Frontiers in Physics (Jun 2023)

Development of an APPLE III undulator prototype with three-dimensional force compensation for SHINE

  • Cheng Yu,
  • Ya Zhu,
  • Wei Zhang,
  • Jie Yang,
  • Yongzhou He,
  • Tingting Zhen,
  • Tao Liu,
  • Yangyang Lei,
  • Qibing Yuan,
  • Dao Yuan,
  • Yongmei Wen,
  • Rongbing Deng,
  • Zhiqiang Jiang,
  • Haixiao Deng,
  • Bo Liu,
  • Dong Wang

DOI
https://doi.org/10.3389/fphy.2023.1174620
Journal volume & issue
Vol. 11

Abstract

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The Shanghai high-repetition-rate XFEL and extreme light facility (SHINE) plans to install several elliptically polarizing undulators (EPUs) as afterburners behind the planar undulator section to obtain nearly saturated circularly polarized free-electron laser (FEL) radiation. Therefore, the SHINE R&D project needs to develop a 4-m-long EPU with an effective magnetic field of 1.5 T, a period of 68 mm, and a minimum gap of 3 mm. A magnetic force compensation EPU prototype has recently been built and tested at the Shanghai Synchrotron Radiation Facility (SSRF) based on the addition of permanent magnets. This prototype can realize magnetic compensation under various polarization modes in all working gaps, thereby reducing the deformation of the girders and maintaining sufficient rigidity of the mechanical structure. A girder deformation monitoring system was established to obtain real force compensation feedback. The final magnetic field measurement results meet the physical requirements, and the proposed scheme can be used as an alternative to the EPU with a high magnetic field and large magnetic force.

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