• High Power Laser Science and Engineering
  • Vol. , Issue , ()
Cristoforetti Gabriele, Hueller Stefan, Koester Petra, Antonelli Luca, Atzeni Stefano , Baffigi Federica, Batani Dimitri, Baird Chris, Booth Nicola, Galimberti Marco, Glize Kevin, Heron Anne, Khan Matthew, Loiseau Pascal, Mancelli Donaldi, Notley Margaret, Oliveira Pedro, Renner Oldrich, Smid Michal, Schiavi Angelo, Tran Guillaume, Woolsey Nigel, Gizzi Leonida
Author Affiliations
  • Ecole Polytechnique
  • University of York
  • Universita degli Studi di Roma La Sapienza
  • University of Bordeaux
  • Science and Technology Facilities Council
  • Shanghai Jiao Tong University
  • Université Paris-Saclay
  • Donostia International Physics Center
  • Institute of Physics
  • Helmholtz-Zentrum Dresden-Rossendorf
  • Università degli Studi di Roma La Sapienza
  • Universite Paris-Saclay
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    We report results and modelling of an experiment performed at the TAW Vulcan laser facility, aimed at investigating laser-plasma interaction in conditions which are of interest for the Shock Ignition scheme to Inertial Confinement Fusion, i.e. laser intensity higher than 10<sup>16</sup> W/cm<sup>2</sup> impinging on a hot (T >1 keV), inhomogeneous and long scalelength preformed plasma. Measurements show a significant SRS backscattering (∼4−20% of laser energy) driven at low plasma densities and no signatures of TPD/SRS driven at the quarter critical density region. Results are satisfactorily reproduced by an analytical model accounting for the convective SRS growth in independent laser speckles, in conditions where the reflectivity is dominated by the contribution from the most intense speckles, where SRS gets saturated. Analytical and kinetic simulations well reproduce the onset of SRS at low plasma densities in a regime strongly affected by non linear Landau damping and by filamentation of the most intense laser speckles. The absence of TPD/SRS at higher densities is explained by pump depletion and plasma smoothing driven by filamentation. The prevalence of laser coupling in the low density profile justifies the low temperature measured for hot electrons (7−12 keV), well reproduced by numerical simulations.
    Manuscript Accepted: Oct. 11, 2021
    Posted: Oct. 11, 2021