Absolute sensitivity of a high-mu metal core solenoid as a magnetic sensor

A high-mu (high permeability) metal core solenoid used as a head sensor of an induction magnetometer is calibrated and a theoretical calculation of its absolute sensitivity is performed. The responses in the field to a moderately intense quasi-sinusoidal Pc 1 event of the high-mu metal core induction magnetometer and an air-core loop antenna induction magnetometer system with a known sensitivity are compared to obtain an absolute sensitivity of 0.0560 Caner for the high-mu metal core magnetometer. The absolute sensitivity of the high-permeability metal core solenoid is also estimated theoretically by approximating the circular or rectangular core by a uniformly magnetized prolate ferromagnetic spheriod. The calculated absolute sensitivity of the core is found to agree well with the experimental value. The analysis indicates that it is possible to use a thin high-permeability metal rod as the core of a sensor, allowing a reduction in weight of the magnetometer without much loss of sensitivity.