The Formation of an Oxygen Wave by Magnetic Reconnection

Abstract

Oxygen of ionospheric origin is a ubiquitous particle species in magnetospheric dynamics. We investigate how an oxygen population influences magnetic reconnection and how it is energized, using particle-in-cell simulations. The oxygen population is inserted initially in the inflow region, at two equal distances above and below the current sheet, and as time evolves it is captured by the reconnection process. Three simulations with different initial oxygen temperature are investigated. As the oxygen gets involved, layers of high-oxygen density forms in a region bounded by the Hall electric field. These density striations consist of a quasi-steady horizontal layer and a dynamic, inclined, wavefront-like layer. The acceleration of the oxygen population is dominated by electric forces, as the oxygen remains approximately demagnetized for the relevant timescales of the simulation. We describe two mechanisms of oxygen acceleration that lead to these two different structures.