Observation and modeling of interspecies ion separation in inertial confinement fusion implosions via imaging x-ray spectroscopy

Abstract

We report first direct experimental evidence of interspecies ion separation in direct-drive ICF experiments performed at the OMEGA laser facility via spectrally, temporally and spatially resolved imaging x-ray-spectroscopy data [S. C. Hsu et al., EPL 115, 65001 (2016)]. These experiments were designed based on the expectation that interspecies ion thermo-diffusion would be strongest for species with large mass and charge difference. The targets were spherical plastic shells filled with D2 and a trace amount of Ar (0.1% or 1% by atom). Ar K-shell spectral features were observed primarily between the time of first-shock convergence and slightly before neutron bang time, using a time- and space-integrated spectrometer, a streaked crystal spectrometer, and two gated multi-monochromatic x-ray imagers fielded along quasi-orthogonal lines of sight. Detailed spectroscopic analyses of spatially resolved Ar K-shell lines reveal deviation from the initial 1% Ar gas fill and show both Ar-concentration enhancement and depletion at different times and radial positions of the implosion. The experimental results are interpreted with radiation-hydrodynamic simulations that include recently implemented, first-principles models of interspecies ion diffusion. The experimentally inferred Ar-atom-fraction profiles agree reasonably with calculated profiles associated with the incoming and rebounding first shock.

arXiv comment13 pages, 11 figures, 1 table, submitted for publication (2017)

References in corpus (7)

• The RAGE radiation-hydrodynamic code
• Electro-diffusion in a plasma with two ion species
• Thermo-diffusion in inertially confined plasmas
• Species separation and modification of neutron diagnostics in inertial-confinement fusion
• Plasma Viscosity with Mass Transport in Spherical ICF Implosion Simulations
• Direct asymmetry measurement of temperature and density spatial distributions in inertial confinement fusion plasmas from pinhole space-resolved spectra
• Observation of interspecies ion separation in inertial-confinement-fusion implosions

Cited by in corpus (3)

• An Eulerian Vlasov-Fokker-Planck Algorithm for Spherical Implosion Simulations of Inertial Confinement Fusion Capsules
• Influence of coupling on thermal forces and dynamic friction in plasmas with multiple ion species
• Observation of Shock-Front Separation in Multi-Ion-Species Collisional Plasma Shocks