Mechanical—electromagnetic property of stainless sheet laminated BSCCO–2223 wires

In order to elucidate the effect of applied tensile stress/strain on the critical current of DI-BSCCO-2223 wires, the critical current measurement and the tensile test were carried out at 77 K. Neutron diffraction measurements were also performed at 77 K to get direct information about the local strain exerted on the BSCCO superconducting filaments. It was reported that the critical current of BSCCO wires decreases linearly in a small range of tensile stress/strain and that the critical current returns reversibly on reducing the stress/strain. The gradual decrease of critical current was observed within the reversible region. When the tensile stress /strain increased beyond a characteristic value, the critical current decreased rapidly due to the brittle fracture of BSCCO filaments. It is proposed that the reversible stress/strain limit of critical current (R _rec and A _rec) can be defined experimentally as the 99% I _c recovery stress (R _99%rec) and strain (A _99%rec). The reversible strain limit is proposed to consist mainly of three factors of pre-strain, thermal strain and tensile fracture strain of SC filaments themselves. The calculated relation between the R _rec and A _rec could well explain quantitatively the observed relation between 99% I _c recovery stress and strain. (paper)