ИСТИНА

In this study we estimate a possible contribution of ULF and VLF mechanisms to the electron acceleration up to relativistic energies. We analyze storm and non-storm periods during high solar wind streams. GOES satellites data are used to describe the electron fluxes (from 40 keV to > 2 MeV), and magnetic field variations. To characterize the magnetospheric wave activity in the Pc5 frequency range (1-7 mHz) the ground ULF index is used. The VLF data from RBSP satellite and Halley Bay station (Antarctica) are used as the chorus proxy in the magnetosphere. Analysis of several typical events demonstrates that the rate of the electron flux increase does not depend on the geomagnetic storm intensity and a substantial increase can occur even without geomagnetic storm. Two necessary conditions for the substantial intensification of relativistic electron fluxes have been found: an occurrence of high-speed solar wind stream and a prolong substorm activity. A good correspondence between the periods with the high solar wind speed and growth of the relativistic electron fluxes with a 1-2 days delay confirms the notion on important role of the electron drift resonance with ULF waves in electron energization. This resonant interaction leads to a preliminary electron acceleration up to sub-relativistic energies upon the radial diffusion deep into the magnetosphere. According to the RBSP satellite data a substantial growth of magnetospheric VLF activity occurs during approximately one day after the injection of seed electrons (50-100 keV). Supposedly, VLF emissions energize pre-accelerated electrons to relativistic energies.