The structure of the outer radiation zone in a simple model of the convecting magnetosphere

Abstract

The variation of the hot plasma bulk parameters with L-value in the outer radiation zone can be obtained by using conservation of the first two adiabatic invariants and Liouville's theorem to ‘map’ a distribution function from its source at large L (i.e. in the plasmasheet) into the outer zone. This simple calculation is valid provided that all of velocity space is accessible to the source. However, for transport by convection electric fields this is not true, due to the formation of forbidden-zones in the flow. As a result, only certain regions of velocity space are accessible to the source, and marked changes in the distribution function are expected across these velocity-space boundaries. Such effects are seen in ring current data, and can be compared with the theoretical profiles.