Tree Growth Characteristics of Epoxy Resin in LN2 Under Magnetic Field

Epoxy resin, which is used as the base material of superconducting magnet insulation, faces the challenge of liquid helium temperature and magnetic field. Investigations about the influence of magnetic field on the electrical tree characteristics in epoxy resin under low temperature are reported in this paper. Samples made of epoxy resin were stressed in the needle-plate geometry electrodes. The experimental temperature ranged from room temperature to liquid nitrogen temperature. The experimental results indicate that both the low temperature and the magnetic field have influences on treeing process. The typical tree structures in epoxy resin are different with the variation of low temperature and magnetic flux density. It is revealed that the epoxy resin sample under low-temperature conditions is resistant to the growth of the electrical tree. However, when under the same low temperature, the tree initiation and propagation processes are accelerated by the high magnetic flux density.