Numerical Analysis of Screening-Current Induced Strain in a 16 T REBCO Insert Within a 20 T Background Field
Liangjun Shao, Peng Song, Yufan Yan, Xintao Zhang, Mianjun Xiao, Fang Liu, Huajun Liu, Timing Qu
Abstract
REBa <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7-<i>x</i></sub> (REBCO) coated conductor has emerged as a promising material for the development of ultra-high-field (UHF) magnets. However, the presence of screening-current induced strain within this tape-shaped conductor exerts a huge impact on the operational stability of REBCO coils. We focused on the design of an all-superconducting 36 T / 40 mm UHF magnet, which included a 16 T insert magnet consisting of two nested REBCO coils. In this study, the screening-current induced strain in the 16 T magnet was numerically studied using the coupled electromagnetic-mechanical model, which considered the tilting angle of REBCO tapes and the strain dependency of the critical current. We calculated the screening-current induced strain of each pancake individually and compared these results with those calculated by the sequential model. According to the coupled model, the maximum hoop strain was 0.52 %, relatively lower than that calculated by sequential model. The most dangerous pancake was estimated to be the outermost pancake of each coils. Additionally, we varied the critical current value of the REBCO tapes and studied the relationship between the critical current value and screening-current induced strain. This work provides a feasible way to calculate the screening-current effect in large-scale HTS magnets.