Linear and Nonlinear Instability in Two-Dimensional Inertial Magnetohydrodynamics
Abstract
We study spectral and nonlinear instability for some steady states of a two-dimensional inertial magnetohydrodynamic system on the torus. For equilibria with aligned velocity and magnetic fields, the linearized problem reduces to a matrix recurrence of Fourier coefficients, and a stable matrix continued fraction produces a smooth eigenmode. For a purely magnetic family, the square of the linearized operator admits a compact self-adjoint reduction on each transverse Fourier blocks that classifies the entire unstable spectrum. In an invariant symmetry class, we identify the unstable branches and a spectral gap below the leading eigenspace. The spectral gap then permits an approximate-trajectory construction that proves nonlinear instability on the logarithmic time scale. Our study is motivated by the physics literature, where the nonlinear instability of purely magnetic tearing modes is invoked to explain magnetic reconnection.
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BibTeX
@misc{choi2026linear,
title = {{Linear and Nonlinear Instability in Two-Dimensional Inertial Magnetohydrodynamics}},
author = {Hyungjun Choi},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.14366},
eprint = {2609.14366},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.14366},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Linear and Nonlinear Instability in Two-Dimensional Inertial Magnetohydrodynamics
AU - Hyungjun Choi
PY - 2026
DA - 2026/09/13
PB - arXiv
DO - 10.48550/arxiv.2609.14366
UR - https://arxiv.org/abs/2609.14366
AB - We study spectral and nonlinear instability for some steady states of a two-dimensional inertial magnetohydrodynamic system on the torus. For equilibria with aligned velocity and magnetic fields, the linearized problem reduces to a matrix recurrence of Fourier coefficients, and a stable matrix continued fraction produces a smooth eigenmode. For a purely magnetic family, the square of the linearized operator admits a compact self-adjoint reduction on each transverse Fourier blocks that classifies the entire unstable spectrum. In an invariant symmetry class, we identify the unstable branches and a spectral gap below the leading eigenspace. The spectral gap then permits an approximate-trajectory construction that proves nonlinear instability on the logarithmic time scale. Our study is motivated by the physics literature, where the nonlinear instability of purely magnetic tearing modes is invoked to explain magnetic reconnection.
ER -