Gas-Kinetic Scheme for Partially Ionized Plasma in Hydrodynamic Regime

TL;DR

This paper develops a gas-kinetic scheme for simulating partially ionized plasmas in the hydrodynamic regime, capturing the transition from neutral gas to fully ionized plasma and validating it with standard MHD and vortex tests.

Contribution

It introduces a coupled kinetic model and a gas-kinetic scheme for neutral and plasma components, enabling accurate simulation of partially ionized plasma dynamics.

Findings

The scheme accurately captures ideal plasma features.

It demonstrates a transition from MHD to Euler wave structures.

Validation includes 1D Riemann and Orszag-Tang vortex tests.

Abstract

Most plasmas are only partially ionized. To better understand the dynamics of these plasmas, the behaviors of a mixture of neutral species and plasma in ideal magnetohydrodynamic states are investigated. The current approach is about the construction of coupled kinetic models for the neutral gas, electron, and proton, and the development of the corresponding gas-kinetic scheme (GKS) for the solution in the continuum flow regime. The scheme is validated in the 1D Riemann problem for an enlarged system with the interaction from the Euler waves of the neutral gas and magnetohydrodynamic ones of the plasma. Additionally, the Orszag-Tang vortex problem across different ionized states is tested to examine the influence of neutrals on the MHD wave evolution. These tests demonstrate that the proposed scheme can capture the fundamental features of ideal partially ionized plasma, and a transition in the wave structure from the ideal MHD solution of the fully ionized plasma to the Euler solution of the neutral gas is obtained.