Definitions for "Plasmasphere"
a region of relatively dense but cool plasma, surrounding Earth, extending to distances of about 5 Earth radii (RE). The plasmasphere is the upward extension of the Earth's ionosphere, getting less and less dense with increasing distance, and it shares the Earth's rotation.
The region of the atmosphere consisting of cold dense plasma originating in the ionosphere and trapped by the Earth's magnetic field.
A region of the inner magnetosphere that contains relatively cool (low energy) and dense plasma. This area can be considered an outer extension of the ionosphere.