Experimental Investigation of the Influence of an Encapsulation Layer on the Lightning Current Characteristics of YBCO Tapes

The over-current performance of high-temperature superconductors (HTSs) has been well studied. However, the superconducting devices used in power grids might also suffer from exposure to lightning current. This paper will focus on the influence of the encapsulation layer of YBCO tapes on the performance degradation of the critical current after suffering lightning current. We prepared and tested six groups of samples with different YBCO tape widths, material types of the encapsulation layer, and thicknesses of the encapsulation layer. For comparison, the performance of YBCO tape without an encapsulation layer was also analyzed. The critical current and n value of each sample were measured and calculated before and after 8/20 mu s lightning current tests. Moreover, two types of damage were observed, i.e., surface melt and delamination, and the reasons were described in detail. The results of this paper could provide useful data for selecting the encapsulation layer of YBCO tapes.