多芯Bi-2223/Ag带材交流损耗的特性研究

characteristic research of multi-core Bi-2223/Ag strip AC loss

Bi-2223/Ag是一种很有前景的高温超导带材,交流损耗是高温超导在大规模电力应用方面的瓶颈,如何降低Bi-2223/Ag中的交流损耗是人们一直关注的问题。带材超导部分的横截面形状对交流损耗有很大的影响,前人曾通过双轴轧制等工艺制造矩形截面的带材,以降低其交流损耗;另有人在单芯带材中得到了环状结构,从中发现可降低交流损耗。本论文尝试利用抽换芯工艺制造多芯环状截面的Bi-2223/Ag高温超导带材,以期降低带材的交流损耗。论文中,通过解析方法计算了临界态模型下,临界电流密度在径向上分布不均匀的超导体的交流损耗特性,并得到结论:带材的外围临界电流密度越高,交流损耗性能越好。

AC losses is one of the most important points on large electric applications of high temperature superconductors. Bi -2223/Ag is a promising superconducting material, which is already in commercial production. How to decrease the AC losses in Bi -2223/Ag tapes is highly concerned. The cross section has a large influence on the AC loss behaviour. The tape with rec- tangular cross section produced by bi - axial rolling was proved to have lower AC losses. Losses in ring - like structure monofila- ment tapes were found to be lower, too. We tried to make a ring -like structure in multifilament Bi -2223/Ag tapes, which was produced by changing superconducting filaments into Ag filaments, to reduce the AC losses. AC losses of superconductors with varying Jc were analyzed at first in the thesis to find that the higher Jc of outer filaments is, the lower AC losses are.