High current, small divergence electron beams produced by laser-induced surface photoelectric effect

Abstract

The potential application of the laser induced linear surface photoelectric effect for high current and small divergence electron beam formation is examined. The temporal evolution of the current pulses and the angular distribution of the photoelectrons produced following KrF laser irradiation of a gold surface is studied as a function of laser intensity. A threshold laser intensity of (140±20) MW/cm2 was determined, below which the single photon photoeffect dominates any laser induced thermionic emission process. Electron current measurements for vertical and horizontal polarization of the incident laser radiation showed that the current contribution from the surface photoeffect is about three times larger than that from the volume photoeffect. Under these conditions, an angular distribution of the produced electrons of 17°±2° was determined. The estimated normalized transverse beam emittance is 20π mm mrad.