Theoretical Building Blocks

Abstract

The previous chapter provided a comprehensive overview of the visible auroral forms, emphasizing our main interest in understanding auroral arcs. The visible aurora is merely the tip of an iceberg leading into the plasma physical phenomena that are taking place in the near-Earth environment. Out along the magnetic field lines that connect to the auroral, it is a rich and exotic world. The visible aurorae are produced by particle precipitation from the magnetosphere into the atmosphere, but the structure is produced by particle acceleration through complex electric fields. At least two major regions are essential in producing auroral forms: a generator region located far out in the magnetosphere, where magnetospheric energy is tapped to power the aurora, and an acceleration region located some 1000s of km above the atmosphere, where electrical energy is converted into particle kinetic energy.