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

超导材料具有在给定临界电流（Ic）和临界温度（Tc）以下传输无损直流电流的独特特性。本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（即77 K（-196℃））以上表现出超导性，这是一种廉价的冷却剂，在电力设备等大规模应用中是负担得起的。高温超导导线以扁平带的形式出现，可以承载惊人的高电流密度，例如在77 K时的bbb20 MA/cm2。它们非常适合高场电磁铁等应用，可以达到前所未有的场值，例如在4 K时高达50 T。这可能会改变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。此外，由于磁铁通常需要数百公里的高温超导胶带，因此它们有望在不久的将来成为寻求扩大生产和降低高温超导电线成本的巨大市场“驱动力”。超导器件最大的挑战是如何可靠地保护它们不受热不稳定性的影响，因为热不稳定性会迅速破坏它们。在这个提案中，我们提议扩大我的研究小组发现的一个概念的应用范围，这个概念被称为“电流分流器”（CFD）。这一概念允许在热不稳定性发生时将其传播速度加快一个数量级，这大大简化了对高温超导器件，特别是高温超导磁体的保护。它被视为该学科的潜在突破，因此在短期内值得认真考虑。该技术于2015年5月获得了美国专利，短期研究可能会产生更多的知识产权，如果进入MRI市场，可能会有广阔的市场。***在本项目中，将追求以下主要目标：***1)找到一种有效和经济的方法，在长长度的商用高温超导胶带上实现电流分流器（CFD）概念***2)了解在各种实验条件下由许多高温超导胶带（例如Roebel或TASC电缆）制成的大电流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铁保护系统结合使用的影响***这些目标是一致的我的研究计划的最终目标是“允许新一代紧凑高效的超导设备的出现，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”。***本项目拟培养博士生3名，硕士生5名，暑期实习生5名。该项目的某些部分将与国际合作伙伴一起进行，以便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.********* *** *** *** *** ******************************************