Magnetic Field Simulation Research Articles

Alternating-Current Copper Loss Reduction in a High-Frequency Transformer for Railways Using a Magnetic Tape

The effective downsizing of power supply for railway by increasing the drive frequency is essential considering the mounting space. However, an increase in the drive frequency increases the loss in switching and magnetic elements used for power supplies. In this study, we focus on reduction of alternating current (ac) copper loss due to the skin and proximity effects by attaching a magnetic material at appropriate positions on the outer circumference of the wire in high-frequency transformers for railway. In this article, we propose a simple method of attaching magnetic materials to a winding in high-frequency transformers using a magnetic tape. In the magnetic field simulation, we could reduce ac copper loss in the high-frequency transformer using magnetic tape. The ac resistance at 16 kHz was reduced by 12.5% for the actual measurement using an impedance analyzer. The temperature rise at the thermal saturation was reduced by 21.4% for the energization experiment with a current of 31.6 A and frequency of 16 kHz. Analysis and actual measurements revealed that employing a magnetic tape in a high-frequency transformer can reduce ac copper loss and heat generation.

Simulation on Influence of Wall Thickness and Probe Channel Numbers on the Examination Rate of Oxides Blocking Ratio in non-Ferromagnetic Tubes

Oxides accumulated in the inner bend of austenite heating tubes of super critical units may cause overheat and bursting. Traditional methods could not examine oxides blocking ratio. A magnetic field simulation of the boiler tube’s oxide skin blockage model has been set up in this paper. The influence of different wall thickness and different accumulation of oxide on the distribution of magnetic field was analyzed. It was demonstrated that the blockage oxide scale could be quantitatively measured by the amplitude and distribution of magnetic field.

Simulation of charged particle beam dynamics extracted from a plasma source

This paper presents the results of computer simulation in COMSOL Multiphysics of the hydrogen isotopes beam dynamics extracted from a plasma source of small linear accelerator. The beam energy was 100 keV. The simulation was carried out taking into account the charge exchange of ions on neutral gas molecules in the accelerating system. At the same time, the calculations took into account the process of secondary ion-electron emission from the surfaces of the accelerating system that are bombarded with both fast and slow ions. Consideration of this process made it possible to determine that the value of the electronic load is at least 50% of the main beam current of 100 μA. The inclusion in the trajectory analysis the magnetic field simulation in the secondary electrons generation area made it possible to determine the magnetic field strength, which effectively blocks secondary electrons on the target (3000 Gauss). Then it has been experimentally demonstrated that the discharge current in a plasma source automatically increases by 20% when using the magnetic suppression system on the target node (magnetic field strength is 3000 Gauss).

Distributed simulation and visualization of the ALICE detector magnetic field

The ALICE detector at CERN uses properties of the magnetic field acting on charged particles as part of the particle tracking and identification system – via measuring the strength of bending of charged particles in a magnetic field supplied by electromagnets. During the calibration of the detector the magnetic field was measured by the scientific team. The measurement points were then fitted using Chebyshev polynomials to create a field model. That model is used extensively in particle trajectory reconstruction, but for maximum compatibility it is handled by CPU-only software. We propose multiple approaches to the implementation of the model in a shader language, which allows it to run in a graphical GPU environment. This makes the model run more efficiently, as well as enables it to be used for field visualisation, which was not previously done for ALICE.

Investigation of Thermoplastic Polyurethane Finger Cushion with Magnetorheological Fluid for Soft-Rigid Gripper

This paper presents a study of penetrating a pin into a magnetorheological fluid (MR) cushion focused on the force measurement. The research is supported by detailed finite element analysis (FEA) of the magnetic field distributions in several magnetic field exciters applied to control rheological properties of the MR inside the cushion. The cushion is a part of the finger pad of the jaw soft-rigid gripper and was made of thermoplastic polyurethane (TPU) using 3D printing technology. For the pin-penetrating setup, the use of a holding electromagnet and a magnetic holder were considered and verified by simulation as well as experiment. In further simulation studies, two design solutions using permanent magnets as the source of the magnetic field in the cushion volume to control MR fluid viscosity were considered. The primary aim of the study was to analyze the potential of using an MR fluid in a cushion pad and to investigate the potential for changing its viscosity using different magnetic field sources. The analysis included magnetic field simulations and tests of pin penetration in the cushion as an imitation of object grasping. Thus, an innovative application of 3D printing and TPU to work with MR fluid is proposed.

Simulation research on magneto-acoustic concentration tomography of magnetic nanoparticles based on truncated singular value decomposition (TSVD).

