Advanced characterization and modeling tools to support the development of REBCO superconducting tapes

超导材料具有在给定的临界电流或临界温度下携带无损直流电流的独特特性。在这个提议中考虑的超导体被称为“高温超导体”（HTS），因为它们在液氮温度（77 K或-196摄氏度）以上表现出超导性，液氮是一种相对便宜和可用的冷却剂。高温超导线以扁平带（高温超导带）的形式出现，可以携带惊人的高电流密度，例如在77 K时每平方厘米超过200万安培。它们非常适用于高功率密度电缆，电机/发电机以及高场电磁铁等应用，特别是在磁共振成像（MRI）系统中使用。商用HTS磁带在工业上已经相当成熟，并将很快出现在许多商业产品中。在许多已知的应用中，它们可能会改变游戏规则，但这些应用的性能和经济性在很大程度上取决于它们的电学特性，以及这些特性的同质性。高温超导胶带最重要的指标是其临界电流，即在不开始加热的情况下所能承载的最大电流。商用高温超导磁带的临界电流沿其长度变化幅度为+/- 10-20%。因此，这种不均匀的临界电流分布可能导致热点状态，如果磁带没有得到适当的保护，可能会破坏设备。解决方案是存在的，但是需要更好地理解临界电流不均匀性的影响，才能真正使HTS磁带达到期望的稳健性水平。在这个研究项目中，我们将利用Polytechnique在数值模拟方面的专业知识和在危险操作条件下对HTS磁带进行先进的无损表征，以获得关于其临界电流分布均匀性等方面的丰富信息。这些信息将与数值模拟结合使用，以更好地了解温度分布如何随着时间的推移而变化，以及这是否会导致高温超导胶带的局部退化。这将产生重要的新知识，以确定我们如何进一步提高HTS磁带的质量和稳健性。为了实现这一目标，需要进一步的研究，特别是：1)改进现有仿真工具的性能，2)进一步研究制造工艺以更好地控制高温超导带上的金属涂层。上述短期目标与本研究计划的最终目标一致，即“为交通和电力系统提供紧凑高效的高温超导设备，并使高场磁体的出现成为可能”。加拿大将从HTS磁带技术的部署中获益良多。这也是一个在高度跨学科的环境中培养高素质的科学和工程人才的绝佳机会。

Superconducting materials have the unique property of carrying lossless DC currents below a given critical current or critical temperature. Superconductors considered in this proposal are called "High Temperature Superconductors" (HTS), because they exhibit superconductivity above liquid nitrogen temperature (77 K or -196 Celsius), which is a relatively cheap and available coolant. HTS wires come in the form of flat tapes (HTS tapes) and can carry amazingly high current densities, e.g. more than 2 millions amps per square centimeter at 77 K. They are perfect for applications such as high power-density cables, motors/generators, and also for high-field electromagnets, used I particular in magnetic resonance imaging (MRI) systems. Commercial HTS tapes are now quite mature industrially and will soon be present in numerous commercial products. They could become a serious game changer in many known applications, but the performance and the economics of these applications strongly depend on their electrical properties, as well as on the homogeneity of these properties. The most important metric for HTS tapes is their critical current, i.e. the maximum current that they can carry without starting to heat. Critical current in commercial HTS tapes can vary by +/- 10-20% along their length. Hence, this inhomogeneous critical current distribution can lead to a hot spot regime that can destroy the device if the tape is not properly protected. Solutions exist, but a better understanding of the impact of critical current inhomogeneities is required to really bring HTS tapes at the desired level of robustness. In this research program, we will take advantage of Polytechnique's expertise in numerical simulation and advanced non-destructive characterization of HTS tapes under dangerous operating conditions, in order to acquire rich information about the homogeneity of their critical current distribution, among other things. This information will be used jointly with numerical simulations to better understand how the temperature profile develops over time, and if this can lead to a local degradation of HTS tapes. This will generate important new knowledge to determine exactly how we can further improve the quality and robustness of HTS tapes. To achieve this, some further side research will be necessary, in particular: 1) an improvement of the performances of existing simulation tools, 2) further research on fabrication processes to better control the metallic coatings on HTS tapes. The short-term objectives above are in line with the ultimate goal of this research program, namely "to allow the emergence of compact and efficient HTS devices for transportation and power systems, as well as enabling the advent of high-field magnets". Canada would benefit a lot from the deployment of the HTS tape technology. This is also a perfect opportunity to train highly qualified personnel in sciences and engineering in a highly inter-disciplinary environment.