A guiding center implementation for relativistic particle dynamics in the PLUTO code

TL;DR

This paper introduces a numerical implementation of the guiding center approximation within the PLUTO code to efficiently simulate relativistic charged particle motion in astrophysical plasmas, reducing computational constraints.

Contribution

The authors develop and validate a guiding center approximation method for relativistic particles in the PLUTO code, employing a variable step-size multistep method for improved efficiency.

Findings

Efficient simulation of relativistic particle dynamics using GCA.

Validation through numerical benchmarks confirms accuracy.

Reduced computational cost compared to traditional methods.

Abstract

We present a numerical implementation of the guiding center approximation to describe the relativistic motion of charged test particles in the PLUTO code for astrophysical plasma dynamics. The guiding center approximation (GCA) removes the time step constraint due to particle gyration around magnetic field lines by following the particle center of motion rather than its full trajectory. The gyration can be detached from the guiding center motion if electromagnetic fields vary sufficiently slow compared to the particle gyration radius and period. Our implementation employs a variable step-size linear multistep method, more efficient when compared to traditional one-step Runge Kutta schemes. A number of numerical benchmarks is presented in order to assess the validity of our implementation.