Electromagnetic Field Research Articles

A Multi-Parameter Optimization Method for Electromagnetic Characteristics Fitting Based on Deep Learning

Electromagnetic technology is widely applied in numerous fields, and precise electromagnetic characteristic fitting technology has become a crucial part for enhancing system performance and optimizing design. However, it faces challenges such as high computational complexity and the difficulty in balancing the accuracy and generalization ability of the model. For example, the Radar Cross Section (RCS) distribution characteristics of a single corner reflector model or Luneberg lens provide a relatively stable RCS value within a certain airspace range, which to some extent reduces the difficulty of radar target detection and fails to truly evaluate the radar performance. This paper aims to propose an innovative multi-parameter optimization method for electromagnetic characteristic fitting based on deep learning. By selecting common targets such as reflectors and Luneberg lens reflectors as optimization variables, a deep neural network model is constructed and trained with a large amount of electromagnetic data to achieve high-precision fitting of the target electromagnetic characteristics. Meanwhile, an advanced genetic optimization algorithm is introduced to optimize the multiple parameters of the model to meet the error index requirements of radar target detection. In this paper, by combining specific optimization variables such as corner reflectors and Luneberg lenses with the deep learning model and genetic algorithm, the deficiencies of traditional methods in handling electromagnetic characteristic fitting are effectively addressed. The experimental results show that the 60° corner reflector successfully realizes the simulation of multiple peak characteristics of the target, and the Luneberg lens reflector achieves the simulation of a relatively small RCS average value with certain fluctuations in a large space range, which strongly proves that this method has significant advantages in improving the fitting accuracy and optimization efficiency, opening up new avenues for research and application in the electromagnetic field.

The Role of the Axes of the Three Metal Nano-ellipsoids of Size Constant in the Energy Absorption Rate Change in the Hybrid System

AbstractThis work discusses the three-dimensional hybrid system of three metal nano-ellipsoids and semiconductor quantum dot to obtain the energy absorption rate caused by the direct and indirect contribution of the interaction between the semiconductor quantum dot and the three metal nano-ellipsoids. We investigate the interaction between excitons and surface plasmons by applying three electromagnetic fields in the three-dimensional directions. We calculate the polarization of the three metal nano-ellipsoids to evaluate the energy absorption rate for all three metal nano-ellipsoids. The energy absorption rate of the semiconductor quantum dot via three electromagnetic fields in the three dimensions is studied. We demonstrated that although the size of the three metal nano-ellipsoids is equal, the axes of the three metal nano-ellipsoids can play a distinct role in influencing energy absorption. We also demonstrated the varying distances between the three metal nano-ellipsoids affect the energy absorption rate. We found the dielectric constant of the surrounding material and semiconductor quantum dot influence the energy absorption rate of the semiconductor quantum dot.

Self-organization of collisionless shocks: from a laminar profile to a rippled time-dependent structure

A collisionless shock structure results from the nonlinear interaction between charged particles and electromagnetic fields. Yet, a collisionless shock is globally governed by the mass, momentum and energy conservation requirements. A stable shock structure must ensure that the fluxes of the conserved quantities are constant on average, and, therefore, is determined by this necessity. Here, we study an observed high upstream temperature high Mach number shock and show that the conservation laws cannot be fulfilled unless the shock is spatially inhomogeneous along the shock front and time-dependent.

Systematic study on the influence of inductive chargers on active personal dosemeters

Electromagnetic compatibility testing plays an important role in the type testing of radiation protection dosemeters in view of technical developments and the associated increase in electromagnetic fields. Lately, the use of inductive charging devices has grown as a user-friendly type of charging mobile-phones. In this article, we investigate their impact on active personal dosemeters (APD). The measurements show a substantial additional dose reading of up to several tens of mSv when exposed to the field of an inductive charger for 20 s. According to the widely used Qi standard, the charging devices operate at frequencies of between 87 kHz and 205 kHz for power transfers between 5 W and 30 W. These parameters fall outside the scope of type-testing standards for APD. An update of the standards might therefore be necessary.

