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

Journal Article · Wed Mar 22 00:00:00 EDT 2017 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4978887· OSTI ID:1356144

Joshi, Tirtha Raj  ^[1]; Hakel, Peter  ^[1]; Hsu, Scott C.  ^[1]; Vold, Erik Lehman  ^[1]; Schmitt, Mark J.  ^[1]; Hoffman, Nelson M.  ^[1]; Rauenzahn, Rick M.  ^[1]; Kagan, Grigory  ^[1]; Tang, Xianzhu  ^[1]; Mancini, R. C. ^[2]; Kim, Yong Ho  ^[1]; Herrmann, Hans W.  ^[1]

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1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2. Univ. of Nevada, Reno, NV (United States)

In this article, we report the first direct experimental evidence of interspecies ion separation in direct-drive inertial confinement fusion experiments performed at the OMEGA laser facility via spectrally, temporally, and spatially resolved imaging x-ray-spectroscopy data [S. C. Hsu et al., Europhys. Lett. 115, 65001 (2016)]. These experiments were designed based on the expectation that interspecies ion thermo-diffusion would be the strongest for species with a 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 the 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 the 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 using radiation-hydrodynamic simulations that include recently implemented, first-principles models of interspecies ion diffusion. Lastly, the experimentally inferred Ar-atom fraction profiles agree reasonably with calculated profiles associated with the incoming and rebounding first shock.

• Research Organization: Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC52-06NA25396
• OSTI ID: 1356144
• Report Number(s): LA-UR-16-29528
• Journal Information: Physics of Plasmas, Vol. 24, Issue 5; ISSN 1070-664X
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Interspecies ion separation
MMI