Generation of kinetic Alfven waves by mirror instability

The perturbed velocity deltaV and deltaB of mirror waves are usually coplanar with the wave vector k and background magnetic field Bo. However, recent satellite observations and hybrid simulations show the presence of extra non-coplanar components in deltaV and deltaB associated with mirror waves. In this paper, we show from hybrid simulations that in the nonlinear stage of mirror instability, the noncoplanar perturbations in deltaV and deltaB of high wavenumber modes can be decoupled from mirror waves and generate a pair of kinetic Alfven waves propagating in opposite direction. The Hall effect can explain the excitation of noncoplanar components in mirror waves. These kinetic Alfven waves can be generated in the dayside magnetosheath, propagate tailward along the magnetic field lines draped around the magnetopause, and contribute to the plasma transport into magnetosphere.