Nuclear Techniques ›› 2020, Vol. 43 ›› Issue (10): 100101-100101.doi: 10.11889/j.0253-3219.2020.hjs.43.100101


Irradiation demagnetization of permanent magnets in insertion device for high-energy synchrotron radiation light source

Pingcheng LIU1,2,3,Qiongyao LIU1,2,3,Zhongjian MA1,Huijie ZHANG1,Mingyang YAN1,Qingbin WANG1,2()   

  1. 1.Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
    2.Spallation Neutron Source Science Center, Dongguan 523803, China
    3.University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2020-06-01 Revised:2020-07-06 Online:2020-10-15 Published:2020-10-14
  • Contact: Qingbin WANG
  • About author:LIU Pingcheng, male, born in 1993, graduated from Harbin Institute of Technology in 2015, doctoral student, focusing on nuclear technology application
  • Supported by:
    National Key Scientific Instrument and Equipment Development Project(2011YQ120096)

Abstract: Background

In synchrotron radiation facilities, the insertion devices are installed on the storage ring to produce high brightness, high coherence, and adjustable polarization synchrotron radiation, which are composed of periodic permanent magnet arrays. The permanent magnets are continuously exposed to beam loss electrons due to the Touschek effect. As a result, the permanent magnets can be more or less damaged and deteriorates the magnetic field of insertion devices. Radiation-induced demagnetization of permanent magnets in the insertion device is one of the critical issues for synchrotron radiation facilities.


This study aims to simulate the irradiation field and radiation damage of the Nd2Fe14B permanent magnet insertion devices during the routine operation of the high energy photon source (HEPS).


First of all, Monte Carlo code FLUKA was utilized to calculate the relationship between the absorbed dose and demagnetization of Nd2Fe14B magnet array based on the Spring-8 experiment. Then the different electronic sampling modes were set to calculate the irradiation field in the insertion device according to the actual beam loss conditions at HEPS. Finally, the demagnetization and countermeasures were analyzed according to the spatial distribution of absorbed dose.


When HEPS works in top-up mode, the irradiation of the magnetic pole in the upstream end of the insertion device is more severe. Most of the absorbed dose (about 99.7%) is contributed by photon, electron and positron. According to the beam loss parameters by physical calculation, the expected life of the insertion device is 2.1 to 4.6 years.


Placing local shielding layer and increasing the gap are the effective measures to protect the insertion devices, hence slow down radiation demagnetization of permanent magnet.

Key words: Demagnetization, Permanent magnet, Insertion device, HEPS, FLUKA

CLC Number: 

  • TL71