E-field Research Articles

ETS-NOCV description of chemical bonding: from covalent bonds to non-covalent interactions

ContextThe interpretation of ETS-NOCV for typical covalent and dative-covalent chemical bonds is presented and compared with that for halogen bonds. Possible tuning of the strength of halogen bonding is considered, first by applying an electric field (modeled by the point charges or the electric field vector), and then by constructing a model transition-metal complex with enhanced strength of halogen bonding. For all the systems, the ETS-NOCV picture is supplemented by the analysis of the deformation in molecular electrostatic potential (ΔMEP). The results demonstrate important characteristic features of the analysis based on NOCV: (i) this approach is based on pairs of orbitals with antibonding and bonding character and, thus, allows us to “extract” the “diatomic-like” picture of chemical bonding; (ii) the NOCV-pair contributions to the deformation density often correspond to donation (AB) and back-donation (AB) of electron density between the fragments. The results for halogen bonding demonstrate that it is possible to tune their strength by an electric field in the molecular environment; the halogen-bond energy can reach the order of magnitude typical of dative-covalent bonds. However, the nature of halogen bonds still differs from that of dative-covalent interactions, as the accumulation of electron density between fragments is of significantly lower magnitude. The main effect of the electric field is an increase in the polarization of the fragments, which is clearly manifested by the deformation in the MEP.MethodsAll calculations were performed using the ADF/AMS package. The BLYP exchange–correlation functional was employed with Grimme’s dispersion correction (D3 version) and Becke-Johnson damping, using TZP basis sets. The deformation in the MEP was determined as ΔVr=VABr-VAr-VBr, with the same fragment definition as in the ETS-NOCV method.

Measurement-Based Neural Network Technique for Modeling the Low-Frequency Electric Field Radiated Behavior of Satellite Units

In this work, a machine learning technique employing a measurement-driven artificial neural network (ANN) architecture is proposed as a solution to the precise determination of the position and the moment of equivalent electric dipoles for unit characterization. These dipoles are used to match the generated electric field from various sources inside the spacecraft, during space exploration missions. Various methodologies for unit characterization have been proposed in the literature, the most common being the heuristic approaches, least squares variants, method of auxiliary sources, etc. Contrary to the previous time-consuming post-process methodologies, the proposed electric dipole neural network (EDMnet) can offer a real-time characterization of the measured unit (Device Under Test) after a proper training stage, especially as a fast pre-compliance method. The network uses the electric field vector, measured at 14 discrete locations, as input and reports the position and moment of the electric dipole that best matches the measured fields. In this work, various ANN architectures are tested and compared in order to select the optimal EDMnet parameters for accurate source identification. It is shown that the size of the artificial training data affects the performance of the network. The proposed EDMnet can provide accuracy in mm-scale, with respect to dipole positioning, greater than 99% in dipole moment prediction.

Precise beam control in optical phased arrays using the four steps rotating element electric field vector method

The integrated optical phase arrays (OPAs) possess the capability for rapid modulation and precise control of output beam deflection, making it widely applicable in fields such as three-dimensional terrain reconstruction, autonomous driving, and holographic imaging. However, the unknown initial phase introduced during the manufacturing and packaging processes of current OPAs results in low beam alignment quality and random output beam phases, significantly limiting the development and application of OPAs. To address these challenges, this paper proposes a precise control technology for OPA output beams, utilizing a beam calibration method we have developed, known as the Four Steps Rotating Element Electric Field Vector Method. This method enables rapid and accurate calibration, achieving precise phase control for each antenna on the OPA chip by calibrating the phase shift and controlling the voltage relationship. It overcomes the challenges of unknown phase distributions common in passive calibration methods, aligning the calibrated phase distribution more closely with theoretical expectations. The proposed method further enhances control over the OPA output beam. Based on this technology, we constructed an experimental platform to achieve a main lobe with a PSLR of 15.98 dB and successfully generated vortex beams using a 4×4 OPA. This innovation not only addresses the initial phase issues caused by manufacturing errors but also significantly enhances the precise control of OPA phases, expanding its applications in LiDAR systems.

