| Abstract: | A new generation of storage ring-based light sources, called diffraction-limited storage rings (DLSR), with emittance approaching the diffraction limit for multi-keV photons by using multi-bend achromat lattice, has attracted worldwide and extensive studies of several laboratories, and been seriously considered as a means of upgrading existing facilities in the imminent future. Among various DLSR proposals, the PEPX design demonstrated that it is feasible to achieve sufficient ring acceptance for off-axis injection in a DLSR, by designing the lattice based on the ‘third-order achromat’ concept and with a special high-beta injection section. For the High Energy Photon Source (HEPS) planned to be built in Beijing, a PEPX-type lattice has been designed and continuously improved. In this paper, we report the evolution of the PEPX-type design for HEPS, and discuss the main issues relevant to the linear optics design and nonlinear optimization. |
