Asymptotically stable Particle-in-Cell methods for the magnetized Vlasov--Poisson equations in orthogonal curvilinear coordinates

TL;DR

This paper develops asymptotically stable Particle-in-Cell methods for the magnetized Vlasov-Poisson equations in orthogonal curvilinear coordinates, extending existing Cartesian coordinate theories to more general geometries in plasma physics.

Contribution

It introduces a semi-implicit numerical method that preserves physical properties and stability in complex coordinate systems for plasma modeling.

Findings

Proves Poisson-bracket structure preservation in curvilinear coordinates.

Develops a semi-implicit method with proven asymptotic stability.

Extends geometric numerical methods to non-Cartesian coordinate systems.

Abstract

In high-temperature plasma physics, a strong magnetic field is usually used to confine charged particles. Therefore, for studying the classical mathematical models of the physical problems it needs to consider the effect of external magnetic fields. One of the important model equations in plasma is the Vlasov-Poisson equation with an external magnetic field. This equation usually has multi-scale characteristics and rich physical properties, thus it is very important and meaningful to construct numerical methods that can maintain the physical properties inherited by the original systems over long time. This paper extends the corresponding theory in Cartesian coordinates to general orthogonal curvilinear coordinates, and proves that a Poisson-bracket structure can still be obtained after applying the corresponding finite element discretization. However, the Hamiltonian systems in the new coordinate systems generally cannot be decomposed into sub-systems that can be solved accurately, so it is impossible to use the splitting methods to construct the corresponding geometric integrators. Therefore, this paper proposes a semi-implicit method for strong magnetic fields and analyzes the asymptotic stability of this method.