A study concerning the reduction of emittance via non-uniform dipoles under the βmin constraint

Low emittance is a primary goal of electron storage ring based light sources. Optics with low emittance always require low beta functions in dipoles, which implies that strong quadrupoles are needed and that natural chromaticity arises. The work presented in this paper demonstrates that by introducing dipoles with a longitudinal dipolar field-variation, the minimum emittance can be lowered even if the minimum beta function is constrained.