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arXiv · 1108.1948

Kinetic simulations of magnetic reconnection in presence of a background O+ population

Stefano Markidis·Giovanni Lapenta·Lapo Bettarini·Martin V. Goldman·David Newman·Laila Andersson
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Abstract

Particle-in-Cell simulations of magnetic reconnection with an H+ current sheet and a mixed background plasma of H+ and O+ ions are completed using physical mass ratios. Four main results are shown. First, the O+ presence slightly decreases the reconnection rate and the magnetic reconnection evolution depends mainly on the lighter H+ ion species in the presented simulations. Second, the Hall magnetic field is characterized by a two-scale structure in presence of O+ ions: it reaches sharp peak values in a small area in proximity of the neutral line, and then decreases slowly over a large region. Third, the two background species initially separate in the outflow region because H+ and O+ ions are accelerated by different mechanisms occurring on different time scales and with different strengths. Fourth, the effect of a guide field on the O+ dynamics is studied: the O+ presence does not change the reconnected flux and all the characteristic features of guide field magnetic reconnection are still present. Moreover, the guide field introduces an O+ circulation pattern between separatrices that enhances high O+ density areas and depletes low O+ density regions in proximity of the reconnection fronts. The importance and the validity of these results are finally discussed.

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Stefano Markidis, Giovanni Lapenta, Lapo Bettarini, Martin V. Goldman, David Newman, Laila Andersson. 2011-08-09. Kinetic simulations of magnetic reconnection in presence of a background O+ population. https://doi.org/10.1029/2011ja016429

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