Articles | Volume 29, issue 10
Ann. Geophys., 29, 1917–1925, 2011

Special issue: Cluster 10th anniversary workshop

Ann. Geophys., 29, 1917–1925, 2011

Regular paper 28 Oct 2011

Regular paper | 28 Oct 2011

Suprathermal electron acceleration during reconnection onset in the magnetotail

A. Vaivads1, A. Retinò2,3, Yu. V. Khotyaintsev1, and M. André1 A. Vaivads et al.
  • 1Swedish Institute of Space Physics, Uppsala, P.O. Box 537, 751 21 Uppsala, Sweden
  • 2Laboratoire de Physique des Plasmas, Laboratoire de Physique des Plasmas, CNRS-Ecole Polytechnique-UPMC, Observatoire de Saint-Maur, 4 avenue de Neptune, 94107 Saint-Maur-des-Fossés, France
  • 3Space Research Institute, Austrian Academy of Sciences, Graz, Austria

Abstract. We study one event of reconnection onset associated to a small substorm on 27 September 2006 by using Cluster observations at inter-spacecraft separation of about 10 000 km. We focus on the acceleration of suprathermal electrons during different stages of reconnection. We show that several distinct stages of acceleration occur: (1) moderate acceleration during reconnection of pre-existing plasma sheet flux tubes, (2) stronger acceleration during reconnection of lobe flux tubes, (3) production of the most energetic electrons within dipolarization fronts (magnetic pile-up regions). The strongest acceleration is reached at the location of Bz maxima inside the magnetic pile-up region where the reconnection jet stops. Very strong localized dawn-dusk electric field are observed within the magnetic pile-up regions and are associated to most of the magnetic flux transport.