Equation For Magnetic Vector Potential Research Articles

Performances of Magnetic Fluid Seal and Application to Turbopumps.

A magnetic fluid shaft seal can achieve zero-leakage and operate stably against shaft vibration, but the sealing pressure is very low. In order to improve the pressure performance of a magnetic fluid seal and apply it to a turbopump, the seal pressure characteristics are studied theoretically and experimentally. The Poisson equation for magnetic vector potential is solved by FEM, and the seal performances are determined by use of the Bernoulli equation. The validity of the theory is confirmed by experiments using the two-dimensional simple model and the real shaft seal model. Furthermore, a magnetic seal is applied to an actual pump and its performance is measured.

Magnetization of a nonlinear ferromagnetic semi-infinite plate by a short coil, in the presence of eddy-currents

The paper deals with the evaluation of magnetic fields in a system of a relatively long-conductive ferromagnetic strip with nonlinear characteristic. The field is produced by an a.c. excited relatively short coil wound around the strip. The investigated system is similar to a magnetic field sensor system (described recently) which employs nonlinear eddy current effects in the sensing process. The analysis in the paper depends on linearization of the magnetic vector-potential equations by assuming that all field components are sinusoidal everywhere, and by imposing an appropriate change of μ with the material depth. The linearization process enables the integration of the field equations by Fourier transform. The evaluated results compare favorably to experimental results.

Simulation of perpendicular recording on Co-Cr media with a thin Permalloy film-ferrite composite head

Numerical analyses of thin film head-medium system for perpendicular recording are performed using a two-dimensional model. The formulation is based on Poisson’s equation for magnetic vector potential in the head-medium system. The following conclusions are drawn: (1) Magneto-motive force needed for producing a sufficient perpendicular field in the medium is about 1/10 that of the SPT (single pole type) head proposed by Iwaski et al. (2) There is an optimum spacing between the magnetic layer and the ferrite of the head that lies 5–20 times the distance between the main pole and the underlayer. (3) The conductor should be placed in the very tip portion of the magnetic layer. (4) Simulation confirms that recording of densities as high as 100 kBPI is possible using a thin film head-Co-Cr medium system.