The electric field and global electrodynamics of the magnetosphere: Review and Quadrennial Report to the IUGG

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Abstract
When the radiation belt was discovered some 20 years ago, its very existence posed a fundamental problem. The way the geomagentic field managed to trap and to hold particles was readily explained—but what processes energized them in the first place, and how were they brought into their trapped orbits?As our knowledge about the Earth's environment increased it became evident that similar questions also applied to other plasma populations such as those of the ring current and of the plasma sheet. In most cases, it turned out, both the particles' energization and their transport were provided by a large‐scale electric field , permeating the magnetosphere. The “main” part of , oriented roughly from dawn to dusk (near the equatorial plane), is the one responsible for a large‐scale sunward plasma flow (“convection”) found throughout most of the magnetosphere. In addition, the various sources of accelerate charged particles in several distinct ways, maintain a global system of electric currents linking the magnetosphere with the ionosphere [Potemra, 1979] and transfer energy from the solar wind to the magnetosphere. For more complete details the reader is referred to a recent review by Stern [1977].