The AC loss occurred in REBa₂Cu₃O_y (REBCO, RE = rare earth elements, Y, Eu, Gd) superconductor is serious problem in AC applications because it may cause a severe temperature rise of superconducting systems. Therefore, it is necessary to understand the AC loss property of REBCO superconducting tape in detail and to reduce that. As AC application such as motor, the tape is mostly stacked into multi-layer. Thus, understanding the relation between the number of the stacked tapes and the AC loss is one of the most important subjects. So far, we confirmed that the AC loss of the n-layer stacked REBCO superconducting tapes decreases to 1/n of that of 1-layer for the magnitude of the applied external field, B_m, below the penetration field, B_p, and such property can be explained from the viewpoint of the demagnetizing coefficient. However, the result in that report was only at 50 K and such property was not systematically confirmed at other temperatures. In this study, the AC loss decreasing property owing to stacking tapes for B_m below B_p was investigated via experiments. Furthermore, such property was considered theoretically from the viewpoint of the demagnetizing coefficient of the stacked REBCO superconducting tapes. Consequently, it was cleared, from theoretical consideration, that the n dependence of the AC loss can be explained quantitatively by the demagnetizing coefficient, and, in order to apply the theory to the experimental results, the stacked tapes have to satisfy the restrictions which are D/w < 0.1 and t/w << 1. Here, D, w and t are the distance between the neighboring superconducting layers, the width and the thickness of the superconducting layer. Moreover, from such AC loss property, it was revealed that the n dependence of B_p can be expressed as a power function. Using the results obtained in this study, the AC losses of the stacked tapes can be estimated easily from that of 1-layer tape.

REBa ₂ Cu ₃ O _y（REBCO，RE =稀土元素，Y，Eu，Gd）超导体中发生的交流损耗在交流应用中是一个严重的问题，因为它可能导致超导系统的严重温度上升。因此，有必要详细了解REBCO超导带的AC损耗特性，并加以降低。作为交流应用，例如电动机，胶带大多被堆叠成多层。因此，了解堆叠带的数量与AC损耗之间的关系是最重要的主题之一。到目前为止，我们已确认，对于所施加的外部电场，n层堆叠的REBCO超导带的AC损耗降至1层的1 / n，可以从退磁系数的角度来解释在穿透场下方的B _m，B _p等特性。但是，该报告中的结果仅在50 K时出现，并且在其他温度下未系统地确认该性质。在这项研究中，通过实验研究了由于堆叠胶带使B _m低于B _p导致的交流电损耗降低特性。此外，从堆叠的REBCO超导带的退磁系数的角度理论上考虑了这种性质。因此，它被清除，从理论上考虑，该ñ交流损耗的依赖性可以通过退磁系数来定量地解释，并且，为了将该理论应用于实验结果，堆叠的带必须满足D / w <0.1和t / w << 1.的限制。在此，D，w和t是相邻的超导层之间的距离，超导层的宽度和厚度。此外，从这种AC损耗特性可以看出，B _p的n依赖性可以表示为幂函数。使用本研究中获得的结果，可以从1层胶带的交流损耗中轻松估算出它们的交流损耗。