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Title: Self-similar solutions for multi-species plasma mixing by gradient driven transport

Abstract

We report that multi-species transport of plasma ions across an initial interface between DT and CH is shown to exhibit self-similar species density profiles under 1D isobaric conditions. Results using transport theory from recent studies and using a Maxwell–Stephan multi-species approximation are found to be in good agreement for the self-similar mix profiles of the four ions under isothermal and isobaric conditions. The individual ion species mass flux and molar flux profile results through the mixing layer are examined using transport theory. The sum over species mass flux is confirmed to be zero as required, and the sum over species molar flux is related to a local velocity divergence needed to maintain pressure equilibrium during the transport process. The light ion species mass fluxes are dominated by the diagonal coefficients of the diffusion transport matrix, while for the heaviest ion species (C in this case), the ion flux with only the diagonal term is reduced by about a factor two from that using the full diffusion matrix, implying the heavy species moves more by frictional collisions with the lighter species than by its own gradient force. Temperature gradient forces were examined by comparing profile results with and without imposing constantmore » temperature gradients chosen to be of realistic magnitude for ICF experimental conditions at a fuel-capsule interface (10 μm scale length or greater). The temperature gradients clearly modify the relative concentrations of the ions, for example near the fuel center, however the mixing across the fuel-capsule interface appears to be minimally influenced by the temperature gradient forces within the expected compression and burn time. Finally, discussion considers the application of the self-similar profiles to specific conditions in ICF.« less

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1484638
Report Number(s):
LA-UR-17-31274
Journal ID: ISSN 0741-3335
Grant/Contract Number:  
89233218CNA000001; AC52-06NA25396
Resource Type:
Accepted Manuscript
Journal Name:
Plasma Physics and Controlled Fusion
Additional Journal Information:
Journal Volume: 60; Journal Issue: 5; Journal ID: ISSN 0741-3335
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; plasma transport; ICF; multi-species diffusion

Citation Formats

Vold, Erik Lehman, Kagan, Grigory, Simakov, Andrei N., Molvig, Kim, and Yin, Lin. Self-similar solutions for multi-species plasma mixing by gradient driven transport. United States: N. p., 2018. Web. doi:10.1088/1361-6587/aab38e.
Vold, Erik Lehman, Kagan, Grigory, Simakov, Andrei N., Molvig, Kim, & Yin, Lin. Self-similar solutions for multi-species plasma mixing by gradient driven transport. United States. doi:10.1088/1361-6587/aab38e.
Vold, Erik Lehman, Kagan, Grigory, Simakov, Andrei N., Molvig, Kim, and Yin, Lin. Fri . "Self-similar solutions for multi-species plasma mixing by gradient driven transport". United States. doi:10.1088/1361-6587/aab38e. https://www.osti.gov/servlets/purl/1484638.
@article{osti_1484638,
title = {Self-similar solutions for multi-species plasma mixing by gradient driven transport},
author = {Vold, Erik Lehman and Kagan, Grigory and Simakov, Andrei N. and Molvig, Kim and Yin, Lin},
abstractNote = {We report that multi-species transport of plasma ions across an initial interface between DT and CH is shown to exhibit self-similar species density profiles under 1D isobaric conditions. Results using transport theory from recent studies and using a Maxwell–Stephan multi-species approximation are found to be in good agreement for the self-similar mix profiles of the four ions under isothermal and isobaric conditions. The individual ion species mass flux and molar flux profile results through the mixing layer are examined using transport theory. The sum over species mass flux is confirmed to be zero as required, and the sum over species molar flux is related to a local velocity divergence needed to maintain pressure equilibrium during the transport process. The light ion species mass fluxes are dominated by the diagonal coefficients of the diffusion transport matrix, while for the heaviest ion species (C in this case), the ion flux with only the diagonal term is reduced by about a factor two from that using the full diffusion matrix, implying the heavy species moves more by frictional collisions with the lighter species than by its own gradient force. Temperature gradient forces were examined by comparing profile results with and without imposing constant temperature gradients chosen to be of realistic magnitude for ICF experimental conditions at a fuel-capsule interface (10 μm scale length or greater). The temperature gradients clearly modify the relative concentrations of the ions, for example near the fuel center, however the mixing across the fuel-capsule interface appears to be minimally influenced by the temperature gradient forces within the expected compression and burn time. Finally, discussion considers the application of the self-similar profiles to specific conditions in ICF.},
doi = {10.1088/1361-6587/aab38e},
journal = {Plasma Physics and Controlled Fusion},
number = 5,
volume = 60,
place = {United States},
year = {2018},
month = {3}
}

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