Improved multispecies Dougherty collisions

TL;DR

This paper extends the Dougherty collision model to accurately describe nonlinear multispecies plasma collisions, ensuring conservation laws and H-Theorem compliance across arbitrary mass ratios.

Contribution

The authors develop a multispecies Dougherty collision operator that maintains conservation laws and satisfies the H-Theorem, applicable for any mass ratios.

Findings

Reproduces known velocity and temperature relaxation rates

Obeys conservation laws in multispecies interactions

Satisfies the H-Theorem unlike Bhatnagar-Gross-Krook operators

Abstract

The Dougherty model Fokker-Planck operator is extended to describe nonlinear full-f collisions between multiple species in plasmas. Simple relations for cross-species interactions are developed which obey conservation laws, and reproduce familiar velocity and temperature relaxation rates. This treatment of multispecies Dougherty collisions, valid for arbitrary mass ratios, satisfies the H-Theorem unlike analogous Bhatnagar-Gross-Krook operators.