Particle integrator for particle-in-cell simulations of ultra-high intensity laser-plasma interactions

TL;DR

This paper identifies key sources of numerical errors in particle-in-cell simulations of ultra-high intensity laser-plasma interactions and proposes an adaptive sub-cycling method with improved field interpolation to enhance accuracy.

Contribution

The paper introduces an adaptive electron sub-cycling technique combined with third-order field interpolation to significantly improve PIC simulation accuracy at high intensities.

Findings

Numerical accuracy deteriorates with increasing wave amplitude using standard PIC methods.

Strong acceleration near stopping points and field interpolation are major error sources.

Adaptive sub-cycling with third-order interpolation greatly enhances simulation precision.

Abstract

Particle-in-cell codes are the most widely used simulation tools for kinetic studies of ultra-intense laser-plasma interactions. Using the motion of a single electron in a plane electromagnetic wave as a benchmark problem, we show surprising deterioration of the numerical accuracy of the PIC algorithm with increasing normalized wave amplitude for typical time-step and grid sizes. Two significant sources of errors are identified: strong acceleration near stopping points and the temporal field interpolation. We propose adaptive electron sub-cycling coupled with a third order temporal interpolation of the magnetic field and electric field as an efficient remedy that dramatically improves the accuracy of the particle integrator.