Characterization of REBCO Superconducting Tape Damage Induced by Various Sample Preparation Methods

Abstract

Superconductors are materials that conduct electricity with no resistance at low temperatures. Superconductors have many applications ranging from MRIs to fusion reactors. Rare-earth barium-copper-oxide (REBCO) superconductors are high-temperature superconductors fabricated in a tape geometry. The sample preparation procedures for mechanical testing and for industrial slitting of the tape can introduce cracks and micro-peels in the REBCO layer, thus potentially limiting its electrical performance of the conductor, or reducing the mechanical strength of the composite tape. In this work, we investigated the damage found in the REBCO layer after industrial slitting and after guillotine cutting in a laboratory environment by imaging the samples using laser confocal microscopy, scanning electron microscopy (SEM), Auger Electron Spectroscopy and digital image analysis. We subsequently quantified the extent of fracture propagation along the slit or cut edge of the samples and the area of the REBCO layer absent. In the slit samples, fracture events in the buffer layers are found to correlate to those in the REBCO layer. Additionally, we identified the exposed buffer layer and quantified its thickness. With a better understanding of how the superconductor is damaged during tape slitting, the slitting process as well as the overall manufacturing process can be improved to provide a more mechanically stable and cost-effective superconductor.