An Excitation Optimization Method for Demagnetization Systems Combined with Magnetic Shaking in MSR

High-precision magnetic field measurements, such as those used in biomagnetism, necessitate near-zero magnetic environments, generally provided by high-permeability magnetic shielding devices. Shielding performance can be improved by adjusting the magnetization strength of the material and reducing hysteresis losses using magnetic shaking and demagnetization techniques. While magnetic shaking increases the permeability of the material, it also introduces magnetic field interference, complicating the magnetic environment. Therefore, this article proposes a demagnetization excitation method combined with magnetic shaking to further improve the shielding performance of magnetically shielded rooms (MSRs). This method enhances the permeability of the material while avoiding the magnetic field interference typically caused by magnetic shaking. The after demagnetization magnetization curve (ADMC) measurement system is established to test the effect of shaking parameters during demagnetization on the magnetization strength of the materials, and a magnetization performance database is constructed. The suppression of hysteresis losses through the demagnetization process combined with shaking is described by introducing a suppression coefficient into the dynamic Jiles-Atherton model, which clarifies the theoretically optimal demagnetization parameters. Using the finite element method (FEM) algorithm in combination with the database, the theoretical limit of remanence for MSR is analyzed. The demagnetization excitation optimization method and the ADMC measurement system are applied to test the remanence and shielding factor (SF) of MSRs. The average residual magnetic field in the central area was reduced by 29.7%, and the average SF was improved in the range of 1-10 Hz.