Characteristics of REBCO Coated Conductors for 25 T Cryogen-Free Superconducting Magnet

Abstract

A 25 T cryogen-free superconducting magnet is under development at the High Field Laboratory for Superconducting Materials (HFLSM), Institute for Materials Research (IMR), Tohoku University. Fujikura has manufactured and supplied REBCO coated conductors for the 25 T cryogen-free superconducting magnet. In-field critical current (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> ) properties in high magnetic fields at lower temperatures below 20 K and mechanical properties are important for design of these superconducting magnets. However, there is insufficient data of I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> properties in high magnetic fields above 15 T. In this work, in-field I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> properties at 20 K, 15 T of several samples cut from commercial coated conductors are evaluated at HFLSM, IMR, Tohoku University. The correlations between I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> at 20 K, 15 T and I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> at 77.3 K are compared. As a result, it is confirmed that I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> at 20 K, 15 T have a stronger correlation with in-field I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> at 77.3 K rather than I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> at 77.3 K, self-field. In addition, tensile strengths at 77.3 K of more than 30 samples of coated conductors are also evaluated.