Analytical Optimization of Low-Frequency Search Coil Magnetometers

An analytical optimization is proposed for the sensitivity threshold of low-frequency search coil magnetometers employing disk-shape flux concentrators. The optimal diameters of the core and the wire are found for a given set of the optimization parameters: frequency, search coil volume and aspect ratio, relative permeability of the core and the flux concentrators, and the noise of the preamplifier. The proposed analytical optimization allows an immediate analysis of the theoretical limits of the magnetometer sensitivity threshold. An approximation is obtained to simplify and clarify the relationship between the minimum possible sensitivity threshold and the optimization parameters. Measurements performed with an experimental magnetometer model confirm the optimization.