Statistical Study of the Response of Ion and Electron Kappa Distribution Functions in the Inner Magnetosphere to Solar Wind and IMF Conditions

The Earth's magnetosphere is filled with a collisionless plasma having non-Maxwellian particle distributions, which are often fitted by a Kappa distribution function. In contrast to the Maxwellian distribution function, the Kappa distribution contains not only density and temperature, but also the kappa index that allows us to characterize the energetic tails. In this study, we investigate the response of the ion and electron Kappa distributions obtained by fitting ion and electron fluxes measured by the five THEMIS satellites spanning the years 2008–2018 to the changes of the solar wind dynamic pressure and the Bz component of the interplanetary magnetic field (IMF). It was found that both quantities strongly affect the values of kappa index, and their impact depends on the MLT sector. The results obtained reflect the global reconfiguration of the magnetosphere by solar wind dynamic pressure and IMF.