Energy conversion and particle transport by a dipolarization front in a global hybrid-Vlasov simulation

Dipolarization fronts (DFs) are transient structures occurring in Earth's magnetotail, characterized in spacecraft observations by sudden enhancements of the dipolar magnetic field component. Often linked to transient channels of fast earthward plasma flow, DFs are responsible for energy conversion, particle acceleration and magnetic flux transport. We investigate a DF event identified in a global hybrid-Vlasov simulation and study how it converts energy from electromagnetic fields to plasma flow and heat. We analyze velocity distribution functions associated with the event and trace test particles sampled from them. Our results indicate that non-compressional effects can be important to DF dissipation processes. Test particle tracing reveals that the DF actively replaces the local plasma population by transporting new particles into the region and displacing the pre-existing plasma, leading to a decoupling between the plasma properties before and after the front. The results may explain atypical temperature decreases reported in spacecraft observations of DFs.