The near-Earth space enviroment is a complex interaction between Earth's magnetic field, cool plasma moving up from Earth's ionosphere, and hotter plasma coming in from the solar wind. This interactions combine to maintain the radiation belts around Earth. Plasma interactions can generate sharply delineated regions in these belts. In addition to the inner and outer radiation belts, the cooler plasma of the plasmasphere interacts so that it keeps out the higher-energy electrons from outside its b