Reconnection flow jets in 3D as a source of structured dipolarization fronts

Abstract

Three-dimensional electromagnetic particle-in-cell simulations are used to investigate the propagation and breakup of a reconnection flow jet of initial cross-tail extent 24 d i (1.5R E ; d i is the ion inertial length). Such a front is found to separate into two segments, with the dawnward portion propagating ahead of the duskward one. Both segments expand duskward, reaching separate lengths of 18-25 d i, and both segments develop internal structures on east-west scales of 1-2 d i . The currents responsible for the ramp up of B z at the fronts are confined to narrow (d i ) ribbons whose localization is primarily associated with the electron U ey flow. The incoming ion flow is slowed down and deflected duskward at the front, and ambient ions are reflected back from the moving front. These processes create regions of enhanced T ixx both downstream and upstream of the front, while there is a local minimum at the front itself. These results help to explain the prevalence of 1R E flow jets in the plasma sheet.