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Fundamental study for the establishment of the design principle of conduction-cooled oxide superconducting magnets

传导冷却氧化物超导磁体设计原理建立的基础研究

基本信息

批准号：
16360139
负责人：
IWAKUMA Masataka
金额：
$ 9.41万
依托单位：
KYUSHU UNIVERCITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16360139/
关键词：
superconducting magnet oxide superconductor conduction-cooling Bi2223 thermal runway cryocooler quench ac loss 酸化物超伝導体

项目摘要

Paying attention to the conduction cooling to cool oxide superconducting magnets in place of the conventional bath-cooling with liquid helium, we studied the stability and the protection method of oxide superconducting magnets. In order to get rid of the design principle for the conventional low-Tc superconducting magnets, which consists of the stability theory based on the cooling characteristics of liquid helium and the protective condition of superconducting magnets, e.g. the recovery-condition of stored energy, we aimed at constructing the new design principle of conduction-cooled oxide superconducting magnets operated at over 20K, including the fabrication method of oxide superconductors with a large current capacity. First we observed the electromagnetic and thermal properties of a 1T cryocooler-cooled oxide superconducting coil. It was shown that the thermal runaway of the coil depended on the local thermal balance between the heat generation due to the flux-flow loss and the cooling due to thermal conduction inside the winding, not on the balance between the total heat generation of the coil and the cooling capacity of the cryocooler. Next we made numerical expressions of the temperature dependencies of the heat generation of oxide superconducting wires due to ac loss and flux-flow loss with large anisotropy and the thermal conductivity inside the winding. We also developed a numerical simulation program of the behavior of the conduction-cooled coil and made it possible to discuss the dependences of the thermal runaway of the coil on temperature and transport current. As a result, we showed the design principle of conduction-cooled oxide superconducting magnets clarifying the difference between the conventional bath-cooled superconducting magnets and conduction-cooled oxide superconducting magnets.

本文研究了氧化物超导磁体的稳定性及保护方法，以导电冷却代替传统的液氦浴冷却。为了摆脱传统低tc超导磁体的设计原则，即基于液氦冷却特性的稳定性理论和超导磁体的保护条件，如存储能量的回收条件，我们旨在构建在20K以上工作的导电冷却氧化物超导磁体的新设计原则。包括具有大电流容量的氧化物超导体的制造方法。首先，我们观察了1T制冷机冷却氧化物超导线圈的电磁和热性能。结果表明，盘管的热失控取决于因流量损失产生的热量与绕组内部热传导产生的冷却之间的局部热平衡，而不是取决于盘管总发热量与制冷机制冷量之间的平衡。其次，对各向异性较大的交流损耗和磁通流损耗对氧化物超导导线发热的温度依赖关系以及绕组内的导热系数进行了数值表达式。我们还开发了一个传导冷却线圈行为的数值模拟程序，并使讨论线圈的热失控对温度和输运电流的依赖成为可能。结果，我们展示了电导冷却氧化物超导磁体的设计原理，澄清了传统的浴冷超导磁体与电导冷却氧化物超导磁体的区别。