Atomic-Level Electric Polarization in Entropy-Driven Perovskites for Boosting Dielectric Response.

Dielectric oxides with robust relaxation responsesare fundamental for electronic devices utilized in energy absorption, conversion, and storage. However, the structural origins governing the dielectric response remain elusive due to the involvement of atomically complex compositional and structural environments. Herein, configurational entropy is introduced as a regulatory factor to precisely control the structural heterogeneity in representative perovskite dielectric oxides. Through advanced structural and electric field visualization studies, a novel quantitative relationship is established between atomic-level structural disorder-induced electric field polarization and macroscopic dielectric properties. The results indicate that the degree of atomic delocalization in perovskite oxides exhibits a near-parabolic trend with increasing entropy, reaching a maximum in medium-entropy perovskite. Correspondingly, the atomic electric field vectors display significant asymmetrical distribution, thus greatly enhancing angstrom-scale electric field polarization. Then, it is experimentally proven that entropy-driven electric polarization can improve the dielectric relaxation behavior characterized by broader frequency and stronger intensity of electromagnetic energy absorption, with improvements of approximately 160% and 413% compared to structurally homogeneous control. This study unveils the quantitative correlation between angstrom-scale electric field polarization and dielectric response in perovskite oxides, offering a novel perspective for exploring the structure-propertyrelationship in dielectric materials.

Phased Array Antenna Calibration Based on Autocorrelation Algorithm

Phased Array Antenna Calibration Based on Autocorrelation Algorithm

Helical-photon-dressed states determining unidirectional π-electron rotations in aromatic ring molecules.

We theoretically demonstrated that helical-photon-dressed states determine the rotational directions of the π-electrons of aromatic ring molecules formed by a circularly polarized or an elliptically polarized laser. This theory was verified using a minimal three-electronic-state model under the frozen nuclei condition. The model consists of the ground state and either a doubly degenerate electronic excited state or two quasi-degenerate excited states. Three helical-photon-dressed states were derived by solving the time-dependent Schrödinger equation within the semi-classical treatment of light-molecule interactions and rotating wave approximation. The angular momenta of the two helical-photon-dressed states represent the classical rotational direction, and that of the remaining state represents the opposite rotation, that is, non-classical rotation. Classical rotation means that π-electrons have the same rotational direction as that of a given helical electric field vector and obeys the classical equations of motion. Non-classical rotation indicates that the rotational direction is opposite to that of the helical electric field vector. Non-classical rotation is forbidden in an aromatic ring molecule with high symmetry formed by a circularly polarized laser but is allowed in a low symmetric aromatic ring molecule. The sum of the angular momenta of the three dressed states is zero. This is called the sum law for the angular momentum components in this paper. Benzene (D6h) and toluene (CS) were adopted as typical aromatic ring molecules of high and low symmetries, respectively. Finally, considering the effects of nuclear vibrations in the adiabatic approximation, an expression for the π-electron angular momentum was derived and applied to toluene.

Pulsed and Polarized X‐Ray Emission From Neutron Star Surfaces

ABSTRACTThe intense magnetic fields of neutron stars naturally lead to strong anisotropy and polarization of radiation emanating from their surfaces, both being sensitive to the hot spot position on the surface. Accordingly, pulse phase‐resolved intensities and polarizations depend on the angle between the magnetic and spin axes and the observer's viewing direction. In this paper, results are presented from a Monte Carlo simulation of neutron star atmospheres that uses a complex electric field vector formalism to treat polarized radiative transfer due to magnetic Thomson scattering. General relativistic influences on the propagation of light from the stellar surface to a distant observer are taken into account. The paper outlines a range of theoretical predictions for pulse profiles at different X‐ray energies, focusing on magnetars and also neutron stars of lower magnetization. By comparing these models with observed intensity and polarization pulse profiles for the magnetar 1RXS J1708‐40, and the light curve for the pulsar PSR J0821‐4300, constraints on the stellar geometry angles and the size of putative polar cap hot spots are obtained.

