Particle-wave-particle interactions involving whistler-mode waves in the magnetosphere

Search for and understanding of mechanisms for particle energization is a key problem in physics of the Earth´s radiation belts. A good deal of suggested mechanisms is related to resonant interactions between waves and energetic particle. In the plasmaspheric region of the magnetosphere, the energy density variation of resonant particles is often much larger than the wave energy density which contradicts energy conservation under the prevalent assumption that the wave serves as the energy source or sink. By examples of whistler-mode wave-electron interactions we emphasize that, in many cases, the energy increase (or decrease) of resonant particles is related to energy transfer from (to) other group of resonant particles, while the wave basically mediates the energization process. The importance of energy transfer between different electron populations for energization processes in the radiation belts has been pointed out in [1, 2].