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Study of high current density superconducting conductor introduced by microfabrication technique.

采用微细加工技术引入高电流密度超导导体的研究。

基本信息

批准号：
15560278
负责人：
HARADA Naoyuki
金额：
$ 2.05万
依托单位：
Yamaguchi University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15560278/
关键词：
Critical Current Superconducting Wire Flux Pinning Microfabrication Fluxoid Nano-technology Nb Thin Film

项目摘要

Practical superconducting wires for power cables and high field magnets require a high critical current density. Effective flux pinning centers are required for the development of these practical superconductors in order to achieve high critical current density. In the case of metallic superconductors, a drawing process introduces artificial pinning centers in metallic superconductors. However, artificial pinning centers cannot be introduced into high-Tc superconductors through the drawing process because these superconductors are brittle. We consider the microfabrication technique, instead of the drawing process, in order to introduce artificial pinning centers into the superconductors. Groove-shaped artificial pinning centers and hole-shaped artificial pinning centers are introduced into 0.22-0.5μm thick evaporated Nb film on a MgO substrate or a sapphire substrate by photolithography. The groove-shaped patterns with two kind of spacing of 2μm and 4μm were introduced by etching on a 0.9 × 0.9mm region of the Nb film. Nb films with varying groove depths were prepared, and the groove depth dependence on critical current density was investigated for the width of the hysteresis curve of the magnetic moment. The hysteresis curves of the specimens with grooves were measured with a SQUID magnetometer. The width of the hysteresis curve decreases with an increasing groove depth for over 70% of the film thickness.

用于电力电缆和高磁场磁体的实用超导导线需要高临界电流密度。为了实现高临界电流密度，这些实用超导体的发展需要有效的磁通钉接中心。在金属超导体的情况下，拉伸过程引入了金属超导体的人工钉钉中心。然而，由于高温超导体易碎，人工钉钉中心不能通过拉伸过程引入到高温超导体中。为了在超导体中引入人工钉钉中心，我们考虑采用微加工技术，而不是采用拉伸工艺。在MgO衬底或蓝宝石衬底上，采用光刻技术在0.22 ~ 0.5μm厚的蒸发Nb薄膜上引入了沟槽形人工钉钉中心和孔洞形人工钉钉中心。在铌薄膜0.9 × 0.9mm的区域上蚀刻出2μm和4μm两种间距的凹槽图案。制备了不同沟槽深度的铌薄膜，研究了沟槽深度随临界电流密度的变化对磁矩磁滞曲线宽度的影响。用SQUID磁强计测量了带凹槽试样的磁滞曲线。在薄膜厚度的70%以上，随着沟槽深度的增加，迟滞曲线的宽度减小。