Magnetic field fluctuations due to movement of objects composed of magnetic materials

Summary form only given. In order to grasp the area at which biomagnetic measurements (BMM, >10/sup -12/ T) and ion beam plots (IBP, >10/sup -7/ T) for semiconductors are affected, a method of predicting the amplitude of fluctuations of magnetic fields (IMF) at low frequencies is investigated. Such IMF occurrs due to the movement of objects composed of magnetic materials such as doors and elevators in buildings. In the proposed method, the 3-D finite element method is applied to the calculation of magnetization M in the object, and then Biot-Savart´s law is used to evaluate the flux density B far from the objects.