Single-blockmeasurement for the cryogenic permanent magnet undulator sorting  

作　　者：Ling-Ling Gong Xiao-Yu Li Yu-Hui Li Ya-Jun Sun Hui-Hua Lu Ke-yun Gong Qing Guo·Shu-Chen Sun Zhi-qiang Li Wan Chen 

机构地区：[1]Laboratory of Particle Acceleration Physics and Technology,Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China [2]University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Radiation Detection Technology and Methods》2021年第1期83-89,共7页辐射探测技术与方法（英文）

基　　金：NSFC funding approval No.12075272.

摘　　要：Purpose The magnet sorting is a standard step in the undulator fabrication procedure.The shortest undulators period used in the High Energy Photon Source(HEPS)is only 12 mm.To the short period undulator,the sorting may be more important than the long-period undulator.Normally,the Helmholtz measurement is used as the input for the work.It is the averaged orthogonal magnetization of each block.In order to investigate whether the Helmholtz coil measurement is enough for the sorting,a careful study has been made.Method Firstly,a magnetic camera was used to scan the 3D surface field of a magnet.Afterward,its field integral ismeasured by the stretched wire.In the measurement,the magnetwas placed at different statuses.The results were checked to seewhether they are consistent with expected features supposing a homogeneous magnetized block.Finally,the results measured by the Helmholtz coil and the stretched wire were compared.Results The surface field scan demonstrates that the field over a magnet block is inhomogeneous.Moreover,the field integral measurement by the stretched wire also shows big difference when the different magnet sides toward thewire.The comparison between the stretched wire and the Helmholtz coil measurement shows no correlation.Conclusion The study presented in this paper reveals that the homogeneity of the magnetization is imperfect.Therefore,the Helmholtz coil data are insufficient to the short-period undulators sorting.

关 键 词：Magnet sorting UNDULATOR Stretched wire Helmholtz coil 

分 类 号：TM273[一般工业技术—材料科学与工程]