Study of chromaticity correction methods for a hybrid multi-bend-achromat lattice

Abstract

The hybrid multi-bend-achromat (MBA) lattice is developed for the demand of higher luminosity at both collider and synchrotron light source. For a hybrid MBA lattice, its negative chromaticities must be corrected with sextupoles, which lead to nonlinearities, thus limiting the dynamic aperture (DA) and momentum aperture (MA). To get efficient injection and long beam lifetime, these nonlinearities must be carefully handled, while it is always difficult to optimize the nonlinearities with limited knobs for the fixed linear lattice. Therefore, conducting chromaticity correction is of importance in linear lattice design that can achieve better nonlinear dynamics. In this paper, three chromaticity correction methods are compared using multi-objective genetic algorithm (MOGA). A hybrid MBA of 2 GeV, as an example, is designed with a natural emittance of 4.4 nm•rad.