The Beijing Electron-Positron Collider II (BEPCII) was upgraded from 1.89 GeV to 2.35 GeV in 2025. Due to the increased electron beam energy, radio-frequency power and voltage requirements have more than doubled. To meet these demands, each ring utilizes two 499.8 MHz cavities. A new cavity module was produced to join the two existing Mitsubishi cavities and one IHEP spare cavity. Upon completion of horizontal tests in Huairou, the module was transported to BEPCII over a distance of approximately 80 km. Finite Element Analysis was conducted to determine the maximum allowable acceleration for critical components during transportation, while providing comprehensive data on modal frequencies, stress distributions, and structural deformation. A shipping frame with an inner bed isolated by springs was subsequently designed to protect the module from shock and vibration. Several road tests were conducted prior to shipment. Subsequently, the fully assembled cryomodule was transported under cavity vacuum to the BEPCII tunnel. This study presents the design and performance of an isolation system specifically developed to safeguard delicate elements throughout the transport process. These results demonstrate the first successful long-distance transport of a fully assembled 499.8 MHz KEKB-type cryomodule under vacuum.
Zheng et al. (Wed,) studied this question.