Particle-In-Cell Modeling of Hall-Driven Magnetic Penetration and Species Separation in Two-Species Plasmas

Understanding the interaction of a strong magnetic field with a plasma is a key problem in plasma physics. In this poster we report on a new systematic study using two-dimensional particle-in-cell simulations designed to explore the interplay between magnetic pushing and Hall-driven magnetic field penetration. In plasma where the ions are infinitely massive and $\nabla n \times B > 0$, the magnetic field penetrates into the plasma at a specific fraction of the Hall speed, $v_b$. When the ions have finite mass, the penetrating magnetic field gives an impulse to the ions, accelerating them to speed $v_i$. In a two-species plasma, simulations show simultaneous pushing of the light-ion species and magnetic field penetration through the heavy-ion species when $v_{heavy} < v_b < v_{light}$. This 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 $v_{heavy} < v_{light} < v_b$. Analytic estimates for both $v_i$ and the mass at which this transition occurs agree well with simulations.