高温超导层状复合材料力电性能的辐照效应研究

Superconducting magnets are one of the core components in magnetic-confined controllable fusion reactors. Recently, people began to consider using high-temperature superconducting coated conductor (CC) tapes instead of the common low-temperature superconducting strands in order to reduce the cooling requirement and lead to a more compact and cheaper design. However, the irradiation issue brings significant influences on the mechanical and electric performances of CC tapes, which will affect the performances and operation safety for superconducting magnets. This project will study the irradiation effects on the mechanical and electric performances of high-temperature superconducting laminar composites, using theoretical modeling and numerical simulation methods. We will establish a multi-scale constitutive model for the irradiated CC tape to acquire the correlations between the macroscopical mechanical properties and material mesoscopic characteristics such as the irradiation defect density, grain size and orientation, and component thicknesses in the composite. Then, study the microscopic mechanisms of the critical current density associated with the irradiation defect and grain boundary. Moreover, investigate the influences of irradiation damage on the electromagnetic field distributions for the CC tape and relevant cable structure and assess their thermal stabilities based on the dynamic electromagnetic-thermal coupling computational framework. Furthermore, establish the electromechanical coupling computational framework so as to analyze the electric and mechanical responses for the CC tape and relevant cable structure in the simultaneous irradiation and strong electromagnetic field conditions, and assess the irradiation influence on the mechanical behaviors. This project will serve as an important theoretical support for the development of superconducting magnet technology.

超导磁体是磁约束型可控核聚变反应堆的核心部件之一。近年来，人们开始考虑采用高温超导带材替代超导磁体中长期使用的低温超导股线，以期降低制冷需求同时带来一种更加紧凑和廉价的设计。然而，辐照环境的引入将显著改变高温超导带的力学和电学性能，影响超导磁体的性能表现和运行安全。本项目将采用理论建模与数值模拟相结合的方法，对受辐照条件下高温超导层状复合材料的力电性能展开研究。建立辐照超导带多尺度本构模型，获得辐照缺陷密度、晶粒尺寸、晶粒取向、组分材料厚度等材料微细观特征与宏观力学性能的关联性认识；开展临界电流密度关于辐照缺陷和晶界作用的微观机理研究；基于电磁-热耦合动力学计算框架，探讨辐照损伤对超导带及其电缆结构电磁场分布的影响，评估热稳定性；搭建力电耦合计算框架，分析辐照和强电磁场并存环境下超导带及其电缆结构的力电响应，评估辐照损伤对力学行为的影响。本项目将为超导磁体技术的发展提供重要的理论支撑。

以REBaCuO带材 (RE表示Y、Dy、Gd等稀有元素)为代表的高温超导材料具有临界温度较高的独特优势，在优良超导电性以及较好机械性能的支撑下，它在电力传输、超导磁体、超导电机、超导变压器、超导储能器等领域展现出巨大的发展潜力。超导材料及其电磁结构的工作环境通常处于高磁场、强电流、极低温、高能粒子辐照等多场耦合复杂环境，而这些环境很可能显著改变高温超导带的力学和电学性能，影响超导设备的性能表现和运行安全。本项目采用理论建模与数值模拟相结合的方法，对强电磁场、低温非平衡态、辐照损伤等条件下高温超导层状复合材料的力电性能展开研究。开展了辐照超导带多尺度本构建模工作，基于位错密度和辐照缺陷密度的动态演化规律，采用自洽的细观过渡方法初步建立超导材料受辐照条件下的跨尺度本构模型。开展受辐照条件下高温超导体热电性能研究，分析REBCO盘式薄饼线圈在失超传播过程中的电磁场、温度场演化行为特征，理解失超激发及其后续传播演化机理，考察若干重要因素对失超行为特征的影响，并初步探索辐照缺陷对临界电流密度影响的微观机理。开展多场耦合环境堆叠超导带结构的力学响应研究，基于物理等效思想，提出各向异性等效电磁模型以及横观各向同性等效力学模型，建立电磁-热-力多物理场耦合分析框架，研究REBCO高场线圈在高磁场、强电流、绕线张力、冷却应力、局部失超等复杂耦合状态中的力学特征，为高温超导高场磁体的机理认知和技术发展提供重要的理论支撑。