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arXiv 1009.4248astro-ph.SRcond-mat.stat-mechnucl-th
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氖在白矮星中的扩散

Diffusion of Neon in White Dwarf Stars

C. J. Horowitz, J. Hughto, A. S. Schneider, D. K. Berry

备注：
6 pages, 5 figures, minor changes, Phys. Rev. E in press
发表信息：
Phys. Rev. E 82, 066401 (2010)
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摘要：

富中子同位素$^{22}$ Ne的沉积可能是白矮星冷却过程中的一个重要引力能量来源。这取决于$^{22}$ Ne在强耦合等离子体混合物中的扩散常数。我们从碳、氧和氖混合物的分子动力学模拟计算自扩散常数$D_i$。我们发现，混合物中的$D_i$与早期的单组分血浆结果没有很大差异。对于强耦合（库仑参数$Γ>$很少），$D_i$对离子种类的电荷$Z_i$有适度的依赖性，$D_i \propto Z_i^{-2/3}$。然而，对于弱耦合（较小的$Γ$），$D_i$更强烈地依赖于$Z_i$。我们的结论是，自扩散常数$D_{\rm Ne}$的$^{22}$氖在碳，氧，氖等离子体的混合物是准确地知道，使$D_{\rm Ne}$的不确定性应该是不重要的模拟白矮星冷却。

英文摘要：

Sedimentation of the neutron rich isotope $^{22}$Ne may be an important source of gravitational energy during the cooling of white dwarf stars. This depends on the diffusion constant for $^{22}$Ne in strongly coupled plasma mixtures. We calculate self-diffusion constants $D_i$ from molecular dynamics simulations of carbon, oxygen, and neon mixtures. We find that $D_i$ in a mixture does not differ greatly from earlier one component plasma results. For strong coupling (coulomb parameter $Γ>$ few), $D_i$ has a modest dependence on the charge $Z_i$ of the ion species, $D_i \propto Z_i^{-2/3}$. However $D_i$ depends more strongly on $Z_i$ for weak coupling (smaller $Γ$). We conclude that the self-diffusion constant $D_{\rm Ne}$ for $^{22}$Ne in carbon, oxygen, and neon plasma mixtures is accurately known so that uncertainties in $D_{\rm Ne}$ should be unimportant for simulations of white dwarf cooling.

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