Magnetic flux concentration and magnetic force enhancement using YBCO cylinders

In this paper, we propose new applications of bulk high-temperature superconductors in high magnetic fields. High-temperature superconductors, such as Bi₂Sr₂CaCu₂O_8+d (BSCCO) or YBa₂Cu₃O_7-x (YBCO), maintain their superconductivity over 30 T at 4.2 K. A field-cooled superconducting hollow cylinder traps the magnetic flux inside 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 hollow cylinders. The cylinders are made of YBa₂Cu₃O_7-x quasi single-crystals containing Y₂BaCuO₅ particles. They have an inner diameter of 5 mm, an outer diameter of 10 mm, and a height of 10 mm. Using three hollow cylinders, a magnetic concentration of 0.49 T was observed in an applied magnetic field of 10.14 T. The energized hollow cylinder with a shielding current modify surrounding magnetic fields and magnetic force fields. A magnetic force field enhanced by using a hollow cylinder was calculated numerically for an applied magnetic field of 10 T and estimated to exceed 6000 T²/m.