The Particle Environment in Space

Abstract

This article reviews the charged and neutral particles in the solar system and particularly in the vicinity of Earth. The average values and ranges of the parameters characterizing the charged particle flux from the sun (the solar wind), mainly protons and electrons, are given and also the correlations between the parameters for large scale fluctuations. Aerodynamics calculations give the physical conditions of the shocked solar wind plasma in the region between the Earth’s bow shock and the boundary with the geomagnetic cavity. The charged particle population inside the geomagnetic cavity and the geomagnetic tail is highly structured both in its spatial distribution and in energy. The average properties and dynamical behavior of the polar cusp, plasma sheet, ring current, and plasmasphere populations are described. Models and dynamical behavior of the neutral particles in the Earth’s exosphere are given.