Uniform Electric Field Research Articles

Improvement in uniformity of co‐linear pulsed electric field treatment chamber by sub‐electrodes and its optimization

AbstractThe uniformity of performance parameters such as electric field and temperature for a co‐linear pulsed electric field (PEF) processing system is one of main factors affecting the processing effect and quality of liquid food. We have proposed a co‐linear PEF treatment chamber configuration with sub‐electrodes to improve the uniformity and processing efficiency. We have first examined how the position of the sub‐electrodes alone affects the uniformity of the performance parameters. Then, we have investigated the variation of the uniformity while changing simultaneously the electrode radius, inter‐electrode gap, and position of sub‐electrodes. As a result, we have found that the most uniform field could be obtained when the electrode radius is 5.5 mm, the inter‐electrode gap is 15 mm, and the sub‐electrodes situate at the middle of the chamber. In this chamber, the region between 95% and 105% of the average electric field covers 83%, which shows much improvement compared to the formers' results, 69.5% and 76%, respectively. Also, the optimal treatment chamber provides greater average electric field under the same voltages as the voltages reported by the formers.Practical applicationsA novel treatment chamber with sub‐electrodes is proposed for pulsed electric fields food processing. The improved treatment design was obtained by changing position of sub‐electrodes, inner radius of electrodes and distance between electrodes. The more uniform electric field was obtained in treatment region. The temperature distribution was more uniformed by increasing flow rates and uniformed electric field strength. The treatment throughput was increased by sub‐electrodes.

Longitudinal Variations of Energetic Electrons Scattered by NWC Transmitter: DEMETER Observations

AbstractLow‐Earth orbit (LEO) satellites often observe wisp‐like energy spectra, characterized by lower energies at higher L values of energetic electrons, resulting from the scattering effect of the narrow‐band artificial transmitter signals. Typically, the flux levels of wisp energy spectra increase as they approach the South Atlantic Anomaly (SAA). Here, we report, for the first time, the longitudinal variations of wisp positions in the energy‐L coordinate based on observations from the DEMETER satellite. The L‐values of wisps decrease at the longitudes <180° and increase at the longitudes >180°. By considering the satellite's orbital characteristics, we found that the longitudinal variations of wisp are essentially the MLT‐dependent radial transport of electrons. This finding indicates that the electron drift paths can be modified within a single drift period. We propose a duskward convection electric field as a potential mechanism to explain the longitudinal variations of wisps. By assuming a uniform duskward convection electric field with an amplitude of ∼1.5 mV/m, our simulations can reasonably reproduce the longitudinal variations of wisps observed in the southern hemisphere on 21 March 2009. Our results support the existence of a convection electric field in the inner belt and suggest that this electric field significantly contributes to the variations in energies and L values of energetic electrons within one drift period.

Modulating the fracture behavior of interface cracks via electric field gradient in flexoelectric solids

Interface cracks seriously affect the performance and service life of layered electronic devices. At nanoscale, the electric field concentration can be generated at the tip of insulating cracks by solely applying a uniform electric field loading, resulting in a large electric field gradient and thus inducing a significant converse flexoelectric effect. The deformation generated by the converse flexoelectric effect is expected to achieve crack shielding, however, its mechanism is still not clear. In this paper, the role of electric field gradients on interface crack behavior is studied by the collocation mixed finite element method (MFEM) and the J-integral. The result shows that the electric field gradient generated by a uniform electric displacement loading can reduce the J-integral of crack tips, achieving crack shielding. The result provides new ideas for the study of failure assessment, nanoscale fracture experiment and others.

