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Ultrahigh accelerating gradient and quality factor of CEPC 650 MHz superconducting radio-frequency cavity

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Abstract

Two 650 MHz single-cell superconducting radio-frequency (SRF) cavities used for the Circular Electron Positron Collider (CEPC) were studied to achieve a high accelerating gradient (Eacc) and high intrinsic quality factor (Q0). The 650 MHz single-cell cavities were subjected to a combination of buffered chemical polishing (BCP) and electropolishing (EP), and their Eacc exceeded 40 MV/m. Such a high Eacc may result from the cold EP with more uniform removal. BCP is easy, cheap, and rough, whereas EP is complicated, expensive, and precise. Therefore, the combination of BCP and EP investigated in this study is suitable for surface treatments of mass SRF cavities. Medium temperature (mid-T) furnace baking was also conducted, which demonstrated an ultrahigh Q0 of 8 × 1010 at 22 MV/m for both cavities, and an extremely low BCS resistance (RBCS) of ~ 1.0 nΩ was achieved at 2.0 K.

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Authors and Affiliations

  1. Institute of High Energy Physics, Chinese Academy of Sciences, Bei**g, 100049, China

    Peng Sha, Wei-Min Pan, Song **, Ji-Yuan Zhai, Zheng-Hui Mi, Bai-Qi Liu, Chao Dong, Fei-Si He, Rui Ge, Liang-Rui Sun, Shi-Ao Zheng & Ling-** Ye

  2. Key Laboratory of Particle Acceleration Physics and Technology, Chinese Academy of Sciences, Bei**g, 100049, China

    Peng Sha, Wei-Min Pan, Song **, Ji-Yuan Zhai, Zheng-Hui Mi, Bai-Qi Liu, Chao Dong, Fei-Si He, Rui Ge, Liang-Rui Sun, Shi-Ao Zheng & Ling-** Ye

  3. Center for Superconducting RF and Cryogenics, Institute of High Energy Physics, Chinese Academy of Sciences, Bei**g, 100049, China

    Peng Sha, Wei-Min Pan, Song **, Ji-Yuan Zhai, Zheng-Hui Mi, Bai-Qi Liu, Chao Dong, Fei-Si He, Rui Ge, Liang-Rui Sun, Shi-Ao Zheng & Ling-** Ye

  4. University of Chinese Academy of Sciences, Bei**g, 100049, China

    Peng Sha, Wei-Min Pan, Ji-Yuan Zhai, Zheng-Hui Mi, Fei-Si He, Rui Ge, Shi-Ao Zheng & Ling-** Ye

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Contributions

All authors contributed to the study conception and design. Material preparation, data collection, and analysis were performed by Peng Sha, Wei-Min Pan, and Song **. The first draft of the manuscript was written by Peng Sha, and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Corresponding authors

Correspondence to Peng Sha or Wei-Min Pan.

Additional information

This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDB25000000), the National Natural Science Foundation of China (No. 12075270), and the Platform of Advanced Photon Source Technology R&D.

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Sha, P., Pan, WM., **, S. et al. Ultrahigh accelerating gradient and quality factor of CEPC 650 MHz superconducting radio-frequency cavity. NUCL SCI TECH 33, 125 (2022). https://doi.org/10.1007/s41365-022-01109-8

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