Design and measurement of a compact EPU magnetic structure

One research direction for future synchrotron light sources is the development of elliptically polarized undulators (EPUs) with a short period and high magnetic field. The Shanghai Synchrotron Radiation Facility (SSRF) has developed a compact EPU prototype with a 16 mm period. The prototype incorporates a novel magnetic structure consisting of 8 magnet arrays, generating a peak magnetic field reaching approximately 0.8 T. Additionally, the magnetic structure is compact and lightweight, featuring a 5 mm aperture (ϕ5mm). To assess its performance, the magnetic field was measured using the pulsed wire and Hall sensor methods. This paper presents a detailed analysis of the physical design, mechanical structure, and measurement results of the compact EPU prototype.