Testing numerical implementations of strong field electrodynamics

TL;DR

This paper evaluates the accuracy of numerical methods in strong field electrodynamics by comparing them with exact analytical results, highlighting the limitations of the locally constant field approximation in reproducing harmonic structures.

Contribution

It provides a systematic assessment of numerical implementations in laser-matter interaction simulations, identifying specific regimes where they deviate from analytical predictions.

Findings

Numerical methods accurately reproduce emission spectra in most regimes.

Discrepancies occur in harmonic structures due to the locally constant field approximation.

The locally constant field approximation limits the accuracy of current numerical implementations.

Abstract

We test current numerical implementations of laser-matter interactions by comparison with exact analytical results. Focussing on photon emission processes, it is found that the numerics accurately reproduce analytical emission spectra in all considered regimes, except for the harmonic structures often singled out as the most significant high intensity/multi-photon effects. We find that this discrepancy originates in the use of the locally constant field approximation.