Challenge to deep-UV and VUV FEL in a small-scale storage ring

The wavelength from the deep ultraviolet (UV) to x-ray is very attractive for free electron lasers (FELs), because there is no conventional laser which can supply powerful coherent light with a wide wavelength tunability in this range. However, a large-scale accelerator is usually required to obtain FELs in such a wavelength range, because of the necessity of high- energy electron beam with a very good beam quality. In this article we report our attempts to realize FELs in the deep UV and vacuum ultraviolet (VUV) on a small-scale storage ring.