Chapter 6: Energy-recovery linacs

Energy Recovery is at the threshold of becoming a key means for the advancement of accelerators. Recycling the kinetic energy of a used beam for accelerating a newly injected beam, i.e. reducing the power consumption, utilising the high injector brightness and dumping at injection energy: these are the key elements of a novel accelerator concept, invented half a century ago. The potential of this technique may be compared with the finest innovations of accelerator technology such as by Widerøe, Lawrence, Veksler, Kerst, van der Meer and others during the past century. Innovations of such depth are rare, and their impact is only approximately predictable.This chapter presents a roadmap, its motivation and key objectives focused on the next five years, for a coordinated, advanced development of ERL technology and facilities in Europe and beyond.