A LiNbO3 Optical Sensor for Measurement of the 2-D Intensive Electric Field Vectors

A LiNbO₃ Optical Sensor for Measurement of the 2-D Intensive Electric Field Vectors

Effect of a longitudinal magnetic field on streamer propagation in air: Numerical simulation

Two-dimensional numerical simulation of the negative streamer propagation in external electric and magnetic fields is performed for the case when applied electric and magnetic field vectors are parallel to the symmetry axis of the problem. The calculations are performed for air (a mixture of 80% N2 and 20% O2) with a concentration of gas molecules equal to Loshmidt's number. It is shown that the presence of a longitudinal field leads to a noticeable increase in the streamer propagation velocity associated with a decrease in its radius, which agrees with the known analytical estimates.

Investigating instabilities in magnetized low-pressure capacitively coupled RF plasma using particle-in-cell (PIC) simulations

The effect of a uniform magnetic field on particle transport in low-pressure radio frequency (RF) capacitively coupled plasma (CCP) has been studied using a particle-in-cell model. Three distinct regimes of plasma behavior can be identified as a function of the magnetic field. In the first regime at low magnetic fields, asymmetric plasma profiles are observed within the CCP chamber due to the effect of E→×B→ drift. As the magnetic field increases, instabilities develop and form self-organized spoke-shaped structures that are distinctly seen within the bulk plasma closer to the sheath. In this second regime, the spoke-shaped coherent structures rotate inside the plasma chamber in the −E→×B→ direction, where E→ and B→ are the DC electric and magnetic field vectors, respectively, and the DC electric field exists in the sheath and pre-sheath regions. The spoke rotation frequency is in the megahertz range. As the magnetic field strength increases further, the rotating coherent spokes continue to exist near the sheath. The coherent structures are, however, accompanied by new small-scale incoherent structures originating and moving within the bulk plasma region away from the sheath. This is the third regime of plasma behavior. The threshold values of the magnetic field between these regimes were found not to vary with changing plasma reactor geometry (e.g., area ratio between ground and powered electrodes) or the use of an external capacitor between the RF-powered electrode and the RF source. The threshold values of the magnetic field between these regimes shift toward higher values with increasing gas pressure. Analysis of the results indicates that the rotating structures are due to the lower hybrid instability driven by density gradients and electron-neutral collisions. This paper provides guidance on the upper limit of the magnetic field for instability-free operation in low-pressure CCP-based semiconductor deposition and etch systems that use the external magnetic field for plasma uniformity control.

Investigation of Coupling Effect for Adjacent Orthopedic Implants on MRI Radio-Frequency Heating

This paper investigates the mechanism of radio-frequency (RF) heating that occurs when two adjacent orthopedic implants are present together under magnetic resonance imaging (MRI) at 1.5 Tesla and 3.0 Tesla. When a patient has multiple implants close to each other, interactions between the implants may increase RF heating. Typical generic interlocking plate and antibiotic nail implants are adopted as examples. To analyze the effect of adjacent implants, the amplitude and direction of incident and scattering vector electric fields at the hot spot position are calculated and extracted using numerical simulation based on Huygens principle. It is shown that a strong coupling effect occurs due to the existence of both the incident field and a strong scattering field. Huygens principle can be used to obtain the first and second order scattering fields generated between implants. If the first- and second-order electric field terms are summed within a certain region, the RF-induced heating of this dual-implant system increases.

