Variation Of Electric Field Research Articles

Investigation of sheath structure in surface flashover induced by high-power microwave

Flashover is a major limiting factor for the transmission and miniaturization of high-power microwave (HPM) devices. We conducted a study to investigate the developmental process of surface flashover on HPM dielectric windows through particle-in-cell-Monte Carlo collision simulations. A one-dimensional spatial distribution and three-dimensional velocity distribution model is established, encompassing the entire process of surface flashover, which includes electrode field emission, single-surface multipactor, outgassing, and gas breakdown. The nonuniform mesh generation method is employed to enhance the simulation accuracy. The growth rates of electron and ion densities increase as gas pressure rises. Additionally, the discharge transitions gradually from multipactor to gas ionization dominance. Notably, a space-charge-limited (SCL)-like sheath occasionally forms during an rf cycle near the surface under intermediate background pressure (∼0.05 Torr). The SCL-like sheath cannot exist stably. Instead, it periodically disappears and appears as the rf electric field changes. The underlying physics are explained by the variations of the rf electric field, which lead to the variations in the surface charge density, thereby affecting the normal electric field. The normal electric field interacts with the spatial distribution of charged particles, ultimately leading to the formation of the SCL-like sheath. This work may facilitate a comprehensive understanding of the developmental processes of surface flashover.

Electrostatic discharge mechanisms and dynamic characteristics of different polarity powders in the Silo

Electrostatic discharge in powder silos poses a significant safety hazard due to the risk of fire or explosion. However, the underlying discharge mechanisms are not fully understood. This study aims to improve the comprehension of electrostatic discharge dynamics and mechanisms by introducing a fluid discharge model for charged powder silos. The model validation is carried out by examining discharge patterns and electric field variations. The investigation of the electrostatic field and potential distribution prior to discharge helps to comprehend the discharge conditions. The discharge modes and evolution laws of different polarity powders are explored to reveal disparities in discharge phenomena. These disparities are further scrutinized in relation to electron density, space charge, electric field, and potential. To elucidate the discharge mechanism, the electric field distortion caused by space charge, electron existence time, and migration law are analyzed. The electrostatic and diffusion effects are the main reasons for the discharge differences.

Ultra-sensitive current bistability and light switching in a resonant tunneling superlattice transistor

Bistability in the current–voltage characteristics of semiconductor superlattices and quantum cascade laser structures has the potential for wide-ranging applications, particularly in sensing systems. However, the interdependency of applied bias and current injection in conventional two-terminal structures has led to complications in analysis and rendered the bistability phenomenon difficult to implement in practical applications. Here, we report a new kind of electronic bistability coupled to optical switching in a resonant tunneling bipolar superlattice transistor. This bistability manifests as sharp discontinuities in the collector current with extremely small variations of the applied voltage, which arise from unstable tunneling transmission across the hetero-barrier between the two-dimensional electron gas (2DEG) at the edge of the transistor base and the collector superlattice structure. The electronic transitions between high and low quantum mechanical transmissions are demonstrated to be caused by self-consistent variations of the internal electric field at the heterointerface between the 2DEG and the superlattice. They are also present in the base current of the three-terminal device and result in sharp switching of near-infrared spontaneous light emission output from an interband radiative recombination process with a peak emission wavelength of 1.58 μm. A comprehensive quantum mechanical theoretical model accounting for the self-consistent bistable tunneling transmission is in quantitative agreement with the experimental data. The measured peak transconductance sensitivity value of 6000 mS can be used in the highly sensitive detector and non-linear device applications.