Electromagnetic Absorption Mechanism of TPMS‐Based Metastructures: Synergy Between Materials and Structures

Abstract3D metastructure absorbers have gained attention for their lightweight, load‐bearing capabilities, and superior electromagnetic wave absorption. However, the complex interplay between unit cell geometry, material properties, and electromagnetic response is not well understood, hindering the design of high‐performance devices. A multi‐scale model, validated is presented by simulations and experiments, that clarify the relationship between materials, structures, and electromagnetic behavior in 3D metastructures. By systematically investigating strut‐based and sheet‐based structures, volume fraction, unit size, crystal lattice orientation, and density gradient within TPMS‐based unit cells, it is revealed that unit geometry significantly influences electromagnetic field propagation and reflection loss. Specifically, under the same unit size, sheet‐based TPMS metastructures exhibit stronger reflectivity than strut‐based ones, while multilayer structures show the opposite trend. The direct correlation is also further confirmed between geometric symmetry and polarization insensitivity, with orthogonal isotropic superstructures displaying excellent polarization‐insensitive properties. This finding provides a new design principle for achieving robust, angle‐independent absorption in these materials. This work enhances understanding of the structure‐electromagnetic behavior interplay, guiding the design of next‐generation broadband, wide‐angle, and polarization‐insensitive devices.

Biaxial Gaussian Beams, Hermite–Gaussian Beams, and Laguerre–Gaussian Vortex Beams in Isotropy-Broken Materials

We have developed the paraxial approximation for electromagnetic fields in arbitrary isotropy-broken media in terms of the ray–wave tilt and the curvature of materials’ Fresnel wave surfaces. We have obtained solutions of the paraxial equation in the form of biaxial Gaussian beams, which is a novel class of electromagnetic field distributions in generic isotropy-broken materials. Such beams have been previously observed experimentally and numerically in hyperbolic metamaterials but have evaded theoretical analysis in the literature up to now. Biaxial Gaussian beams have two axes: one in the direction of the Abraham momentum, corresponding to the ray propagation, and another in the direction of the Minkowski momentum, corresponding to the wave propagation, in agreement with the recent theory of refraction, ray–wave tilt, and hidden momentum [Durach, 2024]. We show that the curvature of the wavefronts in the biaxial Gaussian beams correspond to the curvature of the Fresnel wave surface at the central wave vector of the beam. We obtain the higher-order modes of the biaxial beams, including the biaxial Hermite–Gaussian and Laguerre–Gaussian vortex beams, which opens avenues toward studies of the optical angular momentum (OAM) in isotropy-broken media, including generic anisotropic and bianisotropic materials.

Spectral characteristics of the digital filter for electromagnetic field decomposition in 3D MCSEM

Spectral characteristics of the digital filter for electromagnetic field decomposition in 3D MCSEM

Rotation of self-generated electromagnetic fields by the Nernst effect and Righi-Leduc flux during an intense laser interaction with targets

Abstract The effect of an external magnetic field on the evolution of the self-generated electromagnetic field during laser ablation is investigated by using the Vlasov-Fokker-Planck simulations. It is found that the self-generated field is rotated and distorted under an external magnetic field, and for highly magnetized plasma, the rotation of the electric field becomes stable after the laser ablation. The theoretical analysis indicates that the rotation and tortuosity are primarily attributed to the advection of the Nernst effect and the Righi-Leduc (RL) flux. The curl of the self-generated field increases with the Hall parameter χe and reaches a peak at χe = 0.075, then it decreases with the χe continuous increase. As the Hall parameter increases, the RL flux contributes more than 60% to the rotation of the electric field. Furthermore, the distortion of the electric field continues to rotate after the laser ablation due to the cross-gradient Nernst transport. These findings provide theoretical references for the evolution of the self-generated electromagnetic field in laser-driven magnetized plasmas.

Overview of High-Performance Timing and Position-Sensitive MCP Detectors Utilizing Secondary Electron Emission for Mass Measurements of Exotic Nuclei at Nuclear Physics Facilities

Timing and/or position-sensitive MCP detectors, which detect secondary electrons (SEs) emitted from a conversion foil during ion passage, are widely utilized in nuclear physics and nuclear astrophysics experiments. This review covers high-performance timing and/or position-sensitive MCP detectors that use SE emission for mass measurements of exotic nuclei at nuclear physics facilities, along with their applications in new measurement schemes. The design, principles, performance, and applications of these detectors with different arrangements of electromagnetic fields are summarized. To achieve high precision and accuracy in mass measurements of exotic nuclei using time-of-flight (TOF) and/or position (imaging) measurement methods, such as high-resolution beam-line magnetic-rigidity time-of-flight (Bρ-TOF) and in-ring isochronous mass spectrometry (IMS), foil-MCP detectors with high position and timing resolution have been introduced and simulated. Beyond TOF mass measurements, these new detector systems are also described for use in heavy ion beam trajectory monitoring and momentum measurements for both beam-line and in-ring applications. Additionally, the use of position-sensitive timing foil-MCP detectors for Penning trap mass spectrometers and multi-reflection time-of-flight (MR-TOF) mass spectrometers is proposed and discussed to improve efficiency and enhance precision.

