View in EDS

Two‐Dimensional Equilibrium Model of Planetary Magnetotail in Generalized Nonthermal Plasmas.

Saved in:
Bibliographic Details
Title: Two‐Dimensional Equilibrium Model of Planetary Magnetotail in Generalized Nonthermal Plasmas.
Authors: Hau, L.‐N.1,2 (AUTHOR) lnhau@jupiter.ss.ncu.edu.tw, Jao, C.‐S.3 (AUTHOR), Chang, C.‐K.1 (AUTHOR)
Source: Journal of Geophysical Research. Space Physics. Mar2026, Vol. 131 Issue 3, p1-20. 20p.
Subject Terms: Plasma equilibrium, Magnetotails, Magnetic reconnection, Non-thermal plasmas, Magnetosphere, Velocity distribution (Statistical mechanics), Solar wind, Plasma instabilities
Abstract: Solar wind‐magnetosphere interaction may result in an elongated magnetotail with stored magnetic field energy. This study presents for the first time a family of asymptotic solutions for stretched two‐dimensional magnetotail equilibrium in generalized nonthermal plasmas, including the Kappa‐like and Maxwellian‐like velocity distributions with distinct temperature profiles. In the kinetic equilibrium model, the thermal pressure as functions of magnetic vector potential p(A) $p(A)$ depends on the kinetic velocity distribution, which is a prescribed function in the MHD Grad‐Shafranov equation. The overall equilibrium structures may be computed using various p(A) $p(A)$ along with the equatorial pressure, density or magnetic field profiles. Thin current sheets with stretched tail‐like magnetic field configurations and small equatorial Bz ${B}_{z}$ may be constructed for various kinetic distributions with enhanced drift velocity and reduced central temperature. The equilibrium models may be used as the initial profiles for analyzing various fluid and kinetic plasma instabilities and magnetic reconnection. The theoretical models may be compared with the observations to infer the corresponding MHD and kinetic distributions. Plain Language Summary: Earth's and planetary magnetospheres possess elongated magnetotails, which store most of the magnetic field energy. Prior to the magnetospheric substorm, the field lines become more stretched and tail‐like, which tend to develop various plasma instabilities. It is generally believed that the magnetospheric substorm is associated with the conversion of magnetic field energy into kinetic and thermal energies in the magnetotail. The formation of thin currents with highly stretched magnetic field configurations has thus been one of the central issues of space plasma physics, which is essentially collisionless and not in thermal equilibrium. In this study, we examine the magnetotail equilibrium in nonthermal plasmas by incorporating the widely observed nonthermal Kappa‐like and Maxwellian‐like velocity distributions. A family of stretched magnetotail equilibriums with thin current sheets may be used to study various plasma instabilities and magnetic field reconnections. Key Points: First study of two‐dimensional magnetotail equilibrium in nonthermal plasmasVarious non‐Maxwellian velocity distributions are incorporated in the modelsThe formulation may be used to construct the observation‐based global equilibrium models [ABSTRACT FROM AUTHOR]
Copyright of Journal of Geophysical Research. Space Physics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: GreenFILE
Description
Abstract:Solar wind‐magnetosphere interaction may result in an elongated magnetotail with stored magnetic field energy. This study presents for the first time a family of asymptotic solutions for stretched two‐dimensional magnetotail equilibrium in generalized nonthermal plasmas, including the Kappa‐like and Maxwellian‐like velocity distributions with distinct temperature profiles. In the kinetic equilibrium model, the thermal pressure as functions of magnetic vector potential p(A) $p(A)$ depends on the kinetic velocity distribution, which is a prescribed function in the MHD Grad‐Shafranov equation. The overall equilibrium structures may be computed using various p(A) $p(A)$ along with the equatorial pressure, density or magnetic field profiles. Thin current sheets with stretched tail‐like magnetic field configurations and small equatorial Bz ${B}_{z}$ may be constructed for various kinetic distributions with enhanced drift velocity and reduced central temperature. The equilibrium models may be used as the initial profiles for analyzing various fluid and kinetic plasma instabilities and magnetic reconnection. The theoretical models may be compared with the observations to infer the corresponding MHD and kinetic distributions. Plain Language Summary: Earth's and planetary magnetospheres possess elongated magnetotails, which store most of the magnetic field energy. Prior to the magnetospheric substorm, the field lines become more stretched and tail‐like, which tend to develop various plasma instabilities. It is generally believed that the magnetospheric substorm is associated with the conversion of magnetic field energy into kinetic and thermal energies in the magnetotail. The formation of thin currents with highly stretched magnetic field configurations has thus been one of the central issues of space plasma physics, which is essentially collisionless and not in thermal equilibrium. In this study, we examine the magnetotail equilibrium in nonthermal plasmas by incorporating the widely observed nonthermal Kappa‐like and Maxwellian‐like velocity distributions. A family of stretched magnetotail equilibriums with thin current sheets may be used to study various plasma instabilities and magnetic field reconnections. Key Points: First study of two‐dimensional magnetotail equilibrium in nonthermal plasmasVarious non‐Maxwellian velocity distributions are incorporated in the modelsThe formulation may be used to construct the observation‐based global equilibrium models [ABSTRACT FROM AUTHOR]
ISSN:21699380
DOI:10.1029/2025JA034861