Enhanced energy storage performance in Bi4Ti3O12 thin films with oxygen depletion layers

The imprint effect in ferroelectric materials can significantly enhance the performance of energy storage devices. Bi4Ti3O12 (BTO) and oxygen-deficient Bi4Ti3O11.2 (DBTO) thin films were deposited on single-crystal Nb-doped SrTiO3 substrates using pulsed laser deposition. In stark contrast, multilayer DBTO/BTO thin films incorporating an oxygen-deficient layer were also fabricated, with the DBTO layers having thicknesses of 5 nm and 10 nm, respectively. Both BTO and DBTO thin films exhibited epitaxial growth and c-axis-oriented crystallinity. Regarding ferroelectric properties, DBTO/BTO capacitors with an oxygen-deficient layer demonstrated a pronounced imprint effect in their ferroelectric hysteresis loops, compared to the BTO and DBTO capacitors. This effect was particularly noticeable in the DBTO/BTO capacitor with a 10 nm oxygen-deficient layer, as opposed to the thin film with a 5 nm oxygen-deficient layer. We suggest that the imprint effect can be attributed to localized electric field variations and imbalances in charge transport at the interface between the oxygen-depleted layer and the remaining thin film. Consequently, the imprint effect observed in the DBTO/BTO capacitors contributed to an enhancement in energy storage density and efficiency, compared to BTO and DBTO capacitors. This study demonstrates the potential of multilayer DBTO/BTO thin films in advancing capacitive energy storage systems.

Identification of cloud-to-ground lightning and intra-cloud lightning based on their radiated electric field signatures using different types of neural networks and machine learning classifiers

The scope of this paper is to test the efficiency of three different neural networks in the area of cloud-to-ground/intra-cloud lightning classification using a not very large data set of electric field data. Effective neural network learning verified for a small lightning event dataset but with whole 2-seconds particular record length is an important feature of fast and efficient procedures implemented into lightning location systems among which discrimination between cloud-to-ground and intra-cloud lightning is one of the most important task. Measurement data obtained at the Lightning Observatory in Rzeszow were used for the analysis. About 100 extremely low/medium frequency bandwidth electric field of cloud-to ground lightning registrations and the same number of intra-cloud lightning events were taken into account. During the study 81% of those registrations were dedicated for learning of neural networks while the remaining 19% were put into the testing set. All data were preselected manually with consideration of the electric field variation and information from the lightning location system database. Lightning events were selected uniformly with the well-pronounced presence of their basic components and reported distance to the registration station which ensured a wide variation of expected lightning electric field signatures. The multilayer perceptron neural network, the radial basis function neural network and the convolutional neural network were tested and compared in different configurations while distinguishing lightning. The results were compared with other conventional classification approaches, such as traditional machine learning methods as well as one a little more contemporary architecture, the long short-term memory neural network. The multilayer perceptron neural network achieved the best detection accuracy overall. Presented research is an extension of lightning identification studies available so far mainly based on the convolutional neural network by the results achieved using the multilayer perceptron neural network, the radial basis function neural network, the long short-term memory neural network and several machine learning-based classification methods.

Assessment of Triboelectric Nanogenerators for Electric Field Energy Harvesting.

Electric-field energy harvesters (EFEHs) have emerged as a promising technology for harnessing the electric field surrounding energized environments. Current research indicates that EFEHs are closely associated with Tribo-Electric Nano-Generators (TENGs). However, the performance of TENGs in energized environments remains unclear. This work aims to evaluate the performance of TENGs in electric-field energy harvesting applications. For this purpose, TENGs of different sizes, operating in single-electrode mode were conceptualized, assembled, and experimentally tested. Each TENG was mounted on a 1.5 HP single-phase induction motor, operating at nominal parameters of 8 A, 230 V, and 50 Hz. In addition, the contact layer was mounted on a linear motor to control kinematic stimuli. The TENGs successfully induced electric fields and provided satisfactory performance to collect electrostatic charges in fairly variable electric fields. Experimental findings disclosed an approximate increase in energy collection ranging from 1.51% to 10.49% when utilizing TENGs compared to simple EFEHs. The observed correlation between power density and electric field highlights TENGs as a more efficient energy source in electrified environments compared to EFEHs, thereby contributing to the ongoing research objectives of the authors.

