Photoemission from U and Mg using a pulsed XeCl laser

Abstract

We report results of photoemission from metal cathodes. The photon source was a pulsed XeCl laser of 10 ns width (FWHM). We obtained a photocurrent density of 600 A/cm2, a quantum efficiency of 8×10−5, and a calculated brightness of 1×108 A/(cm2 rad2) for a uranium cathode and a photocurrent of 60 A/cm2, a quantum efficiency of 8×10−6 and brightness of 1×107 A/(cm2 rad2) for a magnesium cathode. Space charge limited and emission limited photoelectrons were studied using high and low energy laser pulses, respectively. The uranium cathode was operated for over 50 h with no reduction of the photocurrent.