The existing magneto-acoustic concentration tomography with magnetic induction (MACT-MI) inverse problem algorithm has some problems such as the singularity of reconstructed boundary and poor anti-noise performance, which make it difficult to be applied to recognition of early breast cancer tumor. Therefore, a system matrix linking the concentration distribution information of magnetic nanoparticles (MNPs) to the ultrasonic signal was built in this paper, and a truncated singular value decomposition (TSVD) based MNPS concentration reconstruction algorithm was proposed. Firstly, a simulation model was established. Secondly, the magnetic field and acoustic field simulation data were substituted into the inverse problem algorithm based on TSVD for concentration reconstruction. Finally, the effects of the number of singular values, SNR and radius of MNPs on the reconstruction results were studied. The simulation results show that, the inverse problem algorithm based on TSVD proposed in this paper can maximize the use of ultrasonic signals, and has a good reconstruction effect on 1mm small-radius MNPs, high resolution reconstructed images can also be obtained under the condition of low SNR, which can effectively promote the clinical application of this imaging method.

Application of numerical simulation of magnetic field for the analysis of dynamic characteristics of an electromagnetic motor

The paper presents an algorithm for finding the optimal ratios of design parameters of an electromagnetic motor using numerical simulation of the magnetic field. One of the stages of the algorithm is the calculation of the dynamic characteristics of the electromagnetic motor using numerical simulation of the magnetic field. The main problem of the ongoing research of the cylindrical linear motor is the increase of its power and energy characteristics. The solution of the problem is directly related to the study of the influence of the mode and design parameters of the electromagnetic motor on the output operating characteristics. The dependencies obtained by means of numerical simulation make it possible to give a qualitative and quantitative evaluation of the influence of design parameters on the operating characteristics of the motor and confirm the results obtained by using physical models. The proposed algorithm makes it possible to obtain the optimal design of an electromagnetic motor and to reduce the time of its development.

Research on the Effect of Core Joints on Transformer Noise

In order to study the effect of different joint types on the core noise of transformer, this article proposes a method based on the equivalent magnetostriction properties of the core joints. First, the 2-D magnetic field simulation of the core model with joints is performed to obtain the flux density distribution, by which the equivalent magnetization and magnetostriction characteristics of the joint are calculated. Then, core joints are defined by a new material with equivalent properties to simulate the magnetic field of the 3-D core models, and the magnetic-force–acoustic coupling analysis is performed by the finite element method to calculate the noise of the models. Finally, the effectiveness of the calculation method is verified by noise test. The results show that the simulation is consistent with the test. This article provides a new method for improving the accuracy of transformer core noise prediction further.

Updated magnetized transport coefficients: impact on laser-plasmas with self-generated or applied magnetic fields

Errors in the Epperlein and Haines (1986 Phys. Fluids) transport coefficients were recently found at low electron magnetizations, with new magnetic transport coefficients proposed simultaneously by two teams (Sadler et al 2021 Phys. Rev. Lett. and Davies et al 2021 Phys. Plasmas); these two separate sets of updated coefficients are shown in this paper to be in agreement. The importance of these new coefficients in laser-plasmas with either self-generated or applied magnetic fields is demonstrated. When an external magnetic field is applied, the cross-gradient-Nernst term twists the field structure; this twisting is reduced by the new coefficients in the low magnetization regime. For plasmas where only self-generated magnetic fields are present, the new coefficients are found to result in the magnetic field moving with the Righi–Leduc heat-flow, enhancing the impact of MHD. Simulations of Biermann battery magnetic fields around ICF hot-spot perturbations are presented, with cross-gradient-Nernst transport increasing spike penetration.

2D MHD simulation of spontaneous magnetic fields generated during interaction of 1315.2-nm laser radiation with copper slabs at 1016 W/cm2

Multidimensional modeling of phenomena and processes occurring during the expansion of the laser-produced plasma for different irradiation conditions related to both the laser beam parameters and the target constructions is a very complex issue, especially when modeling requires consideration of kinetic processes associated with the development of various types of microscopic instability. Multidimensional PIC codes create such a possibility, but their use is limited to modeling phenomena even in a very narrow timescale due to the limited computational capabilities of current supercomputers. For this reason, the paper attempts to interpret the results of the spontaneous magnetic field (SMF) measurements obtained during the PALS (Prague Asterix Laser System) experiment [Pisarczyk et al., AIP Adv. 10, 115201 (2020); Pisarczyk et al., Phys. Plasmas 22, 102706 (2015)] based on the 2D magneto-hydrodynamic (MHD) model [Jach et al., Computer Modeling of Dynamic Interaction of Bodies by Free Point Method (PWN, Warsaw, 2011)]. The MHD equations were used with included arbitrary (i) current of hot electrons treating it as an additional external current and (ii) ion-sound instability responsible for the increase in anomalous resistance in areas with high temperature and low-density plasma. The spatial distribution of magnetic fields and current density obtained from 2D modeling are in acceptable agreement with the experimental results [Pisarczyk et al., Plasma Phys. Controlled Fusion 62, 115020 (2020); Zaraś-Szydłowska et al., AIP Adv. 10, 115201 (2020); Pisarczyk et al., Phys. Plasmas 22, 102706 (2015)]. The inclusion of temporal changes in anomalous resistance in modeling allowed us to explain the persistence of high SMF amplitude at the level of several megagauss after the laser pulse ended due to the effect of magnetic field freezing.

