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, assembled and tested at IHEP for the Dalian Advanced Light Source (DALS) and CEPC R&D. The 9-cell cavities in the cryomodule achieved an unprecedented highest average Q0 of 3.8E10 at 16 MV/m and 3.6E10 at 21 MV/m in the horizontal test. The cryomodule can operate stably up to a total CW RF voltage greater than 191 MV, with an average cavity CW accelerating gradient of more than 23 MV/m. The results significantly exceed the specifications of CEPC, DALS and the other high repetition rate free electron laser facilities (LCLS-II, LCLS-II-HE, SHINE, S3FEL). There is evidence that the mid-T bake cavity may not require fast cool-down or long processing time in the cryomodule. This paper reviews the cryomodule performance and discusses some important issues in cryomodule assembly and testing.
@article{arxiv.2312.01175,
title = {High Q and high gradient performance of the first medium-temperature baking 1.3 GHz cryomodule},
author = {Jiyuan Zhai and Weimin Pan and Feisi He and Rui Ge and Zhenghui Mi and Peng Sha and Song Jin and Ruixiong Han and Qunyao Wang and Haiying Lin and Guangwei Wang and Mei Li and Minjing Sang and Liangrui Sun and Rui Ye and Tongxian Zhao and Shaopeng Li and Keyu Zhu and Baiqi Liu and Xiaolong Wang and Xiangchen Yang and Xiaojuan Bian and Xiangzhen Zhang and Huizhou Ma and Xuwen Dai and Zhanjun Zhang and Liang Zhang and Hui Zhao and Runbing Guo and Zhihui Mu and Conglai Yang and Xiaobing Zheng and Chao Dong and Tongming Huang and Qiang Ma and Hongjuan Zheng and Ming Liu and Zihan Wang and Wenzhong Zhou},
journal= {arXiv preprint arXiv:2312.01175},
year = {2023}
}