title: Controlling the fast electron divergence in a solid target with multiple laser pulses.
abstract: Controlling the divergence of laser-driven fast electrons is compulsory to meet the ignition requirements in the fast ignition inertial fusion scheme. It was shown recently that using two consecutive laser pulses one can improve the electron-beam collimation. In this paper we propose an extension of this method by using a sequence of several laser pulses with a gradually increasing intensity. Profiling the laser-pulse intensity opens a possibility to transfer to the electron beam a larger energy while keeping its divergence under control. We present numerical simulations performed with a radiation hydrodynamic code coupled to a reduced kinetic module. Simulation with a sequence of three laser pulses shows that the proposed method allows one to improve the efficiency of the double pulse scheme at least by a factor of 2. This promises to provide an efficient energy transport in a dense matter by a collimated beam of fast electrons, which is relevant for many applications such as ion-beam sources and could present also an interest for fast ignition inertial fusion.
authors.affiliation: Univ. Bordeaux, CNRS, CEA, CELIA, UMR 5107, F-33405 Talence, France and ELI-ALPS, ELI-Hu Nkft, Dugonics ter 13, Szeged 6720, Hungary.
authors.forename: L
authors.initials: L
authors.lastname: Volpe
authors.affiliation: Univ. Bordeaux, CNRS, CEA, CELIA, UMR 5107, F-33405 Talence, France.
authors.forename: J-L
authors.initials: JL
authors.lastname: Feugeas
authors.affiliation: Univ. Bordeaux, CNRS, CEA, CELIA, UMR 5107, F-33405 Talence, France.
authors.forename: Ph
authors.initials: P
authors.lastname: Nicolai
authors.affiliation: Univ. Bordeaux, CNRS, CEA, CELIA, UMR 5107, F-33405 Talence, France.
authors.forename: J J
authors.initials: JJ
authors.lastname: Santos
authors.affiliation: Univ. Bordeaux, CNRS, CEA, CELIA, UMR 5107, F-33405 Talence, France.
authors.forename: M
authors.initials: M
authors.lastname: Touati
authors.affiliation: Univ. Bordeaux, CNRS, CEA, CELIA, UMR 5107, F-33405 Talence, France.
authors.forename: J
authors.initials: J
authors.lastname: Breil
authors.affiliation: Univ. Bordeaux, CNRS, CEA, CELIA, UMR 5107, F-33405 Talence, France.
authors.forename: D
authors.initials: D
authors.lastname: Batani
authors.affiliation: Univ. Bordeaux, CNRS, CEA, CELIA, UMR 5107, F-33405 Talence, France.
authors.forename: V
authors.initials: V
authors.lastname: Tikhonchuk