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Accueil > Séminaires et conférences > Séminaires, soutenances de thèses et HDR précédents > 2015 > Séminaires 2015 > Le mardi 16 juin à 11h

Le mardi 16 juin à 11h

Yoshiharu Omura, Research Institute for Sustainable Humanosphere, Kyoto University

Titre : Nonlinear wave-particle interactions in the planetary radiation belts

Lieu : Salle de réunion, Jussieu

Resumé :
We give a brief review of the nonlinear theory and simulations of the generation mechanism of whistler-mode 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 observed in spacecraft data. 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.


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Tutelles : CNRS Ecole Polytechnique Sorbonne Université Université Paris Sud Observatoire de Paris Convention : CEA
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