Physics department (Colloquium)

Variation of Electrons Distributions in the Outer Radiation Belt Caused by Whistler-Mode Chorus Emissions

Speaker : Prof. Hsieh Yikai 謝怡凱 (Kyoto University ; Research Institute for Sustainable Humanosphere)
Time : 2024 / 03 / 22 14:10
Room 36102, 1F, Department of Physics, Science Building
Whistler mode waves, which are right-hand polarized electromagnetic waves in a plasma, are frequently observed outside of the plasmapause of the Earth’s inner magnetosphere. Energetic electron accelerations and precipitations in the Earth’s outer radiation belt are highly associated with wave-particle interactions between whistler mode chorus waves and electrons. Two nonlinear processes take place in whistler mode wave-particle interactions and cause effective energy and pitch angle changes of resonant electrons. One is the nonlinear scattering, which makes electron energy slightly smaller. The other is the nonlinear trapping, which makes effective energy gain of the resonant electrons. We utilized numerical simulation to reproduce the wave-particle interactions in the radiation belt and investigate the electron acceleration and precipitation interacting with parallel and obliquely propagating chorus emissions. The simulation results show the formation processes and the loss processes of the outer radiation belt electrons interacting with consecutive chorus emissions. We found that the acceleration process is stronger than the loss process, indicating that the radiation belt becomes stronger under the wave-particle interaction between chorus emissions and electrons comprehensively.