Multispecies structure-preserving particle discretization of the Landau collision operator

This paper proposes a novel numerical integrator for modeling multispecies Coulomb collisions in kinetic plasmas. The proposed scheme provides an energy-, momentum-, and positivity-preserving particle discretization of the nonlinear Landau collision operator, extending the works of Carrillo et al. [J. Comput. Phys. 7, 100066 (2020)] and Hirvijoki [Plasma Phys. Controlled Fusion 63, 044003 (2021)]. The discrete-time conservation properties are analyzed both algebraically and numerically, and an efficient, graphics processing unit-parallelized implementation is validated against inhomogeneous temperature relaxation, isotropization, and thermalization examples. The results agree with analytical estimates, confirming the method capable of reproducing physics.