Design and testing of a conventional clutch filled with magnetorheological fluid activated by a flexible permanent magnet at low compressive load: Numerical simulation and experimental study

Abstract In this research article, the working of conventional clutch (CC) filled with magnetorheological (MR) fluid was tested at low compressive load. The flexible permanent magnetic sheet (FMS) controlled the chain strength of MR fluid. A single clutch plate based on FMS was fabricated and tested on the developed test rig. The characteristics of the developed single plate MR clutch (SPMRC) were found by the testing and mathematical calculations. Magnetic circuit analysis presents the magnetic field distribution in the developed MR clutch. The mathematical expression for the torque transmission due to shear and compression is presented. COMSOL Multiphysics 5.3a software is used for the magnetic field simulation at different loading conditions. The temperature distribution in the developed clutch is simulated and experimented. It is observed from the results that the input shaft oscillation in the reduces more during disengagement in the SPMRC than the CC.

Phase-field modeling of magnetic field-induced grain growth in polycrystalline metals

A constitutive model for diffuse interface description of magnetic field-induced grain boundary migration in polycrystalline metals is developed based on the laws of thermodynamics. Within this phase field modeling framework, simultaneous minimization of the total grain boundary energy and the stored magnetic energy within grains provides the driving force for grain growth in a polycrystal material exposure to a magnetic field. Using the available experimental data, phase field simulations of magnetic field induced grain growth in bicrystalline zinc and polycrystalline titanium with two-dimensional columnar microstructure are performed and the model is validated by demonstrating a qualitative and quantitative match with experimental data. Using the validated constitutive model, the effects of magnetic field intensity and direction on evolution of microstructure and polycrystalline texture in titanium are investigated. Quantitative simulation results show that under certain magnetic field directions and sufficient magnetic field intensity, the magnetic energy minimizing driving force can overcome the curvature driving force and cause texture evolution towards less magnetic energy grain orientations during annealing. However, magnetic fields with insufficient intensity or improper direction have negligible effect on grain coarsening by nearly normal grain growth. The desired magnetic field direction and intensity are quantitatively presented for cold-rolled and annealed sheet titanium samples.

Central Bulge Ferrite Core for Efficient Wireless Power Transfer

To improve the efficiency of the wireless power transfer (WPT) system without increasing the system size, a central bulge ferrite core with a novel configuration is proposed. The mutual inductance between magnetic coupling structures is able to increase obviously, which is approved by eigenfunction expansion method. In this paper, the mathematical models of the planar core and the central bulge core are established, respectively, as two types of the mutual inductance are calculated in same condition. The structure parameters of the central bulge ferrite core are further optimized by Maxwell magnetic field simulation. Experiments are conducted to compare the WPT efficiency of two types of ferrite cores in improving the efficiency of WPT system, in which the influence of transmission distance, lateral misalignment, and load variation are taken into account. The results show that central bulge ferrite core has better performance in WPT efficiency than the planar one, even in the case of long power transfer distance and lateral misalignment.

Evolution of field line helicity in magnetic relaxation

Plasma relaxation in the presence of an initially braided magnetic field can lead to self-organization into relaxed states that retain non-trivial magnetic structure. These relaxed states may be in conflict with the linear force-free fields predicted by the classical Taylor theory, and remain to be fully understood. Here, we study how the individual field line helicities evolve during such a relaxation, and show that they provide new insights into the relaxation process. The line helicities are computed for numerical resistive-magnetohydrodynamic simulations of a relaxing braided magnetic field with line-tied boundary conditions, where the relaxed state is known to be non-Taylor. First, our computations confirm recent analytical predictions that line helicity will be predominantly redistributed within the domain, rather than annihilated. Second, we show that self-organization into a relaxed state with two discrete flux tubes may be predicted from the initial line helicity distribution. Third, for this set of line-tied simulations we observe that the sub-structure within each of the final tubes is a state of uniform line helicity. This uniformization of line helicity is consistent with Taylor theory applied to each tube individually. However, it is striking that the line helicity becomes significantly more uniform than the force-free parameter.

