The acceleration of electrons in the magnetotail and their auroral signatures

Magnetic reconnection in a magnetized plasma represents a change in the topology of the magnetic field and is associated with a concomitant energization of charged particles that results in a conversion of magnetic energy into particle energy. In the Earth´s magnetosphere, during southward interplanetary magnetic field, reconnection occurs first on the dayside then in the near Earth magnetotail. By using data from the THEMIS and Cluster missions together with global MHD and Large Scale Kinetic (LSK) particle simulations, we demonstrated that electrons were energized in two distinct regions: in the magnetotail: (1) a low energy population (up to a few keV) that arose in the reconnection region where particles were demagnetized and the magnetic topology changes and (2) a high energy component that was further energized by betatron acceleration within dipolarization fronts as they swept Earthward far from the diffusion region. In general it is concluded that particle energization in the Earth´s magnetotail during substorms is not associated solely with the conversion of magnetic to kinetic energy within the reconnection region, but also arises in conjunction with macroscopic flows(Ashour-Abdalla et al 2011).