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Electron Emission of over 200 A/CM2 from a Pulsed-Laser Irradiaied Photocaihode

High-current-density, bunched electron beams with low emittance are required for efficient operation of rf-linac-driven free-electron lasers (FELs). Laser-irradiated, photoemissive electron sources are suitable for this application. Currents of over 200 A have been generated in an ultrahigh vacuum chamber from a 1-cm2 Cs3Sb photocathode irradiated by a frequency-doubled, Q-switched pulse from a Nd: glass laser. These currents are over two times larger than previously reported from any photocathode. The duration of the electron pulse was 50 ns (FWHM), corresponding to the width of the 532-nm laser pulse.