Spatial Distribution of Energetic Electrons during Magnetic Reconnection

Electron acceleration by the inductive electric field near the X point in magnetic reconnection is an important generation mechanism for energetic electrons. Particle simulations have revealed that most of energetic electrons reside in the magnetic field line pileup region, and a depletion of energetic electrons can be found near the centre of the diffusion region [Phys. Plasmas, 13 (2006) 012309]. We report direct measurement of energetic electron in and around the ion diffusion region in near-Earth tail by the cluster, and our observations confirm the above predictions: a depletion of the high-energy electron fluxes is detected near the centre of the diffusion region. At the same time, the plasma temperature has a similar profile in the diffusion region. .