ИСТИНА

It is considered traditionally that the appearance of relativistic electrons is one of the manifestations of the magnetic storms in the near-Earth environment. Here we present some events showing that the rate of the electron flux increase does not depend on the geomagnetic storm intensity and such increase can even occur without geomagnetic storm. Using the magnetic field and charged particle data from the GOES geostationary satellites the acceleration of the electrons with energies from 40 keV to > 2 MeV in the outer radiation belt is investigated. To characterize the magnetospheric wave activity in the Pc5 frequency range (1–7 mHz) the ULF index is used. The electron fluxes with lower energies start to grow earlier than fluxes of subrelativistic and relativistic electrons. The necessary condition of the electron acceleration to the relativistic energies is a prolong substorm activity which is accompanied by the injection of seed electrons (50–100 keV), generation of VLF waves, and the occurrence of the high speed solar wind streams promoting the Pc5 wave generation. The correlation between the periods with the high solar wind speed and growth of the relativistic electron fluxes with a 1–2 days delay confirms the idea about the important role of the drift resonance of the magnetospheric electrons with MHD waves in the Pc5 frequency range. The resonant interaction between them leads to the electron radial diffusion deep into the magnetosphere and their preliminary acceleration up to the subrelativistic energies.