Cross-Field Transport in Magnetized, Multi-ion Plasma

Abstract

Multi-ion transport is important in a number of applications, including nuclear fusion and plasma mass filters. In particular, in fusion devices it is necessary to control impurity density and fuel mix in order to improve fusion performance. This thesis explores collisional multi-ion cross-field transport in a variety of parameter regimes, expanding the range of applicability of transport models. We discover new and curious effects in multiple ion species plasma, including charge incompressibility, heat pump, and ion stratification when plasma is subjected to external forces or temperature gradient. Then we show that the equilibrium state and the direction of impurity transport strongly depend on plasma magnetization, which is characterized by ion Hall parameter, and find out that the Hall parameter of interest is the ratio of light ion gyrofrequency to collision frequency between light and heavy ion species. In particular, ion density profiles evolve sufficiently fast for radial impurity transport to be observable around stagnation on MagLIF, leading to expulsion of heavy ion impurities from the hotspot as long as plasma becomes sufficiently collisionally magnetized during the implosion. Finally, we show that multi-ion transport changes its nature in partially ionized plasma, where ions can be in different charge states, and identify partial-ionization deconfinement effect in magnetized plasma.