Separatrices: the crux of reconnection

TL;DR

This paper investigates the role of separatrices in magnetic reconnection, highlighting their importance in plasma flow, energization, and instabilities in kinetic physics.

Contribution

It presents new insights into the processes occurring at separatrices that influence plasma dynamics during reconnection events.

Findings

Separatrices are critical layers where key plasma processes occur.

Reconnection involves energy release from magnetic to kinetic forms.

New results detail processes regulating plasma flow and energization at separatrices.

Abstract

Reconnection is one of the key processes in astrophysical and laboratory plasmas: it is the opposite of a dynamo. Looking at energy, a dynamo transforms kinetic energy in magnetic energy while reconnection takes magnetic energy and returns is to its kinetic form. Most plasma processes at their core involve first storing magnetic energy accumulated over time and then releasing it suddenly. We focus here on this release. A key concept in analysing reconnection is that of the separatrix, a surface (line in 2D) that separates the fresh unperturbed plasma embedded in magnetic field lines not yet reconnected with the hotter exhaust embedded in reconnected field lines. In kinetic physics, the separatrices become a layer where many key processes develop. We present here new results relative to the processes at the separatrices that regulate the plasma flow, the energisation of the species, the electromagnetic fields and the instabilities developing at the separatrices.