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346 results on '"Tang, Yuejin"'

8. Analytical Model for Magnetic Field and Inductance of Toroidal D-Shaped HTS Magnet

Author

Qiu, Yifeng, Ren, Li, Xu, Ying, Yang, Zhixing, Li, Hao, and Tang, Yuejin

Abstract

The electromagnetic calculations of large-size high-temperature superconducting (HTS) toroidal D-shaped magnets present structural complexity and modeling difficulties, resulting in high complexity in the evaluation of the energy storage, critical current and central magnetic field, which pose significant challenges to the electromagnetic design. This paper established an analytical calculation model for the inductance and magnetic field of the toroidal D-shaped HTS magnet under the assumptions of static magnetic field and current distribution, and developed the discrete method and accelerate calculation further through integral transformations. The discrete method was compared and validated against the finite element analysis (FEM) method and 3D T-A homogenization method. The results indicate that the discrepancies in inductance and parallel fields between the discrete analytical method and the 3D T-A are less than 3%, with errors in perpendicular fields within 20%, and exhibit a computational speed 4 to 6 orders of magnitude faster than FEM. The larger error in the perpendicular field is due to the non-uniform superconducting current distribution, which occurs mainly inside the magnet. This approach can be applied to the preliminary evaluation of performance parameters such as stored energy and critical current in toroidal HTS magnets, thereby enhancing the efficiency of electromagnetic design.

Published
2024
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9. Dynamic Analysis of No-Insulation Insert Coil Under Changing Background Magnetic Field

Author

Duan, Pu, Ren, Li, Xu, Ying, Shi, Jing, Tang, Yuejin, and Li, Jingdong

Abstract

Due to the excellent thermal stability and high-power density in steady state, no-insulation (NI) winding technology is widely used in the application of superconducting magnets. However, current ripple and background magnetic field fluctuations caused by relative devices result in changing turn-to-turn current of the NI insert magnet, which will impose a great impact on the thermal stability of the NI magnet. This paper analyzes the thermal characteristics and other electromagnetic parameters of NI magnet under dynamic operating conditions by improved 2D finite-element method. The results provide references of thermal conductive structure design and assessment of operational reliability of NI magnets in changing working conditions.

Published
2024
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12. Analysis and Optimization of Impregnation Material Parameters for Superconducting Coils

Author

Wu, Jiajie, Xu, Ying, Li, Jingdong, Ren, Li, Shi, Jing, Tang, Yuejin, and Guo, Fang

Abstract

High-field magnets fabricated from Rare Earth-Barium-Copper-Oxide (REBCO) coated conductor (CC) tapes have substantial prospects across diverse application domains. The impregnation process is frequently employed to enhance the mechanical structure stability of superconducting magnets. However, impregnation can lead to damage, such as degradation of critical current (Ic). In this study, a three-dimensional multilayer delamination finite element (FE) model for REBCO CC tape is developed to investigate the impact of impregnation material parameters on damage behavior during the cooling process. Firstly, the accuracy of the established FE model and the feasibility of damage analysis were verified. Then the relationship between damage and Ic is established based on experimental data. It was found that when the normalized Ic degraded to 95%, the normalized damage area caused by both thermal and mechanical stresses was 0.22. Finally, after decoupling and analyzing the influence of each impregnation material parameter on the damage behavior of REBCO tape, the optimization direction of the impregnation material parameters is given from four aspects: material thickness, coefficient of thermal expansion, cohesive strength, and structural strength.

Published
2024
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13. Instantaneous AC Loss and Inductance Measurement of HTS Coil With Finite-Data-Window Least Squares

Author

Long, Feiyang, Xu, Ying, Li, Xin, Ren, Li, Shi, Jing, Tang, Yuejin, Song, Meng, and Li, Li

Abstract

AC loss is a critical concern for the stability of superconducting device. Various experimental methods are available for measuring AC loss in superconductors, with electrical measurement techniques being widely adopted. However, these methods only measure average loss and often disregard variations in superconductor inductance with current, which may lead to inaccuracy. This study introduces a finite-data-window least squares method to measure instantaneous AC loss in coils wound with YBCO tapes. By comparing the results with those obtained through the integral method, it is demonstrated that the proposed approach effectively measures instantaneous AC loss for coils with limited turns. Furthermore, the pattern of superconducting coil inductance in relation to current variations is examined.

Published
2024
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