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

在该项目的第一年，开发了精确评估REBCO绕组电磁行为的数值模型，并在小规模测试饼上进行了实验验证，证实了其准确性。在最后一年，对测试线圈进行了详细的比较，以了解电流分布动态，电压和产生的磁场之间的关系，这导致与格勒诺布尔CNRS合作发表了一篇联合论文。然后，在功能更强大的工作站的帮助下继续开发，这使得模拟全尺寸非常高的现场插入物的一半成为可能，就像在30 T CSM项目的框架内在HFLSM开发的模型一样。一旦磁体在未来几年内进行测试，就必须确认模型预测在大规模系统上的准确性，但是已经在该磁体的磁场均匀性，磁场漂移和交流损耗方面获得了重要的见解。这为磁体的有效控制铺平了道路，特别是补偿磁场漂移。同时，该项目也朝着计算REBCO导体中不均匀电流分布在机械应力方面的后果发展。这一发展是由应用超导社区对REBCO绕组中应力集中所带来的风险日益担忧引发的。在本项目过程中开发的模型可随时加以调整，以提供对该专题的深入了解。这一发展导致了2021年7月在国际会议CEC-ICMC上的邀请口头报告。

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.