Ion distribution functions in magnetotail reconnection: global hybrid-Vlasov simulation results

Abstract. We present results of noon–midnight meridional plane global hybrid-Vlasov simulations the magnetotail ion dynamics under a steady southward interplanetary magnetic field using Vlasiator model. The simulation show reconnection and formation earthward tailward fast plasma outflows. approach allows us to study velocity distribution functions (VDFs) that are self-consistently formed during evolution. examine VDFs collected by virtual detectors placed along equatorial within outflows around quasi-steady X line in at X≈-14RE. This follow evolution motion reconnected flux tubes as well signatures unmagnetized weak near line. indicate actions Fermi-type betatron acceleration mechanisms, electric field, Speiser-type ions simulated compared good agreement with observed Time History Events Macroscale Interactions Substorms (THEMIS) Acceleration, Reconnection, Turbulence Electrodynamics Moon's Interaction Sun (ARTEMIS) spacecraft. find become more gyrotropic but retain transverse anisotropy counterstreaming beams when being convected earthward. presented valuable for understanding physical processes reconnection, interpretation situ observations, future mission development setting requirements on pitch angle energy resolution upcoming instruments.