The role Alfv\'en waves in the generation of Earth polar auroras

The acceleration of electrons at 1-10 keV energies is the cause of the polar aurora displays, and an important factor of magnetic energy transfer from the solar wind to the Earth. Two main families of acceleration processes are observed: those based on coherent quasi-static structures called double layers, and those based of the propagation of Alfv\'en Waves (AW). This paper is a review of the Alfv\'enic acceleration processes, and of their role in the global dynamics of the auroral zone.