Influence of Strands Trajectories of JT-60SA TF Conductors on Their Hydraulic and Electromagnetic Properties

In the framework of the JT-60SA project, Europe provides the toroidal field magnets system through Fusion for Energy (F4E, the EU Domestic Agency) procuring of 27 km of toroidal field (TF) conductor. The complex trajectories of the strands interleaved in the conductor cable volume cannot be easily predicted while having an influence on both hydraulic and electromagnetic performances. In this context, a nondestructive examination method has been developed at INFLPR (RO) using tomographic facility providing strands positions in successive cross sections. An algorithm was developed to reconstruct the strand trajectories with a satisfactory efficiency. The strands trajectories database is then used to refine the cable performances in operation conditions and quote the influence of current-field angle variation on performances. In addition, a statistic of the interstrand contact distribution within the cable volume is identified and interpreted in terms of contribution to the ac losses in case of transient B variation. Finally, the statistic of void local fraction is investigated and tentatively correlated with mass flow variations, together with considerations on determination of operation mass flow along TF conductor production according to the experimental database.