Plasma Sheet Dynamics: Effects on, and Feedback from, the Polar Ionosphere

Abstract

The plasma sheet as a distinct region of the terrestrial magnetosphere historically was first identified in the observations of plasma and energetic particles; in a systematic approach appropriate to a tutorial lecture, it is more conveniently described by reference to the configuration of the magnetic field. The magnetic field lines within the magnetosphere can be divided into two broad morphological classes: the basically dipolar (although sometimes significantly distorted) field lines of the inner magnetosphere, and the highly stretched-out field lines of the magnetotail. The plasma sheet lies in between and occupies the region of transition between these two classes of field lines; it may be viewed as a very broad boundary layer separating the inner magnetosphere from the geomagnetic tail and at the same time separating the two lobes of the magnetotail from each other. Figure 1 schematically illustrates the configuration of the plasma sheet in the noon-midnight meridian plane.