A Recirculating Linac-based Facility for Ultrafast X-ray Science*

* This work supported by the U.S. Department of Energy under Contract No. DE-AC03-76SF00098 Abstract We present an updated design for a proposed source of ultra-fast synchrotron radiation pulses based on a recirculating superconducting linac [1,2], in particular the incorporation of EUV and soft x-ray production. The project has been named LUX – Linac-based Ultrafast X-ray facility. The source produces intense x-ray pulses with duration of 10-100 fs at a 10 kHz repetition rate, with synchronization of 10’s fs, optimized for the study of ultra-fast dynamics. The photon range covers the EUV to hard x-ray spectrum by use of seeded harmonic generation in undulators, and a specialized technique for ultra-shortpulse photon production in the 1-10 keV range. Highbrightness rf photocathodes produce electron bunches which are optimized either for coherent emission in freeelectron lasers, or to provide a large x/y emittance ration and small vertical emittance which allows for manipulation to produce short-pulse hard x-rays. An injector linac accelerates the beam to 120 MeV, and is followed by four passes through a 600-720 MeV recirculating linac. We outline the major technical components of the proposed facility. 1 OVERVIEW