title: Spatial and Transient Effects during the Amplification of a Picosecond Pulse Beam by a Nanosecond Pump.
abstract: Amplification of a picosecond pulse beam by a lower intensity nanosecond pulse beam was experimentally observed in a flowing plasma. Modifications of intensity distributions in beam focal spots due to nonhomogeneous energy transfer and its transient regime were investigated. The mean transferred power reached 57% of the incident power of the nanosecond pulse beam. An imaging diagnostic allowed the intensity profile of the picosecond pulse beam to be determined, bringing to evidence the spatial nonuniformity of energy transfer in the amplified beam. This diagnostic also enabled us to observe the temporal evolution of the speckle intensity distribution because of the transfer. These results are reproduced by numerical simulations of two complementary codes. The method and the observed effects are important for the understanding of experiments with multiple crossing laser beams in plasmas.
authors.affiliation: CEA, DAM, DIF, F-91297 Arpajon, France.
authors.forename: C
authors.initials: C
authors.lastname: Neuville
authors.affiliation: LULI, UMR 7605 CNRS-Ecole Polytechnique-CEA-Université Paris VI, 91128 Palaiseau cedex, France.
authors.forename: C
authors.initials: C
authors.lastname: Baccou
authors.affiliation: CEA, DAM, DIF, F-91297 Arpajon, France.
authors.forename: A
authors.initials: A
authors.lastname: Debayle
authors.affiliation: CEA, DAM, DIF, F-91297 Arpajon, France.
authors.forename: P-E
authors.initials: PE
authors.lastname: Masson-Laborde
authors.affiliation: Centre de Physique Théorique, UMR 7644, CNRS-Ecole Polytechnique, 91128 Palaiseau cedex, France.
authors.forename: S
authors.initials: S
authors.lastname: Hüller
authors.affiliation: CEA, DAM, DIF, F-91297 Arpajon, France.
authors.forename: M
authors.initials: M
authors.lastname: Casanova
authors.affiliation: CEA, DAM, DIF, F-91297 Arpajon, France.
authors.forename: D
authors.initials: D
authors.lastname: Marion
authors.affiliation: CEA, DAM, DIF, F-91297 Arpajon, France.
authors.forename: P
authors.initials: P
authors.lastname: Loiseau
authors.affiliation: LULI, UMR 7605 CNRS-Ecole Polytechnique-CEA-Université Paris VI, 91128 Palaiseau cedex, France.
authors.forename: K
authors.initials: K
authors.lastname: Glize
authors.affiliation: LULI, UMR 7605 CNRS-Ecole Polytechnique-CEA-Université Paris VI, 91128 Palaiseau cedex, France.
authors.forename: C
authors.initials: C
authors.lastname: Labaune
authors.affiliation: CEA, DAM, DIF, F-91297 Arpajon, France.
authors.forename: S
authors.initials: S
authors.lastname: Depierreux