Non-stationary 3D Perturbation Theory for Describing Nonlinear Interaction of Electric Field with Matter in Inhomogeneous Plasma with Current. Vysikaylo’s Electric Field Shock Waves and Plasma Nozzles

In our works we theoretically prove that the cumulation (self-focusing) of charged particles in a inhomogeneous plasma (with current) is a universal property of cumulative-dissipative structures with characteristic sizes from 10-15 to 1026 m. Electrical phenomena are observed in non-uniform atmospheres and ionospheres of all planets of the Solar System. In this paper, the most complete theory of perturbations to describe phenomena in gas discharge plasma is formulated and, based on this theory, the most complete classification of ambipolar transfer processes in plasma with current and the classification of non-uniform plasma parameter profiles are given. We compare our theoretical results with existing experiments and results obtained in other areas of the natural sciences. In this work, we theoretically (Part 6.1) and experimentally (Part 6.2) we prove that shock waves of electric fields are focusing shells for inhomogeneous plasma cumulative-dissipative positively charged 3D structures. In the Part 6.1 of this work, we provide detailed theoretical justifications for the possibility of the existence of (locally self-focusing by ambipolar drift) Vysikaylo’s electric field shock waves caused by ambipolar diffusion due to a violation of the electrical neutrality of the plasma (in the presence of an electric current). Due to the greater mobility of electrons (ions are more massive), a structure with a positive space charge is formed in the electric field shock waves that self-form in the plasma (with current). Unlike Mach’s shock waves, in closed Vysikaylo’s shock waves transverse electric fields are generated due to the space charge. This makes the problem (in the electric field shock wave region) three-dimensional (in particular, spherically or cylindrical symmetric in this region). In Part 6.1, we will limit ourselves to the study of stationary one-dimensional profiles: 1) parameters in shock waves of the electric field and 2) processes of ambipolar drift, leading to local cumulation of positive charge in the shock wave of the electric field. In Part 6.1, the author will limit himself to obvious remarks arising from the properties of three-dimensional structures with a positive space charge. Based on laboratory 3D experiments (Part 6.2) and theoretical studies of gas-discharge plasma, we prove that ambipolar drift caused by different dependences of the mobility of electrons and positive ions in a simple plasma (with one type of ions) determines the dynamic processes of cumulation of plasma structures – 4D plasmoids in plasma (with current). 4D plasma structures are non-stationary three-dimensional structures. The author draws attention to self-formation in plasma structures (plasmoids) of stationary Vysikaylo’s plasma nozzles - analogues of Laval’s nozzles. A comparison of theoretical 1D and experimental 3D observations of discharge glow (this corresponds to changes in the main parameters) in gas discharge tubes will be presented in Part 6.2. In these experiments, a homogeneous plasma in a gas discharge tube is locally disturbed by a beam of fast electrons. This leads to the self-formation: 1) of electric field shock waves (a layer of positive volume charge) stopped by gas pumping and 2) of transition 3D profiles and Vysikaylo’s plasma 3D nozzles already in a quasi-neutral inhomogeneous plasma. In this work, we were the first to theoretically and experimentally study the processes of nonlinear ambipolar transport caused by the violation of electrical neutrality and 3D interaction of electric fields with matter (charged particles) in an inhomogeneous plasma with current. For the first time it has been proven that the coefficients of ambipolar diffusion due to the violation of electroneutrality are vectors determined by the electric field vector.

Bilberry Extract in Macular Pigment Density Improvement

Macular Pigments (MPs), by absorbing potentially toxic short-wavelength (400–500 nm) visible light, provide protection against photo-chemical damage. A new method of MPs levels screening analyzes polarization-dependent absorption of blue light by MPs, which results in the entoptic phenomenon called Haidinger’s Brushes (HB). Subjects identify the direction of rotation of HB when presented with a circular stimulus illuminated with an even intensity of polarized white light in which the electric field vector was rotating either clockwise or anti-clockwise. The examination was performed at baseline and after 3 months of daily intake of 320 mg bilberry extract, from Vaccinium myrtillus L. and standardized to contain more than 36% of anthocyanins (anthocyanosides), in normal subjects and MPs improvement was recorded after 3 months of dietary supplements. The results suggest a challenging role of daily intake of 320 mg bilberry extract in macular pigment density improvement possibly due to a macular protection from oxidative damage by bilberry.

