Successive Dipolarization Fronts With a Stepwise Electron Acceleration During a Substorm in Saturn's Magnetotail

Substorms are a fundamental phenomenon in planetary magnetospheric systems. Using Cassini measurements, we report typical event which four successive dipolarization fronts (DFs) were observed within 1 hour during the substorm Saturn's magnetotail. The last three DFs caused type of stepwise electron acceleration and generated energetic electrons. pitch angle distributions electrons show evidence Fermi mechanism behind these DFs. Therefore, infer magnetotail dynamics process substorm: by powerfully accelerates field-aligned generates These high-energy injected into inner magnetosphere become an important trigger aurora. Our results efficient for confirm source particles Saturn, findings improve our understanding dynamics.