A microdosimetry analysis of reversible electroporation in scattered, overlapping, and cancerous cervical cells

We present a numerical method for studying reversible electroporation on normal and cancerous cervical cells. This microdosimetry analysis builds on a unique approach for extracting contours of free and overlapping cervical cells in the cluster from the Extended Depth of Field (EDF) images. The algorithm used for extracting the contours is a joint optimization of multiple-level set function along with the Gaussian mixture model and Maximally Stable Extremal Regions. These contours are then exported to a multi-physics domain solver, where a variable frequency pulsed electric field is applied. The trans-Membrane voltage (TMV) developed across the cell membrane is computed using the Maxwell equation coupled with a statistical approach, employing the asymptotic Smoluchowski equation. The numerical model was validated by successful replication of existing experimental configurations that employed low-frequency uni-polar pulses on the overlapping cells to obtain reversible electroporation, wherein, several overlapping clumps of cervical cells were targeted. For high-frequency calculation, a combination of normal and cancerous cells is introduced to the computational domain. The cells are assumed to be dispersive and the Debye dispersion equation is used for further calculations. We also present the resulting strength-duration relationship for achieving the threshold value of electroporation between the normal and cancerous cervical cells due to their size and conductivity differences. The dye uptake modulation during the high-frequency electric field electroporation is further advocated by a mathematical model.

Multi-mode resonance of bound states in the continuum in dielectric metasurfaces

Bound states in the continuum (BIC) represent distinct non-radiative states endowed with infinite lifetime and vanishing resonance linewidth. Introducing asymmetric perturbation to the system can convert true BICs into high quality leaky modes which is useful in many photonic applications. Previously, such perturbation and resonance of interest is only limited to a single factor. However, different perturbations by unit cell gap, geometry and rotation angle result distinctive resonance modes. The combination of two perturbation factors can excite multi-mode resonance contributed from each asymmetric factor which coexist simultaneously; thus, the number of reflectance peaks can be controlled. In addition, we have carefully analyzed the electric field variations under different perturbation factors, followed by a multipolar decomposition of resonances to reveal underlying mechanisms of distinct resonance modes. Through simulations, we find that the introduction of multiple asymmetric perturbations also influences the metasurface sensitivity in refractive index sensing and compare the performance of different resonance modes. These observations provide structural design insights for achieving high quality resonance with multiple modes and ultra-sensitive sensing.

Time-domain electric field analysis of few-cycle pulse damage behavior in ultra-broadband chirped mirrors

The laser-induced damage resistance performance of ultra-broadband chirped mirrors (UBCM) is a critical factor influencing the generation of petawatt or exawatt laser pulses in thin film compression techniques. In this study, a few-cycle pulse damage testing platform was set up, and two UBCMs with different designs were fabricated for a comparative study of their laser-induced damage. Because light of varying wavelengths forms an electric field at different times within UBCMs under few-cycle pulse irradiation, a time-domain electric field model was developed to obtain transient electric field variations and explain the damage behavior. The model successfully elucidated the origin of the damage and discrepancy between the two UBCMs in terms of damage thresholds, showcasing its potential applications in designing high-threshold UBCMs for high-power laser systems.

Direct interconnection of seismicity with variations of the Earth's electric and magnetic field before major earthquakes

Upon employing the new concept of time, termed natural time, the analysis of seismicity reveals that, before major earthquakes, the variations of the Earth's electric and/or magnetic field are accompanied by increase of the fluctuations of the entropy change of seismicity under time reversal as well as by decrease of the fluctuations of the seismicity order parameter. Hence, natural time analysis reveals that before major earthquakes independent datasets of different geophysical observables (seismicity, Earth's magnetic and/or electric field) exhibit changes, which are observed simultaneously. To the memory of the Academician Seiya Uyeda.

