Physical Review Accelerators and Beams (Sep 2024)

High Q and high gradient performance of the first medium-temperature baking 1.3 GHz cryomodule

  • Weimin Pan,
  • Jiyuan Zhai,
  • Feisi He,
  • Rui Ge,
  • Zhenghui Mi,
  • Peng Sha,
  • Song Jin,
  • Ruixiong Han,
  • Qunyao Wang,
  • Haiying Lin,
  • Guangwei Wang,
  • Xuwen Dai,
  • Zhanjun Zhang,
  • Mei Li,
  • Minjing Sang,
  • Liangrui Sun,
  • Rui Ye,
  • Tongxian Zhao,
  • Shaopeng Li,
  • Keyu Zhu,
  • Baiqi Liu,
  • Xiaolong Wang,
  • Xiangchen Yang,
  • Xiaojuan Bian,
  • Xiangzhen Zhang,
  • Huizhou Ma,
  • Jianbing Zhao,
  • Liang Zhang,
  • Hui Zhao,
  • Runbing Guo,
  • Zhihui Mu,
  • Conglai Yang,
  • Xiaobing Zheng,
  • Chao Dong,
  • Hongjuan Zheng,
  • Zhengze Chang,
  • Xiaochen Yang,
  • Tongming Huang,
  • Qiang Ma,
  • Zihan Wang,
  • Ming Liu,
  • Wenzhong Zhou,
  • Senyu Chen

DOI
https://doi.org/10.1103/PhysRevAccelBeams.27.092003
Journal volume & issue
Vol. 27, no. 9
p. 092003

Abstract

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The world’s first 1.3 GHz cryomodule containing eight 9-cell superconducting radio-frequency (rf) cavities treated by medium-temperature furnace baking (mid-T bake) was developed at the Institute of High Energy Physics, Chinese Academy of Sciences. The 9-cell cavities in the cryomodule achieved an unprecedented high average intrinsic quality factor (Q_{0}) of 3.8×10^{10} at 16 MV/m and 3.6×10^{10} at 21 MV/m in the horizontal test. The cryomodule can operate stably up to a total continuous wave rf voltage greater than 193 MV, with an average cavity usable accelerating gradient of more than 23 MV/m. The results significantly exceed the specifications of Circular Electron Positron Collider and Dalian advanced light source and the other high repetition rate free electron laser facilities [Linac Coherent Light Source II (LCLS-II), LCLS-II-high energy, Shanghai High Repetition Rate X-ray FEL and Extreme Light Facility, Shenzhen Superconducting Soft X-Ray Free Electron Laser, etc.]. There is evidence that the mid-T bake cavity may not require fast cooldown or long processing time in the cryomodule. This paper reviews the cryomodule performance and discusses some important issues in cryomodule assembly and testing.