High-Charge, Multi-MeV Electron Bunches Accelerated in Moderate Laser-Plasma Interaction Regime

Experiments [I], and simulations[2] have shown that quasi-monoenergetic electron bunches can be accelerated from the background electron plasma population up to relativistic energies. Theoretical work [3] indicated that with a proper choice of laser, plasma, and injection parameters the acceleration of electron bunches with small energy spread and short bunch length can occur in moderate intensity regime. Here we present the results of an experiment on electron acceleration carried out at the IPCF-CNR's Intense Laser Irradiation Laboratory in Pisa [4], within a wide national collaboration leaded by INFN named PLASMONX [5]. High-charge, multi-MeV electron bunches were accelerated in moderated intensity regime by focusing the laser beam on a laminar gaseous target produced by a supersonic gas-jet. The laser-gas interaction was studied via interferometry, and Thomson scattering while the electron bunches were detected and characterised using a phosphor screen coupled with a magnetic spectrometer or a dosimetric detector. In some cases highly collimated electron bunches with moderate energy spread were observed, while the generation of high-charge, MeV energies electron bunches were obtained with high reproducibility for each gases tested.