High-efficiency rarefied neutral gas computational model for plasma simulation

A rarefied neutral gas computational model is proposed for efficiently evaluating quasi-steady-state neutral particle density distributions in plasma simulations. The linear evolution approximation of neutral phase space distribution under rarefied flow conditions is introduced and the steady-state solution is connected to the tracking and accumulation of the impulse response using the Duhamel principle. This method is validated against analytical benchmarks and compared with existing classic methods, demonstrating its advantages in resolving steady-state neutral distribution. When coupled with the plasma model, this model achieves accelerated convergence and eliminates transient ionization overshoot. Due to its low computational cost and compatibility with the standard plasma simulation method, this model serves as a practical tool for steady-state plasma research in scenarios with high ionization rates and rarefied neutral flows.