Generation of a highly collimated, mono-energetic electron beam from laser-driven plasma-based acceleration

Abstract

An electron acceleration experiment in a self-modulated laser wake-field acceleration regime was carried out using a 45 fs duration Ti:sapphire laser focused to an intensity of 1.8×1018 W cm−2 on helium gas-jet plasma. A highly collimated and mono-energetic electron beam was observed at a plasma electron density of ∼8.5×1019 cm−3. The electron beam was produced with a minimum full cone divergence angle of 4 mrad, an energy spread of ±4% and a peak energy up to 21 MeV. The experimental results were explained on the basis of self-modulation of the laser beam and acceleration in the bubble regime.