Electron acceleration behind a wavy dipolarization front.

In this paper, with the in-situ observations from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) probes we report a wavy dipolarization front (DF) event, where the DF has different magnetic structures and electron distributions at different y<inline-graphic></inline-graphic> positions in the Geocentric Solar Magnetospheric (GSM) coordinates. At y∼2.1RE<inline-graphic></inline-graphic> (RE<inline-graphic></inline-graphic> is the radius of Earth), the DF has a relatively simple structure, which is similar to that of a conventional DF. At y∼3.0RE<inline-graphic></inline-graphic>, the DF is revealed to have a multiple DF structure, where the plasma exhibits a vortex flow. Such a wavy DF could be the results of the interchange instability. The different structure of such a wavy DF at different sites has a great effect on electron acceleration. Fermi acceleration can occur at the site of the DF with a simple or multiple DF structure, while betatron acceleration as a local process has the contribution to energetic electrons only at the site of the DF with a simple structure. [ABSTRACT FROM AUTHOR]