Modelling of high temperature superconductor magnetic systems to enable low carbon advancements in science and technology

高温超导磁系统建模，促进科学技术的低碳进步

• 批准号: 2739448
• 金额: --
• 依托单位: Brunel University London
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2739448
• 关键词: Modelling; temperature; superconductor; magnetic; systems

This project will explore Quench initiation and propagation in a high temperature superconductor (HTS) coil by creating new coupled electromagnetic and thermal models. In order to achieve magnetic fields in excess of approximately 20 Tesla at an operating temperature of 4.2 Kelvin, HTS must be utilised. Typically, these are used as inserts within low temperature superconducting (LTS) 'outserts'. The ability to model quench behaviour accurately in LTS coils has been explored, however due to the differences in behaviour of HTS materials these techniques are not directly applicable to HTS insert coils. Accurate modelling capability in this area will aid the design of compact, high field magnets quantum materials analysis, high-resolution NMR and energy applications such as fusion. Models must couple Electromagnetic and thermal behaviour of the material, and its interaction with its environment, including with LTS magnets. Heat transfer within a superconducting coil is governed by a partial differential equation with a first term representing heat diffusion and other terms representing mechanisms of heat generation including resistive heating and AC losses in response to changes in current density and magnetic field. Current in the HTS insert coil is governed by an inductor-resistor (LR) circuit of coils and protection circuit with mutual inductance with between the coils and resistance in the HTS coils arising from EM and thermal effects. The magnetic field is determined by two-dimensional Biot-Savart integration of the coil currents. Before the instant of quench initiation in the HTS the problem is axisymmetric. At the instant of quench, the axial symmetry is broken and the simulation of quench propagation must then be switched to three dimensions. The role of random variations in the material properties in determining the location of the quench initiation will need to be considered. In this project new models will be created to explore this behaviour. A two-dimensional axisymmetric model will be created to predict the behaviour of the HTS coil in the lead up to the quench. The concept of Minimum Quench Energy for a superconductor at critical state will be exploited to determine the time at which the quench begins to propagate. The propagation of the quench in the circumferential direction will then be solved in three dimensions by application of a Fourier series, with parallel processing applied to solve for each Fourier coefficient independently.The project will focus on the case of a HTS test coil operating in a LTS background field of ~10T. This will enable experiments to be carried out to test the predictions of the model. These experiments are in addition to this project, not part of it.

该项目将通过创建新的耦合电磁和热模型来探索高温超导 (HTS) 线圈中的淬火引发和传播。为了在 4.2 开尔文的工作温度下实现超过约 20 特斯拉的磁场，必须使用高温超导 (HTS)。通常，它们用作低温超导 (LTS)“外插件”内的插入件。人们已经探索了在 LTS 线圈中精确模拟失超行为的能力，但是由于 HTS 材料的行为差异，这些技术并不直接适用于 HTS 插入线圈。该领域的精确建模能力将有助于设计紧凑的高场磁体、量子材料分析、高分辨率核磁共振和核聚变等能源应用。模型必须耦合材料的电磁和热行为及其与环境（包括 LTS 磁体）的相互作用。超导线圈内的热传递由偏微分方程控制，其中第一项代表热扩散，其他项代表发热机制，包括响应于电流密度和磁场变化的电阻加热和交流损耗。 HTS 插入线圈中的电流由线圈的电感电阻 (LR) 电路和保护电路控制，保护电路具有线圈之间的互感以及 HTS 线圈中因电磁和热效应而产生的电阻。磁场由线圈电流的二维毕奥-萨伐尔积分确定。在高温超导中淬火开始之前，问题是轴对称的。在失超的瞬间，轴对称性被打破，失超传播的模拟必须切换到三维。需要考虑材料特性的随机变化在确定淬火起始位置中的作用。在这个项目中，将创建新的模型来探索这种行为。将创建二维轴对称模型来预测高温超导线圈在失超之前的行为。将利用临界状态超导体的最小失超能量的概念来确定失超开始传播的时间。然后，将通过应用傅立叶级数在三个维度上求解失超在圆周方向上的传播，并应用并行处理来独立求解每个傅立叶系数。该项目将重点关注在LTS 背景场约为 10T。这将使我们能够进行实验来测试模型的预测。这些实验是该项目的补充，而不是该项目的一部分。