A structure-preserving multiscale solver for particle-wave interaction in non-uniform magnetized plasmas

TL;DR

This paper introduces a structure-preserving multiscale numerical solver for modeling particle-wave interactions in non-uniform magnetized plasmas, effectively conserving physical quantities and reducing computational costs.

Contribution

It develops a novel multiscale solver combining LDG and trajectory averaging methods to accurately simulate electron-plasmon dynamics in complex plasma environments.

Findings

The LDG scheme rigorously conserves mass, momentum, and energy.

Trajectory averaging reduces computational cost significantly.

Numerical examples demonstrate the solver's effectiveness in non-uniform plasmas.

Abstract

Particle-wave interaction is of fundamental interest in plasma physics, especially in the study of runaway electrons in magnetic confinement fusion. Analogous to the concept of photons and phonons, wave packets in plasma can also be treated as quasi-particles, called plasmons. To model the ``mixture" of electrons and plasmons in plasma, a set of ``collisional" kinetic equations has been derived, based on weak turbulence limit and the Wentzel-Kramers-Brillouin (WKB) approximation. There are two main challenges in solving the electron-plasmon kinetic system numerically. Firstly, non-uniform plasma density and magnetic field results in high dimensionality and the presence of multiple time scales. Secondly, a physically reliable numerical solution requires a structure-preserving scheme that enforces the conservation of mass, momentum, and energy. In this paper, we propose a struture-preserving multiscale solver for particle-wave interaction in non-uniform magnetized plasmas. The solver combines a conservative local discontinuous Galerkin (LDG) scheme for the interaction part with a trajectory averaging method for the plasmon Hamiltonian flow part. Numerical examples for a non-uniform magnetized plasma in an infinitely long symmetric cylinder are presented. It is verified that the LDG scheme rigorously preserves all the conservation laws, and the trajectory averaging method significantly reduces the computational cost.