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Suprathermal ion distributions in burning plasmas on the NIF

ORAL

Abstract

For hydrodynamic plasmas described by Maxwellian ion distributions, a well-described relationship exists between the mean (<E>) and variance of the neutron energy spectrum1. On the National Ignition Facility (NIF), the addition of the quartz Cherenkov neutron time-of-flight (nToF) spectrometers and a fifth nToF line-of-sight has extended the ability to measure <E> to a precision of 5 parts in 100,000 for high yield DT shots. Observations using this new capability on NIF shots with the highest neutron yield have revealed a significant deviation from the hydrodynamic relationship and disagreement with radiation-hydrodynamic simulations.

Experimental results are described and compared to predicted neutron spectra for a range of candidate ion distributions. This supports the claim that suprathermal ions are required to increase the mean of the neutron kinetic energy faster than the variance. The result suggests that the significant a-heating present in a burning plasma is sufficient to generate non-Maxwellian DT ion distributions. LLNL-ABS-824483

1. D. H. Munro, Nucl. Fusion 56 036001 (2016) https://doi.org/10.1088/0029-5515/56/3/036001

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Publication: Observation of suprathermal ion distribution in burning plasmas at the National Ignition Facility (NIF). E. P. Hartouni, A. S. Moore et al. - submitted to Nature Physics

Presenters

  • Alastair S Moore

    Lawrence Livermore Natl Lab

Authors

  • Alastair S Moore

    Lawrence Livermore Natl Lab

  • Edward P Hartouni

    Lawrence Livermore Natl Lab, Lawrence Livermore National Lab

  • Aidan C Crilly

    Imperial College London, CIFS, The Blackett Laboratory, Imperial College London

  • Brian D Appelbe

    Imperial College London, CIFS, The Blackett Laboratory, Imperial College London, Imperial College

  • David J Schlossberg

    Lawrence Livermore Natl Lab

  • Shaun M Kerr

    Lawrence Livermore Natl Lab, Lawrence Livermore National Laboratory

  • Mark J Eckart

    Lawrence Livermore National Laboratory

  • Scott M Sepke

    Lawrence Livermore Natl Lab, Lawrence Livermore National Laboratory

  • Gary P Grim

    Lawrence Livermore National Laboratory, Lawrence Livermore Natl Lab