High power accelerators

This paper presents some important specificities of high power accelerators. A general overview of some projects is given, followed by some basic recalls in accelerators physics. These recalls are used to describe the fundamental mecanisms leading to emittance growth and halo generation in high intensity beams. The next part is a presentation of some subsystems (RFQ, linear accelerator), and, as a conclusion, some specific issues related to high power proton accelerators are rewiewed