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Force‐Free Current Sheets in the Jovian Magnetodisk: The Key Role of Electron Field‐Aligned Anisotropy.

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Title: Force‐Free Current Sheets in the Jovian Magnetodisk: The Key Role of Electron Field‐Aligned Anisotropy.
Authors: Artemyev, A. V.1 (AUTHOR) aartemyev@igpp.ucla.edu, Ma, Q.2,3 (AUTHOR), Ebert, R. W.4,5 (AUTHOR), Zhang, X.‐J.1,6 (AUTHOR), Allegrini, F.4,5 (AUTHOR)
Source: Journal of Geophysical Research. Space Physics. Mar2023, Vol. 128 Issue 3, p1-13. 13p.
Subject Terms: Current sheets, Magnetic field measurements, Electron configuration, Thermal electrons, Thermal instability, Anisotropy
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. Key Points: We report Juno observations of thin anisotropic current sheets in the Jovian magnetodiskThe contribution of electron streams to the current sheet stress balance is estimatedWe show force‐free current sheet configuration supported by strong electron field‐aligned currents [ABSTRACT FROM AUTHOR]
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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. Key Points: We report Juno observations of thin anisotropic current sheets in the Jovian magnetodiskThe contribution of electron streams to the current sheet stress balance is estimatedWe show force‐free current sheet configuration supported by strong electron field‐aligned currents [ABSTRACT FROM AUTHOR]
ISSN:21699380
DOI:10.1029/2022JA031280