Explaining the rolling‐pin distribution of suprathermal electrons behind dipolarization fronts. Issue 13 (3rd July 2017)

• Record Type: Journal Article
• Authors: Liu, C. M.; Fu, H. S.; Xu, Y.; Cao, J. B.; Liu, W. L.
• Is Part Of: Geophysical research letters. Volume 44:Issue 13(2017)
• Page Start: 6492
• Page End: 6499
• Publication Date: 2017-07-03
• Subjects: rolling pin distribution -- dipolarization front -- suprathermal electrons -- Fermi acceleration -- betatron acceleration -- energy threshold; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2017GL074029
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: The rolling‐pin distribution of suprathermal electrons (40–200 keV), showing electron pitch angles primarily at 0°, 90°, and 180°, has recently been reported behind dipolarization fronts (DFs) both in observations and simulations. The formation of such type of distribution, however, has been unclear so far. In this study, we present an observation of such type of distribution by Cluster in the magnetotail behind a DF. We interpret the formation of such distribution using the global‐scale Fermi acceleration together with local‐scale betatron acceleration. We quantitatively reproduce these two processes and therefore the rolling‐pin distribution of suprathermal electrons using an analytical model. We further reveal that only at energies higher than 26 keV can such distribution be formed. This study, quantitatively explaining the formation of rolling‐pin distribution, can improve the understanding of electron dynamics behind DFs. Key Points: The rolling pin distribution of suprathermal electrons is studied It is a consequence of global‐Fermi and local‐betatron acceleration It can only be formed at energies higher than 26 keV