Winding rigidity of impregnated coil with large conductor

The high rigidity and strength of winding pack are required to realize a large superconducting magnet for a fusion reactor. Adhesive samples were evaluated to compare conductor insulators in order to improve adhesive strength. Epoxy and bismaleimide-triazine resin (BT resin) were used as the conductor insulator. Stainless steel (SS) 304 bars, whose surface was treated mechanically and chemically, were applied to the modeled conductor. The model coil was bundled with the model conductors covered with the insulator by a grand insulator. A winding model combining 3×3 conductors was produced for measuring shearing rigidity. The sample was loaded with pure shearing force at LN ₂ temperature. It is shown that the maximum adhesive strength reaches 67 MPa with the epoxy and 48 MPa with the BT resin at 77 K. Comparing the experimental results with stress analysis, the Young´s modulus of insulator is less than 1 GPa in the bending rigidity. In the compressive test, the Young´s modulus of the insulator is 3.5 GPa in the axial rigidity. Therefore, it is necessary to consider the anisotropic rigidity of the insulator in the winding pack