摘要：In order to meet the requirements of the Circular Electron Positron Collider(CEPC),a 650-MHz 2-cell superconducting cavity was proposed and *** this study,we show the progress in the cavity design for the *** radio frequency and mechanical designs are ready for the first design version,called CEPC-V1.A cryomodule,which consists of two 650-MHz 2-cell cavities,was scheduled the last ***,prototypes of the 2-cell cavity based on this design were fabricated and tested the following *** vertical test results show that multipacting(MP)exists from 10 to 19 MV/*** will increase the operational risk of the CEPC,while the continuous-wave operation for the 650-MHz cavity is 19.7 MV/*** trapped modes were also found,which exist because of the identical half-cell ***,a few improvements regarding MP and more efficient extraction of higher-order mode power are discussed.A new type of cavity design,called CEPC-V2,is also discussed in this paper.