Earth Planets Space, Vol. 53 (No. 6), pp. 655-661, 2001
K. Arzner and M. Scholer
Centre for Interdisciplinary Plasma Science, Max-Planck-Institut für Extraterrestrische Physik, 85740 Garching, Germany
(Received June 5, 2000; Revised October 12, 2000; Accepted November 7, 2000)
Abstract: In a recent kinetic computer simulation (Arzner and Scholer, 2001), magnetotail reconnection was studied with emphasis on the kinetic (particle) aspect. Complementary, we focus in the present paper on the magnetic fields. Examples of time series of the magnetic field at a fixed position, as predicted for spacecraft probes, are given. Different spatial regions are classified according to their signatures in these time series, and criteria for the proximity to the reconnection point, the post-plasmoid plasma sheet (PPPS) and the boundary layer are derived. The kinetic simulation reveals an instability of the PPPS, which is discussed in terms of an anisotropic 3-layer fluid model with the free energy is provided by the velocity anisotropy (T|| > T) due to the simultaneous presence of inflowing lobe ions and outflowing ions deflected in the field reversal. In its nonlinear stage, this instability creates higher harmonics and finally leads to turbulence characterized by power law spatial and temporal spectra. The latter allow a direct comparison with GEOTAIL and AMPTE observations. It is found that the simulated and observed turbulence spectra agree well.