Mechanisms for ion species segregation in the Schunk-Zimmerman multispecies ion-transport model

The Schunk-Zimmerman model of multispecies ion transport is based on diffusion in local gradients of concentration, pressure, and temperature [Hoffman \textit{et al}. Phys. Plasmas \textbf{22}, 052707 (2015)]. It represents barodiffusion as well as loss of low-Z ions across a high-Z interface. We demonstrate these phenomena in simple planar simulations of shock waves and low-Z/high-Z interfaces in multicomponent plasmas, and assess the possibility that the model may explain long-standing observations that have been interpreted as evidence for ion species segregation in inertial-fusion capsule implosions [Rygg \textit{et al}. Phys. Plasmas \textbf{13}, 052702 (2006); Herrmann \textit{et al}. Phys. Plasmas \textbf{16}, 056312 (2009); Casey \textit{et al}. PRL \textbf{108}, 075002 (2012); Amendt \textit{et al}. PRL \textbf{105}, 115005 (2010)].