Electron acceleration and small-scale coherent structure formation by an Alfvén wave propagating in coronal interplume region

We use the 2.5-D electromagnetic particle-in-cell simulation code to investigate the acceleration of electrons in solar coronal holes through the interaction of Alfvén waves with an interplume region. The interplume is modeled by cavity density gradients that are perpendicular to the background magnetic field. The aim is to help explain the observation of suprathermal electrons under a relatively quiet Sun. Simulations show that Alfvén waves interacting with the interplume region give rise to a strong local electric field that accelerates electrons in the direction parallel to the background magnetic field. Suprathermal electron beams and small-scale coherent structures are observed within interplume of strong density gradients. These features result from the nonlinear evolution of the electron beam plasma instability.