Cluster encounter of a magnetic reconnection diffusion region in the near‐Earth magnetotail on September 19, 2003

Abstract

We report a clear encounter by the Cluster spacecraft of a magnetic reconnection diffusion region in the near‐Earth magnetotail at X GSM = −17.5 R E on September 19, 2003. In addition to the reversals of the plasma jets and of GSM‐z (∼normal) component of the magnetic field, clear signatures of Hall quadrupolar (GSM‐y) magnetic fields as well as bipolar Hall (GSM‐z) electric fields with amplitude up to 80 mV/m directed toward the neutral sheet in both hemispheres were observed. Furthermore, large fluctuations in the electric field perpendicular to the magnetic field with amplitudes reaching 65 mV/m were observed near the separatrices in both hemispheres and in association with local density minima.