Non-linear mirror instability

F. Rincon, A. A. Schekochihin, S. C. Cowley

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

Slow dynamical changes in magnetic-field strength and invariance of the particles' magnetic moments generate ubiquitous pressure anisotropies in weakly collisional, magnetized astrophysical plasmas. This renders them unstable to fast, small-scale mirror and firehose instabilities, which are capable of exerting feedback on the macroscale dynamics of the system. By way of a new asymptotic theory of the early non-linear evolution of the mirror instability in a plasma subject to slow shearing or compression, we show that the instability does not saturate quasi-linearly at a steady, low-amplitude level. Instead, the trapping of particles in small-scale mirrors leads to non-linear secular growth of magnetic perturbations, δB/Bt2/3. Our theory explains recent collisionless simulation results, provides a prediction of the mirror evolution in weakly collisional plasmas and establishes a foundation for a theory of non-linear mirror dynamics with trapping, valid up to δB/B = O(1).

Original languageEnglish (US)
Pages (from-to)L45-L49
JournalMonthly Notices of the Royal Astronomical Society: Letters
Volume447
Issue number1
DOIs
StatePublished - Jan 1 2015
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Clusters
  • Instabilities-magnetic fields-MHD-plasmas-turbulence-solar wind-galaxies
  • Intracluster medium

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