REBCO High Temperature Superconducting Magnets With High Field Stability : Understanding And Mitigating The Shielding Current Effects

在项目的第一年，建立了精确评价REBCO绕组电磁行为的数值模型，并在小型试验薄饼上进行了实验验证。去年，我们对测试线圈进行了详细的比较，以了解电流分布动态、电压和产生场之间的关系，并与格勒诺布尔CNRS合作发表了一篇联合论文。然后，在更强大的工作站的帮助下，开发工作继续进行，这使得模拟全尺寸超高场插入的一半成为可能，就像HFLSM在30T CSM项目框架中开发的那样。模型预测在大型系统上的准确性将在未来几年内进行测试后得到证实，但在磁场均匀性、磁场漂移和交流损耗方面已经获得了重要的见解。这为磁体的有效控制，特别是场漂移的补偿铺平了道路。与此同时，该项目发展到计算REBCO导体中不均匀电流分布在机械应力方面的后果。这一发展是由应用超导界对REBCO绕组应力集中所带来的风险的日益关注引发的。在这个项目过程中开发的模型可以很容易地进行调整，以提供对该主题的见解。这一发展导致了2021年7月在cecc - icmc国际会议上的受邀口头报告。

In the first year of the project, the numerical model evaluating precisely the electromagnetic behavior of REBCO winding was developed, and experimental validations confirmed its accuracy on small scale test pancakes.In this last year detailed comparison were conducted on test coils to understand the relationship between current distribution dynamics, voltage, and generated field, which lead to the publication of a joint paper in collaboration with Grenoble CNRS.Then, the development was continued with the help of a more powerful workstation, which made it possible to simulate one half of a full-size very high field insert, like the one developed at HFLSM in the framework of the 30T CSM project.The accuracy of the model predictions on large scale systems will have to be confirmed once the magnet is tested in the next years, but already significant insights were obtained in terms of field homogeneity, field drift and AC losses for that magnet. This pave the way for an efficient control of the magnet, and the compensation of field drift in particular.In parallel, the project evolved toward calculating the consequences of inhomogenous current distribution in REBCO conductors in terms of mechanical stress. This development was triggered by rising concerns in the Applied Superconductivity community about the risk posed by stress concentrations in REBCO windings. The model developed in the course of this project could be readily adapted to provide insight on that topic. This development lead to an invited oral presentation at international conference CEC-ICMC in July 2021.