Analysis of the Fluctuation of Resonance Driving Terms for Nonlinear Lattice Optimization

Minimizing resonance driving terms (RDTs) of nonlinear magnets is a traditional approach to enlarge the dynamic aperture (DA) of a storage ring. The local cancellation of nonlinear dynamics, which is adopted by some diffraction-limited storage rings, is more effective than the global cancellation. The former has smaller fluctuation of RDTs along the ring. In this paper, the correlation between two kinds of RDT fluctuations is found. The qualitative analysis shows that minimizing the RDT fluctuations is beneficial for controlling the crossing terms and thus enlarging the DA. This qualitative analysis is supported by the statistical analysis of nonlinear solutions of a double-bend achromat lattice.