CERN needs for future accelerators in high energy physics

Several new accelerator projects are being studied at CERN in a broad energy range from atomic to Tera scale level. The beam energy as well as the beam quality requirements raise the need for new future acceleration concepts to achieve more efficient accelerating structures and / or more compact devices. The article gives a number of examples of the studies, the beam parameters that are foreseen in the different projects and their proposed technical layout.