Non-linear modelling of performance limiting MHD and disruptions in spherical tokamaks

为了使MAST-U达到高性能、长脉冲运行，并为STEP的设计做出贡献，了解、避免、减轻或控制可能导致球形托卡马克中限制退化的MHD不稳定性是至关重要的。同样重要的是，提高我们对中断途径的理解，以便我们可以更好地预测和避免它们。该项目将从分析MAST-U高性能实验的数据开始，以确定重要的不稳定性(如新古典撕裂模式)。然后将使用JOREK进行非线性3D MHD建模，并将其与实验进行比较。在这种不稳定性期间模拟的3D MHD场也将被用来追踪快速粒子轨迹或在中断时产生失控电子。该项目的下一步将是探索避免或减轻这些不稳定性的策略，这将为未来的Mast-U操作提供参考，并有助于STEP的设计。也有可能研究分裂热猝灭过程和测试理论，例如从太阳物理社区或通过布泽尔快速磁重联和磁场的理想演变。该项目与在达勒姆大学进行的聚变科学与技术研究很好地一致。学生将主要在英国航空航天局，但最好也包括在达勒姆的整个项目中的长期停留，可能每6个月两次。学生将在该大学参加相关的入门和研究培训。学生、UKAEA主管和大学主管之间将通过电子邮件和团队/Zoom电话(通常是每周)、大学主管访问UKAEA和学生访问达勒姆等方式进行定期联系。与NSTX-U团队进行更多的合作将是非常可取的，关于MHD代码的培训将由英国能源署的专家提供，并通过参加代码年度大会进行。

For MAST-U to reach high performance, long pulse operation and contribute to the design of STEP, it is essential to understand, avoid, mitigate or control MHD instabilities which could lead to degraded confinement in spherical tokamaks. It is also important to improve our understanding of the pathways to disruptions so that we may better predict and avoid them. The project will start by analysing data from MAST-U high-performance experiments to identify important instabilities (such as neoclassical tearing modes). Non-linear 3D MHD modelling using JOREK will then be performed and compared to experiments. 3D MHD fields modelled during such instabilities will also be used to trace fast particle trajectories or in disruptions the generation of runaway electrons. Next steps of the project will be to explore strategies to avoid or mitigate these instabilities, which will inform both future MAST-U operation and help the design of STEP. It may also be possible to investigate the disruption thermal quench process and test theories, for example from the Solar Physics community or by Boozer Fast magnetic reconnection and the ideal evolution of a magnetic field.The project aligns well with the Fusion Science & Technology research performed at Durham University.The student will be mainly based at UKAEA, but it would be desirable to also include long stays at Durham throughout the project, possibly twice every 6-months. The student will attend relevant induction and research training at the university. There will be regular contact between the student, UKAEA supervisors and the university supervisor, through emails and Teams/Zoom calls (generally weekly), visits of the university supervisor to UKAEA and the student to Durham. Additional collaboration with the NSTX-U team would be highly desirable, and training on MHD codes will be given by UKAEA experts and through participation in the code annual general meeting.