2D Implementation of Kinetic‐Diffusion Monte Carlo in Eiron

ABSTRACT Particle‐based kinetic Monte Carlo simulations of neutral particles are one of the major computational bottlenecks in tokamak scrape‐off layer simulations. This computational cost comes from the need to resolve individual collision events in high‐collisional regimes. However, in such regimes, one can approximate the high‐collisional kinetic dynamics with computationally cheaper diffusion. Asymptotic‐preserving schemes make use of this limit to perform simulations in these regimes, without a blow‐up in computational cost as incurred by standard kinetic approaches. One such scheme is kinetic‐diffusion Monte Carlo. In this paper, we present a first extension of this scheme to the two‐dimensional setting and its implementation in the Eiron particle code. We then demonstrate that this implementation produces a significant speedup over kinetic simulations in high‐collisional cases.