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Thermal stability of high-strength Nb_3Sn wire and relevant application to the cryocooled superconducting magnet

高强度Nb_3Sn线材的热稳定性及其在低温超导磁体中的应用

基本信息

批准号：
11555083
负责人：
WATANABE Kazuo
金额：
$ 6.08万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11555083/
关键词：
Nb_3Sn CuNb high strength thermal stability cryogenic stability superconducting magnet helium-free GM-cryocooler

项目摘要

A test coil employing CuNb/Nb_3Sn multifilament superconducting wire was prepared, and the cryogenic stability for the CuNb/Nb_3Sn coil was examined in liquid helium cooling and cryocooler cooling conditions. It is found that a minimum quench energy MQE in the cryocooling condition is reduced to 1/3 in comparison with the liquid helium cooling condition, and on the contrary a normal zone propagation velocity is enlarged by a factor of 3 to 4. These behaviors are dependent on the loading current ratio between the operation current and the critical current, and in particular the cryocooling condition reveals the strong dependence of the current ratio.Further, the CuNb/Nb_3Sn test coil fabricated by a react and wind technique was investigated in a large electromagnetic stress state. It is found that the test coil wound by the bending strain of 0.33% stood with the Hoop stress of 330Mpa, and that no degradation of the critical current for the test coil was observed. This surely results in confirmation of the patent for the CuNb/Nb_3Sn wire with reinforcing stabilizer.Finally, we started to construct the world's first cryogen-free hybrid magnet consisting of an outer cryogen-free compact wide bore superconducting magnet and an inner water-cooled resistine magnet. A cryogen-free 23 T hybrid magnet by the combination of a cryogen-free 8 T superconducting magnet with a 360mm warm bore magnet and a 15T water-cooled magnet will realize in near future.

制备了CuNb/Nb_3Sn多芯超导线圈，并在液氦冷却和低温制冷机冷却条件下对CuNb/Nb_3Sn多芯超导线圈的低温稳定性进行了研究。结果表明，低温冷却条件下的最小失超能MQE比液氦冷却条件下的最小失超能MQE减小1/3，而法向区传播速度则增大3 ~ 4倍。这些行为依赖于工作电流与临界电流之间的负载电流比，特别是低温冷却条件揭示了电流比的强烈依赖性。进一步，研究了用反应缠绕技术制备的CuNb/Nb_3Sn测试线圈在大电磁应力状态下的性能。实验结果表明，弯曲应变为0.33%的线圈承受330 MPa的环向应力，其临界电流没有下降。最后，我们开始研制世界上第一个由外部无制冷剂的紧凑型大口径超导磁体和内部水冷电阻磁体组成的无制冷剂混合磁体。将8 T无冷剂超导磁体与360 mm温膛磁体和15 T水冷磁体相结合，可实现23 T无冷剂混合磁体。