Nonlinear theory of mirror instability near threshold

TL;DR

This paper develops an asymptotic nonlinear model for mirror instability in magnetized plasmas, revealing subcritical bifurcation behavior and formation of small-scale magnetic structures near the instability threshold.

Contribution

It introduces a new asymptotic model based on perturbative expansion of drift kinetic and Maxwell equations to analyze mirror instability nonlinear dynamics.

Findings

Mirror modes exhibit subcritical bifurcation near threshold.

Small-scale magnetic structures form with amplitudes comparable to the ambient field.

The model captures nonlinear behavior close to the instability threshold.

Abstract

An asymptotic model based on a reductive perturbative expansion of the drift kinetic and the Maxwell equations is used to demonstrate that, near the instability threshold, the nonlinear dynamics of mirror modes in a magnetized plasma with anisotropic ion temperatures involves a subcritical bifurcation,leading to the formation of small-scale structures with amplitudes comparable with the ambient magnetic field.