Study of nonlinear beam dynamics of an asymmetric NSLS-II lattice

NSLS-II is planning an upgrade to an ultra-low emittance storage ring using a novel lattice concept, the complex bend, composed of combined-function magnets. To evaluate technical challenges and study beam dynamics with complex bend, two bending magnets of existing NSLS-II bare lattice are proposed to be replaced with complex bends, introducing lattice asymmetry. To study the impact of asymmetry on NSLS-II bare lattice, an asymmetric lattice is developed by adjusting quadrupole triplets in the Cell 8 long straight section. This paper presents the modified linear optics, optimization of nonlinear dynamics, and a comparison with the nominal bare lattice. The optimized asymmetric bare lattice is also experimentally measured in the machine, and dynamic aperture measurements are reported.