Analysis of Magnetization Losses of Twisted Stacked-Tape Cables With Striated Strands

Twisted stacked-tape cable (TSTC) is one of the high temperature superconducting (HTS) conductors with a large current capacity. These HTS cables for large currents need their strands to be transposed for even current distribution. The strands, stacked tapes, in TSTC can be transposed by twist. Moreover, the twist can also decouple the filaments in an HTS strand when the tape is striated. We made short samples of TSTC with striated or non-striated tapes to verify the effect of the magnetization loss reduction. The samples were made with 4 mm HTS tapes that did not have copper stabilizers. In this paper, a striation on an HTS tape of 4 mm width was made through chemical etching. We made four types of samples, including straight ones with and without a striation and TSTC ones with and without a striation. The magnetization losses varied by the angular position of the sample because the length of the twist pitch was longer than the length of the measurement system. So, the magnetization losses of the samples were measured at various angular positions. The results showed that the magnetization loss of the stacked samples with striation was caused by the combination of shielding and striation effects. We found that there was a break-even point where the loss of TSTC without striation was greater than that of the striated TSTC.