HT: Tutorial H: Theory and simulations of nonlinear wave-particle interactions in the planetary radiation belts

Tuesday, August 19  11:00-12:00,  Room #11

Session Chair: O. Santolik

There has been significant progress in understanding the generation mechanism of whistler-mode chorus emissions in recent years. This is partly due to the successful reproduction of chorus emissions by computer simulations and partly due to precise observations of the emissions by spacecraft. We give a brief review of the nonlinear theory and simulations on the generation mechanism of chorus emissions that have been revealed by the simulations and observations. We describe the nonlinear dynamics of resonant electrons and the formation of electromagnetic electron holes or hills that result in resonant currents generating rising-tone emissions or falling-tone emissions, respectively. We also describe the mechanism of nonlinear wave damping due to quasi-oblique propagation, which results in the formation of a gap at half the electron cyclotron frequency. The nonlinear wave growth theory of chorus emissions can also be applied to the generation mechanism of electromagnetic ion cyclotron (EMIC) triggered emissions recently found in spacecraft observations. Hybrid code simulations have confirmed that coherent rising-tone emissions are generated by energetic protons at frequencies below the proton cyclotron frequency. EMIC waves can also interact with relativistic electrons. Both chorus emissions and EMIC triggered emissions play important roles in controlling radiation belt particle dynamics.


Y. Omura

Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Kyoto, Japan