A Fabrication Design For The Correction Coil Support Thermal Shield In Iter And Its Performance Evaluation

Correction coil support (CCS) thermal shield (TS) is a key component in the ITER magnet that supports and serves to interrupt the heat from toroidal field case (TFC) to the correction coil superconductor. In this paper, a feasible fabrication design for the CCS TS is presented which is accomplished by 3 kinds of jointing processes (vacuum brazing, friction stir weld, and tungsten inert gas weld). The finite element analysis (FEM) is employed to speculate whether there is any interaction between different jointing processes. Based on the fabricating design, a prototype CCS TS is fabricated based on the fabricating design. Subsequently, the qualification test is carried out to characterize the property of the joints. The macro metallographic shows that the braze ratio of the as-brazed joint is 100%, and no crack or defect is observed in all the joints. The OM and EBSD results illustrate that the Ag6%Cu eutectic phase penetrates along the crystal grain boundary of the copper. The dynamic re-crystallization behavior of friction stir weld (FSW) joint is demonstrated by EBSD observation. The tensile test shows that the shear strength of the SS/Cu joint is 205MPa, and the fracture strength of Cu/Cu FSW joint is 212MPa. The leakage rate of the CCS TS sealing with the 3MPa He is lower than 4x10- (10) Pa*m(3)/s. Based on the above work, the fabrication plan is feasible and can be utilized in the manufacturing of ITER CCS TS.