Constant rate of change of magnetization hysteresis loop tracer

Abstract

An experimental procedure has been developed by which magnetization curves may be traversed at a constant rate of change of magnetic polarization, J̇. The new technique involves, in an iterative procedure, the use of a combination of closed- and open-loop digital strategies to control the magnetic field so that J̇ remains constant over the majority of the hysteresis loop. As an application of the effectiveness of the technique, results obtained using Alnico permanent magnet materials are presented. The limitations of this method are reviewed in relation to material properties and the type of measurement system utilized. The consequences of using a digital control system and digital measurement techniques in the characterization of magnetic materials are discussed.