Kinetic‐diffusion asymptotic‐preserving Monte Carlo algorithms for plasma edge neutral simulation

Abstract

AbstractWe developed novel Monte Carlo simulation strategies for the neutral model in plasma edge simulations where both low‐collisional and high‐collisional regimes are present. To maintain accuracy and reduce simulation costs in high‐collisional regimes, we use hybridized particles that exhibit both kinetic and diffusive behaviour depending on the local collisionality. The method maintains an asymptotically correct distribution and a correct mean, variance, and time correlation for all values of the collisionality. We apply this scheme to a fusion case with a strongly heterogeneous background, prompting the inclusion of a diffusion‐induced drift. Our numerical results show a large increase in efficiency at the expense of a minor bias.