Cluster observations of ULF waves with pulsating electron beams above the high latitude dusk-side auroral region

We report observations by the four Cluster satellites of particle acceleration associated with ULF (Alfvén) waves at an altitude of 6RE above the dusk‐side auroral region. All satellites observed upward accelerated ions and upgoing electron beams, which coincided with the upward field‐aligned current around the plasmasheet boundary region. Here we study in detail one region of Alfvénic ULF waves observed together with upward electron beams, both having a quasi‐periodicity of about 2 minutes. The ULF waves have a downward Poynting flux. Comparing data from different spacecraft, the observed electron beams are likely caused by the ULF waves in localized (0.5° latitude extension) flux tubes in the plasmasheet boundary region. The high‐energy keV plasmasheet dispersive ion signatures showed similar periodicity, which suggests that the generation region of the ULF Alfvén waves is near the magnetospheric flank, and in turn induce time‐varying particle energization.