Transport Current Measurement of <inline-formula><tex-math notation="LaTeX">$I_{c}(T, B,\theta)$</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">$n(T, B,\theta)$</tex-math></inline-formula> for a Bulk REBCO Superconductor

Bulk rare-earth barium cuprate (REBCO) high-temperature superconductors are attractive for many electromagnetic applications due to their ability to support large current densities and trap large magnetic fields. At present, magnetisation techniques are the predominant method of measuring the critical current density, <inline-formula><tex-math notation="LaTeX">$J_\text {c}$</tex-math></inline-formula>, for bulk superconductors, due to the abundance of measurement devices and ease of sample preparation and measurement. However, this approach does not provide direct access to measurements of magneto-angular anisotropy of <inline-formula><tex-math notation="LaTeX">$J_\text {c}$</tex-math></inline-formula> nor <inline-formula><tex-math notation="LaTeX">$n$</tex-math></inline-formula>-value. By contrast, transport current techniques allow direct measurement of the full thermo-magneto-angular dependence of both <inline-formula><tex-math notation="LaTeX">$I_\text {c}$</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">$n$</tex-math></inline-formula>, but limited data is available for REBCO bulks, due to the difficulties of sample preparation and measurement. This work introduces a reproducible method to prepare a single-grain bulk GdBCO-Ag superconductor for transport current characterisation, and presents measured data for both <inline-formula><tex-math notation="LaTeX">$I_\text {c}$</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">$n$</tex-math></inline-formula> that has been obtained over a broad parameter-space. The measured <inline-formula><tex-math notation="LaTeX">$n$</tex-math></inline-formula>-values are lower than is commonly assumed, with typical <inline-formula><tex-math notation="LaTeX">$n$</tex-math></inline-formula>-values at 77 K being in the range of 10 to 14. An accurate value of <inline-formula><tex-math notation="LaTeX">$n$</tex-math></inline-formula> is required when computationally modelling transient effects.