Critical Current Evaluation of REBCO Tapes Across Entire Temperatures and Magnetic Fields up to 25 T Using a 5 kA Pulsed Current Supply

In this study, we developed a measurement method for the temperature and magnetic field dependences of the critical currents in full-width REBCO tapes using a 5 kA pulsed current. The confined space in high magnetic field environments and limited cooling power under variable temperature conditions give rise to challenges, particularly due to heat generation in the current leads under DC large currents. While microbridge processing is commonly used to limit current, it is less reliable due to the inhomogeneity of the REBCO tapes, making it necessary to measure the characteristics of full-width REBCO tapes. Therefore, we have addressed these challenges by using pulsed currents. By configuring supercapacitors and current regulators, a stable 5 kA pulsed power supply was developed. Using this power supply, the temperature and field dependences of the critical currents in REBCO tapes with full-widths were measured, including at 4.2 K under self-field condition. The suppression of mechanical vibrations reduced noise levels to several µV/cm, even under a magnetic field of 25 T. This approach provides a reliable method for evaluation of the performance of full-width REBCO tapes in high-field and variable-temperature environments.