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EFFECTS OF FILAMENT SIZE ON SUPERCONDUCTIVITY IN MULTIFILAMENTARY WIRES

细丝尺寸对多丝线材超导性的影响

基本信息

批准号：
06650316
负责人：
SUZUKI Mitsumasa
金额：
$ 0.32万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06650316/
关键词：
Multifilamentary Superconducting Wire Proximity Effect Critical Temperature Upper Critical Field Critical Current Density NbTi 近接効果

项目摘要

To realize superconducting devices operated by AC power sources of 50-60Hz, the development of multifilamentary superconducting wires with finer filaments and CuNi barrier of high resistivity is in progress. In this work, we have investigated the effects of filament size on superconductivity from experimental and theoretical standpoints, especially, in ultra-fine multifilament NbTi wires consisting of filaments of 0.1 mum or below in diameter, which are promising wires for AC use. Obtained results are summarized as follows.1. Ultra-fine multifilament wires show high critical current density j_c compared to conventionally fabricated NbTi wires with filaments of 1 mum or above in diameter. Their field dependence, however, is highly strong and the critical current density is appreciably lowered with increasing temperature. These results suggest that the performance of applications being constructed of these wires is considerably affected by temperature and magnetic field.2. Most of investigated wires show anomalous high-J_c nature in temperatures near critical temperature T_c suggesting that the mechanism of flux-pinning varies with temperature.3. In superconducting superlattices where two layrs with different Debye frequencies alternately pile up, values of upper critical field B_<c2> parallel and perpendicular to the layr plane are appreciably different. Similar results are seen in superlattices with different BCS coupling constants.The pinning mechanism in multifiamentary superconducting wires must be clarified and their temperature and field dependence should be improved.

为了实现由50- 60 Hz交流电源运行的超导器件，具有更细细丝和高电阻率CuNi阻挡层的多芯超导线材的开发正在进行中。在这项工作中，我们已经研究了超导电性的影响，从实验和理论的角度来看，特别是在超细复丝NbTi线组成的细丝的直径为0.1微米或以下，这是有前途的电线AC使用。所得结果总结如下.超细复丝线显示出高的临界电流密度j_c相比，传统制造的NbTi线与1微米或以上的直径的细丝。然而，它们的场依赖性非常强，并且临界电流密度随着温度的升高而明显降低。这些结果表明，这些导线构造的应用程序的性能受到温度和磁场的显著影响.在临界温度T_c附近，大多数被研究的金属丝表现出反常的高J_c特性，表明磁通钉扎机制随温度的变化而变化.在具有不同德拜频率的两层交替堆积的超导超晶格中，平行于层平面和垂直于层平面的上临界场B_的值<c2>有明显的不同。在不同BCS耦合常数的超晶格中也观察到类似的结果，多芯超导线材中的钉扎机制有待进一步阐明，其温度和场依赖性有待进一步改善。