Lattice and dynamic aperture of the Duke FEL storage ring
A low emittance lattice of the Duke FEL (Free Electron Laser) storage ring dedicated to drive UV-VUV FELs is presented. The second order geometrical aberration is compensated to increase the dynamic aperture. The 6-D dynamic aperture study has been performed on this lattice using symplectic tracking codes, which demonstrates a large energy aperture. The influences of higher-order multipoles (HMs), RMS errors and 6.8-m OK-4 undulator on dynamic aperture are studied. The transverse dynamic aperture is mainly limited by HMs in the straight section quadrupoles. For future FEL operations, we have designed a new straight section lattice for a 26-m long FEL undulator. The dynamic aperture for this lattice is discussed.<<ETX>>