Buckling Behavior of Nb3Sn Strand Caused by Electromagnetic Force and Thermal Mismatch in ITER Cable-In-Conduit Conductor

Recent experiments on the international thermonuclear experimental reactor Nb
₃
Sn cable-in-conduit conductor have shown degradation in current-sharing temperature (T
_cs
) over several thousand electromagnetic (EM) cycles. The destructive investigations on these specimens have found that the Nb
₃
Sn strand buckled and cracked on the surface of the long twist pitch cable at the low EM load side. In order to discuss the strand buckling behavior, we propose a theoretical model to analyze the influences of twisting pitch, stainless steel tape width (wrap width), coverage rate, wrap stiffness, and friction factor on the buckling behavior of the Nb
₃
Sn strand. The cases of Nb
₃
Sn strand with and without EM loading are discussed, respectively. Moreover, a slip of the cable within jacket, which often reinforces the plastic deformation of the strand, is also considered in this study.