Twisting characteristics of a quasi-isotropic strand fabricated by 2G HTS tapes

With the development of the second generation of high temperature superconducting (2G HTS) tapes, a several cabling conductors with different configurations, such as TSTC, CORC, have been proposed and some prototypes were developed. The alternative current (AC) loss will create in HTS tapes if it operates in AC operation. Thus, AC loss is important parameter for its application since it determines stability and operation cost. Conventionally, twisting technique is one of reduce effectively AC loss. This paper presents twisting properties of a quasi-isotropic strand made from 2G tapes. The strand consists of 2G tapes, aluminum foil and metal sheath. A twisting apparatus is designed and demonstrated to research its characteristics in twisting situations. Critical currents of a single tape in different twist pitch were firstly tested in self-field and 77 K, the critical currents of the strands under different twist pitches were also tested. The results show that the twist pitch of strands is higher than a single tape.