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

采用种晶熔炼法制备的c轴取向REBa_2Cu_3O_<7*>准单晶在77 K下可捕获1特斯拉量级的磁场，并通过降低温度来增强其性能。我们认为，如果控制好超导永磁体的微观结构，超导永磁体的俘获场能力可以进一步提高到普通Nd-Fe-B永磁体的10倍以上。本工作的目标是研制在自由空间产生3-5特斯拉的超导永磁材料，并开发脉冲场磁化技术对合成的超导体进行磁化。1997年，我们合成了熔体超导体，并分析了脉冲场驱动下超导体磁通量的动态运动。我们观察到磁化曲线与静态场下的磁化曲线不同。当脉冲场强度为1…时，磁通量进入超导体的速度很慢，但当脉冲场强度超过2-4特斯拉时，磁通量进入超导体的速度很快。我们获得了脉冲磁场下磁通量的粘性运动和钉钉机理的重要信息。通过将211粒子均匀分散在基体中，我们还成功地合成了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粒子，提高了Sm-123块体超导体的超导性能和力学性能，并在77 K下捕获了1.7特斯拉的磁场。在25 K时，该值可以增加到9特斯拉。所有这些数据都是文献中报道的未经辐照合成的Sm-123超导体的最高数据。这是Nd-Fe-B永磁体的30倍（平成10年3月27日晚报《Chunichi-Shinbun》报道）。并对该超导体进行了脉冲磁场磁化的研究。我们的结论是，在不久的将来，在自由空间产生3-5特斯拉的磁场发生器将被开发出来。少

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