Effect of epoxy insulation on strain distribution in superconducting coil

Epoxy resin insulation affects the stress distribution inside a superconducting coil. In this study, the effect of insulation was calculated by adopting an improved wire dynamic simulation method. A real Nb₃Sn coil was used as an example. The strain distribution was obtained by calculating the motion of the wires and the forces applied on each wire. The strain distribution was compared with that obtained from finite element simulation. Result showed that the strain on the wire increased after considering the insulation. The relationships between the maximum strain in the coil and the thickness/elastic modulus of the insulation were also calculated. Furthermore, impregnation defects may result in strain concentration; the effects of these defects were also discussed at different locations of the coil.