Scenarios for magnetic X-point collapse in 2D incompressible dissipationless extended magnetohydrodynamics

Fuente: arXiv
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Main Author: Brizard, Alain J.
Format: Preprint
Published: 2025
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author Brizard, Alain J.
author_facet Brizard, Alain J.
contents The equations of 2D incompressible dissipationless extended magnetohydrodynamics (XMHD) extend the equations of incompressible Hall MHD (HMHD) by retaining finite-electron inertia. These XMHD equations couple the fluid velocity ${\bf V} = \wh{\sf z}\btimes\nablaϕ+ V_{z}\,\wh{\sf z}$ with the magnetic field ${\bf B} = \nablaψ\btimes\wh{\sf z} + B_{z}\,\wh{\sf z}$ in a process that is known to support dissipationless solutions that exhibit finite-time singularities associated with magnetic X-point collapse in the magnetic plane $(B_{x} = \partialψ/\partial y, B_{y} = -\,\partialψ/\partial x)$. Here, by adopting a 2D self-similar model for the four XMHD fields $(ϕ,ψ,V_{z},B_{z})$, we obtain five coupled ordinary differential equations that are solved in terms of the Jacobi elliptic functions based on an orbital classification associated with particle motion in a quartic potential. Excellent agreement is found when these analytical solutions are compared with numerical solutions, including the precise time of a magnetic X-point collapse.
format Preprint
id arxiv_https___arxiv_org_abs_2504_07311
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Scenarios for magnetic X-point collapse in 2D incompressible dissipationless extended magnetohydrodynamics
Brizard, Alain J.
Plasma Physics
Mathematical Physics
The equations of 2D incompressible dissipationless extended magnetohydrodynamics (XMHD) extend the equations of incompressible Hall MHD (HMHD) by retaining finite-electron inertia. These XMHD equations couple the fluid velocity ${\bf V} = \wh{\sf z}\btimes\nablaϕ+ V_{z}\,\wh{\sf z}$ with the magnetic field ${\bf B} = \nablaψ\btimes\wh{\sf z} + B_{z}\,\wh{\sf z}$ in a process that is known to support dissipationless solutions that exhibit finite-time singularities associated with magnetic X-point collapse in the magnetic plane $(B_{x} = \partialψ/\partial y, B_{y} = -\,\partialψ/\partial x)$. Here, by adopting a 2D self-similar model for the four XMHD fields $(ϕ,ψ,V_{z},B_{z})$, we obtain five coupled ordinary differential equations that are solved in terms of the Jacobi elliptic functions based on an orbital classification associated with particle motion in a quartic potential. Excellent agreement is found when these analytical solutions are compared with numerical solutions, including the precise time of a magnetic X-point collapse.
title Scenarios for magnetic X-point collapse in 2D incompressible dissipationless extended magnetohydrodynamics
topic Plasma Physics
Mathematical Physics
url https://arxiv.org/abs/2504.07311