Construction of strong magnetic field generators by high T_c bulk superconductors and its applications

The authors have succeeded in constructing a superconducting permanent magnet system capable of generating the highest magnetic field of 3.15 T in the open space between the face-to-face magnetic poles containing the melt-processed RE-Ba-Cu-O bulk superconductors. A pair of bulk samples was cooled to 38 K by using small GM-refrigerators (15 W at 77 K), and magnetized by the pulsed field magnetization (PFM) process called "IMRA" method. The values and distributions of trapped magnetic fields were measured. The authors will refer to a novel face-to-face field generator using seven bulk superconductors arranged on a couple of the cold stages. The size of the magnetic pole is 150 mm in diameter. The highest magnetic field obtained by the field cooling method operated at 5 T has reached 1.4 T on the right-hand side magnetic pole surface and 0.9 T at the center of the open space of 34 mm between the magnetic poles, respectively. The intense magnetic fields are investigated to be applied to various industries such as the magnetic separation technique and so on.