Analysis of Using Absolute X-Ray Emission to Infer Hot-Spot Mix for OMEGA Direct-Drive Layered Implosions

ORAL

Abstract

A general approach for estimating hot-spot mix is being pursued for direct-drive layered implosions on OMEGA. Previously, ablator mix was estimated at the National Ignition Facility by comparing the ratio of measured x-ray over neutron yield to an initially no-mix, ice-block model estimate [T. Ma \textit{et al.}, Phys. Rev. Lett. \textbf{111}, 085004 (2013)]. However, tests with the 1-D LILAC code show that mix can be overestimated because temperature nonequilibrium in OMEGA-scale hot spots causes a breakdown of the ice-block model assumption of equal neutron and x-ray emission volumes. Crucially, this overestimation can be of the order considered important. We explore using a spatially varying hot-spot profile model [R. Betti \textit{et al.}, Phys. Plasmas \textbf{8}, 5257 (2001)] that allows for differing emission volumes to ameliorate mix discrepancies associated with the ice-block assumption. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0003856.

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Authors

  • D. Cao

    • Laboratory for Laser Energetics, U. of Rochester
    • University of Rochester
    • Lab for Laser Energetics
    • Laboratory for Laser Energetics, University of Rochester

  • Rahul Shah

    • University of Rochester Laboratory for Laser Energetics
    • Laboratory for Laser Energetics, U. of Rochester
    • Laboratory for Laser Energetics
    • Laboratory for Laser Energetics, University of Rochester
    • Lab for Laser Energetics
    • University of Rochester

  • Reuben Epstein

    • Laboratory for Laser Energetics, University of Rochester
    • LLE, University of Rochester
    • Laboratory for Laser Energetics, U. of Rochester
    • Laboratory for Laser Energetics

  • Alison Christopherson

    • Laboratory for Laser Energetics, U. of Rochester

  • Varchas Gopalaswamy

    • Laboratory for Laser Energetics, U. of Rochester

  • Sean Regan

    • Laboratory for Laser Energetics, U. of Rochester

  • Chuck Sorce

    • Laboratory for Laser Energetics, U. of Rochester

  • Wolfgang Theobald

    • Laboratory for Laser Energetics, U. of Rochester

  • Tim Collins

    • Laboratory for Laser Energetics, U. of Rochester

  • Valeri Goncharov

    • Laboratory for Laser Energetics, U. of Rochester