Study on the generation mechanism of relativistic electrons due to wave-particle interactions in the radiation belts via spacecraft observation

High-energy particles trapped in the radiation belts surrounding the Earth are known as mainly composed of electron and protons. It is supposed that relativistic electrons are accelerated by the mechanism of interaction between electron-whistler mode waves through cyclotron resonance (wave-particle interaction). To further elucidate the mechanism, we have started a geo-space search project including satellite observations called ERG (Exploration of energization and Radiation in Geospace). The satellite ERG is to be loaded by a SWPIA (Software-type Wave-Particle Interaction Analyzer) system which measures directly and records each energy exchange event occurring between wave and particles. The principles and main performances of the system are described. (S. Ohno)