Science Seminars

Unraveling Mysteries behind the Energetic Particle Dynamics in Earth’s Magnetosphere

Speaker: Hong Zhao (LASP)
Date: Friday, May 22, 2020
Time: 1:30 PM
Location: Zoom

Seminar Abstract:

The Earth’s magnetosphere is filled with charged particles of a wide range of energies, spanning from ~eV in cold, dense plasmasphere to relativistic energies in Earth’s radiation belts. In particular, ~10s of keV to ~10s of MeV electrons, trapped by Earth’s magnetic field in the radiation belts, exhibit energy-dependent acceleration, transport, and loss processes. These energetic particles pose potential threats to both spacecraft and humans in space and technical systems on the ground. Thus, understanding and eventually predicting Earth’s radiation environment is of both scientific interests and practical needs. Utilizing measurements from past and current missions, combined with numerical modeling, the physical mechanisms responsible for the acceleration, transport, and loss of energetic particles have been revealed. This talk will feature some recent advances in the understanding of energy-dependent dynamics of radiation belt electrons, including 1) a newly-discovered reversed energy spectrum of radiation belt electrons generated by the plasmaspheric hiss waves which highlights the critical role of wave-particle interaction in causing energy-dependent losses of energetic particles, and 2) the energy-dependent acceleration of relativistic and ultrarelativistic electrons which suggests a two-step acceleration mechanism while also raises questions that point to the need for a future space mission. These results aid in a deeper understanding of energy-dependent particle dynamics in Earth’s magnetosphere and shed light on future directions toward the prediction of Earth’s radiation environment.