Magnetic Shielding Research Articles

Research on the stress magnetic coupling effect of a permalloy based on an optimized Jiles Atherton model in magnetic shielding devices

Magnetic shielding devices are extensively used in the measurement of quantum physics, the static magnetic field shielding layer made of permalloy in the magnetic shielding device will work under different stresses. Due to the magnetic properties of permalloy being sensitive to the applied stress, it is necessary to establish a magnetic property model considering stress to accurately evaluate the residual magnetic field in magnetic shielding devices under different stresses. However, the measurement and modeling of the magnetic properties of permalloy under different stresses have not been considered in relevant research. In this paper, the magnetic properties of permalloy under different tensile and compressive stresses were measured, and the optimized Jiles Atherton (JA) model of permalloy considering stress constructed. The parameters of the JA model are extracted by a genetic algorithm,-the particle swarm optimization algorithm, through measurement. Finally, the effectiveness of the model in predicting magnetic properties is validated. The JA optimization model considering stress can improve the calculation accuracy of magnetic shielding devices, which is of great significance for the design and application of magnetic shielding devices.

The Effect of a Ferromagnetic Steel Enclosure on Magnetic Shielding Systems: Analysis, Modeling, and Experimental Validation

The Effect of a Ferromagnetic Steel Enclosure on Magnetic Shielding Systems: Analysis, Modeling, and Experimental Validation

HighNESS conceptual design report: Volume II. The NNBAR experiment.

A key aim of the HighNESS project for the European Spallation Source is to enable cutting-edge particle physics experiments. This volume presents a conceptual design report for the NNBAR experiment. NNBAR would exploit a new cold lower moderator to make the first search in over thirty years for free neutrons converting to anti-neutrons. The observation of such a baryon-number-violating signature would be of fundamental significance and tackle open questions in modern physics, including the origin of the matter-antimatter asymmetry. This report shows the design of the beamline, supermirror focusing system, magnetic and radiation shielding, and anti-neutron detector necessary for the experiment. A range of simulation programs are employed to quantify the performance of the experiment and show how background can be suppressed. For a search with full background suppression, a sensitivity improvement of three orders of magnitude is expected, as compared with the previous search. Civil engineering studies for the NNBAR beamline are also shown, as is a costing model for the experiment.

Development and Study of Magnetic Shields for Neutrino Detector Photomultiplier Tubes under Neutrino-4M Experiment on PIK and SM-3 Reactors

Development and Study of Magnetic Shields for Neutrino Detector Photomultiplier Tubes under Neutrino-4M Experiment on PIK and SM-3 Reactors

Improved Common-Mode Leakage Current Measurement Method for Insulation Condition Monitoring in Distribution Grids

Common-mode (CM) leakage current is an essential insulation indicator for condition monitoring in distribution grids. However, online measurement of CM leakage current is a difficult task in the industry due to the disturbances of far larger load currents. To address this challenge, a novel CM leakage current measurement method based on multi-layer magnetic shield has been proposed in this paper. The analytical solution for the magnetic field around the shield is firstly derived and validated by finite element analysis. Comprehensive comparison with previous single-layer shield design is then conducted for a typical industrial case, proving that an improvement of about 46 dB can be achieved for CM leakage current measurement by the novel design. A sensor prototype has also been developed with optimized parameters and validated by experiments. The effectiveness of the proposed method is proved, with minor CM leakage current accurately extracted from load currents which are 3000 times larger.

Magnetic noise modeling and calculation of Fe-based nanocrystalline in the SERF magnetometer considering temperature effects

The Fe-based nanocrystalline has been widely used in the innermost magnetic shielding of the spin-exchange relaxation-free (SERF) magnetometer due to its high permeability and low magnetic noise, which are significant factors limiting the sensitivity and accuracy of the measurements. However, the operating temperature of the inner shielding layer is around 80°C, and temperature has a significant impact on the magnetic noise of Fe-based nanocrystalline. To precisely analyze the magnetic noise of the Fe-based nanocrystalline in the SERF magnetometer, we first numerically simulate the 1K107 Fe-based nanocrystalline magnetic shielding barrel using the finite element method (FEM). Then, a variable-temperature dynamic Jiles-Atherton (VTDJA) model is proposed. The losses of 1K107 under various temperature are separated. The magnetic noise of 1K107 is computed using the Fluctuation-Dissipation theory. Finally, the magnetic noises of 1K107 at 25℃ and 80℃ are measured by setting up an experimental test system. Results show that the simulated deviation of the magnetic noise at 80°C and 25°C is 32 %, and the actual measured deviation is 48 %. The errors between simulated and measured magnetic noises at 25°C and 80°C are 5.29 % and 6.54 %, respectively. This study provides a novel method for the performance optimization of the SERF magnetometer.

