Highly coupled off-resonance lattice design in diffraction-limited light sources

A round beam generation method basedon theglobal settingof skewquadrupoles andthe applicationof a non-dominated sorting genetic algorithm was proposed in this study. Two schemes, including large-emittance coupling introduced via betatron coupling and vertical dispersion, were explored in a candidate lattice for an upgrade-proposal of the Shanghai Synchrotron Radiation Facility.

Emittance variations with lattice imperfections and their influence on the beam dynamics of beam optic distortions were investigated. The results demonstrated that a precise coupling control ranging from 10% to 100% was achieved under low optical distortion, whereas full-coupling generation and its robustness were achieved by our proposed method by adjusting the skew quadrupole components located in the dispersion-free sections.