Abstract: To explore flashover characteristics of different insulation materials induced by electromagnetic pulse (EMP) produced during electrostatic discharge (ESD), the ESD EMP-induced flashover test system was employed. According to the theory of secondary electron emission avalanche and superposition principle, and combined with the experiments, the induced flashover law of finger metal electrodes covered by three commonly used spacecraft insulation materials, namley, polymethyl methacrylate (PMMA), polytetrafluoroethylene (PTFE) and epoxy resin (EP) were investigated under the condition of ESD EMP irradiation. The results showed that: the ESD simulator generates EMP radiation field through electrostatic discharge by contacting with vertical metal coupling plate, which forms a compound electric field induced flashover combinded with the DC electric field on both ends of the electrode; when the induced voltage produced by the compound field between two electrodes is less than the flashover voltage of the insulation material, induced flashover cannot be generated; when the induced voltage is close to the material flashover voltage, induced flashover probability exists; the higher the ESD output voltage, the greater the induced voltage generated by the compound field, and the higher the induced flashover probability of the insulation materials, the dielectric strength of the three insulating materials is, the lower the probability of induced flashover under the condition of ESD EMP of the same intensity, so the time required to form a perforative discharge channel between the electrodes during flashover induction increases, the time delay becomes longer, and the induced flashover current increases accordingly.

Key words: spacecraft, insulationmaterials, inducesurfaceflashover, fingermetalelectrode, ESDEMP