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Visualization of local dissipation in superconducting tapes under the influence of external magnetic field and mechanical strain simulating practical operation conditions

模拟实际操作条件下外部磁场和机械应变影响下超导带局部耗散的可视化

基本信息

批准号：
18360153
负责人：
KISS Takanobu
金额：
$ 10.41万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

We have succeeded to developed several techniques which allow us to visualize local electromagnetic properties of superconducting tapes.(1) High field type low temperature scanning laser microscope (HF-LTSLM): We succeeded to visualize local dissipation in the tape with a micro-meter resolution for the first time under high external field up to 5 T.(2) Laser induced Seebeck Voltage Imaging: By use of asymmetric Seebeck constant at defect or tilted grain, we visualized defect position and grain structure in the coated conductors.(3) Scanning SQUID microscopy: Dynamics of the trapped vortices in the tape and local current flow have been investigated by high resolution and high sensitive magnetic microscopy using SQUID sensor coupled with a small pickup coil with a diameter of 10 μm.(4) Scanning Hall probe microscopy: High current and wide range magnetic microscopy has been achieved by developing a system using micro-Hall probe as a sensor head. It reveals current blocking obstacles and c … More urrent distribution in processed tapes such as multi-filamentary structures.In a tight collaboration with processing groups, we have found different types of obstacles depending on processing combination, and therefore could improve the process conditions effectively. Finally, the maximum critical current density, J_c, has reached to 5.2 MA/cm^2 (I_c=413 A/cm-w) even in narrow filament having 80 μm of width. This is comparable to the value on single crystalline substrate.Furthermore, a method has been established to investigate the influence of axial mechanical strain on current transport in the superconducting tape under external magnetic field. Based on the insights on the local electromagnetic behavior, we have also improved our physical model to describe global electric field-v. s.-current density characteristics as a function of temperature, external field and strain. This also allows us to predict the properties over broad operation conditions based on limited sets of measurements. Less

我们成功开发了多种技术，使我们能够可视化超导带的局部电磁特性。(1) 高场型低温扫描激光显微镜 (HF-LTSLM)：我们首次成功地在高达 5 T 的高外场下以微米分辨率可视化带中的局部耗散。(2) 激光诱导塞贝克电压成像：通过使用不对称技术通过在缺陷或倾斜晶粒处的塞贝克常数，我们可视化了涂层导体中的缺陷位置和晶粒结构。(3) 扫描 SQUID 显微镜：使用 SQUID 传感器与直径为 10 μm 的小型拾波线圈耦合，通过高分辨率和高灵敏度磁显微镜研究了带中陷涡的动力学和局部电流。(4) 扫描霍尔探针显微镜：高电流和宽范围通过开发使用微霍尔探针作为传感器头的系统，已经实现了磁显微镜。它揭示了加工带（如多丝结构）中当前的阻塞障碍物和电流分布。在与加工团队的密切合作中，我们根据加工组合发现了不同类型的障碍物，因此可以有效地改善加工条件。最终，即使在宽度为 80 μm 的窄灯丝中，最大临界电流密度 J_c 也达到了 5.2 MA/cm^2 (I_c=413 A/cm-w)。这与单晶衬底上的值相当。此外，还建立了一种研究外磁场下轴向机械应变对超导带中电流传输影响的方法。基于对局部电磁行为的见解，我们还改进了描述全局电场 v 的物理模型。 s.-电流密度特性作为温度、外场和应变的函数。这也使我们能够根据有限的测量集来预测广泛操作条件下的特性。较少的