Firehose and Mirror Instabilities in a Collisionless Shearing Plasma
By Matthew W. Kunz, A. Schekochihin, James M. Stone. 2014
163 citations recorded by the source corpus.
Hybrid-kinetic numerical simulations of firehose and mirror instabilities in a collisionless plasma are performed in which pressure anisotropy is driven as the magnetic field is changed by a persistent linear shear $S$. For a decreasing field, it is found that mostly oblique firehose fluctuations grow at ion Larmor scales and saturate with energies $\sim$$S^{1/2}$; the pressure anisotropy is pinned at the stability threshold by particle scattering off microscale fluctuations. In contrast, nonlinear mirror fluctuations are large compared to the ion Larmor scale and grow secularly in time; marginality is maintained by an increasing population of resonant particles trapped in magnetic mirrors. After one shear time, saturated order-unity magnetic mirrors are formed and particles scatter off their sharp edges. Both instabilities drive sub-ion-Larmor--scale fluctuations, which appear to be kinetic-Alfven-wave turbulence. Our results impact theories of momentum and heat transport in astrophysical and space plasmas, in which the stretching of a magnetic field by shear is a generic process.
Subfields: Astronomy and Astrophysics
View Paper: https://www.semanticscholar.org/paper/a934bd1281e0cf02057dc5c4ad2da87e63f20757
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In Astronomy and Astrophysics
Citations in the corpus
- A new bound on axion-like particles (2017, background): “For example, kinetic-numerical simulations indicate that mirror and firehose instabilities driven by shear in the turbulent cluster plasma can generate field fluctuations of order δB/B0 ' 1 on scales comparable to the ion Larmor radius [53], which is microscopic compared to the coherence scales infe”