Articles | Volume 16, issue 2
Nonlin. Processes Geophys., 16, 275–285, 2009
https://doi.org/10.5194/npg-16-275-2009

Special issue: Coupling between large and small scale turbulence in space...

Nonlin. Processes Geophys., 16, 275–285, 2009
https://doi.org/10.5194/npg-16-275-2009

  08 Apr 2009

08 Apr 2009

Alfvén wave filamentation and dispersive phase mixing in a high-density channel: Landau fluid and hybrid simulations

D. Borgogno1, P. Hellinger2, T. Passot1, P. L. Sulem1, and P. M. Trávníček2 D. Borgogno et al.
  • 1Université de Nice Sophia Antipolis, CNRS, Observatoire de la Côte d'Azur, B.P. 4229, 06304 Nice Cedex 4, France
  • 2Institute of Atmospheric Physics and Astronomical Institute, AS CR Bocni II/1401, 14131 Prague, Czech Republic

Abstract. The propagation of dispersive Alfvén waves in a low-beta collisionless plasma with a high-density channel aligned with the ambient magnetic field, is studied in three space dimensions. A fluid model retaining linear Landau damping and finite Larmor radius corrections is used, together with a hybrid particle-in-cell simulation aimed to validate the predictions of this Landau-fluid model. It is shown that when the density enhancement is moderate (depending on the pump wavelength and the plasma parameters), the wave energy concentrates into a filament whose transverse size is prescribed by the dimension of the channel. In contrast, in the case of a stronger density perturbation, the early formation of a magnetic filament is followed by the onset of thin helical ribbons and the development of strong gradients. This "dispersive phase mixing" provides a mechanism permitting dissipation processes (not included in the present model) to act and heat the plasma.