Formation of Magnetic Particle Chains in Ultra High Magnetic Field

Abstract

Magnetic particles form chain-like clusters in the magnetic field. This phenomenon is of interest in two separate fields, one is a development system of the laser printer and another is an electromagnetic manipulation of biological cells. Experiments on the chain formation in air and oil have been performed in the ultra high magnetic field created by a superconducting magnet. It has been clarified that the chain length first increased and then decreased in accordance with the increase of the magnetic field. The result has been confirmed by a numerical calculation with the Distinct Element Method that included the mechanical contact force between particles and the magnetic force due to the field created by the coil and adjacent magnetized particles. A periodic boundary condition was employed to perform realistic calculation in a reasonable calculation time. The effect of the density and the diameter of particles was investigated experimentally. The effect of the dry friction between particles was also examined by comparing experimental results performed in air and oil. Lastly, it has been discussed that the static stability of the chain was determined by a minimization principle of the potential energy that consists of the gravitational and magnetic potential energy.

Pressless process in route of obtaining sintered Nd–Fe–B magnets

“…Largescale Atomic/Molecular Massively Parallel Simulator. DEM has been used for simulation of magnetic particles placed in external magnetic field in a magnetic brush development system adopted in high-speed electrophotography machines [26,27] and in the permanent magnet production to study the magnetic alignment of powders [28][29][30]. Kitahara et al investigated the influence of the axial, transverse and isostatic pressing on the degree of alignment of spherical and non-spherical particles constructed from parts of two spheres.…”