Characterization of electric field distribution in valve-side casing of 500 kV converter transformer considering AC and DC mixed voltage

The converter transformer, as one of the indispensable core devices in the ultra-high voltage direct current (UHVDC) transmission system, exhibits highly complex electric field distribution characteristics within the valve-side bushing. In-depth research into the electric field distribution characteristics and variation patterns of the valve-side bushing under both alternating current (AC) and direct current (DC) voltage conditions is crucial for ensuring the reliable operation of the transmission system. This study focuses on investigating the electric field distribution of the valve-side bushing under AC and DC voltage excitations. A full-scale finite element model of the valve-side bushing of the converter transformer is constructed using finite element simulation software for modeling and research purposes. The results indicate that the internal electric field distribution of the bushing is generally similar under both AC and DC voltage excitations. However, in the SF6-filled region, a steeper voltage drop is observed under DC excitation compared to AC. The space charges generated in the DC electric field due to field polarization have a significant impact on the distortion of the electric field on the inner and outermost layer electrode plates. These conclusions provide theoretical guidance for the insulation design of the valve-side bushing in converter transformers at the 500 kV voltage level and similar ratings.

Simultaneous measurement of electrical potential on both sides of the dielectric surface in a parallel-plate dielectric barrier discharges and analysis of net electric field

Dielectric barrier discharges (DBDs) are widely used for ozone generation and surface treatment owing to their ability to generate reactive species. Surface charges generated during discharges distort the electric field between the dielectrics and affect the generation of reactive species. Therefore, the net electric field variations are of significant interest. Herein, a DBD measurement system for the net electric field based on the Pockels effect is established for the first time. The proposed system can simultaneously measure the surface potentials on both sides of the dielectric, thereby obtaining the net electric field at the discharge gap. The net electric field distribution varies insignificantly with the magnitude of the applied voltage but significantly with gap length. Moreover, the breakdown electric field increases with a decreasing gap length. This study provides a physical explanation for microgap reactors, demonstrating that the electric field in a DBD can be manipulated.

Electrically Tunable Single Polaritonic Quantum Dot at Room Temperature.

Exciton-polaritons confined in plasmonic cavities are hybridized light-matter quasiparticles, with distinct optical characteristics compared to plasmons and excitons alone. Here, we demonstrate the electric tunability of a single polaritonic quantum dot operating at room temperature in electric-field tip-enhanced strong coupling spectroscopy. For a single quantum dot in the nanoplasmonic tip cavity with variable dc local electric field, we dynamically control the Rabi frequency with the corresponding polariton emission, crossing weak to strong coupling. We model the observed behaviors based on the quantum confined Stark effect in the strong coupling regime.

Spectroscopic method to study the effect of lightning return stroke channel expansion on atmospheric pressure

Using the plasma radiation spectra of three natural cloud-to-ground multi-strike lightning discharges recorded by a slitless grating spectrograph, and based on the spectral wavelengths and relative intensities, combined with information about the lightning-synchronized ground electric field variations, we calculated the temperatures, line-charge densities, initial radii, and final radii of the lightning-strike channels. This was achieved by applying the theory of air plasma transport, lightning electrodynamics, the laws of conservation of energy and pressure. Subsequently, we determined the initial internal energies of the lightning plasma channels, the final internal energies, the work done by the return stroke channel expansion against atmospheric pressure, equivalent impedances, and the speed of charge movement. The results show that the temperature of the return stroke channel and the work done by the expansion of the return channel on the atmospheric pressure decrease with the development of the return stroke process. The final radius and the initial internal energy, as well as the initial peak electric field and the work done by the return stroke channel expansion on the atmospheric pressure, exhibit a strong linear relationship. The equivalent impedance and speed of charge movement show a nonlinear relationship with the work done by the return stroke channel expansion against atmospheric pressure. The changes in initial internal energy, final internal energy, and the expansion work of the return stroke channel against atmospheric pressure are essentially consistent and positively correlated. The initial peak electric field of the return channel increases, leading to enhanced spectral intensity. The return stroke channel temperature, initial radius, final radius, initial internal energy, final internal energy, and the work done by the return stroke channel expansion against atmospheric pressure all increase. Meanwhile, the equivalent impedance and speed of charge movement decrease.

