Articles | Volume 22, issue 7
Ann. Geophys., 22, 2541–2546, 2004
https://doi.org/10.5194/angeo-22-2541-2004

Special issue: Spatio-temporal analysis and multipoint measurements in space...

Ann. Geophys., 22, 2541–2546, 2004
https://doi.org/10.5194/angeo-22-2541-2004

  14 Jul 2004

14 Jul 2004

Double peak structure and diamagnetic wings of the magnetotail current sheet

G. Zimbardo1,*, A. Greco1,*, P. Veltri1,*, A. L. Taktakishvili2, and L. M. Zelenyi3 G. Zimbardo et al.
  • 1Physics Department, University of Calabria, Ponte P. Bucci, Cubo 31C, I-87036 Rende, Italy
  • 2Abastumani Astrophysical Observatory, A. Kazbegi str., 2a, 380060, Tbilisi, Georgia
  • 3Space Research Institute, Profsoyuznaya 84/32, 117810 Moscow, Russia
  • *Also at Istituto Nazionale di Fisica della Materia, Unita’ di Cosenza, Italy

Abstract. Recent Cluster observations in the magnetotail at about 20 Earth radii downtail have unambiguously shown that sometimes the current sheet is bifurcated, i.e. it is divided in two layers. We report numerical simulations of the ion dynamics in a quasi-neutral sheet in the presence of magnetic turbulence, which is often observed in the magnetotail, and for various anisotropies of the ion distribution function. Ions are injected at the boundary of the simulation box with a velocity distribution corresponding to a shifted Maxwellian. The simulation parameters, are adjusted to be similar to those of Cluster observations. We find that even for moderate fluctuation levels, the computed current density profile develops a double peak, in agreement with the observations. By varying the anisotropy of the injected distribution function, we are able to reproduce, for weak anisotropy, the magnetic field overshoots which are sometimes observed prior to magnetotail traversals. Therefore, we suggest an ion current profile with a double peak due to magnetic turbulence, and with possible diamagnetic current wings, present in the case of weak anisotropy of the ion distribution function.