Parametric Sensitivity of the Formation of Reversed Electron Energy Spectrum Caused by Plasmaspheric Hiss

Scattering by plasmaspheric hiss is responsible for the newly reported reversed energy spectra with abundant high-energy but fewer low-energy electrons between hundreds of kiloelectronvolts and similar to 2 MeV in the inner magnetosphere. To deepen our understanding of the contributions of plasmaspheric hiss to the formation of reversed electron energy spectrum, we conduct a detailed theoretical parametric analysis through numerical simulations to explore the sensitivity of hiss-induced reversed electron energy spectrum to ambient magnetic field, plasma density, and hiss wave distribution properties. Given L-shell, variations of ambient plasma density and wave frequency spectrum contribute importantly to the formation of reversed electron energy spectrum, while variations of background magnetic field (which usually shows small changes in the plasmasphere) and wave normal angle distribution play a less effective role. Our study suggests that the reversed electron energy spectrum has important implications for unveiling the sophisticated energy-dependent nature of wave-particle interactions and energetic particle dynamics in geospace.