An effective way to reduce AC loss of second-generation high temperature superconductors

Abstract

Second-generation (2G) high temperature superconducting (HTS) devices have high power density and efficiency for energy applications. However, in alternative current conditions, the vortex movement in 2G HTS leads to energy dissipation at low temperatures, which significantly affects efficiency and adds an extra burden to cooling systems. This energy dissipation is identified as AC loss. Reducing AC loss to improve efficiencies of 2G HTS devices, e.g. HTS machines, cables and fault current limiters, has become a key research focus. We report here on an effective way to reduce AC losses by using a new 2G HTS wire. The principle is to stack narrow 2G HTS tapes into a wire structure, which is called a soldered-stacked-square (3S) wire. Our experiments on solenoid coils have proved that the 3S wire helps to reduce the AC loss by 80%. Moreover, the critical current of the 3S wire can be easily adjusted for various applications. It is envisioned that the 3S wire will become a powerful technology enabling the development of 2G HTS power devices with high efficiency.