The world’s first Nb3Sn Superconducting Radio-frequency (SRF) electron accelerator recently achieved stable beam acceleration, reaching a maximum energy of 4.6 MeV with an average macro-pulse beam current exceeding 100 mA. Cooled directly by cryocoolers in a novel liquid-helium-free (LHe-free) design, the Nb3Sn SRF electron accelerator was developed by researchers from the Institute of Modern Physics (IMP) at the Chinese Academy of Sciences (CAS) and the Advanced Energy Science and Technology Guangdong Laboratory. SRF accelerators currently rely on resonant cavities made from niobium (Nb) and cooled via LHe immersion (typically to 2K for electron machines). A major pursuit of SRF scientists has been cavity fabrication using new materials with higher transition temperatures than niobium. Most popular among prospective new materials is Nb3Sn, whose superconducting transition temperature is twice that of metallic niobium. With great potential to boost the performance of next-generation cavities, Nb3Sn SRF technology is a forefront research topic in the SRF field. IMP initiated its research program on Nb3Sn SRF technology in 2018, and gradually developed a comprehensive production process that overcame challenges from areas including deposition system, growth mechanisms and coating processes of Nb3Sn thin films. These efforts culminated in the successful construction of the conduction-cooled LHe-free Nb3Sn SRF electron accelerator at the beginning of 2024. Stable electron beam acceleration in this accelerator is a pioneering achievement that demonstrates, for the first time, the feasibility of utilizing Nb3Sn thin film SRF cavities in both large-scale scientific facilities and compact industrial accelerators. This breakthrough technology can significantly reduce thermal loads and raise the operation temperature of SRF accelerators such that simpler LHe-free cooling schemes become viable. Apart from reducing the demand for large-scale cryogenic systems and lowering the operation costs of SRF accelerators, this new technology will enable miniaturization to promote industrial applications in such fields as wastewater treatment, preservation and sterilization, and medical isotope production. Figure. The Nb3Sn SRF electron accelerator. (Image from IMP) Contact:LIU FangInstitute of Modern Physics |
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