Evaluation of magnetic force distribution on a pair of superconducting bulk magnets

Abstract

We study on the construction of superconducting permanent magnets by RE123 bulk materials and the investigation of these industrial applications such as a magnetic separation. A bulk magnet can generate strong magnetic fields exceeding 2 T, which is the limit of ordinary iron-cored electromagnets, in a compact device with a low running cost. A magnetic field distribution of the bulk magnet is a cone shape, and it contributes to an increase of magnetic force which is proportional to the product of a magnetic field and its gradient. It is important to evaluate magnetic force when the application of the bulk magnet is discussed. In this paper, two Gd123 bulk materials of 65 mm in diameter were magnetized using a pair of superconducting bulk magnet system and three-axis components of magnetic flux density (B x , B y , and B z ) in an open space between the magnetic poles were scanned with pitch of 2 mm in each direction. From these measured data, the axial and radial components of magnetic force factor, B z ⋅dB z /dz and B r ⋅dB r /dr, were calculated. At 10 mm gap, the B z ⋅dB z /dz value reached 180.6 T 2 /m for a field of 2.33 T, which is comparable to B z =6.76 T for a common 10 T-100 mmφ superconducting magnet.