Generation of relativistic photoelectrons induced by an ultraviolet laser and their propagation characteristics in a longitudinal guiding magnetic field

摘要

Photoelectrons from a metal surface irradiated by a pulsed ultraviolet laser were accelerated to relativistic energy to obtain a very cold and relatively high‐current electron beam. Typical values of the transverse velocity component bgr;⊥/bgr;∥were measured to be less than 8×10−3, which leads to a spread of the parallel energy component Dgr;ggr;∥ /ggr;∥of 1×10−4or less. Propagation characteristics in a longitudinal guiding magnetic field were investigated. A nonadiabatic factor was defined to estimate the conservation of the magnetic moment of the electrons moving along the magnetic flux, and this was shown experimentally to be reasonable. Spacial controllability of the cross section of this electron beam was demonstrated.