Simulations of remanence and field distributions of permanent magnet array with rectangular cavity

Abstract

The magnetic phenomena of a Halbach-type permanent magnet array under a strong self-field such as demagnetization, saturation, deflection, and rotation of remanence vectors occur deep in the interior of the magnets, and thus lead to an inhomogeneous field even for a hollow cylindrical permanent magnet array with circular cavity. Considering the anisotropic magnetization loops of commercially available permanent magnets, the self-consistent remanence and field distributions of a 16 piece hollow cylindrical permanent magnet array with rectangular cavity (HCPMARC) are presented here to simulate the magnetic phenomena inside the magnets. The field distribution of a HCPMARC can be modulated by array structure while keeping both the cross sectional areas of the cavity and the magnets constant. At the expense of field uniformity, a HCPMARC acquires greater center field uniformity than a HCPMACC does. Furthermore, we simulated the magnetization and field distributions for a yoked HCPMARC obtained by replacing the partial permanent magnets with soft ones on both magnetic poles of a yokeless HCPMARC. Such substitution always enhances field uniformity but depresses the center field. This, in turn, causes changes in the average magnitude of the field in the entire rectangular cavity.