Particle-in-cell modeling of species separation in two-species plasmas

Summary form only given. Understanding the interaction of a strong magnetic field with a plasma is one of the fundamental problems in plasma physics. In this talk we report on a new systematic study using two-dimensional particle-in-cell simulations designed to explore the interplay between magnetic pushing¹ (MHD time scales) and magnetic field penetration due to the Hall effect². A two-ion-species plasma that consists of a heavy-ion species and a light-ion species is simulated. In a single-species plasma where the ions are infinitely massive and ∇n×B > 0, the magnetic field penetrates into the plasma at the Hall speed. In a two-species plasma, the simulations show simultaneous pushing of the light ions and magnetic field penetration through the heavy ions, when the Hall speed is between the Alfvén speeds of the heavy and light ion species^3-4 (i.e. V_AH <;<; V_Hall <;<; V_AL). The simultaneous pushing of the light ion species and penetration of the magnetic field through the heavy species leads to a separation of the two ion species. If the mass of the light ions is increased, a transition to magnetic penetration of both species is observed when V_AH <;<; V_AL <;<; V_Hall. In the opposite limit where the Hall speed is small compared to the Alfvén speeds of both ion species, magnetic pushing of both species is observed.