The 500MHz TM020 room-temperature high-frequency cavity, a key component of the STCF accelerator built by Lanzhou Taiji, passed factory acceptance on July 28, 2026. This marks significant progress in the key technology research project of the Super Tau-Charm Facility (STCF), a new generation electron-positron collider led by the University of Science and Technology of China.
This review meeting brought together experts from the Institute of High Energy Physics of the Chinese Academy of Sciences, Shanghai Advanced Research Institute of the Chinese Academy of Sciences, Chongqing University, Tsinghua University, University of Science and Technology of China, and Dongsheng Fusion (Shanghai) Technology Co., Ltd. The expert group conducted a comprehensive and rigorous review of the structural design, secondary vacuum brazing, precision machining methods, vacuum performance, and cold test results of the high-frequency cavity (1200mm large-diameter cavity), unanimously concluding that all indicators meet the design requirements. The measured unloaded quality factor (Q₀) reached 56900 (design value 61500), placing its performance at the leading level among similar high-performance room-temperature high-frequency cavities in China.
Compared to conventional TM010 cavities, this TM020 cavity, with its larger structural dimensions, higher operating voltage, higher unloaded quality factor (Q₀), and lower R/Q value, can effectively suppress beam instability. Additionally, its longitudinal structure is more compact, significantly optimizing the spatial layout of the collider ring. The technical design of this high-frequency cavity was completed by the team of Researcher Wei Yelong from the University of Science and Technology of China, while the process design and manufacturing were carried out by Lanzhou Taiji.
With guidance and support from the expert group, Lanzhou Taiji iteratively optimized and formed complete process standards, machining plans, and full-sequence manufacturing procedures through repeated process trials and validations. The success of this project not only lays a solid technical foundation for the development of domestic TM020 mode room-temperature high-frequency cavities but also cultivates a group of core process design talents with strong technical capabilities.
