Variational approach to low-frequency kinetic-MHD in the current coupling scheme

TL;DR

This paper develops new low-frequency kinetic-MHD models using Hamilton's variational principle, incorporating guiding-center and gyrocenter coordinates to improve the physical accuracy of hybrid plasma simulations.

Contribution

It introduces a variational framework for current-coupling kinetic-MHD models in the low-frequency regime, ensuring energy consistency and including guiding-center and gyrocenter formulations.

Findings

Formulated energy-conserving kinetic-MHD models using variational methods.

Derived guiding-center and gyrocenter hybrid schemes for energetic particles.

Enhanced the theoretical foundation of kinetic-MHD modeling with Hamiltonian approaches.

Abstract

Hybrid kinetic-MHD models describe the interaction of an MHD bulk fluid with an ensemble of hot particles, which is described by a kinetic equation. When the Vlasov description is adopted for the energetic particles, different Vlasov-MHD models have been shown to lack an exact energy balance, which was recently recovered by the introduction of non-inertial force terms in the kinetic equation. These force terms arise from fundamental approaches based on Hamiltonian and variational methods. In this work we apply Hamilton's variational principle to formulate new current-coupling kinetic-MHD models in the low-frequency approximation (i.e. large Larmor frequency limit). More particularly, we formulate current-coupling hybrid schemes, in which energetic particle dynamics are expressed in either guiding-center or gyrocenter coordinates.