Analysis of the Interaction between Low-Frequency Waves and Ions in the High-Altitude Cusp Region Observed by Satellite Cluster

The energy transfer between ions (protons) and low frequency waves (LFWs) in the frequency range f₁ from 0.3 to 10Hz is observed by Cluster crossing the high-altitude polar cusp. The energy transfer between low frequency waves and ions has two means. One is that the energy is transferred from low frequency waves to ions and ions energy increases. The other is that the energy is transferred from ions to low frequency waves and the ion energy decreases. Ion gyratory motion plays an important role in the energy transfer processes. The electromagnetic field of f₁ LFWs can accelerate or decelerate protons along the direction of ambient magnetic field and warm or refrigerate protons in the parallel and perpendicular directions of ambient magnetic field. The peak values of proton number densities have the corresponding peak values of electromagnetic energy of low-frequency waves. This implies that the kinetic Alfven waves and solitary kinetic Alfven waves possibly exist in the high-altitude cusp region.