Simulation Study of Dynamic Rotation and Deformation for Plasmonic Electric Field-Skyrmions

The topological properties of optical skyrmions in confined electromagnetic fields are perfectly presented through spin vectors and electric-field vectors. However, currently, electric-field optical skyrmions in surface plasmon polaritons are mostly presented in the form of a Néel type. Most control strategies involve linear directional movement, and topological manipulation methods are monotonous. We specifically propose a multi-arc symmetric slit array, which generates skyrmions from the surface plasmon polariton (SPP) field under excitation of a linearly polarized Gaussian light-source array and exhibits strong dependence processes on the rotation, deformation, and phase distribution of the incident light source. We also discuss the independence and synthesis of deformation and rotation related to phase difference and positions of regulation, respectively, which provide the possibility for rich deformations under different rotation states. Our work extends new ideas for the dynamic control of plasmonic skyrmions, which is of great significance to fields such as spin photonics and nano-positioning.

Understanding Cyclotron Motion: A Visual Approach to Electron Dynamics in Electric and Magnetic Fields

Physics material is often material that is difficult for students to understand because of its abstract concepts, one of which is in the material of electric and magnetic fields that discuss the motion of cyclotrons in connecting theoretical concepts and practical applications. Cyclotron motion is accelerated by an electric field that is influenced by the Lorentz force on the combination of electric and magnetic fields. This paper is made with the aim to analyze and visualize the electric field and magnetic field around the cyclotron motion particles using Python animation. In this study, a helix-shaped trajectory is used to represent the movement of electron particles. The animation developed depicts the electric and magnetic field vectors moving around the helix trajectory. In running the particle trajectory animation, numerical equations are involved. The involved numerical equations are second-order ordinary differential equations. This research not only provides theoretical insights into the electrostatic and magnetostatic properties of electron particles but also provides effective visualizations for further education and research. The resulting animation facilitates to enhance the understanding of the concept of how electric and magnetic fields interact and move in the context of electron particles moving in a helix trajectory, opening up opportunities for further exploration in the development of knowledge related to cyclotron motion that is often difficult to understand only through theoretical approaches.

A decomposition of light’s spin angular momentum density

Light carries intrinsic spin angular momentum (SAM) when the electric or magnetic field vector rotates over time. A familiar vector equation calculates the direction of light’s SAM density using the right-hand rule with reference to the electric and magnetic polarisation ellipses. Using Maxwell’s equations, this vector equation can be decomposed into a sum of two distinct terms, akin to the well-known Poynting vector decomposition into orbital and spin currents. We present the first general study of this spin decomposition, showing that the two terms, which we call canonical and Poynting spin, are chiral analogies to the canonical and spin momenta of light in its interaction with matter. Like canonical momentum, canonical spin is directly measurable. Both canonical and Poynting spin incorporate spatial variation of the electric and magnetic fields and are influenced by optical vortices. The decomposition allows us to show that a linearly polarised vortex beam, which has no total SAM, can nevertheless exert longitudinal chiral pressure due to equal and opposite canonical and Poynting spins.

Observation of strong in-plane perpendicular electric field in a radio frequency plasma with a time-varying magnetic nozzle

The spatiotemporal evolution of the electron temperature and plasma potential in a 200-W radio frequency argon discharge with a time-varying (approximately 60 kHz) magnetic nozzle was measured. Unlike in conventional static magnetic nozzles, the two-dimensional profiles of the electron temperature and plasma potential changed in sync with the applied azimuthal electric field, not with the magnetic field. The temporally resolved electric field vectors demonstrated an enhancement of the perpendicular component, where the direction fairly matched that of electron Eθ×B drift, indicating a space charge separation. This observation suggests that the applied time-varying field actively enhanced cross field electron transport, resulting in a unique potential structure and charged particle acceleration.