A High-Performance Microwave Heating Device Based on a Coaxial Structure

Continuous-flow microwave heating stands out for its ability to rapidly and uniformly heat substances, making it widely applicable in chemical production. However, in practical applications, the permittivity of the heated liquid changes dramatically as the reaction progresses, affecting the efficiency and uniformity of continuous-flow heating. Herein, this work presents a novel microwave heating device based on a coaxial structure for high-performance heating. Our approach commenced with the development of a multiphysical field model, incorporating spiraled polytetrafluoroethylene (PTFE) as a water channel and the coaxial waveguide as a container. The analysis shows that the uniform distribution of the sectional electric field of electromagnetic waves in the TEM mode within the coaxial structure can enhance heating uniformity. Then, a continuous-flow microwave heating system for different liquid loads was established, and experimental measurements were conducted. The heating efficiency for all loads exceeded 90%, which basely matched the simulation results, validating the accuracy of the model. Finally, the heating efficiency and uniformity under different permittivity loads were analyzed, as well as the impact of channel radius on heating efficiency. The device exhibits high heating efficiency under different loads, with uniform radial electric field distribution and stable heating uniformity. This continuous-flow microwave device is suitable for chemical research and production because of its high adaptability to the large dynamic range of permittivity, contributing to the promotion of microwave energy applications in the chemical industry.

Enhanced horizontal alignment of InGaN/GaN nanorod LEDs via insulator-based dielectrophoresis

GaN-based nanorod light emitting diodes (LEDs) are key to the development of high brightness, small pixel size, and long lifetime for high-resolution display applications. To manufacture individual nanorod LEDs as compact light sources, it is necessary to separate the nanorod LEDs from the substrate and transfer them to the electrode. Dielectrophoresis (DEP) is a highly suitable technique for transferring the individual nanorod LEDs. However, there are still challenges in achieving a high alignment yield. In this work, nanorod LEDs are successfully fabricated and separated to enhance the horizontal alignment in interdigitated electrodes via insulator-based DEP (iDEP). In iDEP, a structure is formed by inserting an insulating layer between the electrodes. This structure manipulates the electric field generated around the electrodes due to polarization by the insulating layer. This results in a relatively uniform electric field distribution on the surface of the insulating layer, thereby enhancing the horizontal alignment of the nanorod LEDs. Herein, the iDEP structure achieves significant nanorod LED alignment yield of up to 91.9 %, compared to 45.5 % for the electrode-based DEP (eDEP) technique. Furthermore, the use of a patterned insulator makes it possible to restrict 1 or 2 aligned nanorod LEDs within a specific pixel region, which is suitable for high-resolution display technologies based on nanorod LEDs.

FS-iTFET: advancing tunnel FET technology with Schottky-inductive source and GAA design

In this paper, we introduce a novel Forkshape nanosheet Inductive Tunnel Field-Effect Transistor (FS-iTFET) featuring a Gate-All-Around structure and a full-line tunneling heterojunction channel. The overlapping gate and source contact regions create a strong and uniform electric field in the channel. Furthermore, the metal–semiconductor Schottky junction in the intrinsic source region induces the required carriers without the need for doping. This innovative design achieves both a steeper subthreshold swing (SS) and a higher ON-state current (ION). Using calibration-based simulations with Sentaurus TCAD, we compare the performance of three newly designed device structures: the conventional Nanosheet Tunnel Field-Effect Transistor (NS-TFET), the Nanosheet Line-tunneling TFET (NS-LTFET), and the proposed FS-iTFET. Simulation results show that, compared to the traditional NS-TFET, the NS-LTFET with its full line-tunneling structure improves the average subthreshold swing (SSAVG) by 19.2%. More significantly, the FS-iTFET, utilizing the Schottky-inductive source, further improves the SSAVG by 49% and achieves a superior ION/IOFF ratio. Additionally, we explore the impact of Trap-Assisted Tunneling on the performance of the three different integrations. The FS-iTFET consistently demonstrates superior performance across various metrics, highlighting its potential in advancing tunnel field-effect transistor technology.

