Energy recovery linacs light sources: an overview

Sparked by the highly successful operation of energy recovery linac (ERL) free electron lasers (FELs) at TJNAF and JAERI and also by the novel MARS light source (LS) proposal from BINP, numerous facilities worldwide are now considering ERL based light source projects. A survey of the various light sources and FELs based on ERL technology will be given. An overview of the critical R&D issues that must be addressed in future ERLs will also be presented.