Magnetization and deff in multifilamentary Nb3Sn strands

The magnetization of various design internal-Sn type Nb₃Sn strands was analyzed in terms of effective filament diameter, d_eff. Assuming circular geometry and ignoring demagnetization, values of d_eff have been calculated numerically for various configurations including unsplit subelement and split subelement cases with 2, 3, 4 and 6 splits. In the numerical calculation, the magnetization was treated as the summation of the magnetization of sections aligned perpendicular to the applied field. The angle-averaged d_eff value was calculated for every degree over the split regions. The d_eff of single restacked strands using subelements with various numbers of splits has been calculated and the results show the influence of the split design of strands on the magnetization in high fields. Furthermore, the numerical results were compared with the reported simplified analytical results, about 20% difference indicates the approximation of the simplification.