Helical Magnetic Core Design for Miniaturized Induction Magnetometer

This paper presents a helical core design for miniaturized induction magnetometers based on finite-element simulations and experiments. The helical cores demonstrate higher apparent permeability than cylindrical cores of the same size. An empirical formula for the DC permeability enhancement factor is derived, with a mean relative error of −0.44% ± 4.53% compared to simulations, though it underestimates the 100 Hz measurements by an average of 23.27%. The long racetrack coil, which encloses multiple turns of the helix, is identified as the optimal pickup coil, reducing inductance to 30–48% of that of an annular coil while maintaining comparable induced voltage. This configuration also exhibits excellent linearity (R² > 0.99) and directional response errors below 0.02. This study establishes a comprehensive design methodology and quantitative guidelines for helical cores in next-generation miniature magnetometers.