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High Power Laser Science and Engineering, Vol. 7, Issue 3, e39 (2019)

Collective absorption of laser radiation in plasma at sub-relativistic intensities

Y. J. Gu1,2,†, O. Klimo1,3, Ph. Nicolaï4, S. Shekhanov1, S. Weber1,5, and V. T. Tikhonchuk1,4

Author Affiliations

  • 1ELI-Beamlines, Institute of Physics, Czech Academy of Sciences, 25241 Dolní Břežany, Czech Republic
  • 2Institute of Plasma Physics of the CAS, Za Slovankou 1782/3, 18200 Prague, Czech Republic
  • 3Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, 11519 Prague, Czech Republic
  • 4Centre of Intense Lasers and Applications, University of Bordeaux, CNRS, CEA, 33405 Talence, France
  • 5School of Science, Xi’an Jiaotong University, Xi’an 710049, China


Processes of laser energy absorption and electron heating in an expanding plasma in the range of irradiances $I\unicode[STIX]{x1D706}^{2}=10^{15}{-}10^{16}~\text{W}\,\cdot \,\unicode[STIX]{x03BC}\text{m}^{2}/\text{cm}^{2}$ are studied with the aid of kinetic simulations. The results show a strong reflection due to stimulated Brillouin scattering and a significant collisionless absorption related to stimulated Raman scattering near and below the quarter critical density. Also presented are parametric decay instability and resonant excitation of plasma waves near the critical density. All these processes result in the excitation of high-amplitude electron plasma waves and electron acceleration. The spectrum of scattered radiation is significantly modified by secondary parametric processes, which provide information on the spatial localization of nonlinear absorption and hot electron characteristics. The considered domain of laser and plasma parameters is relevant for the shock ignition scheme of inertial confinement fusion.