Linac technology for free-electron lasers

The properties of high energy electron linear accelerators for use in free electron lasers operating principally in the Compton regime are discussed. Electron energies in the 20- to 200-MeV range and requirements for high power free electron lasers operating in the 0.5- to 10-micron range are emphasized. A motivational analysis that introduces the two principal types of linacs and indicates the utility of both for free electron laser work is presented. The accelerator and its design is an integral part of the free electron laser system, and not just a given entity around which laser designs must be based. High power free electron laser amplifiers and oscillators and desirable characteristics of the linacs that deliver electron beams for these devices are also discussed.