The oblique firehose instability in a bi-kappa magnetized plasma

Abstract

In this work, we derive a dispersion equation that describes the excitation of the oblique (or Alfvén) firehose instability in a plasma that contains both electron and ion species modelled by bi-kappa velocity distribution functions. The equation is obtained with the assumptions of low-frequency waves and moderate to large values of the parallel (respective to the ambient magnetic field) plasma beta parameter, but it is valid for any direction of propagation and for any value of the particle gyroradius (or Larmor radius). Considering values for the physical parameters typical to those found in the solar wind, some solutions of the dispersion equation, corresponding to the unstable mode, are presented. In order to implement the dispersion solver, several new mathematical properties of the special functions occurring in a kappa plasma are derived and included. The results presented here suggest that the superthermal characteristic of the distribution functions leads to reductions to both the maximum growth rate of the instability and of the spectral range of its occurrence.

References in corpus (6)

• The Electron Temperature and Anisotropy in the Solar Wind. I. Comparison of the Core and Halo Populations
• Predicted Impacts of Proton Temperature Anisotropy on Solar Wind Turbulence
• A Majority of Solar Wind Intervals Support Ion-Driven Instabilities
• Obliquely propagating electromagnetic waves in magnetized kappa plasmas
• The general dielectric tensor for bi-kappa magnetized plasmas
• Electromagnetic ion-cyclotron instability in a dusty plasma with product-bi-kappa distributions for the plasma particles

Cited by in corpus (2)

• Linear Dispersion Theory of Parallel Electromagnetic Modes for Regularized Kappa-Distributions
• Electron Weibel instability and~quasi-magnetostatic structures in~an~expanding collisionless plasma