Ion dynamics in the magnetospheric flanks of Mercury - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Communication Dans Un Congrès Année : 2017

Ion dynamics in the magnetospheric flanks of Mercury

Sae Aizawa
N. Terada
  • Fonction : Auteur

Résumé

Because of a large velocity shear in the flanks of Mercury's magnetosphere, Kelvin-Helmholtz (KH) instability is expected to develop and to play a role in mass and momentum transport across the magnetopause. Using single particle simulations in field configurations obtained from MHD simulations, we investigate the dynamics of ions in this region. We focus on heavy ions of planetary origin (e.g., Na , K , Mg ) that may be found on either side of the magnetopause, due to the ionization of exospheric neutrals. Because characteristic spatial and temporal scales of KH instability at Mercury are comparable to or smaller than typical ion scales, we show that under such conditions the guiding center approximation is invalid and that planetary ions may be transported in a non-adiabatic (magnetic moment violation) manner. In this study, we focus on the effect of the electric field that develops within KH vortices. We show that the intensification rather than the change of orientation of this electric field is responsible for large (up to hundreds of eVs or a few keVs) energization of heavy planetary ions. This energization occurs systematically for particles with low initial energies in the perpendicular direction, the energy realized being of the order of the energy corresponding to the maximum ExB drift speed, εmax, in a like manner to a pickup ion process. It is also found that particles that have initial energies comparable to εmax may be decelerated depending upon gyration phase. Finally, we find that particles with initial perpendicular energies much larger than εmax are little affected during transport through KH vortices. We suggest that the development of KH instabilities in Mercury's magnetospheric flanks may lead to significant ion energization and pitch angle diffusion, and may thus play a prominent role in plasma mixing at the magnetopause.
Fichier non déposé

Dates et versions

hal-02796738 , version 1 (05-06-2020)

Identifiants

  • HAL Id : hal-02796738 , version 1

Citer

Sae Aizawa, Dominique Delcourt, N. Terada. Ion dynamics in the magnetospheric flanks of Mercury. American Geophysical Union, Fall Meeting 2017, Dec 2017, New Orleans, Louisiane, United States. pp.P51G-05. ⟨hal-02796738⟩
17 Consultations
0 Téléchargements

Partager

Gmail Facebook X LinkedIn More