Exploration of the copper–niobium composite superconducting cavities for pursuing extremely high operational stability at IMP  

作　　者：Shi-Chun Huang Yuan He Long Peng Chun-Long Li Sheng-Xue Zhang Meng-Xin Xu Zi-Qin Yang Hao Guo Lu-Bei Liu Ping-Ran Xiong An-Dong Wu Qing-Wei Chu Xiao-Fei Niu Teng Tan Zhi-Jun Wang Jun-Hui Zhang Sheng-Hu Zhang Hong-Wei Zhao Wen-Long Zhan 

机构地区：[1]Institute of Modern Physics,Chinese Academy of Sciences,Lanzhou 730000,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]Advanced Energy Science and Technology Guangdong Laboratory,Huizhou 516007,China [4]School of Nuclear Science and Technology,Lanzhou University,Lanzhou 730000,China

出　　处：《Nuclear Science and Techniques》2025年第5期19-29,共11页核技术(英文)

基　　金：supported by the Large Research Infrastructures China initiative Accelerator Driven System(No.2017-000052-75-01-000590);the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2022422);the Young Scientists of National Natural Science Foundation of China(No.12005275);the Advanced Energy Science and Technology Guangdong Laboratory(No.HND22PTZZYY)。

摘　　要：Theoretically,copper–niobium(Cu-Nb)composite superconducting cavities have excellent potential for high thermal and mechanical stability.They can appropriately exploit the high-gradient surface processing recipes developed for the bulk niobium(Nb)cavity and the thick copper(Cu)layer’s high thermal conductivity and rigidity,thereby enhancing the operational stability of the bulk Nb cavities.This study conducted a global review of the technical approaches employed for fabricating Cu-Nb composite superconducting cavities.We explored Cu-Nb composite superconducting cavities based on two technologies at the Institute of Modern Physics,Chinese Academy of Sciences(IMP,CAS),including their manufacturing processes,radio-frequency(RF)characteristics,and mechanical performance.These cavities exhibit robust mechanical stability.First,the investigation of several 1.3 GHz single-cell elliptical cavities using the Cu-Nb composite sheets indicated that the wavy structure at the Cu-Nb interface influenced the reliable welding of the Cu-Nb composite parts.We observed the generation and trapping of magnetic flux density during the T_c crossing of Nb in cooldown process.The cooling rates during the T_c crossing of Nb exerted a substantial impact on the performance of the cavities.Furthermore,we measured and analyzed the surface resistance R_(s)attributed to the trapped magnetic flux induced by the Seebeck effect after quenching events.Second,for the first time,a low-beta bulk Nb cavity was plated with Cu on its outer surface using electroplating technology.We achieved a high peak electric field E_(pk)of~88.8 MV/m at 2 K and the unloaded quality factor Q_(0)at the E_(pk)of 88.8 MV/m exceeded 1×10^(10).This demonstrated that the electroplating Cu on the bulk Nb cavity is a practical method of developing the Cu-Nb composite superconducting cavity with superior thermal stability.The results presented here provide valuable insights for applying Cu-Nb composite superconducting cavities in superconducting accelerators with stringent o

关 键 词：Superconducting radio-frequency cavities Cu-Nb composite Mechanical and thermal stability Thermoelectrical effect Magnetic flux trapping effect 

分 类 号：O511[理学—低温物理]