Weakly collisional shocks of multicomponent plasmas in hohlraums of indirect-drive inertial confinement fusion.

Abstract

In indirect-drive inertial confinement fusion (ICF), a hohlraum serves the purpose of converting laser energy into thermal x-ray energy. This process involves the interaction of low-density ablated plasmas, which can give rise to weakly collisional shocks characterized by the Knudsen number Kn on the order of 1. The Knudsen number highlights the importance of kinetic effects. Preliminary investigations have demonstrated that the kinetic effects associated with weakly collisional shocks significantly impact the efficiency of the ICF process. The study explores the development and structural properties of weakly collisional shocks in hohlraums, focusing on ion mixing and separation in multicomponent plasmas, based on large-scale kinetic simulations. Key findings include the behavior of ions and electrons, which is different from strongly collisional shocks in hydrodynamic theory. The influence of charge-to-mass ratios on ion species separation results in two subshocks and deviations in hydrogen ion concentration from hydrodynamic predictions. The effects of weakly collisional shocks on electron and ion distributions are crucial for understanding laser energy coupling and improving diagnostics. Increased collision frequency could transition shock wave physical behavior from kinetically dominated to fluid-dominated. It further clarifies the impact of these shocks on electron and ion kinetics, providing valuable insights for future research in ICF and astrophysics.