Magnetic Field and Temperature Scaling of the Critical Current of REBCO Tapes
G. Succi, A. Ballarino, Simon C. Hopkins, Christian Barth, Y. Yang
Abstract
High temperature superconductors (HTS) in the form of REBCO (RE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> Ba <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7-δ</sub> ) coated conductor tapes have undergone, in recent years, major improvement of their transport current properties in high magnetic fields and at liquid helium temperature. The modelling of coils and other applications using REBCO tapes requires accurate characterization and precise knowledge of their properties. In this paper, we report on an anisotropic scaling law that describes the field dependence of the critical current of REBCO tapes up to the irreversibility field, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{{\bm{B}}}_{{\bm{irr}}}}$</tex-math></inline-formula> , and at temperatures of up to the critical temperature, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{{\bm{T}}}_{\bm{c}}}$</tex-math></inline-formula> . We performed an experimental campaign to investigate the properties of recently produced commercial tapes and verify the validity of the scaling law. We measured the magnetic field dependence of the critical current in liquid helium at 4.2 K and in applied perpendicular fields of up to 15 T. The experimental setup allowed the characterization of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{{\bm{I}}}_{\bm{c}}}$</tex-math></inline-formula> of tapes up to 2.6 kA. Magnetization measurements were also used to complement the transport measurements for temperatures in the range from 4.2 K up to close to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{{\bm{T}}}_{\bm{c}}}$</tex-math></inline-formula> and in background fields of up to 10.5 T.