Fractional derivative resolution of the anomalous magnetic field diffusion through a ferromagnetic steel rod: Application to eddy current testing

Electromagnetic evaluations are performed daily by steel manufacturers and steel user companies. Among different methods, Eddy Current Testing (ECT) is routinely used. It is versatile, simple, and conveys rich information. ECT evaluations on steel specimens remain complex to interpret quantitatively. Most steels are ferromagnetic and exhibit high nonlinear magnetic behaviors. Such nonlinearities are an issue when it comes to signal analysis and interpretation. The magnetic field diffusion in a steel rod is highly frequency-dependent. It is the direct consequence of the Eddy current generation. If the rod is ferromagnetic, the unstable distribution of the magnetic domains interacts with the macroscopic Eddy current circulation and perturbs the magnetic field diffusion, which becomes anomalous. Fractional derivative diffusion equations are appropriate tools for the simulation of these phenomena. The fractional order acts as an adjustment parameter that provides flexibility in the simulation method. In this study, a 2D fractional diffusion equation has been solved by using finite differences in polar coordinates to anticipate the magnetic field diffusion and the ECT measurement in a steel rod specimen. Defects have been simulated through local variations of the physical properties. Good simulation results have been obtained and validate the fractional diffusion equation as an efficient method for the simulation of the anomalous diffusion magnetic field and the interpretation of ECT measurements.

Projectile wireless setting and Mechanical testing technology

This paper discusses the mechanical testing technology used in the wireless setting system of projectile, mainly including sensor, signal processing, system analysis, error analysis and data processing theory. The circuit simulation and system analysis are carried out by using Multisum, and the magnetic field simulation is carried out by using CST. The wireless setting scheme based on electromagnetic induction is designed, and the scheme is analyzed and improved. Finally, the data of range and firing angle of the projectile in high-speed motion can be set quickly.

Fully developed MHD mixed convective flow through a composite system in a vertical channel

A mixed convective momentum and heat transfer in a composite system, consisting of electrically conducting fluid and saturated porous medium in a vertical channel, have been studied. The flow, subjected to a linearly varying space dependent wall temperature engenders a convection current in the flow domain. The present study accounts for the effects of viscosities, and electrical conductivities of both the regions. The Brinkman model has been used to model the flow through porous region. The novel results of the analysis are: the simulation of external magnetic field (control input) in porous region affects momentum transport in both the regions; the amount of resistivity developed in primary velocity due to application of magnetic field can be experienced in the clear-fluid region by applying nearly 50 percent less magnetic field strength in conjunction with requisite porosity of the saturated porous medium; porous matrix is having higher thermal diffusivity than clear fluid provided bounding surfaces are of the same material.

FDTD Simulation of Magnetic Field Distribution in Normal and Blood Cancer for Treatment

Non-invasive cancer treatment has the potential to eliminate infection and scar formation associated with surgery to minimize side effects. Light stimulation can use for treatment to increase efficiency, reduce treatment costs, eliminate infection, etc. Magnetic fields can improve blood circulation in tissues and stimulate the body’s metabolism. The magnetic field can induce joule heating and expand the blood vessels of cancerous tumors. These blood vessels increase the possibility of excess oxygen to enter the tumor creating obstacles to the survival of oxygen-rich cancers. In this study, we investigate finite difference times domain (FTDT) simulation of magnetic field in normal and blood cancer. The low frequency with range 10-106 is used in this study. The maximum magnetic field for normal blood and CLL1 is 400 nm and 250 nm in 125 cm electrode size. While for 50 nm electrode size, the maximum magnetic field in normal blood and CLL 1 is 400 nm and 300 nm. But there The maximum magnetic field for normal blood and CLL1 is 400 nm and 250 nm in 125 cm electrode size. While for 50 nm electrode size, the maximum magnetic field in normal blood and CLL 1 is 400 nm and 300 nm. But there is no peak for blood cancer in final stage CLL2.

Measurement and Simulation of the Near Magnetic Field Radiated by Integrated Magnetic Inductors

Measurement and Simulation of the Near Magnetic Field Radiated by Integrated Magnetic Inductors

Design and modeling of intelligent shock isolation bearing based on negative stiffness platform

In this paper, an intelligent shock isolation bearing based on the negative stiffness platform (SIBP) is designed, manufactured, and modeled. The addition of the negative stiffness platform to the SIBP can further reduce the natural frequency of the structure and enable the isolator to a broader range of isolation frequencies. It is noteworthy that the stiffness of the magnetorheological elastomer (MRE) limit layer can be adjusted to provide controllable seismic resistance and to achieve isolation and vibration reduction under various seismic conditions, such as small and large displacements. Through the theoretical analysis and magnetic field simulation of the SIBP’s damping force, the structure of the SIBP is designed and established. Then, the MRE for the SIBP is prepared. The shear storage modulus and damping factor of MRE with different strains are tested and analyzed. A novel dynamics model is established to model the displacement–force hysteretic curve of the SIBP under small displacement and large displacement input. The experiment results show that the theoretical calculation results are in good agreement with the actual shock isolation bearing, and the proposed model can accurately describe the dynamic characteristics of the SIBP, which provides the design basis for the application of the SIBP in active control.