ITER用ケーブル・イン・コンジット導体におけるNb₃Sn生成熱処理による熱歪の評価

抄録

Cable-in-conduit (CIC) conductors using Nb₃Sn strands will be used in ITER toroidal field (TF) coils. Heat treatment generates thermal strain in CIC conductors because of the difference of the thermal expansion between the Nb₃Sn strands and the stainless steal jacket. The TF coil winding fabrication method and design of the conductor joint should be determined while taking into account the elongation/shrinkage of the CIC conductor and its residual force as the result of thermal strain. The authors developed a new apparatus to evaluate these factors, and the conductors for the TF coils were measured. The maximum elongation/shrinkage of the conductors was 0.03%, and the maximum residual force was 35 kN. A winding method for the TF coil is proposed based on these results.