Hysteresis Torque in Elliptically Polarized Fields

Abstract

In ferromagnetic materials if the magnitude and direction of the magnetic field intensity are changed hysteresis occurs. This, in general, is of two types: the usual alternating hysteresis, and the torque component of hysteresis which gives rise to the rotational loss when the direction of the magnetic field intensity is changed and the magnitude is held fixed. By means of a torque magnetometer, the time average of the torque has been observed as a function of the applied magnetic field intensity for elliptical fields of different eccentricity. For the silicon iron disk investigated, and with the field along one axis (the first axis) as a parameter, the time average of the torque increases with applied field along the mutually perpendicular axis, reaching a maximum value at the bend in the magnetization curve and then decreases as saturation is approached. The torque curves first increase, go through a limiting curve, and then decrease as the field along the first axis is increased. A qualitative explanation of the shape and variation of the torque curves with field strength is suggested.