An off-energy multipole kicker injection scheme designed with an acceptance analysis method for a diffraction-limited storage ring

Abstract Diffraction-limited storage rings (DLSRs) have restricted dynamic apertures (DAs) due to their ultralow emittances and very strong nonlinearity. Off-energy multipole kicker injection (MKI) scheme, in which off-energy beam is injected onto the corresponding off-energy orbit, can reduce the requirement of DAs. However, it requires relatively large energy acceptance and high dispersion bumps. For a DLSR lattice with relatively large energy acceptance and off-momentum DAs, off-energy beam can be injected into the off-momentum DA but with an additional offset from the off-energy closed orbit to increase the total offset of the injected beam from the on-energy closed orbit, which is favorable to the application of the off-energy MKI. In this paper, such an off-energy MKI is designed for a DLSR, and an acceptance analysis method based on 6D particle tracking is utilized to design and optimize this injection scheme. Detailed simulation is carried out, and the results demonstrate the feasibility of this injection scheme.