1 After the solar proton events, the enhanced proton intensities of the Inner Radiation Belt decreased gradually to their stationary level.

2 But some astronomers always suspected that the remaining antiprotons must become trapped by the Earth's magnetic field, forming an antiproton radiation belt.

3 Explorer 1, the first satellite sent into orbit by the U. S. , discovered the innermost Van Allen radiation belt.

4 It is supposed that the main phase is caused by the ring current of the "storm belt" situated outside the centre of the radiation belt and consisted of solar plasma penetrating into the magnetosphere.

5 Instruments on board have additional shielding because this is in the outer reaches of the Earth's radiation belt where levels can be quite high.

6 For the typical high energy electron spectrum in outer radiation belt, the charging time for dielectrics is of the order of an hour.