We report the first experimental demonstration of longitudinal compression of laser-accelerated electron pulses. Accelerated by a femtosecond laser pulse with an intensity of ${10}^{18}\mathrm{W}/{\mathrm{cm}}^2$, an electron pulse with an energy of around 350 keV and a relative momentum spread of about ${10}^{-2}$ was compressed to a 500-fs pulse at a distance of about 50 cm from the electron source by using a magnetic pulse compressor. This pulse was used to generate a clear diffraction pattern of a gold crystal in a single shot. This method solves the space-charge problem in ultrafast electron diffraction.

• Received 15 July 2010

DOI:https://doi.org/10.1103/PhysRevLett.105.215004