A SIMPLE MEANS OF PRODUCING HIGH CURRENT BEAMS, AND COULD BE USED AS THE INJECTOR FOR LARGE SCALE INDUCTION LINACS. IN ADDITION, AN ION BEAM PRODUCED IN THE GLOW DISCHARGE MAY PROVE USEFUL AS A SOURCE IN A HIGH CURRENT ION ACCELERATOR. THE PHASE I PROGRAM WILL DEMONSTRATE ELECTRON BEAM PRODUCTION IN AN OPTICALLY TRIGGERED BLT/PSEUDOSPARK DEVICE AT HIGH REPETITION RATES, AND A PHASE II PROGRAM WOULD PRODUCE A 10KA, 10KHZ ELECTRON SOURCE.