Development of advanced magnetically-levitated high-temperature superconducting coils with YBCO coated conductors

开发先进的YBCO涂层导体磁悬浮高温超导线圈

基本信息

批准号：
17560735
负责人：
NAGATO Yanagi
金额：
$ 2.11万
依托单位：
National Institute for Fusion Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

项目摘要

Magnetic levitations of high-temperature superconducting coils were examined using state-of-the-art YBCO coated conductors. Three coils (diameter: 90-140 mm) were fabricated and tested by inducing persistent currents using liquid nitrogen under external magnetic field (field-cooling method). These coils, despite their small sizes, have become the world first magnetically-levitated YBCO coils. The decay time constant of persistent currents were found to be long enough (2-7 hours) owing to the application of sophisticated joint structures between pancakes of the coils. When the external magnetic field was applied in a special way, it was found that the persistent current even increased after the initial excitation. This phenomenon can be explained by the magnetic coupling between the locally induced shielding currents in the superconducting layers and the transport current through the coil windings. By using stable persistent currents, magnetic levitation experiments were carried out with and without feedback controls. Self-stabilized magnetic levitations were observed with specified conditions, which could be explained by conservation of magnetic flux in the superconducting floating coils. These results are supposed to be valuable for designing the upgraded high-field version of the present Mini-RT device for internal plasma confinement. Furthermore, feasibility studies for applying YBCO high-temperature superconductors for fusion machines have been carried out. It is shown that field correction coils used for helical machines, such as the Large Helical Device, can be provided by high-temperature superconducting coils. They are supposed to be much more efficient than the present copper coils and will soon be available with the near future technology.

使用最先进的YBCO涂层导体检查了高温超导线圈的磁悬浮。制造三个线圈（直径：90-140 mm），并通过在外部磁场（现场冷却方法）下使用液氮诱导持续电流来测试。这些线圈虽然尺寸很小，但已成为世界上第一个磁性滑动的YBCO线圈。由于线圈之间的复杂关节结构的应用，发现持续电流的衰减时间常数足够长（2-7小时）。当以特殊方式应用外部磁场时，发现持续电流甚至在初始激发后甚至增加。这种现象可以通过超导层中局部诱导的屏蔽电流与通过线圈绕组的传输电流之间的磁耦合来解释。通过使用稳定的持续电流，进行磁悬浮实验，并没有反馈对照。在指定条件下观察到自动稳定的磁悬浮，可以通过在超导浮动线圈中保存磁通量来解释。这些结果应该对于设计目前的Mini-RT设备的升级高场版本是有价值的，以进行内部等离子体限制。此外，已经进行了用于融合机YBCO高温超导体的可行性研究。结果表明，用于高温超导线圈可以提供用于螺旋机的场校正线圈，例如大型螺旋装置。它们应该比目前的铜线圈更有效，并且很快将与不久的将来的技术一起使用。