Experimental and numerical study of fast electron beam characteristics in laser-irradiated thin foil targets using bremsstrahlung emission

ORAL

Abstract

Laser to fast electron conversion efficiency and hot electron temperature are two important parameters for fast ignition ICF. Experiments are reported where bremsstrahlung emission data from short-pulse laser-irradiated foils was collected with high-energy x-ray spectrometers at multiple angles. These instruments show that bremsstrahlung emission is consistent with an electron beam in the target with a 60 degree half-width divergence angle and a conversion efficiency of 30-35{\%} using the Monte Carlo code ITS. In addition, multiple electron distributions, including the electron distributions predicted by particle-in-cell codes, were modeled in the electron transport code ZUMA, and their bremsstrahlung emission predictions tested against the experimental data. Resistivity and electromagnetic fields were taken into account in the ZUMA calculations, allowing the experimental data to constrain the electron source distribution with greater accuracy.

*This work performed under the auspices of the U. S. Dept. of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

–

Authors

  • Brad Westover

    • University of California San Diego
    • UCSD

  • Cliff Chen

    • Lawrence Livermore National Laboratory
    • LLNL

  • Prav Patel

    • LLNL
    • Lawrence Livermore National Laboratory

  • M.H. Key

    • LLNL
    • Lawrence Livermore National Laboratory

  • Harry McLean

    • LLNL
    • Lawrence Livermore National Laboratory

  • Farhat Beg

    • UCSD
    • UC San Diego
    • University of California San Diego
    • U California San Diego
    • University of California-San Diego, La Jolla, California 92093, USA
    • University of California-San Diego, USA