Analysis of the magnetic fields in magnetostrictive rare earth-iron transducers

The magnetic problems encountered in the design of underwater transducers based on magnetorestrictive rare earth/iron alloys are using the finite element package FLUX2D. Dynamic magnetic circuit design is studied using the concept of an open magnetic circuit. Eddy-current computations show that this effect can be accurately taken into account by an analytical method. The presence of leakage flux due to the low permeability of the magnetorestrictive alloy is fully revealed with finite-element computations and is expressed by low magnetic coupling factors. The results of a systematic study of this coefficient and of the coil quality factor are presented. Different solutions for the magnetic bias using permanent magnets are discussed.>