Abstract

The emergence of second generation (2G) high-temperature superconductor (HTS) tapes has favored the development of HTS magnets for their applications in areas such as NMR, MRI and high field magnets. The screening current-induced field and the field drift are two major problems hindering the use of HTS tapes in the mentioned areas. Both problems are caused by the screening current, then it is necessary to have a modeling strategy capable to estimate such phenomena. Thus far, the H formulation has been a widely used approach to model medium-size systems (hundreds of tapes). However, its application to large-scale systems is still impaired by excessive computation times and memory requirements. Homogenization and multi-scaling strategies have been successfully implemented to increase the computational efficiency. In this contribution, we show that using the homogenization technique with the recently developed T-A formulation allows reducing the computation time and the amount of memory up to the point that realtime simulations of slow ramping cycles of large-scale systems are possible. At the same time, the T-A homogeneous model provides enough resolution to investigate the screening current using numerical simulations.

Highlights

  • The quality of second-generation high-temperature superconductor (HTS) tapes has improved during recent years

  • In coils wound with HTS tapes, the large aspect ratio of the tapes favours the presence of screening currents

  • Finite element models based on the H formulation have been successfully used during the last years to model systems made with HTS tapes [12]

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Summary

Introduction

The quality of second-generation high-temperature superconductor (HTS) tapes has improved during recent years. The HTS materials are performing so well that they preserve their high critical current even under the effect of high magnetic fields that exceed the critical fields of low-temperature superconductors. T-A homogenous and T-A multi-scale strategies have further reduced the computation time and the amount of memory up to the point that it is possible to achieve real-time simulations of slow ramping cycles of large-scale superconducting systems [18] In this manuscript, we present the T-A homogenous model of an HTS solenoidal coil. The T-A homogenous model allows to study the effectiveness of two remedies for the SCIF and field drift: the striation of the tapes [11] and the current sweep reversal [2, 22]

T-A homogenous approach
Case study
Screening current-induced field
Field drift
Striation and current sweep reversal
Findings
Conclusions
Full Text
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