ESA Science & Technology - A Cluster measurement of fast magnetic reconnection in the magnetotail

Publication date: 03 January 2007

Authors: Xiao, C.J. et al.

Journal: Geophysical Research Letters
Volume: 34
Issue: 1
CiteID: L01101
Year: 2007

Copyright: American Geophysical Union

Fast reconnection is crucial to magnetospheric substorms, solar and stellar flares and fusion plasmas. Ultimate confirmation of fast reconnection must be achieved by multi-spacecraft detections of the reconnection rate itself and associated dimensions of the diffusion region. Here we report a multi-spacecraft measurement of fast reconnection rate gamma_rec ~ V_in ~ (0.07-0.15)V_A based on directly measurements of the plasma flow into the diffusion region, where V_in is the speed of reconnecting flux and V_A the characteristic Alfvén speed. It falls in the range of ~(0.03-0.2)V_A predicted in steady state reconnection simulation. The characteristic sizes for the diffusion region of the width L_z ~ 0.9 d_i (= 460 km) and the length L_x ~ (3.3-5.1)d_i (= 1680-2597 km) are measured as well. The length of the diffusion region L_x is determined for the first time based on the in situ observations. Furthermore, other features detected during the event also match the previous observation and simulation results.