Articles | Volume 33, issue 12
Regular paper
01 Dec 2015
Regular paper |  | 01 Dec 2015

Comparisons of electron acceleration efficiency among different structures during magnetic reconnection: a Cluster multicase study

M. Zhou, T. Li, X. Deng, S. Huang, and H. Li

Abstract. Magnetic reconnection has long been believed to be an efficient engine for energetic electrons production. Four different structures have been proposed for electrons being energized: flux pileup region, density cavity located around the separatrix, magnetic island and thin current sheet. In this paper, we compare the electron acceleration efficiency among these structures based on 12 magnetotail reconnection events observed by the Cluster spacecraft in 2001–2006. We used the flux ratio between the energetic electrons (> 50 keV) and lower energy electrons (< 26 keV) to quantify the electron acceleration efficiency. We do not find any specific sequence in which electrons are accelerated within these structures, though the flux pileup region, magnetic island and thin current sheet have higher probabilities to reach the maximum efficiency among the four structures than the density cavity. However, the most efficient electron energization usually occurs outside these structures. We suggest that other structures may also play important roles in energizing electrons. Our results could provide important constraints for the further modeling of electron acceleration during magnetic reconnection.

Short summary
Electron energization is an outstanding issue in magnetic reconnection, which is a hot topic in plasma physics and astrophysics. Four different structures have been proposed for electron energization during reconnection. We find that there is no specific sequence of electron energization through the four structures; there is no specific order of electron acceleration efficiency among the four structures, and electron energization occurs in a wide region around X-line.