Lattice modification and nonlinear dynamics for elliptically polarized VUV OK-5 FEL source at Duke storage ring

The Duke storage ring is a light source ring optimized for driving the Free Electron Lasers (FELs). To take advantage of the high brightness of the electron beam in the storage ring, a next generation FEL source — an elliptically polarized OK-5 FEL system, has been designed to match the electron beam quality of the Duke storage ring. In this paper, we present the storage ring lattice modifications which are necessary to accommodate the 24 m long OK-5 FEL. Because of its length and strong nonlinear focusing, the OK-5 FEL is expected to have a significant impact on the electron beam dynamics. We also present the preliminary results on the dynamic aperture calculation for the OK-5 FEL operated in different modes.