Enhancement of Cobalt Bismuth Nano-Ferrite via Heat Treatment to be Applied in High-Frequency and Antimicrobial Applications

Cobalt bismuth nano-ferrite (Co/Bi) with the chemical formula CoBi0.02Fe1.98O4 was produced using a simple flash auto-combustion method at three different temperatures: as-prepared, 600°C, and 800°C. A single-phase spinel structure was confirmed using X-ray diffraction, and the nano-scale morphology was examined using AFM (atomic force microscopy). Magnetic measurements demonstrated that increasing the annealing temperature increased the saturation magnetization Ms by 1.3 times. However, the coercivity Hc changed from semi-hard ferrite (as-prepared sample) to soft ferrite (Co/Bi nano-ferrite at 800°C) and reduced 10.7 times that of as-prepared nanoparticles. Therefore, the 800°C Co/Bi nano-ferrite with a low coercive field is recommended for transformers, recording heads, inductor cores, magnetic shielding, and microwave devices. The as-prepared sample and that at 600°C displayed super-high microwave frequency (SHF) in the X band in high-frequency applications calculated from magnetic measurement. The 800°C sample also has an extremely high microwave frequency in the Ku band, which is utilized in radar and satellite communications. Antimicrobial characterization showed that raising the annealing temperature increased the effectiveness of the samples against tested microorganisms. Thus, the samples under investigation are highly suggested for ultra-high microwave frequency applications and biological antibacterial nanomaterials.

Influence of Al addition on the microstructure and properties of Fe25Co25Ni25(Si0.3B0.7)25 high entropy metallic glass

This research work was focused on the development of a new series of high entropy metallic glasses (HE-MGs) combined with higher thermal stability, acceptable soft magnetic property, microhardness and good corrosion resistance by adding various Al content (1–8 at.%) on the basis of Fe25Co25Ni25(Si0·3B0.7)25 high entropy metallic glass using single-roller melt-spinning approach. It is found that the proper addition of Al can efficiently improve the anti-corrosion performance of high entropy metallic glasses, in particular, the corrosion current density is decreased from 7.61 μA/cm2 and 9.26 μA/cm2 for the 1 at.% and 2 at.% Al-added alloys to 5.11 μA/cm2 for the 5 at.% Al-added alloy. However, the improvement of Al content could deteriorate the soft magnetic property and thermal stability of HE-MGs. The saturation magnetization flux density and onset crystallization temperature reduce from 0.85 T to 766.15 K for the 1 at.% Al-added alloy to 0.53 T and 736.75 K for the 8 at.% Al-added alloy. Besides, the Vickers’ microhardness of all investigated alloy ribbons can reach 1124 HV0.2 or above. Therefore, this kind of senary new-type HE-MGs can be used as a promising magnetic shielding metal material with high hardness, superior thermal stability and good anti-corrosion performance for the surface protection of key component in harsh marine corrosive environment.

Design and measurement of three-dimensional uniform-field coils based on swarm intelligence algorithms under ferromagnetic boundaries

Combination systems of high permeability magnetic shields and coils are widely used in fields such as the magnetic field standard metrology and the zero magnetic room construction. To solve the problem that the magnetic field of uniform-field coils under the ferromagnetic boundary of magnetic shields is difficult to design precisely and the uniformity is difficult to improve, three-dimensional uniform field coils are designed based on the magnetic field model of coils under the ferromagnetic boundary using the target-field method (TFM), and the weight coefficient vectors determining the coils’ structure are optimized using intelligent optimization algorithms, which improves the uniformity of the magnetic field in the target region by 2 orders of magnitude through whale optimization algorithm (WOA). Then, the radial WOA-TFMUFY coil and the axial WOA-TFMUFZ coil are designed considering sidewall optical holes, and their magnetic field distribution is analyzed and verified under different permeabilities and axial opening sizes of the shield. Compared to the traditional saddle coil and Lee-whiting coil, the maximum magnetic field non-uniformity in the target uniform field region is reduced by 82.2 % and 92.8 % for the WOA-TFMUFY coil and WOA-TFMUFZ coil. The maximum relative errors between the measured magnetic field generated by the designed coils and the finite element method (FEM) simulation results are no higher than 2.2%. This novel method can provide more precise and uniform magnetic field metrology standard elements.

