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

点击翻译按钮获取中文摘要

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.