Observations of kinetic Alfvén waves and associated electron acceleration in the plasma sheet boundary layer

Kinetic Alfvén waves (KAWs), with a strong parallel disturbed electric field, play an important role in the energy transport and particle acceleration magnetotail. Based on high-resolution observations of Magnetospheric Multiscale (MMS) mission, we present detailed process electrons by KAWs plasma sheet boundary layer (PSBL). MMS observed electromagnetic disturbances carrying field amplitude up to 8 mV/m. The measured ratio magnetic perturbations is larger than local speed enhances as frequency increases, consistent theoretical predictions for KAWs. These evidences indicate that should be identified During KAWs, flux at energies above 1 keV anti-parallel direction significantly enhance, implying occurrences electron beams higher energies. Meanwhile, become more electrostatic-like filled high ion acoustic waves. enhancement accords derived work done indicating caused Therefore, paper provides direct evidence embodying electrostatic PSBL.