A structure-preserving particle discretisation for the Lenard–Bernstein collision operator

Abstract

Collisions are an important dissipation mechanism in plasmas. When approximating collision operators numerically, it is important to preserve their mathematical structure in order to retain the laws of thermodynamics at the discrete level. This is particularly challenging when considering particle methods. A simple but commonly used collision operator is the Lenard–Bernstein operator, or its modified energy- and momentum-conserving counterpart. In this work, we present a macro-particle discretisation of this operator that is provably energy and momentum preserving.