Temperature anisotropy instabilities driven by intermittent velocity shears in the solar wind

Where and under what conditions the transfer of energy between electromagnetic fields and particles takes place in the solar wind remains an open question. We investigate the conditions that promote the growth of kinetic instabilities predicted by linear theory to infer how turbulence and temperature-anisotropy-driven instabilities are interrelated. Using a large dataset from Solar Orbiter, we introduce the radial rate of strain, a novel measure computed from single-spacecraft data, which we interpret as a proxy for the double-adiabatic strain rate. The solar wind exhibits high absolute values of the radial rate of strain at locations with large temperature anisotropy. We measure the kurtosis and skewness of the radial rate of strain from the statistical moments to show that it is non-Gaussian for unstable intervals and increasingly intermittent at smaller scales with a power-law scaling. We conclude that the velocity field fluctuations in the solar wind contribute to the presence of temperature anisotropy sufficient to create potentially unstable conditions.

JWST observations constrain the time evolution of fine structure constants and dark energy-electromagnetic coupling

Abstract It was hypothesized in the literature that some physical parameters may be time-evolving and the astrophysical data can serve as a probe. Recently, James Webb Space Telescope (JWST) have released its early observations. In this work, we select the JWST spectroscopic observations of the high redshift ($z>7.1$) galaxies with strong [\ion{O}{III}] ($\lambda=4959$\AA \,and $5007$\AA \,in the rest frame) emission lines to constraint the evolution of the fine structure constant ($\alpha$). With the spectra from two galaxies at redshifts of $7.19$ and $8.47$, the deviation of $\alpha$ to its fiducial value is found to be as small as $0.44^{+8.4+1.7}_{-8.3-1.7} \times 10^{-4}$ and $-10.0^{+18+1.5}_{-18-1.5} \times 10^{-4}$, respectively (the first error is statistical and the latter is systematic). The combination of our results with the previous data reveals that $\frac{1}{\alpha} \frac{d \alpha}{dt} = 0.30^{+4.5}_{-4.5} \times 10^{-17}~{\rm yr^{-1}}$. Clearly, there is no evidence for a cosmic evolution of $\alpha$. The prospect of further constraining the time evolution of $\alpha$ is also discussed. The scalar field of dark energy is hypothesized to drive the acceleration of the universe's expansion through an interaction with the electromagnetic field. By integrating the observational data of the fine-structure constant variation, $\frac{\Delta\alpha}{\alpha}(z)$, we have established a stringent upper limit on the coupling strength between dark energy and electromagnetism. Our analysis yields $\zeta \leq 3.92 \times 10^{-7}$ at the 95\% confidence level, representing the most stringent bound to date.

Design of a Multiband Antenna Using Auxiliary Classifier Wasserstein Generative Adversarial Network for IoT Applications

ABSTRACTThe rapid expansion of Internet of Things (IoT) applications presents unprecedented challenges for antenna design, demanding solutions that are versatile, efficient, and capable of operating across multiple frequency bands. This paper addresses these challenges through the development of a design of a multiband antenna using Auxiliary Classifier Wasserstein Generative Adversarial Network for IoT applications (DMA‐ACWGAN‐IoT). Here, the Auxiliary Classifier Wasserstein Generative Adversarial Network (ACWGAN) is employed to generate synthetic data representing electromagnetic field distributions and antenna characteristics across various frequencies. The proposed metamaterial‐based Multiple‐Input Multiple‐Output (MIMO) antenna contains four discrete elements, each provided by a micro strip feed. The structures overall width and length are 60 and 52 mm. The metamaterial is printed on a patch and dispersed from the fields with the most effective coupling. The proposed structures strong impedance bandwidth works at 8.3 GHz, 10.8 GHz, 12.3 GHz, 13.7 GHz, 16.1 GHz, and 18.1 GHz, fabricating the proposed antenna prototype using a substrate made of FR‐4 material. The proposed DMA‐ACWGAN‐IoT design provides 6.5 dB maximum gain and 25.40%, 21.60%, and 20.05% higher efficiency compared to existing dual band antenna design with resonance frequency prediction under machine learning models (DBA‐PRF‐ML), machine learning verification depending on a distinctive SWB multiple slotted four‐port high isolated MIMO antenna loaded with metasurface for the applications of IoT (SWB‐MIMO‐IOT‐ML), and dual‐band miniaturized composite right–left‐handed transmission line ZOR antenna along machine learning method for microwave communication (DB‐ZORA‐MC‐ML).

