Space Physics Seminar fall-2024

Wave-particle resonance, a ubiquitous process in the plasma universe, occurs when resonant particles observe a constant wave phase to enable sustained energy transfer. In this talk, we will present spacecraft observations in the terrestrial foreshock region where macroscale waves in the ultra-low-frequency band and microscale whistler waves resonate simultaneously with the ions. The ion acceleration from ultra-low-frequency waves leads to velocity distributions unstable to the growth of whistler waves, which in turn resonate with the electrons and dissipate energy at electron-scales. These observations demonstrate that the chain of wave-particle resonance is an efficient mechanism for cross-scale energy transfer, which could redistribute the kinetic energy and accelerate the particles upstream of the shocks.