Using the maximum entropy distribution to describe electrons in reconnecting current sheets

TL;DR

This paper applies the maximum entropy fluid closure to reconstruct electron distributions in reconnection regions, capturing general features but not all details, and compares it to traditional methods.

Contribution

It demonstrates the use of maximum entropy closure for modeling electron distributions in reconnection regions, highlighting its advantages over Grad closure.

Findings

Reconstructed distributions match general structure

Maximum entropy closure outperforms Grad closure in stability

Finer details of distributions are not captured

Abstract

Particle distributions in weakly collisional environments such as the magnetosphere have been observed to show deviations from the Maxwellian distribution. These can often be reproduced in kinetic simulations, but fluid models, which are used in global simulations of the magnetosphere, do not necessarily capture any of this. We apply the maximum entropy fluid closure of Levermore, which leads to well posed moment equations, to reconstruct particle distributions from a kinetic simulation in a reconnection region. Our results show that without information other than the moments, the model can reproduce the general structure of the distributions but not all of the finer details. The advantages of the closure over the traditional Grad closure are also discussed.