Construction of a strong magnetic field generator with wide magnetic poles by bulk superconductors

The authors have succeeded in constructing a novel face-to-face field generator using seven RE-Ba-Cu-O bulk superconductors arranged on a couple of wide cold stages with a size of 150 mm in diameter. The cold stages were cooled to 67 K by using Stirling-cycle pulse tube cryocoolers (8 W at 77 K), and magnetized by the field cooling process operated by a superconducting solenoid magnet at 5 T. The highest magnetic field has reached 1.4 T on the pole surface and 0.9 T at the center of the open space of 34 mm between the bulk magnets, respectively. The maximum value of the total fluxes has reached 4.5 mWb that corresponds to nearly four times as much as that obtained when a single bulk sample was magnetized at 35 K. The intense magnetic fields are investigated to be applied to various industries such as magnetic separation systems and so on in Iwate CREATE project.