Precipitation of radiation belt electrons by magnetospherically reflected (MR) whistlers

Abstract

We use a test particle simulation model based on gyro-averaged equations of motion to study the influence of oblique magnetospherically reflected (MR) whistlers on the near-loss-cone distribution function of radiation belt electrons. We find that MR whistlers originating in lightning can resonantly interact with radiation belt electrons over a broad range of L-shells and precipitate higher energy electrons from lower L-shells. Electrons in the energy range of 1–2.6 MeV are precipitated from L=2, whereas from L=4 the precipitated electron energy range is 150–220 keV. The precipitated differential electron flux due to this interaction is higher for higher L-shells, and the maximum value ranges from$\Phi _{E_{prec} } (1.11 MeV) = 5.2 \times 10^{ - 4} el/cm^2 \cdot s \cdot keV$ at$L = 2 to \Phi _{E_{prec} } (173 keV) = 4.6 \times 10^{ - 1} el/cm^2 \cdot s \cdot keV$ at L=4. The lifetimes of radiation belt electrons in a given magnetic flux tube around the L-shell on which the interaction takes place are found to be of the order of several days, comparable to lifetimes corresponding to electron loss induced by hiss, which was heretofore assumed to be the dominant loss mechanism [1]. The minimum electron lifetimes vary from 2.47 days for E=1.11 MeV electrons at L=2 to 4.64 days for E=173 keV electrons at L=4.