Atypical current sheets and plasma bubbles: A self-consistent kinetic model

Abstract

As revealed by CLUSTER observations, thin current sheets in the magnetotail may strongly differ from the conventional Harris profile due to the effects of embedding and bifurcation. At the same time, they often have no signatures of collisionless magnetic reconnection. A universal phenomenon involving such atypical current sheets, which is connected but not identical to reconnection, is the formation of plasma bubbles. We present a self-consistent kinetic model of plasma bubbles based on a 2-D generalization of earlier atypical current sheet models that also takes into account the south-then-north sense of B _z perturbations typical for earthward traveling compression regions and fast flows in the central plasma sheet. The new model predicts that the dominant structural element of bubbles is a region of the local reduction of the cross-tail current provided by the current bifurcation effect.