Analysis and measurement of magnetic noise in multilayer magnetic shielding system combined with mu-metal and ferrite for atomic sensors

The multilayer magnetic shielding system is widely used in atomic sensors. However, for miniaturized atomic sensors with volume limitations, such as spin-exchange relaxation-free (SERF) gyroscopes, the remaining environmental magnetic interference and mu-metal magnetic noise will affect the sensitivity of atomic sensors. In this study, we establish a comprehensive magnetic noise calculation model for the magnetic shielding system of a SERF gyroscope, which considers the influence of the environmental magnetic noise on the magnetic shielding and the coupling effect between different layers. For suppressing magnetic noise of the magnetic shielding system, the property of different ferrites was measured and compared, then the particle swarm optimization is applied to design the magnetic shielding structure. Finally, the experimental device is established for measuring performances of the magnetic shielding system per and post optimization. By comparison, radial and axial magnetic noise post optimization are decreased by 37% and 22%, respectively.

ParaStell: parametric modeling and neutronics support for stellarator fusion power plants

The three-dimensional variation inherent to stellarator geometries and fusion sources motivates three-dimensional modeling to obtain accurate results from computational modeling in support of design and analysis of first wall, blanket, and shield (FWBS) systems. Manually constructing stellarator fusion power plant geometries in computer-aided design (CAD) and defining the corresponding fusion source can be cumbersome and challenging. The open-source parametric modeling toolset ParaStell has been developed to automate construction of such geometries in low-fidelity. Low-fidelity modeling is useful during the conceptual phase of engineering design as a means of rapidly exploring the design space of a given device. The modeling capability of ParaStell includes in-vessel components and magnets, for any given stellarator configuration, using a parametric definition and plasma equilibrium data. Furthermore, the toolset automates the generation of detailed, tetrahedral neutron source definitions and DAGMC geometries for use in neutronics modeling. ParaStell assists rapid design iteration, parametric study, and design optimization of stellarator fusion cores. As a demonstration of the design iteration capability, the effect of the three-dimensional parameter space on tritium breeding and magnet shielding is investigated, using the WISTELL-D configuration as a design basis. Blanket and shield thicknesses are varied in three dimensions, using the space available between the plasma edge and magnet coils as a constraint. The corresponding effects on tritium breeding ratio and magnet heating are tallied using the open-source Monte Carlo particle transport code OpenMC. The inclusion of additional and higher-fidelity modeling capabilities is planned for ParaStell’s future, as well as its implementation in machine-driven optimization.

Multisensor Magnetic Scanning Microscope for Remanent Magnetic Field Measurements.

Magnetic Scanning Microscopy (MSM) emerged with the aim of allowing the visualization of magnetic fields of a sample or material through scanning and proved particularly useful for geology, biomedicine, characterization of magnetic materials, and in the steel industry. In this regard, the reading system of an MSM was modified using a μ-metal magnetic shielding structure to analyze remanent fields. The MSM was adapted to perform readings using two different types of sensors. The sensitive area of the sensors was evaluated, and the HQ-0811 (AKM-Asahi KaseiTM Microdevices) and STJ-010 (Micro MagneticsTM) sensors were chosen, with the HQ-0811 standardized on Printed Circuit Boards (PCBs) to facilitate handling and increase the system's robustness. In the shielded chamber, two piezoelectric ANC-150 stepper motors (Attocube Systems) were used, arranged planarly, to allow the movement of the analyzed samples under the mounted sensors. To acquire data from the sensors, the Precision Current Source Model 6220 and the Nanovoltmeter Model 2182A (both from Keithley) were used, along with Keithley's Delta-Mode integrated system. To analyze the system's effectiveness, three distinct samples were analyzed for calibration, and a MATLAB program was written to analyze the images and extract the material's magnetization. Additionally, a rock sample from the Parnaíba Basin was mapped to demonstrate the system's capabilities.

