An implicit, conservative and asymptotic-preserving electrostatic particle-in-cell algorithm for arbitrarily magnetized plasmas in uniform magnetic fields

TL;DR

This paper presents a new electrostatic particle-in-cell algorithm that enables large timesteps in simulations of magnetized plasmas, conserving energy and charge while significantly improving computational efficiency.

Contribution

The paper introduces an asymptotic-preserving, implicit PIC scheme that handles large timesteps and coexisting magnetized and unmagnetized particles efficiently and accurately.

Findings

Achieves large-timestep speedups over standard PIC algorithms.

Preserves particle drifts and full orbits depending on timestep size.

Demonstrates effectiveness on plasma instability problems.

Abstract

We introduce a new electrostatic particle-in-cell algorithm capable of using large timesteps compared to particle gyro-period under a uniform external magnetic field. The algorithm extends earlier electrostatic fully implicit PIC implementations with a new asymptotic-preserving particle-push scheme that allows timesteps much larger than particle gyroperiods. In the large-timestep limit, the integrator preserves all particle drifts, while recovering the full orbit for small timesteps. The scheme allows for a seamless, efficient treatment of particles with coexisting magnetized and unmagnetized species, and conserves energy and charge exactly without spoiling implicit solver performance. We demonstrate by numerical experiment with several problems of variable species magnetization (diocotron instability, modified two-stream instability, and drift instability) that orders of magnitude wall-clock-time speedups vs. the standard fully implicit electrostatic PIC algorithm are possible without sacrificing solution accuracy.