QED Effects on Kerr-Newman Black Hole Shadows

Abstract Incorporating first-order QED effects, we explore the shadows of Kerr-Newman black holes with a magnetic charge through the numerical backward ray-tracing method. Our investigation accounts for both the direct influence of the electromagnetic field on light rays and the distortion of the background spacetime metric due to QED corrections. We notice that the area of the shadow increases with the QED effect, mainly due to the fact that the photons move more slowly in the effective medium and become easier to be trapped by the black hole.

CTNI-27. SYSTEMIC DELIVERY OF LOW ENERGY RADIOFREQUENCY ELECTROMAGNETIC FIELDS FOR THE TREATMENT OF PATIENTS WITH PRIMARY BRAIN TUMORS

Abstract BACKGROUND Tumor Treating Fields plus maintenance temozolomide (mTMZ) showed a survival advantage in the first-line glioblastoma (GBM) treatment. The survival benefit remains limited in patients with unmethylated MGMT gene promoter. The AutEMsys device emits low-energy amplitude modulated systemic electromagnetic fields (EMF) at patient specific frequencies. It is an outpatient procedure that can be integrated with mTMZ. METHODS This study involved a prospective compassionate access program targeting adult GBM patients using an intrabuccal EMF exposure via AutEMsys in addition to chemoRT+mTMZ. The program explored the effects on survival and patients’ reported quality-of-life (QOL) by EORTC-QL-C30. Patients underwent a 90-minute session of EMF exposure therapy repeated every 2 weeks until progression, deterioration in QOL or death. All patients had pathological specimens for diagnosis, IDH mutation status through NGS techniques, and MGMT promoter region methylation status. RESULTS 31 participants were enrolled, including 29 with GBM and 2 with diffuse midline glioma. 14 patients (45%) received EMF+chemoRT followed by EMF+mTMZ and 17 patients (55%) received EMF+mTMZ (post chemoRT). Survival time was measured from the start of mTMZ to the date of the last follow-up. The median overall survival (mOS) for all 31 patients was 26.0 months (95% CI: 14.4 – 37.2 months). Specifically for 21 patients with unmethylated MGMT, the mOS was 25.0 months (95% CI: 15.9 – 34.1 months). Similarly, for the 28 patients with IDH wildtype status, the mOS remained 26.0 months (95% CI: 9.6 – 42.4 months). The addition of AutEMsys with chemoRT+mTMZ demonstrated an improved role functioning in 79% of patients with 25% of these with >10-point score. CONCLUSION The AutEMsys device has shown promising initial results when added to chemoRT+mTMZ treatment of GBM. These findings warrant further prospective investigation and validation in a multicenter clinical trial setting.

MORPHOFUNCTIONAL CHARACTERISTICS OF THE TESTES IN YOUNG SEXUALLY MATURE RATS FOLLOWING PRENATAL EXPOSURE TO LOW-LEVEL ELECTROMAGNETIC RADIATION

The aim of this study is to investigate the functional and morphological characteristics of the testes in young sexually mature rats exposed to low-intensity centimeter-range electromagnetic radiation during the intrauterine period (within the “mother-fetus” system). Materials and methods. Intrauterine exposure to electromagnetic radiation was simulated using a high-frequency generator G4-190-3/1, equipped with a P-6-23A radiating antenna. To evaluate the reproductive system, a morphological examination of the testes and measurement of blood testosterone levels were performed. Morphometric methods were employed to quantify histological findings. The area of Leydig cell nuclei was measured, and the optical density of stromal connective tissue was assessed using the PAS reaction. The proliferative activity of spermatogenic epithelium cells was determined through an immunohistochemical reaction to the Ki-67 antigen. Results. In this experiment, the consequences of intrauterine damage to the testicles of male offspring were observed. We can presume that there is not only intrauterine damage, which may undergo regeneration later in life, but also the formation of epigenetic changes of regulatory factors that affect the expression of genes determining the morphofunctional state of the spermatogenic epithelium. Epigenetic changes developed during intrauterine period can manifest throughout the offspring’s lifetime after birth. Conclusions. Functional and morphological changes were found in the testes of sexually mature young males, offspring of mothers exposed to low-intensity centimeter-level electromagnetic fields during pregnancy. Hypoplastic changes in the testicles, a decrease in the proliferative potential of the spermatogenic epithelium were revealed. Hormonal stimulation of spermatogenesis (hypertestosteronemia and an increase in the number of Leydig cells and the size of their nuclei) obviously have a compensatory nature. The obtained results provide the basis for large epidemiological studies with the involvement of a wide range of specialists in both medical and technical specialties.