Ground Electric Field, Atmospheric Weather and Electric Grid Variations in Northeast Greece Influenced by the March 2012 Solar Activity and the Moderate to Intense Geomagnetic Storms

In a recent paper, we extended a previous study on the solar solar influence to the generation of the March 2012 heatwave in the northeastern USA. In the present study we check the possible relationship of solar activity with the early March 2012 bad weather in northeast Thrace, Greece. To this end, we examined data from various remote sensing instrumentation monitoring the Sun (SDO satellite), Interplanetary space (ACE satellite), the Earth’s magnetosphere (Earth-based measurements, NOAA-19 satellite), the top of the clouds (Terra and Aqua satellites), and the near ground atmosphere. Our comparative data analysis suggests that: (i) the winter-like weather (rainfall, fast winds, decreased temperature) in Thrace started on 6 March 2012, the same day as the heatwave started in USA, (ii) during the March 2012 winter-like event in Thrace (6–15 March), the ACE satellite recorded enhanced fluxes of solar energetic particles (SEPs), while SOHO and PAMELA recorded solar protons at very high energies (>500 MeV), (iii) Between 3–31 March, the temperature in Alexandoupoli and the ACE/EPAM solar high energy (1.88–4.70 MeV) proton flux were strongly anticorelated (r = −0.75, p = 0.5). (iv) Thrace experienced particularly intense cyclonic circulation, during periods of magnetic storms on 8–10 and 12–13 March, which occurred after the arrival at ACE of two interplanetary shock waves, on March 8 and March 11, respectively, (v) at the beginning of the two above mentioned periods large atmospheric electric fields were recorded, with values ranging between ~−2000 V/m and ~1800 V/m on 8 March, (vi) the winter-like weather on 8–10 March 2012 occurred after the detection of the main SEP event related with a coronal mass ejection released in interplanetary space as a result of intense solar flare activity observed by SDO on 7 March 2012, (vi) the 8–10 March weather was related with a deep drop of ~63 °C in the cloud top temperature measured by MODIS/Terra, which favors strong precipitation. Finally, we analyzed data from the electric power network in Thrace (~41°N) and we found, for the first time sudden voltage changes of ~3.5 kV in the electric grid in Greece, during the decay phase of the March 2012 storm series. We discuss the winter-like March 2012 event in Thrace regarding the influence of solar cosmic rays on the low troposphere mediated by positive North Atlantic Oscillation (NAO). Finally, we infer that the novel finding of the geomagnetic effects on the electric power grid in Thrace may open a new window into space weather applications research.

Enhancement of Luminescence from Lanthanide Metal–Organic Frameworks by Ytterbium and Calcium Doping: Application to Photonic Barcodes and Fingerprint Detection

AbstractEmission from metal–organic frameworks (MOFs) made from Eu3+ and 1,3,5‐benzenetricarboxylic acid (BTC) is enhanced eightfold by doping with Y3+ and Ca2+ ions. The Ca2+ ions are shown to substitute into the MOFs, and the MOFs structure is shown to be retained at high Y3+ doping levels. The emission enhancement is shown to be associated with variations in the local electric field at the Eu3+ centers in the MOFs. Calculations indicate that the HOMO and LUMO levels vary considerably with both Y3+ doping and with low‐level Ca2+ doping. These then modulates Eu3+ concentration quenching, ligand‐metal energy transfer processes, and the local electric field at the Eu3+ centers, qualitatively accounting for the primary observed features. For UV excitation (250, 295, and 393 nm, respectively), the greatest emission enhancement comes from the doped MOFs with 10% Eu3+, 89% Y3+, and 1% Ca2+. In a photonic barcode application, the doped MOFs are shown to facilitate increased information storage density, and in a fingerprinting application, they are displayed to lead to higher photostability and reduced materials demand.

