2-DIMENSIONAL HYBRID SIMULATIONS OF A MAGNETOSHEATH FILAMENT INTERACTION WITH THE MAGNETOPAUSE

Two-dimensional hybrid simulations are used to investigate the impulsi ve penetration process when a magnetosheath plasma irregularity intera cts with the magnetopause. The irregularity is modeled as a field-alig ned filament with an excess density impinging on the magnetopause. Dif ferent configurations are used defined by a parallel or anti-parallel magnetic field in both regions (magnetosheath and magnetosphere) and a lso in the case of sheared magnetic fields. The results show that a MH D approach is not totally usefull and emphasize the kinetic effects of the ions on the propagation of the plasma irregularities and their co nsequences on the energy balance between the two regions. Moreover, sh eared magnetic field configurations allow inferences about the actual solar wind - magnetosphere interaction and show that the threshold con ditions for penetration are much more restrictive than MHD results. Th is study strongly harms the impulsive penetration mechanism to explain the transfer of mass and energy from the magnetosheath to the magneto pshere.