Investigation of Stress/Strains and Related Properties in Superconducting Wires and Conductors by Means of Neutron Diffraction at J-PARC

Abstract

Recently the investigations on the local stress/strains and related properties in the engineered superconducting composites have been extensively carried out by using the pulsed neutron facilities, J-PARC TAKUMI. Firstly the key concepts are described in order to understand their mechanical-electromagnetic properties after the performance of TAKUMI is briefly introduced. Unique and important results have been obtained by the present diffraction studies. Highlights of the present review are the three dimensional description of strains in Nb₃Sn filaments, the determination of force free strains at RT and 77 K for BSCCO and YBCO tapes, and of T_o for the BSCCO tape and Nb₃Sn wires, which is the initiation temperature of thermally induced residual strains. Typically the local axial strain exerted on Nb₃Sn filaments has been firstly measured along the TF coil used for ITER project in the world.