Force-free current sheets in the Jovian magnetodisk: the key role of electron field-aligned anisotropy

TL;DR

This paper investigates a new type of force-free current sheet in Jupiter's magnetodisk, supported by electron field-aligned currents, which significantly influence magnetic field structure and stability.

Contribution

It introduces and analyzes a novel current sheet configuration supported by electron streams, highlighting their role in magnetic shear and force-free conditions.

Findings

Electron streams increase thermal anisotropy near fire-hose instability threshold.

Current sheets are nearly force-free with constant magnetic field across the sheet.

Juno measurements reveal detailed internal structure of these electron-supported current sheets.

Abstract

Current sheets are an essential element of the planetary magnetotails, where strong plasma currents self-consistently support magnetic field gradients. The current sheet configuration is determined by plasma populations that contribute to the current density. The most commonly investigated configuration is supported by diamagnetic cross-field currents of hot ions, typical for the magnetospheres of magnetized planets. In this study, we examine a new type of the current sheet configuration supported by field-aligned currents from electron streams in the Jovian magnetodisk. Such bi-directional streams increase the electron thermal anisotropy close to the fire-hose instability threshold and lead to strong magnetic field shear. The current sheet configuration supported by electron streams is nearly force-free, with B=const across the sheet. Using Juno plasma and magnetic field measurements, we investigate the internal structure of such current sheets and discuss possible mechanisms for their formation.