A Sensitive Element Based on the Giant Magnetoimpedance Effect for Detecting Stray Fields

摘要

Features of the magnetoimpedance effect of a sensitive element in the form of an amorphous ribbon of an Fe_(2.5)Co_64_(15)Cr_3Si_(15)B_(15) alloy were studied in the absence and presence of a ferromagnetic object in the form of a parallelepiped (0.65 × 3 × 25 mm) manufactured from high-carbon steel. Measurements of the magnetic-hysteresis loops and the values of the magnetoimpedance were performed for specimens of an amorphous ribbon (0.018 × 0.75 × 56 mm). The frequency range of exciting currents was 1-20 MHz. The possibility of detecting a model object by a contactless technique at a comparatively long distance (1 mm) was shown. The frequency ranges—a low-frequency range of 1-7 MHz and a high-frequency range of 10-20 MHz—within which detection can be performed were determined. A physical model of the detection of ferromagnetic model objects with a magnetoimpedance sensitive element in the form of an amorphous ribbon was proposed. Stray fields of model objects cause significant changes in the value of the magnetoimpedance at low external fields, and the frequency of the exciting current is an additional variable parameter.