plasmasphere(redirected from plasmaspheres)
plasmasphere(plaz -mă-sfeer) A small toroidal region of plasma, primarily protons and electrons, that lies within the Earth's magnetosphere above the ionosphere. The plasma is produced by the action of the Sun's ultraviolet radiation and X-rays on molecules, etc., in the upper atmosphere. The plasmasphere is bounded by the plasmapause, where the plasma density drops abruptly.
A region of relatively dense, cold plasma surrounding the earth and extending out to altitudes of approximately 2 to 6 earth radii, composed predominantly of electrons and protons, with thermal energies not exceeding several electronvolts.