Effects of Magnetic Field on Surface Flashover Behavior of Epoxy Resin for High-Field Magnets

Abstract

Surface flashover taken place along the epoxy resin at the terminal of high-field magnets is a serious defect which threatens the safety operation of the whole device. Flashover behavior is different from that in other traditional electric equipment due to the presence of high magnetic field. In this paper, a superconducting magnet system was set up to investigate the surface flashover behavior of epoxy resin in presence of different strengths and directions of external magnetic field. Experimental results show that flashover voltage decreases first and then shows reverse trend with the increase of magnetic field strength when Lorentz force drifts the electrons away from the surface. And the flashover voltage increases when Lorentz force drifts the electrons along or into the surface. High magnetic field restricts the polarization of epoxy resin and the initial electron emission at the triple junction is reduced. Lorentz force not only changes the collision ionization probability on the gas side but also affects the flashover path. This work will be helpful to the terminal insulation design of high-field magnets.