Protection of superconducting wires and cables used in high power/high field applications

超导材料具有在给定的临界电流（Ic）和临界温度（Tc）以下承载无损DC电流的独特性质。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以上表现出超导性，即77 K（-196oC），这是一种廉价的冷却剂，在大规模应用中可以负担得起，例如功率设备。高温超导导线以扁平带的形式出现，并且可以承载惊人的高电流密度，例如在77 K下>2 MA/cm 2。它们非常适合高场电磁铁等应用，可达到前所未有的磁场值，例如在4 K时高达50 T。这可能是高分辨率磁共振成像（MRI），核聚变，粒子加速器等领域的游戏规则改变者。此外，由于磁体通常需要数百公里的HTS磁带，因此预计它们将成为在不久的将来扩大生产和降低HTS导线成本的大市场“驱动力”。超导设备面临的最大挑战是可靠地保护它们免受可能迅速摧毁它们的热不稳定性的影响。在这个提案中，我们建议扩大我的研究小组发现的一个概念的应用范围，这就是所谓的“电流分流器”（CFD）。该概念允许在热不稳定性发生时将热不稳定性的传播加速一个数量级，这大大简化了对HTS装置、特别是HTS磁体的保护。它被视为该学科的一个潜在突破，因此值得在短期内认真考虑。该技术于2015年5月获得美国专利，进一步的IP可能会从短期研究中产生，如果它渗透到MRI市场，可能会有广阔的市场。 在该项目范围内，将追求以下主要目标： 1)找到一种有效且经济的方法，在长的商用高温超导带材上实施电流分流器（CFD）概念 2)了解在各种实验条件下，由许多HTS带材制成的高电流电缆（例如Roebel或TASC电缆）中热点成核的影响 3)评估将CFD概念与最先进的高温超导磁体保护系统相结合的影响 这些目标与我的研究计划的最终目标是一致的，即“允许出现新一代紧凑高效的超导设备，以提高电力系统的供电安全性，并使高场高温超导磁体的出现”。 沿着项目，计划培养3名博士。学生，5名硕士生，5名暑期实习生。该项目的某些部分将与国际合作伙伴一起实施，以利用现有的基础设施并加快研究成果的产生。

Superconducting materials have the unique property of carrying lossless DC currents below a given critical current (Ic) and critical temperature (Tc). Superconductors considered in this proposal are called “High Temperature Superconductors” (HTS), because they exhibit superconductivity above liquid nitrogen temperature, i.e. 77 K (-196oC), a cheap coolant that is affordable in large-scale applications such as power devices. HTS wires come in the form of flat tapes and can carry amazingly high current densities, e.g. >2 MA/cm2 at 77 K. They are perfect for applications such as high field electromagnets, which allow reaching unprecedented field values, e.g. up to 50 T at 4 K. This could be a game changer in high-resolution magnetic resonance imaging (MRI), nuclear fusion, particle accelerators, etc. Also, since magnets typically require hundreds of kilometers of HTS tapes, they are expected to be the big market “driver” sought for scaling-up the production and reduce costs of HTS wires in a near future. The biggest challenge with superconducting devices is to protect them reliably against thermal instabilities that can destroy them rapidly. In this proposal, we propose to expand the application range of a concept discovered within my research group and that is called “current flow diverter” (CFD). This concept allows speed-up by an order of magnitude the propagation of a thermal instability when it occurs, which considerably simplifies the protection of HTS devices, in particular HTS magnets. It is seen as a potential breakthrough in the discipline, and therefore deserves serious consideration in the short term. The technology was awarded a U.S. patent in May 2015, and further I.P. could arise form short-term research, with potentially wide market if it penetrates the MRI market. Within this project, the following main objectives will be pursued: 1) Find an effective and economical approach to implement the current flow diverter (CFD) concept on long lengths of commercial HTS tapes 2) Understand the impact of a hot spot nucleation in high-current cables made of many HTS tapes (e.g. Roebel or TASC cables) under various experimental conditions 3) Evaluate the impact of using the CFD concept combined with state-of-the-art protection systems for HTS magnets These objectives are aligned with the ultimate goal of my research program, which is to “allow the emergence of a new generation of compact and efficient superconducting devices for improving security of supply in power systems and enable the emergence of high field HTS magnets”. Along the project, it is planned to train 3 Ph.D. students, 5 Master’s student, and 5 summer interns. Some parts of the project will be carried out with international partners in order to take advantage of existing infrastructures and speed-up the generation of research results.