A digitally controlled AF demagnetizer for peak fields of up to 0.1 T

Abstract

An alternating field (AF) demagnetizer capable of generating a peak field of 0.1 T at a frequency of about 300 Hz, with provision for tumbling the sample about two axes is described. An optoelectronic device, driven by linear and digital integrated circuitry, is used for transient-free closed loop control of the field. The entire sequence of a demagnetizing cycle (the rise of the field to its exact preset peak value and its decay to zero) is digitally controlled. The amplitude-time profile of the field is well suited for the demagnetization of rock samples.