Ion Energization by Turbulent Electric Fields in Fast Earthward Flows and Its Implications for the Dynamics of the Inner Magnetosphere

Abstract

Large‐amplitude electric fields (>50 mV/m) typical to bursty bulk flow (BBF) braking regions of the Earth’s magnetotail can accelerate energetic electrons and ions to many times their initial thermal energies. We follow up on the Usanova and Ergun (2022) study of electron energization and examine wave and plasma observations from the THEMIS satellites over four tail seasons to investigate the transfer of BBF energy to ions by turbulent electric fields. The results show that the large‐amplitude electric fields are accompanied by an ion temperature increase of ∼50% when compared to times when the turbulence is not observed. Electric field turbulence is also associated with a roughly ten‐fold increase in temperature fluctuations and a five‐fold increase in variations of energetic ion fluxes. We discuss the contribution of this turbulent energy transfer process to the dynamics of energetic ions in the magnetosphere.