Performance Test of Search Coil Sensors with Different Core Types

A search coil magnetometer (SCM) is a common equipment to observe energy transmission and vibrations in space physics, enabling measurements across a wide frequency range of up to tens of kilohertz. This study proposes the designs of a magnetic core that allows a low-mass sensor and improves its performance: a rod core, sheet-stacked core, and rolling-sheet core. Subsequently, the performance of each sensor was investigated. The sheet-stacked core using the cobalt-based alloy exhibited the highest sensitivity, although it exhibited instability beyond 20 kHz. In contrast, the rod and rolling-sheet core sensors demonstrated stability in the magnetic field measurements (10 Hz–40 kHz). Moreover, the noise equivalent magnetic induction (NEMI) of the rod- and rolling-sheet core sensors were 0.014 pT Hz–1/2 and 0.012 pT Hz–1/2 at 1 kHz, respectively. The rolling-sheet core with high relative permeability achieved a mass reduction of over three times that of the rod core while exhibiting sufficient sensitivity.