The Earth's plasmasphere is an inner part of the magnetosphere. It is a doughnut-shaped region of low energy charged particles (cold plasma) centred around the planet's equator and rotating along with it. It forms a plasma cloud that enshrouds the Earth. Its toroidal shape is determined by the magnetic field of Earth.
The plasmasphere is located above the ionosphere and extends outwards, with the outer boundary varying (depending on geomagnetic conditions). The size of the plasmasphere changes, depending on the solar wind – magnetosphere interaction.
The outer boundary of the plasmasphere is known as the plasmapause.