Mirror Instability in the Turbulent Solar Wind
Abstract
The relationship between a decaying strong turbulence and the mirror instability in a slowly expanding plasma is investigated using two-dimensional hybrid expanding box simulations. We impose an initial ambient magnetic field perpendicular to the simulation box, and we start with a spectrum of large-scale, linearly polarized, random-phase Alfvénic fluctuations that have energy equipartition between kinetic and magnetic fluctuations and a vanishing correlation between the two fields. A turbulent cascade rapidly develops, magnetic field fluctuations exhibit a Kolmogorov-like power-law spectrum at large scales and a steeper spectrum at sub-ion scales. The imposed expansion (taking a strictly transverse ambient magnetic field) leads to the generation of an important perpendicular proton temperature anisotropy that eventually drives the mirror instability. This instability generates large-amplitude, nonpropagating, compressible, pressure-balanced magnetic structures in a form of magnetic enhancements/humps that reduce the perpendicular temperature anisotropy.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 2017
- DOI:
- 10.3847/1538-4357/aa67e0
- arXiv:
- arXiv:1703.07377
- Bibcode:
- 2017ApJ...838..158H
- Keywords:
-
- instabilities;
- solar wind;
- turbulence;
- waves;
- Physics - Space Physics;
- Astrophysics - Solar and Stellar Astrophysics;
- Physics - Plasma Physics
- E-Print:
- ApJ, 7 pages, 9 figures. arXiv admin note: text overlap with arXiv:1508.03159