Electrode Effect on the Daily Variation in the Atmospheric Electric Field in the Surface Air Layer

Electrode Effect on the Daily Variation in the Atmospheric Electric Field in the Surface Air Layer

Molecular dynamics method to investigate the effect of variable electric field on the first charge of Li-Ion Nanobattery with carbon anode

Lithium-ion batteries are popular in the market due to their ability to charge and many applications in life. In these rechargeable batteries, Lithium ions move from the positive electrode to the negative electrode during charging and in the opposite direction during discharge. In the present research, the effect of external electric field amplitude (EEFA) with different ratios of 0.1, 0.2, 0.3, and 0.5 V/Å on the Li-ion-C-anode nanobattery was investigated by molecular dynamics (MD), and the effect of EEFA (0.1–0.5 V/Å) on the Mean squared displacement (MSD) was checked. It is concluded that for the Li-Li pair, the NN distance presents a slight tendency to decrease. Moreover, with the increase in the intensity of the EEFA, the number of mobile lithium ions increased from 60 to 183. Numerically, with increasing EEFA from 0.1–0.2, 0.3, and 0.5 V/Å, the MSD of lithium increased from 38.28–59.22, 89.91, and 113.04 nm2. This behaviour indicated that the lithiation of the carbon is occurring and that the lithium ions can diffuse through the carbon structure by breaking C–C bonds and forming a LiC alloy wall.

Observations and Variability of Near-Surface Atmospheric Electric Fields across Multiple Stations

The near-surface atmospheric electrostatic field plays a pivotal role in comprehending the global atmospheric circuit model and its influence on climate change. Prior to delving into the intricate interplay between solar activities, geological activities, and atmospheric electric field, a comprehensive examination of the diurnal fair atmospheric electric field’s baseline curve within a specific region is essential. Based on the atmospheric electric field network monitoring in Yunnan Province in the year 2022, this study systematically investigated the distribution of the atmospheric electric field under both fair-weather and disturbed weather conditions at a quadrilateral array encompassing Chuxiong Station, Mouding Station, Lufeng Station, and Dali Station. The primary focus was on elucidating the variations in the daily variation curves of fair atmospheric electric fields and conducting a comparative analysis with the Carnegie curves. The possible reasons for the differences among them are also discussed in this study, but more observational evidence is required to confirm the specific causes in the future.

Design and simulation of a germanium source dual‐metal dopingless tunnel FET as a label‐free biosensor

AbstractThis study presents a new dual‐metal dopingless tunnel field effect transistor with a Germanium source (GeS‐DM‐DLT) for label‐free biomolecule detection. Introducing a Ge source and dual‐metal gate provides improved drain current. We have considered an L‐shaped cavity at the top and bottom source metal region for investigating the sensitivity. The biosensor's sensitivity has been measured using the neutral biomolecules' dielectric constants (varying the k‐values in the cavity). The sensor's DC performance is investigated using transfer characteristics, BTBT rate, energy band, and electric field variation for different k‐values. The sensitivity performance of the proposed biosensor is evaluated in terms of different DC parameters (drain current, surface potential, subthreshold swing, interband tunneling rate, electric field) and RF parameters (parasitic capacitance, transconductance, cut‐off frequency, maximum frequency). The suggested biosensor offers a much‐improved SON of 9.86 × 108 and SRATIO of 1.94 × 104 for a dielectric constant of 22.0 at room temperature. Further research has been done to study the effects of dielectric materials, interface trap carriers (ITC), and temperature on drain current, drain current sensitivity, and other sensitivity parameters. The article also includes investigating the influence of the fill factor on sensitivity performance. The GeS‐DM‐DLT sensor performs best in fully‐filled conditions compared to the partially‐filled condition inside the cavity region.