Lignin-Derived Lightweight Carbon Aerogels for Tunable Epsilon-Negative Response.

Electromagnetic (EM) metamaterials have garnered considerable attention due to their capacity to achieve negative parameters, significantly influencing the integration of natural materials with artificially structural media. The emergence of carbon aerogels (CAs) offers an opportunity to create lightweight EM metamaterials, notable for their promising EM shielding or absorption effects. This paper introduces an efficient, low-cost method for fabricating CAs without requiring stringent drying conditions. By finely tuning the ZnCl2/lignin ratio, the porosity is controlled in CAs. This control leads to an epsilon-negative response in the radio-frequency region, driven by the intrinsic plasmonic state of the 3D carbon network, as opposed to traditional periodic building blocks. This approach yields a tunable and weakly epsilon-negative response, reaching an order of magnitude of -103 under MHz frequencies. Equivalent circuit analysis highlights the inductive characteristics of CAs, correlating their significant dielectric loss at low frequencies. Additionally, EM simulations are performed to evaluate the distribution of the electric field vector in epsilon-negative CAs, showcasing their potential for effective EM shielding. The lignin-derived, lightweight CAs with their tunable epsilon-negative response hold promise for pioneering new directions in EM metamaterials and broadening their application in diverse extreme conditions.

Highly integrable planar-structured printed circularly polarized antenna for emerging wideband internet of things applications in the millimeter-wave band

This paper proposes a numerically and experimentally validated printed wideband antenna with a planar geometry for Internet of Things (IoT) applications. This design tackles the challenges associated with deploying IoT sensors in remote areas or across extensive geographical regions. The proposed design exploits a coplanar-waveguide-fed modified microstrip line monopole for excitation of circularly polarized waves radiating in the broadside direction. The primary design is based on perturbations of the microstrip line protracted from a grounded coplanar waveguide. The capacitively coupled short rectangular stubs are periodically inserted alternately and excited asymmetrically on each side of the microstrip line parallel to the direction of the electric field vector. The sequential phase excitation of the periodic stubs generates a rectangular-cascaded electric field, which suppresses the stop band at the open end. As a result, the antenna radiates in the broadside direction. The impedance bandwidth of the antenna exceeds 8 GHz in the 28 GHz mm-wave band, i.e., it ranged from 25 to 33.5 GHz. Additionally, an axial ratio below 3 dB is achieved within the operating band from 26 to 33.5 GHz with the alterations of the surface current using straightforward topological adjustments of the physical parameters. The average in-band realized gain of the antenna is 10 dBic when measured in the broadside direction. These results indicate that the proposed design has the potential to improve the connectivity between IoT devices and the constantly varying orientation of satellites by mitigating the polarization mismatch.

Optimization of laser-driven quantum beam generation and the applications with artificial intelligence

We have investigated space and astrophysical phenomena in nonrelativistic laboratory plasmas with long high-power lasers, such as collisionless shocks and magnetic reconnections, and have been exploring relativistic regimes with intense short pulse lasers, such as energetic ion acceleration using large-area suspended graphene. Increasing the intensity and repetition rate of the intense lasers, we have to handle large amounts of data from the experiments as well as the control parameters of laser beamlines. Artificial intelligence (AI) such as machine learning and neural networks may play essential roles in optimizing the laser and target conditions for efficient laser ion acceleration. Implementing AI into the laser system in mind, as the first step, we are introducing machine learning in ion etch pit analyses detected on plastic nuclear track detectors. Convolutional neural networks allow us to analyze big ion etch pit data with high precision and recall. We introduce one of the applications of laser-driven ion beams using AI to reconstruct vector electric and magnetic fields in laser-produced turbulent plasmas in three dimensions.