Non-Destructive Evaluation of the Initial Imperfection and the Coil Rigidity of the Superconducting Magnet

Abstract

A large superconducting magnet for fusion reactor, which is one of the composite structure, have initial imperfections caused by the complicated residual stress distribution, irregular winding situation, cracking and delamination of GFRP insulator during fabrication and cooling down, respectively. This initial imperfection propagates by thermal cycling. The intial imperfection and its subsequent propagation by thermal cycling causes a significant decrease in the coil rigidity. We detected the initial imperfection and its propagation in the GFRP insulator non-destructively by using the SPATE 9000 stress analyzer, Taking the result, we evaluated the relationship between the coil rigidity, the initial imperfection and its propagation quantitatively.