Whistler Growth Rates in the Magnetosphere According to Measurements of Energetic Electron Fluxes on the Van Allen Probe A Satellite

摘要

Measurements of the differential fluxes of energetic electrons in the equatorial region of the magnetosphere in the energy range from units of keV to hundreds of keV carried out on Van Allen Probes make it possible to obtain the distribution function of electrons resonantly interacting with whistlers in the VLF range and to calculate the corresponding local growth rates (or increments) of the waves. The article presents the results of the reconstruction of the distribution function of energetic electrons, as well as the direct calculation of the wave increments without any model assumptions about the form of the distribution function. The data from the Van Allen Probe A satellite on electron fluxes in the energy range of 33-143 keV are used, and the dependence of the increment on frequency along the satellite path is calculated. The obtained increment values are compared with the spatial and temporal variations in VLF emissions detected by the satellite. An important feature of the calculated increments is their significant variation during the time between successive measurements of the fluxes, i.e., at times on the order of 11 s.