Magnetization Process of High-Tc Superconductors due to Pulsed Field and Development of Superconducting Permanent Magnet

已知通过使用籽晶进行熔融加工而生长的c轴取向REBa_2Cu_3O_<7*>准单晶在77K下捕获1特斯拉量级的磁场，并通过降低温度来增强其能力。我们相信，如果控制好其微观结构，超导永磁体的俘获磁场能力可以进一步提高到普通Nd-Fe-B永磁体的10倍以上。目前工作的目标是开发在自由空间中产生3-5特斯拉的超导永磁材料，并开发脉冲场磁化技术来磁化合成超导体。1997年，我们合成了熔融加工的块体超导体，并分析了脉冲场驱动的超导体中磁通量的动态运动。我们观察到磁化曲线与静态场下获得的磁化曲线不同。当脉冲场强度较低时，磁通量进入超导体的速度非常慢，但一旦脉冲场的强度超过 2-4 特斯拉，磁通量就开始非常快地进入。我们获得了有关脉冲场存在下磁通量的粘性运动和钉扎机制的重要信息。我们还通过将211个颗粒均匀分散在基体中，成功合成了Y-123、Sm-123和Nd-123准单晶。1998年，我们通过在基体中分散细小的Ag颗粒，增强了Sm-123体超导体的超导性能和机械性能，并在77 K时捕获了1.7特斯拉的磁场，在77 K时该值可提高到9特斯拉。 25 K.所有这些在没有任何辐照辅助下合成的Sm-123超导体的数据都是文献中报道的最高值。这是Nd-Fe-B永磁体的30倍（中日新闻晚报平成10年3月27日报道）。还进行了通过脉冲场磁化这种超导体的研究。我们得出的结论是，在不久的将来将开发出在自由空间中产生 3-5 特斯拉的磁场发生器。较少的

The c-axis oriented REBa_2Cu_3O_<7*> quasi-single crystal grown by the melt-processing with the use of a seed crystal is known to capture magnetic fields of the order of 1 Tesla at 77 K and to enhance its capability by lowering the temperature. We believe that the trapping field ability of a superconducting permanent magnet can be further enhanced to the level more than 10 times as high as that of the ordinary Nd-Fe-B permanent magnet, if its microstructure is well controlled. The objective of the present work is to develop superconducting permanent magnetic materials generating 3-5 Tesla in the free space and to develop the pulsed field magnetization technique to magnetize the synthesized superconductor.In 1997, we synthesized the melt-processed bulk superconductors and analyzed the dynamical motion of the magnetic fluxes in the superconductor driven by the pulsed field. We observed the magnetization curve different from that obtained under the static field. When the pulsed field is l … More ow, the magnetic fluxes enter into the superconductor very slowly but begin to enter very rapidly once the intensity of the pulsed field exceeds 2-4 Tesla. We obtained crucial information about the viscous motion of the magnetic fluxes and pinning mechanism in the presence of the pulsed field. We could also successfully synthesized the Y-123, Sm-123 and Nd-123 quasi-single crystal by dispersing the 211 particles in the matrix uniformly.In 1998, We could enhance both superconducting and mechanical properties of the Sm-123 bulk superconductor by dispersing fine Ag particles in the matrix and could trap magnetic field of 1.7 Tesla at 77 K.The value could be increased to 9 Tesla at 25 K.All these data for the Sm-123 superconductors synthesized without any assistance of irradiation are the highest reported in the literature. This is 30 times as high as that of the Nd-Fe-B permanent magnet (reported in Chunichi-Shinbun, evening newspaper, March 27th, Heisei 10) . The research to magnetize this superconductor by the pulsed field has been also conducted. We have concluded that a magnetic field generator producing 3-5 Tesla in free space will be developed in very near future. Less