Amplitude limits and nonlinear damping of shear-Alfvén waves in high-beta low-collisionality plasmas

J. Squire, A. A. Schekochihin, E. Quataert

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

This work, which extends Squire et al (Astrophys. J. Lett. 2016 830 L25), explores the effect of self-generated pressure anisotropy on linearly polarized shear-Alfvén fluctuations in low-collisionality plasmas. Such anisotropies lead to stringent limits on the amplitude of magnetic perturbations in high-β plasmas, above which a fluctuation can destabilize itself through the parallel firehose instability. This causes the wave frequency to approach zero, 'interrupting' the wave and stopping its oscillation. These effects are explored in detail in the collisionless and weakly collisional 'Braginskii' regime, for both standing and traveling waves. The focus is on simplified models in one dimension, on scales much larger than the ion gyroradius. The effect has interesting implications for the physics of magnetized turbulence in the high-β conditions that are prevalent in many astrophysical plasmas.

Original languageEnglish (US)
Article number055005
JournalNew Journal of Physics
Volume19
Issue number5
DOIs
StatePublished - May 2017
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Keywords

  • Alfvén waves
  • collisionless plasma
  • firehose instability
  • high-beta plasma
  • magnetized turbulence
  • pressure anisotropy

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