Mechanical Analysis of Full-Scale Nb3Sn CICC Designs for Tokamaks

Abstract

Several designs of Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn Cable-In-Conduit Conductors (CICCs) have been proposed so far for high-performance tokamak magnets. The Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn strands composing the conductors are subjected to mechanical stresses of electromagnetic (EM) and thermal origin, inducing local deformations and affecting the strands critical current carrying capability. In the last ten years a numerical tool based on a finite element (FE) code has been developed to simulate the mechanical behavior of the CICCs subjected to operating loads. The main goal of this tool is to predict the electro-mechanical performance of the conductor in operation as a function of the design parameters such as the void fraction, the twist pitches and the conductor shape. In this work, a detailed model of a full-cable ITER TF CICC is presented. This model proves useful for a deeper understanding of the mechanical phenomena occurring among the sub-cables during the conductor operation. Moreover, the numerical modelling of different conductors from the ITER, DTT and JT60 projects is also presented to highlight the versatility of the code.