Plasmonic gold-enhanced GaAs for femtosecond laser generation

Surface plasmon resonance (SPR) can significantly enhance the local electromagnetic fields, facilitating the interaction between light and matter at the nanoscale. However, its ultrafast photonics application in lasers remains unexplored, especially for femtosecond pulsed laser generation. In this work, we investigate the femtosecond pulse generation based on SPR-enhanced nonlinear absorption characteristics in GaAs for the first time, to the best of our knowledge. The gold nanoparticles (GNPs)+GaAs bilayer saturation absorber (SA) decorated on the tapered fiber generates a modulation depth of 2.02% and a saturable intensity of 3.13 MW/cm2. Stable mode-locked pulses can be obtained in an erbium-doped fiber cavity, as demonstrated here. The signal-to-noise ratio (SNR) of the pulses is 75 dB and the shortest pulse duration can reach 384 fs, highlighting the potential of the SPR effect in manufacturing ultrafast optical devices.

Comprehensive Analysis of Optical Resonances and Sensing Performance in Metasurfaces of Silicon Nanogap Unit

Metasurfaces composed of silicon nanogap units have a variety of optical resonances, including bound states in the continuum (BIC). We show comprehensive numerical results on metasurfaces of Si-nanogap units, analyze the optical resonances, and clarify optically prominent resonances as well as symmetry-forbidding resonances that are the BIC, based on the numerical analyses of optical spectra and resonant electromagnetic field distributions. Introducing asymmetry in the unit cell, the BIC become optically allowed, being identified as magnetic dipole, electric quadrupole, and magnetic quadrupole resonances. Moreover, the optical resonances are examined in terms of refractive index sensing performance. A pair of the resonances associated with electric field localization at the nanogap was found to be sensitive to the refractive index in contact with the metasurfaces. Consequently, the gap mode resonances are shown to be suitable for a wide range of refractive index sensing over 1.0–2.0.

Electromagnetic Modeling of Superconducting Bulks in Applied Time-Varying Magnetic Field

An integrodifferential model formulated in terms of the electric vector potential is developed for the 3D numerical modeling of the electromagnetic field in superconducting bulks, for AC losses evaluation. The Newton Raphson method is applied to accelerate the convergence. The model is validated on a benchmark. The comparison results show the accuracy of the model and its performances in terms of computation time compared to classical approaches.

An Electromagnetic Field Concentrator for Process Chambers

This paper describes selected results of the design and optimization of an electromagnetic field concentrator (MFC) for process chambers. On the basis of 2D/3D FE analysis, it was confirmed that the presented new structure for an electromagnetic field concentrator with three-phase windings and an additional DC central coil excites, in the working space of the device, a steady or time-varying magnetic field with adjustable peak value, pulsation amplitude and vector magnetic field orientation. The presented field concentrator can be used for process chambers carrying out chemical, biological, thermal and measurement processes, among others.

In Situ SERS Monitoring of Schiff Base Reactions via Nanoparticles on a Mirror Platform

Schiff base reactions are widely used in pharmacy, catalysis, and volatile aldehyde detection. However, common biomarker sensing methods struggle to monitor this reaction process precisely due to their sensitivity, their time-consuming nature, and complex substrates. Here, we introduce the Nanoparticle-on-Mirror structure for in situ monitoring this reaction process through the application of a Au nanoparticle-p-Aminothiophenol-Au thin-film platform by surface-enhanced Raman scattering (SERS). Owing to the exposure of -NH2 groups and the local ultra-strong electromagnetic field in the nanocavity, the Schiff base reactions process can be rapidly monitored within two minutes. Meanwhile, the monitoring platform can detect benzaldehyde molecules as low as 10−6 M, showing excellent SERS performance. Notably, the Au-nanoparticle-p-Aminothiophenol-Au thin-film platform exhibited anti-interference and specificity, being able to identify BA in the presence of interference. The use of the Au-nanoparticle-p-Aminothiophenol-Au thin-film platform provides a sensing method for Schiff base reactions with accuracy and simplicity of operation, achieving a balanced approach for low-cost and high-performance real-time monitoring, which is expected to be applied in various catalytic reaction process monitoring and catalyst design processes.