Design of the 500 MHz 2-cell superconducting cavity for the SILF

The design of the main accelerating cavity in the storage ring of synchrotron radiation sources has consistently been an important area of research. In order to save the number of straight sections in the Shenzhen Innovation Light source Facility (SILF) storage ring and reduce the cost of the superconducting cavity modules, this study planned to design a 500 MHz 2-cell superconducting cavity to replace the original single-cell cavity scheme. In this paper, we optimized the design of the 500 MHz 2-cell superconducting cavity and explored the impact of different dimensional parameters on the performance of the cavity's resonant modes. We compared the multipacting phenomena on the inner surfaces of superconducting cavities treated with three different methods. Additionally, the suppression effect on Higher-order modes (HOM) and the limit of the HOM on the threshold of the stored beam current were analyzed. Finally, we analyzed the mechanical performance of the cavity, including Lorentz force detuning (LFD), Liquid helium (LHe) pressure fluctuations, cooling frequency shifts, tuning sensitivity and modal. Through the calculations and optimizations of the 500 MHz 2-cell superconducting cavity, we finally designed a superconducting cavity that meets the requirements and obtained satisfactory results.