title: Electron vacuum acceleration in a regime beyond Brunel absorption.
abstract: We describe a new regime of electron acceleration in laser plasmas driven by ultrafast pulses of relativistic intensity, in which space-charge separation leads to strongly enhanced laser absorption and the production of 20 MeV (p/m0c approximately = 40) electrons driven outward in vacuum. 1D PIC simulations show that intense attosecond pulses generated around critical density can sweep electrons outward over many wavelengths in distance. With increasing interaction scale length, absorption generalizes from the Brunel regime to one in which absorption is primarily into electrons of energy >>5 MeV.
authors.affiliation: Laboratoire pour l'Utilisation des Lasers Intenses, Ecole Polytechnique Route de Saclay, 91128 Palaiseau cedex, France.
authors.forename: J P
authors.initials: JP
authors.lastname: Geindre
authors.forename: R S
authors.initials: RS
authors.lastname: Marjoribanks
authors.forename: P
authors.initials: P
authors.lastname: Audebert