Azimuthal Uniformity of Cylindrical Implosions on OMEGA

ORAL

Abstract

A laser pointing for an azimuthal uniform cylindrical implosion is determined empirically from x-ray self-emission images of the implosion end-on. The images are decomposed into cylindrical harmonics to determine the degree of uniformity and to measure the transfer of imposed laser intensity modes onto the cylinder. Two cases, one with an imposed mode-5 perturbation and another that is the most azimuthally uniform are compared. Despite a mode-5 persisting for the latter case, the implosion is measured to be uniform to within the resolvable features of the x-ray image. The growth of the modes for the imposed mode-5 case over time demonstrate that mode-5 growth occurs throughout the entire acceleration of the cylindrical shell, with exceptions in the case of shell defects that seed either mode-4 or mode-6 growth. Mode growth is independent of shell thickness and shell outer diameter. In all cases, there is no measurable mode-10 growth, despite the mode-10 amplitude increasing by a factor of 4 from the mode-5 pointing to the uniform pointing.

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Authors

  • Daniel Barnak

    University of Rochester

  • J.R. Davies

    Laboratory for Laser Energetics, U. Rochester, Laboratory for Laser Energetics, U. of Rochester, LLE, LLE, Univ. Rochester, USA, University of Rochester, U. of Rochester, NY, LLE, UR, USA

  • D. R. Harding

    University of Rochester, Laboratory for Laser Energetics, Laboratory for Laser Energetics, University of Rochester

  • J. L. Peebles

    Laboratory for Laser Energetics, U. of Rochester, NY, University of Rochester

  • R. Betti

    Laboratory for Laser Energetics, U. of Rochester, LLE, University of Rochester, LLE, Univ. of Rochester, Laboratory for Laser Energetics, University of Rochester, Lab for Laser Energetics

  • Po-Yu Chang

    Natl Cheng Kung Univ, National Cheng Kung University

  • John Moody

    LLNL, Lawrence Livermore Natl Lab, Lawrence Livermore National Laboratory

  • Brad Pollock

    Lawrence Livermore Natl Lab, Lawrence Livermore National Laboratory, LLNL

  • Edward Hansen

    University of Rochester

  • M. J. Bonino

    University of Rochester