Effect of Magnetic Field on Concentration of Magnetic Particles in a Magnetic Fluid Plug. Local Concentration under Nonuniform Transverse Field.

Abstract

Experimental study is carried out to clarify the local concentration of magnetic particles in a magnetic fluid plug in a nonuniform magnetic field. The intensity and the phase differences of the He-Ne laser beam which transmits the magnetic fluid within a duct of rectangular cross section are measured. The polarization angles of polarizer and analyzer are set to the directions of magnetic flux at each measured point. Also, the relationship between the phase difference of the transmitted light and the concentration of the magnetic particles is determined using the magnetic fluid film which has a small area and the same thickness as the plug. This relationship is used to estimate the local concentration of magnetic particles at each measured point in the plug. It is clarified that the region with higher concentration of magnetic particles is formed near the magnetic pole pieces and it is enlarged with magnetic flux density.