Upgrade of the UVSOR storage ring FEL

The UVSOR electron storage ring has been shutdown since April till August 2003 for upgradation of its performance. This upgrade includes high brightness lattice, longer straight sections for in-vacuum undulators and high-quality vacuum system, and it can increase the brightness of synchrotron radiation from undulators with reduced beam emittance. The improved quality of the electron beam is also of great advantage to the storage ring FEL. To further improve the performance of the FEL and deliver shorter wavelength laser to the user, we are considering a project, which can upgrade the FEL system. One of the solutions is to construct a new in-vacuum optical klystron type undulator in the new long straight section, which is optimized for lasing in the deep UV and VUV region.