Magnetic flux concentration using YBCO hollow and solid cylinders

We have proposed new applications of bulk high-temperature superconductors in high magnetic fields. High-temperature superconductors, such as BSCCO or YBCO, maintain their superconductivity over 30 T at 4.2 K. A field-cooled superconducting hollow cylinder traps the magnetic flux inside itself. A field-cooled superconducting solid cylinder traps in the interior of it. An increase of the applied magnetic field induces shielding current in the interior of the cylinder to maintain the magnetic flux constant. By suitably arranging the cylinders, we can concentrate the magnetic flux and enhance the gradient of the magnetic field. In order to confirm these concepts, we performed experiments using bulk YBCO cylinders. The cylinders are made of YBa₂Cu₃O_7-x quasisingle crystals containing Y₂BaCuO₅ particles. Hollow and solid cylinders were employed to concentrate the magnetic flux. Using three hollow cylinders, the concentrated magnetic field of 0.49 T was observed in the applied magnetic field of 10.14 T. The concentrated magnetic field of 0.64 T was observed for the solid cylinders in the applied magnetic field of 10.24 T. The magnetic flux concentration was observed even in the high magnetic field over 20 T.