 |
| Titel |
Fluid simulations of space plasmas at ion scales |
| VerfasserIn |
Pierre-Louis Sulem, Thierry Passot, Dimitri Laveder, Pierre Henri |
| Konferenz |
EGU General Assembly 2014
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250088740
|
| Publikation (Nr.) |
 EGU/EGU2014-2884.pdf |
|
|
|
|
|
| Zusammenfassung |
| We present three-dimensional simulations of turbulence in collisionless plasmas in the
absence of cyclotron resonance, by using a fluid model which extends the anisotropic MHD
to transverse scales comparable to or smaller than the ion gyroradius. Retaining ion and
electron Landau damping and finite Larmor radius(FLR) corrections, this model provides an
accurate description of the linear properties of kinetic Alfvén waves and, in the presence of
temperature anisotropy, accurately reproduces the mirror instability at all scales. Simulations
of turbulence with Alfvénic driving lead to power law spectra for the electric and magnetic
fields which compare well with Solar Wind data. It turns out that, at least in the regimes
where the turbulence level is moderate, the dissipation due to ion and electron Landau
dampings permits simulations without filtering or artificial dissipation, leading
to power-law spectra extending to the smallest retained scales. In physical space,
density fluctuations take the form of elongated filaments. Similar structures are
also observed after the saturation of the mirror instability. However, the magnetic
compressibility spectrum displayed by this "mirror" turbulence, that possibly develops in
planetary magnetosheaths, differs significantly from that of Alfvénic turbulence. |
|
|
|
|
|
|