Guiding-center approximation in the diamagnetic ring current

Abstract

Guiding-center approximation for protons in the diamagnetic ring current is valid when two known conditions are satisfied. The critical energies, magnetic rigidities, and pitch angles in the geomagnetic field and the field of the ring current are studied, and the results are applied, as an example, to a model ring current belt proposed by Akasofu and Chapman. It is found that protons with energies 20–40 kev are most likely to be responsible for the belt. The lifetime of these protons in the ring current belt is estimated at 10 days, as observed on the magnetograms. The pp pulsations may, as it seems, be the cause of magnetic scattering of the ring current. This is suggested on the basis of the coincidence of commencements of pp pulsations observed by Troitskaya and the quicker increase of the H force during the main phase at equatorial magnetic stations.