A comprehensive study on the weak magnetic sensor character of different geometries for proton precession magnetometer

Abstract

The measurement precision or uncertainty of proton precession magnetometer (PPM) depends on the signal-to-noise ratio (SNR) of the free induction decay (FID) signal induced in the sensing coil. A diversity of weak magnetic measurement applications has benefited from various coils through a more comprehensive and reliable design. Likewise, numerous optimized sensors for PPM have been proposed and published in literature. However, due to lack of commonly accepted assessment measures and benchmark resources, it is hard to identify the performance of the proposed sensors and corresponding implementations. This paper investigates and categorizes sensing coils for PPM which are well used and accepted. Three state-of-the-art geometries of the coil including solenoid, toroid, and cylindric, are considered to evaluate the significance of these designs in terms of sensing signal strength analyses within their respective applications. Furthermore, the electromotive force (EMF) of FID signal is calculated as a function of sensing coils' geometrical parameters, and numerous critical factors such as the polarizing current, the orientation of the coil axis with respect to the direction of the external magnetic field, etc., are considered. Although the results of these calculations are limited by prerequisites, e.g. the sensor should be in a uniform magnetic field, it is a critical step for future sensor research. This paper aims to advance weak magnetic sensor development by establishing a comparative study to allow the optimum geometrical shapes to be chosen for different applications.