Dynamics of radiating particles in current sheets with a transverse magnetic field component

TL;DR

This paper develops an analytical model to understand how radiation reaction influences the motion of particles in current sheets with a transverse magnetic field, relevant for extreme plasma structures created by high-intensity laser interactions.

Contribution

The authors extend the quasiadiabatic approach to include radiation reaction effects in 3D particle motion, deriving (quasi)invariants that simplify the analysis of dissipative particle dynamics.

Findings

Derived evolution equations for (quasi)invariants under radiation losses

Reduced the particle motion system from six to two dimensions

Provided a framework applicable to various problems involving radiation reaction

Abstract

Upcoming multipetawatt laser facilities are capable of inducing effects of quantum electrodynamics (QED) in laser-plasma interaction such as strong radiation reaction and QED cascades, both of which can significantly influence the properties and dynamics of laser plasma. This can result in the formation of extreme plasma structures with unprecedented TG levels of quasistatic magnetic fields, for example current sheets or pinch configurations of nanometer scale or smaller. In such structures radiation losses can play a significant role, so the influence of radiation losses onto the evolution of extreme current sheets deserves a separate and thorough investigation. In the current work we develop an analytical model and extend the quasiadiabatic approach describing individual particle motion onto 3D particle motion in the case when radiation reaction is non-negligible. Given that particle motion is determined by (quasi)invariants of non-dissipative motion, we derive how these (quasi)invariants evolve under the influence of radiation losses, quantify this influence and obtain a (quasi)invariant of dissipative motion. This allows reducing the dimensionality of the system of differential equations describing particle motion to just two instead of six. It is also discussed how the presented method can be used in a wider range of problems.