Investigation of Inter-Ion Species Diffusion in Inertial Confinement Fusion Implosions

Anomalous fusion yield degradation has been observed for gas fill mixtures in inertial confinement fusion (ICF) implosions. These mixtures have included D/3He [Rygg, et al., Phys Plasmas, \textbf{13}, 052702 (2006)], D/T/3He [Herrmann, et al., Phys Plasmas, \textbf{16}, 056312 (2009)], D/Ar [Lindl, et al., Phys Plasmas, \textbf{11}, 339-491 (2004)] and even D/T [Casey, et al., PRL \textbf{108}, 075005 (2012)]. Fuel ion segregation has been suggested as a possible cause [Amendt, et al., PRL \textbf{18}, 056308 (2011); Kagan, et al., Phys Ltr A 10.1016 (2014)]. Segregation may be caused by inter-ion species diffusion driven by gradients in plasma pressure, temperature and electric field, either across a relatively narrow shock boundary or across the entire interior of the compressed capsule. It is expected that lower Z {\&}/or A ions will diffuse outward while higher Z {\&}/or A diffuse inward. In the case of D/T/3He, the 3He diffuses inward to the hotter core, reducing the DT reactivity. A D/T/H mixture should result in H diffusing outward, leaving the hotter core D {\&} T rich and hence enhance reactivity over the simulated expectation. Past results will be reviewed and plans for a hydro-equivalent comparison D/T/$^{\mathrm{3}}$He and D/T/H will be presented.