Nuclear Instruments and Methods in Physics Research A 475 (2001) 20–27 First lasing and initial performance of the European UV/VUV storage ring FEL at ELETTRA $ R.P. Walker a, *, J.A. Clarke b , M.E. Couprie c , G. Dattoli d , M. Eriksson e , D. Garzella c , L. Giannessi d , M. Marsi a , L. Nahon c , D. N . olle f,1 , D. Nutarelli c , M.W. Poole b , H. Quick f , E. Renault c , R. Roux a , M. Trov " o a , S. Werin e , K. Wille f a Sincrotrone Trieste, Trieste 34012, Italy b CLRC-Daresbury Laboratory, Warrington, UK c CEA-SPAM and LURE, Orsay, France d ENEA-Frascati, Frascati, Italy e MAX-lab, Lund, Sweden f University of Dortmund, Dortmund, Germany Abstract An overview of the European storage ring FEL project is presented, including a description of the main components, details of initial lasing at 350 and 220 nm and future prospects. r 2001 Elsevier Science B.V. All rights reserved. PACS: 29.20.Dh; 41.60.Cr Keywords: Storage ring; Free-electron laser 1. Introduction The European storage ring FEL project at ELETTRA [1–3] began officially in May 1998 and is a collaboration between six laboratories interested in the development of storage ring free- electron lasers (FEL). The goal of the project is the development of the FEL as a future user facility in the UV/VUV, providing tuneable output between 350 nm and at least 190 nm. Important issues to be addressed, other than the FEL itself, will be the compatibility with operation of other synchrotron radiation (SR) beamlines, and the carrying out of pilot user experiments. The main distinguishing features of the project are * the integration of the FEL on a low emittance ‘‘third-generation’’ synchrotron radiation facil- ity, * the use of a helical undulator (optical klystron) to reduce power loading on the mirrors, and * the use of sophisticated mirror chambers that allow in situ switching between different mir- rors. Hardware installation was completed in mid- February 2000 and FEL shifts started immediately afterwards. After only 30h of beam time, first $ Partly funded under EC RTD Contract No. ERBFMGE- CT98-0102. *Corresponding author. Tel.: +39-040-3758225; fax: +39- 040-3758565. E-mail address: richard.walker@elettra.trieste.it (R.P. Walker). 1 Now at SD&M AG, Ratingen, Germany. 0168-9002/01/$-see front matter r 2001 Elsevier Science B.V. All rights reserved. PII:S0168-9002(01)01529-7