R&D towards an ERL
The science potential of xray storage rings would be largely enhanced if electron pulses with smaller emittances, i.e. reduced cross section, and with shorter pulse length could be produced. Energy Recovery Linacs (ERLs) have the potential to provide the required unprecedented beam properties, and advantages of ERLs as drivers of x-ray sources will be explained. The status of plans for ERL xray facilities will be described, some of which are extensions of existing accelerators, some are green-field designs. Subjects that are investigated to prepare for construction of ERLs will be discussed, including prototype ERL injectors for high current c.w. beams with ultra low emittances, low emittance transport, superconducting c.w. technology, mitigation of ion effects, and suppression of instabilities. It will become clear that several of these research topics could become important for other modern light source projects, e.g. SASE FELs, HGHG FELs, and X-FELOs.