Hybrid Active and Passive Cable Contour Shielding of Magnetic Fields of Double-Circuit Overhead Power Lines

The purpose of the work is to design a hybrid screen designed to reduce the level of the magnetic field generated by double-circuit overhead power lines, to increase the efficiency of shielding the original magnetic field in residential buildings, to the level of sanitary standards and to reduce the sensitivity of the system to changes in system parameters. To achieve this goal, the structure of a hybrid screen was determined, consisting of a double contour active and a cable contour passive part. The developed hybrid screen is characterized by increased efficiency in reducing the magnetic field of industrial frequency. Designing a hybrid screen comes down to solving a minimax vector optimization problem, in which the vector objective function is calculated based on solution to Maxwell's equations in a quasi-stationary approximation using the COMSOL Multiphysics software package. The solution to the minimax vector optimization problem is calculated based on multi-particle swarm optimization algorithms from Pareto-optimal solutions taking into account binary preference relations. During the design of the hybrid screen, the coordinates of the spatial location of the two compensation windings, as well as the magnitude of the currents and its phases in the windings of the active screen, were calculated. The important results are theoretical and experimental studies on the effectiveness of the designed hybrid magnetic field shield generated by double-circuit overhead power lines. The significance of the results obtained lies in the fact that practical recommendations are given for a reasonable choice of the spatial arrangement of two shielding windings of a robust system of hybrid shielding of the magnetic field generated by double-circuit overhead power lines.

Design of Magnetic Shield and System Test of Strong Static Magnetic Field for ITER Radial X-Ray Camera Electronics

Design of Magnetic Shield and System Test of Strong Static Magnetic Field for ITER Radial X-Ray Camera Electronics

Analysis of comprehensive magnetic shielding and optimization design of high-conductive layers in magnetic shielding devices for atomic magnetometer

Since the frequency of the biological magnetic field is DC to 500 Hz, it is important to improve the ability of the magnetic shielding device within this range for the measurement of the biological magnetic field and the reduction of the magnetic noise of the SERF magnetometer. At present, the optimization of AC magnetic field shielding in the frequency range of 0.01 to 500 Hz is rarely considered. To optimize the AC shielding factor, this paper analyzed the influence of the position and structure of the high-conductive layer in the magnetic shielding device and proposed an optimized structure of the high conductive layer. What’s more, the theoretical formula was improved by introducing frequency coefficients, solving the problem of significant differences between theoretical calculation results, FEM results and measurement results. Finally, it was verified by experiments that the optimized high-conductivity layer structure can improve the AC shielding factor of magnetic shielding device.

3D modeling of a double-driver ion source considering ion magnetization: an investigation of plasma symmetry modulation methods

A three-dimensional fluid model of a double-driver negative hydrogen ion source for China Fusion Engineering Test Reactor (CFETR) neutral beam injection is developed. In this model, the magnetic filter field is generated by 16 permanent magnets, which are surrounded by a soft iron. In order to accurately describe the transportation of charged species in the presence of strong magnetic field, both the electron magnetization and ion magnetization are taken into account, and the accuracy of the model has been proved by comparison with experimental data. By employing this model, the spatial distributions of the plasma parameters have been investigated, and three methods are proposed to optimize the symmetry at the bottom of the expansion region of a double-driver source. The results indicate that by adjusting the power of Driver I while keeping the power of Driver II constant, the symmetry of the electron density and negative hydrogen ion density could be improved. Furthermore, the inclusion of partition improves the symmetry of the electron temperature and density but has no impact on the regulation of the negative hydrogen ion density distribution. Finally, the application of magnetic shield can not only improve the symmetry of the electron density and negative hydrogen ion density, but also increase their densities at the bottom of the expansion region.

Enhancing electric vehicle charging performance through series-series topology resonance-coupled wireless power transfer.

The current electric vehicles (EVs) market is experiencing significant expansion, underscoring the need to address challenges associated with the limited driving range of EVs. A primary focus in this context is the improvement of the wireless charging process. To contribute to this research area, this study introduces a circular spiral coil design that incorporates transceiver coils. First, an in-depth analysis is conducted using Ansys Maxwell software to assess the effectiveness of the proposed solution through the magnetic field distribution, inductance properties, and mutual inductance between receiver and transmitter coils. In the next step, a direct shielding technique is applied, integrating a ferrite core bar to reduce power leakage and enhance power transmission efficiency. The ferrite magnetic shielding guides magnetic field lines, resulting in a significant reduction in flux leakage and improved power transmission. Lastly, a magnetic resonance series (SS) compensation wireless system is developed to achieve high coupling efficiency and superior performance. The system's effectiveness is evaluated through co-simulation using Ansys Simplorer software. The results confirm the effectiveness of the proposed solution, showing its ability to transmit 3.6 kilowatts with a success rate approaching 99%. This contribution significantly advances the development of wireless charging systems for electric vehicles, addressing concerns and promoting global adoption.

