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以下承载无损DC电流的独特性质。该提案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且可用的冷却剂。HTS导线以扁平带（HTS带）的形式出现，并且可以承载惊人的高电流密度，例如，在77 K下每平方厘米超过200万安培。它们非常适用于高功率密度电缆、电动机/发电机等应用，也适用于高场电磁铁，特别是用于磁共振成像（MRI）系统。商业HTS磁带在工业上现已相当成熟，很快将出现在众多商业产品中。在许多已知的应用中，它们可能会成为一个严重的游戏规则改变者，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气特性以及这些特性的均匀性。高温超导带材最重要的指标是它们的临界电流，即它们在不开始发热的情况下可以承载的最大电流。商用HTS带材中的临界电流可沿其长度变化+/-10至20%沿着。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，该热点状态可能会损坏设备。解决方案是存在的，但需要更好地理解临界电流不均匀性的影响，才能真正使HTS磁带达到所需的鲁棒性水平。在这项研究计划中，我们将利用Polytechnique在危险操作条件下的数值模拟和高温超导带材先进的无损表征方面的专业知识，以获得有关其临界电流分布均匀性的丰富信息。这些信息将与数值模拟结合使用，以更好地了解温度曲线如何随时间推移而发展，以及这是否会导致HTS磁带的局部退化。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，将需要进行一些进一步的研究，特别是：1）改进现有模拟工具的性能，2）进一步研究制造工艺，以更好地控制高温超导带材上的金属涂层。上述短期目标与该研究计划的最终目标一致，即“允许出现用于运输和电力系统的紧凑高效的HTS设备，以及实现高场磁体的出现”。加拿大将从HTS磁带技术的部署中受益匪浅。这也是在高度跨学科的环境中培养高素质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.