LAUSR

Demagnetization of ferromagnetic vessels, or deperming, is a common practice used to reduce the magnetic signature. The general approach for ship deperming presented in the literature is the anhysteretic protocol, where the applied field is reduced at equidistant intervals. In reality, the method involves the complications of having a bias (Earth’s magnetic) field present and the practical impossibility of magnetizing the ship to saturation. When anhysteretic demagnetization cannot be applied, past experience is used to empirically estimate the necessary magnetic treatment for each vessel. In this article, we examine the ship deperming on a fundamental basis by describing it using the Jiles–Atherton (J-A) model. The ship model parameters were estimated by inversion from measurements taken at certain points of the demagnetization cycle. The model is useful for testing different protocols of, in general, not-unique deperming operation. The proposed J-A analysis of hysteresis offers a theoretical basis to predict the demagnetization results a priori. The model simulation study of the demagnetization process is demonstrated with the measurements from HMCS Toronto.