Theoretical Analysis of a Magnetic Shielding System Combining Active and Passive Modes.

Considering the magnetic shielding requirements of both geomagnetic field and 50 Hz power-line frequency in the complex working conditions of the power grid, an electromagnetic shielding system combining active and passive modes is proposed in this article. A three-dimensional Helmholtz coil with a magnetic shielding barrel nested inside is established by the COMSOL simulation tool, and the magnetic shielding efficiency of the system is analyzed. Comparing different materials, the simulation results indicate that permalloy alloy exhibits better shielding performance than pure iron and nickel materials. Additionally, the overall shielding efficiency of the shielding barrel increases linearly with the number of multiple layers. Under the combined active and passive electromagnetic shielding conditions, the system achieves a shielding efficiency of SE = 113.98 dB, demonstrating excellent performance in shielding both AC and DC interference magnetic fields. This study provides theoretical guidance for the construction of magnetic shielding systems in electromagnetic interference environment.

Study on the magnetic shielding properties of nanocrystalline strips under bending stress

The study of the magnetic properties of nanocrystalline materials under stress is of great significance for the construction of small and lightweight magnetic shielding rooms. Therefore, this paper investigates the effect of stress on the magnetic properties of nanocrystalline materials under the action of external bending stress. By comparing the test results of the soft magnetic measuring device with and without bending stress, it is found that the magnetic permeability (μ i) decreases by about 51.41% when the introduced bending stress σ is increased by about 5.96 × 107 pa, whereas the KuFe−Si (induced magnetic anisotropy constant) and Hk (field of magnetic anisotropy) increase by 5.30 × 102 J m–3 and 1.08 × 102 A m−1, respectively. The Jiles-Atherton (J-A) model considering the bending stress and radius of change correlation is established, and the typical parameters of the J-A model are fitted using the Gazelle Optimization Algorithm (GOA), and the RMSE (root mean square error) of all of them are less than 0.056 T. The magnetic domain density increased with the increase of bending stress, which verified the correlation between the J-A model parameters and the bending stress. Our results reveal that the nanocrystalline macroscopic and micromechanical magnetic properties can be effectively combined with the J-A model, which will provide a theoretical basis for the simulation study of the nanocrystalline magnetic shielding device in the actual stress situation.

From Stilbenes to carbo-Stilbenes: an Encouraging Prospect.

Beyond previously described carbo-naphthalene and carbo-biphenyl, a novel type of bis-carbo-benzenic molecules is envisaged from the stilbene parent. The synthesis, structure, spectroscopic and electrochemical properties of two such carbo-stilbenes are described at complementary experimental and computational DFT levels. In the selected targets, the bare skeletal carbo-mer of carbo-stilbene is decorated by 8 or 10 phenyl groups, 0 or 2 tert-butyl groups, and 2 n-octyl chains, the later substituents being introduced to compensate anticipated solubility issues. As in the parent stilbene series, isomers of the phenylated carbo-stilbenes are characterized. The cis- and trans-isomers are, however, formed in almost equal amounts and could not be separated by either chromatography or crystallization. Nevertheless, due to a slow interconversion at the NMR time scale (up to 55 °C) the 1H NMR signals of both isomers of the two carbo-stilbenes could be tentatively assigned. The calculated structure of the cis-isomer exhibits a helical shape, consistent with the observed magnetic shielding of phenyl p-CH nuclei residing inside the shielding cone of the facing C18 ring. The presence of the two isomers in solution also gives rise to quite broad UV-vis absorption spectra with main bands at ca 460, 560 and 710 nm, and a significant bathochromic shift for the decaphenylated carbo-stilbene vs the di-tert-butyl-octaphenylated counterpart. Square wave voltammograms do not show any resolution of the two isomers, giving a reversible reduction wave at -0.65 or -0.58 V/SCE, and an irreversible oxidation peak at 1.11 V/SCE, those values being classical for most carbo-benzene derivatives. Calculated NICS values (NICS(1)=-12.5±0.2 ppm) also indicate that the aromatic nature of the C18 rings is not markedly affected by the dialkynylbutatriene (DAB) connector between them.