Eddy Current Testing of Eccentricity in Tokamak In-Vessel Coil Conductors Based on Flexible Probe

The conductor of ITER In-Vessel Coil (IVC) is of three-layer tubular structure. During manufacture procedure of IVCs, eccentricity may occur between the copper tube conductor and stainless-steel supporting tube. Large eccentricity may seriously reduce the insulation property of the middle ceramic layer of IVC conductor and cause big influence on the performance of entire IVC. Therefore, it is critical to evaluate the eccentricity of IVCs by using non-destructive testing techniques. Our group has proposed an eddy current testing method based on absolute pancake coil in earlier studies. To enhance the evaluation efficiency of the eddy current testing method and to improve evaluation precision, in this paper, ECT based on TR type flexible probe is proposed and its detect ability is demonstrated. In addition, optimized probe structure and arrangement are also investigated by comparing the detect ability of different probe structures.