NEW RESULTS OF THE CLIO INFRARED FEL USING A NEW UNDULATOR AND HOLE COUPLING EXTRACTION

The ''CLIO'' laser spectral range has been extended towards longer wav elengths. With this aim, the previous undulator of CLIO has been repla ced [O. MarcouillC et al., A new undulator for the extension of the sp ectral range of the CLIO FEL, these proceedings, Nucl. Instr. and Meth . A 375 (1996) 465], and consists now of N = 38 periods of lambda(0) = 5.04 cm, instead of N = 48 and lambda(0), = 4 cm. A larger undulator vacuum chamber has also been installed to avoid diffraction. The extra ction plate output coupling system has been replaced by a hole coupler to allow lasing beyond 17 mu m. This paper summarises the general per formance of CLIO with this new configuration, and shows that two colou r operation has also been observed with hole coupling [D.A. Jaroszynsk i et al., Step tapered operation of the FEL: efficiency enhancement an d two colour operation, these proceedings, Nucl. Instr. and Meth. A 37 5 (1996) 647].