Trapping Region and Currents due to Trapped Particles

Abstract

Although early descriptions of charged particle motion in the geomagnetic field were applied mainly to cosmic ray trajectories, geomagnetic storms, and auroral phenomena (Stormer, 1907, 1933, 1955; Chapman and Ferraro, 1931, 1932; Alfven, 1939, 1940, 1950; Singer, 1956, 1957a, b), the concept of charged particle trapping, the overall trapping region geometry in relation to a dipole magnetic field, and trapped particle motion within such a field were well understood quantitatively (see Chapter 2) before the discovery of the earth’s trapped radiation (Van Allen et al.,1958). Verification of the interpretation that the newly observed charged particles above the atmosphere were trapped geomagnetically came from a number of experiments, all of which demonstrated the direct control exerted by the earth’s magnetic field on the observed particle intensities. An early example of this is shown in Figure 3.1 (from Yoshida et al., 1960) where the ordering of the data by the earth’s magnetic field is clearly demonstrated.