Revisiting the Charged Harmonic Oscillator in a Uniform Electric Field

Revisiting the Charged Harmonic Oscillator in a Uniform Electric Field

Insight into the Impact of Electron Drift Trajectory on Charge Collection in Silicon Drift Detector

The internal electric field distribution is one key design consideration, which affects the charge collection efficiency in silicon drift detectors (SDDs). The internal electrostatic potential distributions along SDD front and back surfaces, which are determined by the applied voltages at cathode electrodes, define the final internal field distribution. Front-back bias coupling leads to the complexity of electrode structure design and voltage tuning. Device simulation is performed to investigate the performance of SDDs with varied bias voltages. When the cathode bias is −40 V with the first ring bias of −15 V and the outermost ring bias of −80 V, the detector is biased with a uniform electric field distribution, favorable electron drift trajectories. The simulation results provide new insight into the influence of internal electric field and electron drift trajectories on the charge collection efficiency. According to the analysis of simulation results, a 2000 × 2000 μm area concentric silicon drift detector was designed and fabricated. The electrical characteristics of the designed detectors were studied to show the validity of the proposed device design methodology. The internal electric field distribution and electron drift trajectories can be tuned to improve the charge collection efficiency.

Ionic liquid-integrated aqueous electrolyte regulation on solvation chemistry and electrode interface for reversible dendrite-free zinc anodes

Zn anodes suffer from poor reversibility and stability owing to nonuniform dendrite growth and self-corrosion. Here, 1-ethyl-3-methylimidazolium acetate (EMImAc) is introduced to reconstruct interfacial electrical double layer with simultaneously manipulating the solvation environment and the adsorption situation on Zn anode. The acetate anions with high nucleophilicity can effectively alter the solvation shell around Zn2+ ions and immobilize the H2O molecules, thus weakening water activity and alleviating water-related parasitic reactions. Concomitantly, both the imidazolium cation and acetate anion are inclined to gather on Zn anode surface for constructing an electrostatic shielding layer, and meanwhile the chemisorbed acetate anions also contribute to accelerate the Zn(H2O)62+ desolvation process. Such a synergistic effect enables uniform electric field distribution and facilitates Zn ion flux, which mitigates the random diffusion of Zn2+ and finally promotes the dendrite-free deposition. As a result, the Zn/Zn symmetric cells with EMImAc-integrated aqueous electrolyte realize an excellent cycling lifespan of 7000 h (0.5 mA cm−2/0.25 mAh cm−2) and high Zn utilization of 61.3 % (15 mA cm−2/20 mAh cm−2). Furthermore, the effective of EMImAc additive is demonstrated in Zn/V2O5 cells. This work offers insights into the ionic liquid-integrated aqueous electrolytes to enhance the interface stability of Zn anode for rechargeable zinc batteries.

Enhanced evaporation and heat transfer of sessile droplets via coupling electric field and temperature field

Controllable evaporation of sessile droplets is essential in diverse applications, ranging from thermal management to chemical reactions and combustion. Despite considerable advances, further enhancement of droplet evaporation is still challenging. Here, an experimental system that couples uniform/non-uniform electric fields with temperature fields to enhance hydrophilic droplet evaporation is introduced. The electric field can generate Coulomb force by changing the redistribution of charges at the droplet interface, which enables highly flexible and precise control of the sessile droplet. By leveraging the uniform electric field, the droplet is stretched upwards, which increases the heat transfer thermal resistance and the vapor concentration near the droplet interface, leading to the deterioration of droplet evaporation. Whereas the application of a non-uniform electric field will flatten the droplets due to the shear effect of the corona wind on the droplet interface, and the reduction of the heat transfer thermal resistance of the droplets, as well as the vapor concentration near the interface, which promotes the droplet evaporation. The coupling of uniform electric and temperature fields could reverse the inhibition effect of droplet evaporation caused by a purely uniform electric field, and the maximum enhancement ratio reaches 5.11 times. The coupling of a non-uniform electric field and temperature field can enhance droplet evaporation up to 29.34 times. The corresponding numerical simulation study reveals the flow and temperature distribution inside the droplet. This research provides critical insights into the precise manipulation of droplet evaporation by applying an electric field.

