Decades of space exploration have demonstrated that, the space environment is not empty and not homogeneous. Regarding electric aspects, it is characterized by the presence of a plasma, the characteristics of which are extremely variables both temporally and spatially.
In the near-Earth region, the plasma is structured by the geomagnetic
field that constitutes a cavity, called the magnetosphere, in the
interplanetary medium, i.e. the solar wind. The external limit of
the magnetosphere is the magnetopause.
The different regions are sketched in Figure 1.