Levy-Motion of Magnetic Field Vector tip in the Plasma Sheet Region: a Case Study

One of the keypoint in the understanding of the plasma transport in the geotail is represented by the topology of the magnetic field in this region. Recently, it has been suggested that the magnetic field topology in the magnetotail plasma and neutral sheet could be equivalent to a disorder medium consisting of coherent magnetic field and plasma structures immersed in a turbulent medium (Chang, 1999, 2001; Consolini and Chang, 2001). Here, we present a case study of the motion of the magnetic field vector tip as observed by INTERBALL Tail in the plasma and neutral sheet. We find the evidence of a Levy nature of the magnetic field fluctuations, showing long correlated jumps of the vector-tip. These results are discussed in relation with the existence of a complex magnetic field topology in the geotail regions as suggested by Chang (1999).