Transport Current Measurement of [Formula Omitted] and [Formula Omitted] 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, [Formula Omitted], 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 [Formula Omitted] nor [Formula Omitted]-value. By contrast, transport current techniques allow direct measurement of the full thermo-magneto-angular dependence of both [Formula Omitted] and [Formula Omitted], 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 [Formula Omitted] and [Formula Omitted] that has been obtained over a broad parameter-space. The measured [Formula Omitted]-values are lower than is commonly assumed, with typical [Formula Omitted]-values at 77 K being in the range of 10 to 14. An accurate value of [Formula Omitted] is required when computationally modelling transient effects.