Nuclear Instruments and Methods in Physics Research A 467–468 (2001) 34–37 The European UV/VUV storage ring FEL at ELETTRA: first operation and future prospects $ R.P. Walker a, *, J.A. Clarke c , M.E. Couprie b , G. Dattoli e , M. Eriksson f , D. Garzella b , L. Giannessi e , M. Marsi a , M.W. Poole c , E. Renault b , R. Roux a , M. Trov " o a , S. Werin f , K. Wille d a Sincrotrone Trieste, 34012 Trieste, Italy b CEA-SPAM and LURE, Orsay, France c CLRC-Daresbury Laboratory, Warrington, UK d University of Dortmund, Dortmund, Germany e ENEA-Frascati, Frascati, Italy f MAX-lab, Lund, Sweden Presented by R.P. Walker on behalf of the Project Team Abstract A European project to develop the first storage ring free-electron laser on a third-generation synchrotron radiation facility is presented, including a description of the main features, initial performance at 350 and 220 nm and future prospects. # 2001 Elsevier Science B.V. All rights reserved. PACS: 29.20.Dh; 41.60.Cr Keywords: Synchrotron radiation facility; Storage ring; Free-electron laser 1. Introduction Free-electron lasers (FELs) are sources of intense, tuneable, spatially coherent, monochro- matic radiation. FELs based on storage rings [1] have a combination of characteristics that make them attractive for a range of experiments in the UV/VUV: * continuous MHz repetition frequency, * synchronization with synchrotron radiation (SR) on a 1 : 1 pulse basis, * average power in the few hundred mW range, * easily tuneable. A storage ring FEL is also a relatively inexpen- sive addition to a low-to-medium energy SR facility, using equipment that can also be utilised for a conventional beamline. E-mail address: richard.walker@elettra.trieste.it (R.P. Walker). $ Partly funded under EC RTD Contract No. ERBFMGE- CT98-0102. *Tel.: +39-040-375-8225; fax: +39-040-375-8565. 0168-9002/01/$ - see front matter # 2001 Elsevier Science B.V. All rights reserved. PII:S0168-9002(01)00213-3