Unique features of the OK-4/Duke storage ring XUV FEL and monochromatic /spl gamma/-ray source

The OK-4 is the first storage ring FEL operating in the United States. It was commissioned in November, 1996 and demonstrated lasing in the near UV and visible ranges (345-413 nm) with extracted power of 0.15 W. In addition to lasing, the OK-4/Duke FEL generated a nearly monochromatic (1% FWHM) /spl gamma/-ray beam. In this paper we describe the initial performance of the OK-4/Duke storage ring FEL and /spl gamma/-ray source.