Nanosecond-length electron pulses from a laser-excited photocathode

Abstract

A photocathode made from polycrystalline lanthanum hexaboride (LaB6) has produced nanosecond-length electron pulses when excited by an excimer laser at 308 nm. Peak currents in excess of 1 A have been observed, with quantum yields of 4×10−5 being measured. A method for extracting the electrons from an emission-limited cathode, plasma extraction, has been demonstrated. This technique uses a low-power continuous discharge to provide the electric field needed to extract the photoelectrons. This technique may be useful in producing high-repetition-rate short-pulse ion sources.