Time domain and statistical modeling of the Barkhausen effect used as a magnetic sensor

Abstract

This research presents a time domain model of the Barkhausen effect as a magnetic field sensor. This type of magnetic field sensor will supplement magnetic field sensors already in use and should have wide applicability in the EMC community. When a silicon steel sheet is placed at the center of a coil, an external magnetic field from a moving magnet will cause the magnetic domain walls to snap and click as they suddenly orient themselves. This sudden orientation of the magnetic domains causes sudden changes in magnetization which produce impulses of EMF which can be heard as distinct clicks on a loudspeaker connected to an amplifier and with the amplifier connected to the coil. This sudden orientation of the magnetic domain walls in the presence of an external magnetic field is called the Barkhausen effect. In this paper a time domain model of the Barkhausen effect as a magnetic sensor is presented. Equations are also developed which model the Barkhausen effect as a motion sensor by sensing magnetic fields in a moving reference frame modeled. The sudden orientation of the magnetic domain described by the Barkhausen effect is mathematically modeled by calculating the energy needed to change the direction of the Bloch wall or the transition layer that separates adjacent domains magnetized in different directions. The spectrum of the Barkhausen effect was theoretically derived.