Study On Carrent Transfer Length Of Multiple Parallel Superconducting Wires

YBCO superconducting tape has a high irreversible field and high critical current density,lower production costs and less AC loss,which has a good application prospects.In fact,YBCO superconducting tapes are usually used in parallel to meet the high-capacity transmission requirements.Due to the difficulty of preparing long high-performance superconducting tapes,it is often necessary to weld multiple YBCO superconducting tapes.In addition,it is also required to weld between the ends of the superconducting tapes and the current lead.The welding length of superconducting tapes plays an important role in the superconducting devices' stability and cooling costs.The current transfer length(ie,the jointing length)of multiple parallel superconducting tapes is studied in detail in this paper.For a single superconducting tape,the current transfer length between the superconducting tape and the copper tape,between the superconducting tape and the superconducting tape are investigated respectively.Depending on the orientation of the tape,the overlap joints between the superconducting tape and copper tape,between the superconducting tape and the superconducting tape will have different modes.In this paper,the "four-lead" method is used to measure the current transfer length under different overlap modes,which provides the basis for the jointing length of a single superconducting tape.At the same time,the thermal stability of different overlap joints under impact current is analyzed theoretically.For the multiple parallel superconducting tapes,two groups of overlap modes between multiple parallel tapes and current lead are adopted respectively in this paper:one is horizontal or side overlap between the several parallel superconducting tapes and current lead,another is unilateral or bilateral overlap between a number of parallel superconducting tapes and current lead.From the experimental point of view,the current transfer lengths of these two groups of multiple parallel superconducting tapes are measured and compared,and the reasons for the difference in current transfer length are analyzed.High-temperature superconducting(HTS)strands are excellent high-temperature superconducting conductors.The study of current transfer length of HTS strands is of great significance.In this paper,the superconducting strands are taken as an example to study the current transfer length of the superconducting tapes connected with the normal metal.The result is compared with that of horizontal or side overlap between the multiple parallel superconducting tapes and current lead.The result provides the basis for the welding of the high temperature superconducting strands.