Inner Magnetospheric Coupling: A Tutorial

Abstract:

Early observations of the Earth’s radiation environment showed that the Van Allen belts could be delineated into an inner zone dominated by high-energy protons and an outer zone dominated by high-energy electrons. These studies showed that electrons in the energy range 100 keV < E< 1 MeV often populated both the inner and outer zones with a pronounced “slot” region relatively devoid of energetic electrons existing between them. The energy distribution, spatial extent and particle species makeup of the Van Allen belts has been subsequently explored by several space missions and are found to be controlled by solar wind forcings and plasma wave properties. In fact, the overwhelming evidence from space missions such as the highly successful Van Allen Probes dual-spacecraft program is that the plasmasphere, the extraterrestrial ring current, and substorm processes originating within the Earth’s magnetotail all play intimate and indispensable roles in the radiation belt behavior. Waves and magnetic field changes provided by wide ranging plasma physical processes couple with the highest energy particles in fascinating ways. We conclude from these recent measurements that Earth’s inner magnetosphere constitutes an amazing laboratory to study energetic particle acceleration, transport, and loss – all driven by powerful solar wind interactions and complex wave-particle couplings.