Electrical performance of TGPAP and DGEBF-based epoxy resin insulation materials for superconducting magnets

For the insulation materials of the superconducting magnet, the mechanical and electrical properties should be guaranteed under stresses of cryogenic temperature and intense radiation. In this study, two types of epoxy resins were prepared, which consist of diglycidyl ether of bisphenol-F (DGEBF) and triglycidyl-p-aminophenol (TGPAP) as matrixes respectively, and diethyl toluene diamine (DETD), isopropylidenebisphenol bis[(2-glycidyloxy-3-n-butoxy)-1-propylether] (IPBE) and boron-free glass fibre were used as curing, toughing and reinforcing agents for each resin. The direct-current (dc) electric breakdown strength and flashover voltage, dielectric properties and space charge characteristics of both epoxy composites were investigated. According to the results, DGEBF composite shown a higher dielectric strength, lower permittivity and dielectric loss at cryogenic temperature and smaller shallow trap density, which makes it more potential to be used for the cryogenic insulation.