High <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>Q</mml:mi> </mml:math> 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, Li ShaoPeng, Keyu Zhu, Baiqi Liu, Xiaolong Wang, Xiangchen Yang, Xiaojuan Bian, Xiangzhen Zhang, Huizhou Ma, Jianbing Zhao, Liang Zhang, Hui Zhao, R. P. Guo, Zhihui Mu, Conglai Yang, Xiaobing Zheng, Chao Dong, Hongjuan Zheng, Zhengze Chang, Xiaochen Yang, Tong-Ming Huang, Qiang Ma, Zihan Wang, Ming Liu, Wenzhong Zhou, Senyu Chen
Abstract
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 ( <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mrow> <a:msub> <a:mi>Q</a:mi> <a:mn>0</a:mn> </a:msub> </a:mrow> </a:math> ) of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mrow> <c:mn>3.8</c:mn> <c:mo>×</c:mo> <c:msup> <c:mn>10</c:mn> <c:mn>10</c:mn> </c:msup> </c:mrow> </c:math> at <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mrow> <e:mn>1</e:mn> <e:mn>6</e:mn> <e:mtext> </e:mtext> <e:mtext> </e:mtext> <e:mi>MV</e:mi> <e:mo>/</e:mo> <e:mi mathvariant="normal">m</e:mi> </e:mrow> </e:math> and <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"> <h:mrow> <h:mn>3.6</h:mn> <h:mo>×</h:mo> <h:msup> <h:mn>10</h:mn> <h:mn>10</h:mn> </h:msup> </h:mrow> </h:math> at <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"> <j:mrow> <j:mn>2</j:mn> <j:mn>1</j:mn> <j:mtext> </j:mtext> <j:mtext> </j:mtext> <j:mi>MV</j:mi> <j:mo>/</j:mo> <j:mi mathvariant="normal">m</j:mi> </j:mrow> </j:math> 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 <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"> <m:mrow> <m:mn>2</m:mn> <m:mn>3</m:mn> <m:mtext> </m:mtext> <m:mtext> </m:mtext> <m:mi>MV</m:mi> <m:mo>/</m:mo> <m:mi mathvariant="normal">m</m:mi> </m:mrow> </m:math> . 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. Published by the American Physical Society 2024