CLARA (Compact Linear Accelerator for Research and Applications) is a proposed FEL test facility at Daresbury Laboratory, a major upgrade to the existing RF photoinjector test facility, VELA. The CLARA project aims to build on the UK’s existing expertise and experimental experience in free electron lasers, to pave the way for a state-of-the-art FEL facility in the UK, whilst simultaneously contributing to international R&D of single pass FELs.

The ultimate aim of CLARA is to develop a normal-conducting test accelerator (delivering approximately 250 MeV electron beam energy), able to generate longitudinally and transversely bright electron bunches, and to use these bunches in the experimental production of stable, synchronized, ultra-short photon pulses of coherent light from a single pass FEL, using techniques directly applicable to the future generation of light source facilities. It is also foreseen that the CLARA beam will be used for testing other advanced concepts such as beam driven wakefield acceleration. CLARA will generate intense pulses of light in the wavelength range 100nm to 400nm, and it will generate pulse lengths of only a few cycles in the most extreme ultrashort pulse demonstration – equivalent to sub-attosecond in the X-ray region.

CLARA will be located in an existing building previously used for the Synchrotron Radiation Source (SRS), and will utilize the VELA RF photoinjector, as a first stage. The conceptual design of CLARA was published in 2013 and the first accelerating section (up to 50 MeV) will be installed in 2015.