Transport current characterisation of the magnetic field-angular dependence of the critical current density for bulk REBCO superconductors

Dec. 1 12:50-13:10

*Ross W. Taylor1,2, Andres E. Pantoja1, Tomáš Hlásek3, Jan Plecháček3, Hubertus W. Weijers1, Mark D. Ainslie4, Chris W. Bumby1,2
Robinson Research Institute, Victoria University of Wellington1
MacDiarmid Institute, Victoria University of Wellington2
Department of Engineering, King’s College London4

Computer modelling of bulk superconductors produced from rare-earth barium cuprates (REBCO) is important in the development of various applications, such as bearings, projected field magnets and levitation devices. Accurate models require input data that describes the critical current density and flux-flow exponent of the superconductor as a function of temperature, and magnetic field amplitude and orientation. However, at present there is a dearth of Jc(T, B, θ) and data n(T, B,θ) for REBCO bulks.

In this work, a technique is described to obtain such data via transport-Ic measurements using the SuperCurrent instrument at the Robinson Research Institute, which has been specifically developed to characterise the angle-, temperature- and field-dependence of critical current in HTS wires.

Superconducting bars with cross-sections of less than 5 mm2 were cut from Ag-infused GdBCO bulks using a diamond wire band saw, and then mounted and polished to produce measurement samples. Four-point probe measurements of transport have then been performed using the SuperCurrent system, which enables measurements at a range of temperatures (down to ~15 K), and with applied fields of up to 8 T and over 360 degrees orientation. Preliminary measurements of REBCO bulks made using this method are reported, in particular, the highly anisotropic field dependence observed, in addition to significant temperature dependence of both self-field Ic and n-value.