The Japanese satellite mission ERG for Geospace research and applications

Energetic particles in the ring current and radiation belts drastically change during magnetic storms. Study of the energetic particle is an exciting subject not only for the space plasma physics but also for the space weather. Comprehensive observations of particles, fields, and waves are necessary to understand key processes of particle acceleration in Geospace. Measurements of both electric and magnetic components of plasma waves in a wide frequency range together with thermal plasma environment are necessary to evaluate non-adiabatic acceleration processes of relativistic particles.