Radiation damage of Nd2Fe14B permanent magnets at 2.5 GeV electron accelerator

Radiation-induced demagnetization of permanent magnets is one of the most important issues of synchrotron radiation facilities, especially the next-generation light sources. In this paper, the radiation damage of the permanent magnet is investigated. The relative reduction of the magnetic field intensity of Nd2Fe14B magnet and its spatial distribution is derived with the radiation damage experiments carried out at a 2.5 GeV electron beam. The radiation field as well as the radiation quantities related to the radiation damage, mainly including the absorbed dose and 1 MeV equivalent neutron fluence are studied with Monte Carlo simulation. The radiation-induced demagnetization is analyzed based on the above results and fitted formulas are proposed to estimate the relative reduction of magnetic field intensity. Good agreement is found between the experiment data and fitted data. The variation of hysteresis loops before and after irradiation show that the remanence could not be restored to its original value by the remagnetization.