Estimation of the radius of the inner core and the angle of the easy axis of its magnetization for as-prepared amorphous magnetostrictive wire

The estimation of the domain structure of an as-prepared amorphous magnetostrictive wire (Fe_77.5Si_7.5B₁₅, 125-μm diameter) is considered. Through this investigation, it is clarified that the second-harmonic component of the voltage induced in a pickup coil wound about the wire is generated essentially from the inner core only when a sufficiently small sinusoidal field is applied in the direction of the wire axis. Using this property, the angle of the easy axis of magnetization in the inner core is estimated. The radius of the inner core is also calculated from the estimated value. In the estimation, it is assumed that the angle of the easy axis is proportional to the distance from the center line of the wire. Based on this assumption, the rectangularity and the magnitude of the pulse voltage are calculated. The validity of the estimation is confirmed by comparing the magnitude of the pulse voltage obtained when the estimated values are substituted into the expression for the pulse voltage with that measured by the Sixtus-Tonks experiment