Eddy Current Effects in the Core of a Magnetic Field Sensor

Aim of this paper is to assess the impact of the eddy currents induced in the core of the FLUXSET probe, a high sensitivity magnetic field sensor. Due to the conductivity of the magnetic core, at high frequencies the skin effect may in fact delay the penetration of the flux generated by the driving solenoid, with a consequent alteration of the output signal. Numerical calculations presented in previous papers indicated that the effects of the eddy currents on the output signal were negligible even at frequencies much higher than the inverse of the penetration time of the magnetic field. In this paper we propose an explanation of this phenomenon, which occurs in both linear and nonlinear cases. We also present 3D numerical calculations with both integral and differential formulations, in comparison with an approximate analytical solution for ID models.