Investigation of Intertape Coupling Losses in YBCO-Stacked Cables

We investigated intertape coupling losses in yttrium barium copper oxide (YBCO)-stacked cables. YBCO stacked cables are being researched and developed as candidates for large 100 kA-class conductors for nuclear fusion. Here, we report intertape coupling losses in a conductor of 50 stacked tapes measured in liquid nitrogen. The measured conductor consists of soldered intertape connections. A copper layer surrounded the YBCO tape in the sample conductor. Fifty YBCO tapes were stacked, and the entire sample was bound with a copper tape and then impregnated with solder. This sample was approximately 100 mm long without twisting. The intertape coupling current flowed over the entire length of the sample conductor due to nontwisting. First, intertape resistance was estimated by comparing the measured and theoretical coupling losses. Subsequently, the coupling current paths in the cross-section of the sample were investigated. We found that intertape resistances were affected by the copper tape used to bind the stacked YBCO tapes. & COPY; 2023 The Japan Society of Plasma Science and Nuclear Fusion Research