Experimental Characterizationof the Magnetic Flucuations in the Magnetosheath: Cluster-Staff data and K-Filtering Method.

Magnetic turbulence in the magnetosheath certainly plays an important role in the transfers between the solar wind and the magnetosphere. A few theoretical models exist for interpreting the role of the magnetic fluctuations in these transfers, but experimental constraints are now needed in order to decide between them and allow to go further. The K-filtering method devoted to the three dimensional description of the electromagnetic field from multi-measurements points has been validated for the case of monochromatic plane waves (see the presentation of J.L Pinçon). We applied this method to the Cluster-STAFF data and we present the preliminary results on the direct determination of the field energy distribution in the (w,k) space in the magnetosheath and the vicinity of the magnetopause. This experimental determination of the dispersion relation of the fluctuations should allow to test the validity of the wave-wave interaction hypothesis, which is adopted in a theoretical model in course of construction, based on the of the Weak/Wave Turbulence Theory of the Hall-MHD system.