A first numerical investigation of a recent radiation reaction model and comparison to the Landau-Lifschitz model

TL;DR

This paper introduces a simplified radiation reaction model, compares it numerically to a more complex model and the Landau-Lifschitz force, and finds their predictions are very similar across various electromagnetic scenarios, with minimal trajectory differences.

Contribution

A new reduced radiation reaction model is developed and systematically compared to existing models and the Landau-Lifschitz force through numerical simulations.

Findings

Deviations between models are small in tested regimes.

The reduced model's integrator is more efficient computationally.

Trajectory differences due to model choice are negligible.

Abstract

In recent work we presented an explicit and non-perturbative derivation of the classical radiation reaction force for a cut-off modelled by a special choice of tubes of finite radius around the charge trajectories. In this paper, we provide a further, simpler and so-called reduced radiation reaction model together with a systematic numerical comparison between both the respective radiation reaction forces and the Landau-Lifschitz force as a reference. We explicitly construct the numerical flow for the new forces and present the numerical integrator used in the simulations, a Gauss-Legendre method adapted for delay equations. For the comparison, we consider the cases of a constant electric field, a constant magnetic field, and a plane wave. In all these cases, the deviations between the three force laws are shown to be small. This excellent agreement is an argument for plausibility of both new equations but also means that an experimental differentiation remains hard. Furthermore, we discuss the effect of the tube radius on the trajectories, which turns out to be small in the regarded regimes. We conclude with a comparison of the numerical cost of the corresponding integrators and find that the integrator of the reduced radiation reaction to be numerically most and the integrator of Landau-Lifschitz least efficient.