Substorms, dipolarization, and particle acceleration
A combination of MHD, PIC, and test particle simulations is used to describe the dynamic evolution of the magnetotail, associated with substorms and other dipolarization events. Quasistatic theory, MHD and PIC simulations demonstrate the formation of thin current sheets, embedded in the wider plasma sheet, as a consequence of changes enforced by the interaction with the solar wind. PIC simulations then demonstrate self-consistently the transition to the onset of tearing instability and magnetic reconnection, causing fast plasma flows and dipolarization. The evolution of flow bursts, dipolarization, and their consequences are then followed by MHD simulations. These simulations form the basis of test particle orbit integrations, which provide detailed information on acceleration mechanisms, sources, and phase space distributions, which compare favorably with THEMIS and MMS observations.