Charged-particle flux at heights of 200-300 KM above earth

The current status of investigations into the 'excess' charged-particle background observed at heights of 200 to 300 km is reviewed, with attention given to possible sources of the excess particles. Charged-particle motion in the geomagnetic field is analyzed, differential spectra are given for the different components of albedo cosmic rays, and satellite observations of the excess background are discussed. It is shown that: (1) the intensity of the excess corpuscular radiation is several times greater than that of primary cosmic rays; (2) the excess background is observed at heights where steady particle trapping is impossible, suggesting the existence of a source which continuously supplies the particles; (3) two possible sources are albedo cosmic rays and the unsteady trapping of particles which lose energy in the upper atmosphere; (4) the intensity of the excess background decreases with increasing particle energy and increases at higher latitudes; and (5) a significant portion of the excess background at midlatitudes can be attributed to an albedo origin.