Measurement and Analysis of Magnetic Properties of Permalloy for Magnetic Shielding Devices under Different Temperature Environments

Abstract

The relative permeability, coercivity, and remanence of permalloy are closely related to the performance of magnetic shielding devices. In this paper, the relationship between the magnetic properties of permalloy and the working temperature of magnetic shielding devices is measured. Firstly, the measurement method of permalloy properties based on the simulated impact method is analyzed. What is more, a magnetic property test system consisting of a soft magnetic material tester and a high–low temperature chamber for permalloy ring samples at different temperatures was established to measure DC and AC (0.01 Hz to 1 kHz) magnetic properties at different temperatures (−60 °C to 140 °C). Finally, the results show that compared with room temperature (25 °C), the initial permeability (μi) decreases by 69.64% at −60 °C and increases by 38.23% at 140 °C, and the coercivity (hc) decreases by 34.81% at −60 °C and increases by 8.93% at 140 °C, which are the key parameters in the magnetic shielding device. It can be concluded that the relative permeability and remanence of permalloy are positively correlated with temperature, while the saturation magnetic flux density and coercivity are negatively correlated with temperature. This paper is of great significance to the magnetic analysis and design of magnetic shielding devices.

Modeling and Simulation of a Planar Permanent Magnet On-Chip Power Inductor

“…To express the saturation current Isat for both the OPI and the PMOI, ( 6) and ( 7) can be rewritten by replacing I by Isat and Φ by Bsat.Ac. This yields (8) and (9).…”

“…However, increasing the core size will significantly increase the size of the power inductor and makes it harder to integrate. Meanwhile, magnetic materials with high magnetization, such as permalloy [8], usually have relatively low resistivity, leading to high eddy current loss in the inductor core. Permanent magnet (PM) materials have been used to increase the saturation current for power inductors with different core structures.…”

Demagnetization Parameters Evaluation of Magnetic Shields Based on Anhysteretic Magnetization Curve

“…Magnetic shields can provide the nearly zero-field environments with small residual field and low field gradient, which is a prerequisite for the above research [7,8]. Common configurations of magnetic shields mainly include cubic MSR [9,10] and cylindrical magnetic shield [11,12], which is composed of high-permeability soft magnetic material like permalloy and highconductivity material like copper [13,14]. The great shielding effect can effectively reduce residual field and magnetic noise and obviously improve the signal-to-noise ratio of biological magnetic field measurement represented by magnetocardiogram (MCG) and magnetoencephalogram (MEG) [15,16].…”