Establishment of DC Electric Field Measurements by Linear Dipole Type Sensor System

Nowadays, electric fields above the ground are measured mainly by so‐called ‘field mill type’ sensor systems. However, their measurements are limited to vertical field component only due to its technical constraint. Out of necessity of measurements of electric field components in arbitrary directions in any spaces, a linear dipole type DC electric field sensor system, which can be immersed within a fully uniform electric field, was developed. However, it had been remained unknown whether its sensor output is parameter‐dependent or not, and unknown whether it can provide reliable intensity value of measured electric fields or not. In order to clarify these points, test observations of natural electric fields have been conducted by means of plural sensor systems having different values of parameter. Obtained electric field intensity derived from the observed data has shown a parameter‐dependence despite that it should be constant for any parameter values. After a detailed analysis of the effect of the parameter along the equivalent electric circuit of the sensor system, a field‐calibrating formula, which can make the sensor system to be parameter‐independent, has been found. Finally, the linear dipole type DC electric field sensor system for obtaining reliable electric field intensities has been established. © 2024 The Author(s). IEEJ Transactions on Electrical and Electronic Engineering published by Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Dielectrophoretic separation of a water-in-oil emulsion

Electric field-assisted separation is considered one of the most effective ways of dehydrating water-in-oil emulsions. In the uniform electric field usually used in electrodehydrators, electrocoalescence leads to droplet enlargement, thus accelerating their gravitational settling. Meanwhile, using a nonuniform field is expected to provide an additional tool for phase spatial separation due to dielectrophoresis while keeping the conditions favorable for electrocoalescence. This study aims to investigate experimentally the dynamics of water-in-oil emulsion in a nonuniform electric field and the efficiency of its separation due to the dielectrophoretic effect. A high-frequency field and emulsions with zero-density contrast were used allowing us to study the action of the dielectrophoretic force in the absence of electrokinetic phenomena and gravitational settling. We found that droplets always move towards the electric field strength gradient, eventually accumulating at the internal electrode. We demonstrate that the separation efficiency increases as the average droplet size, the voltage, the dispersion medium permittivity, and the initial droplet concentration increase. In the latter case the separation enhancement is due primarily to droplet coalescence, the rate of which increases appreciably with increasing concentration. We demonstrate that all the experimental results can be combined into unified dependence based on a simple physical model.

The effect of electric field uniformity on electrospun jet evolution and fiber morphology

Electric field distribution has a considerable impact on jet motion and resultant fibers’ diameter and morphology in electrospinning process. This study aims to explore the effect of electric field uniformity on jet evolution and fiber morphology by using auxiliary electrodes. Four disc auxiliary electrodes with different external diameters were designed. A high-speed photography equipment was employed to capture the jet motion. The morphology the fibers obtained from different locations of the jet were observed by the SEM to investigate jets evolution under different electric fields. The three-dimensional electric field were calculated by the ANSYS Maxwell software to simulate and quantify the electric field distribution throughout the electrospinning process. The results show that the larger diameter of the auxiliary electrode creates more uniform electric field distribution, smaller jet straight lengths, larger whipping amplitude, and lower the jet velocity. These factors result in finer and more uniform fibers. It was found that the morphology of fiber surface, beads shape and size also influenced by the uniformity of electric field distribution. This research indicates that a controllable uniform electric field was essential in preparing high-performance fibers.

ЕЛЕКТРИЧНЕ ПОЛЕ НАПІВПРОВІДНОГО ЕКРАНА СИЛОВОГО КАБЕЛЮ З ПОЛІМЕРНОЮ ІЗОЛЯЦІЄЮ З УРАХУВАННЯМ СТРУКТУРНИХ НЕОДНОРІДНОСТЕЙ

The non-homogeneous electric field distributions in the cross-linked polyethylene insulation of 330 kV power cable with multi-conductor core depending on the electrical conductivity and thickness of the semiconducting screen as well as at different frequency of applied voltage (from 50 to 104 Hz) are studied by finite-element analysis. As shown, taking into account the periodic structure of core surface, the electrical conductivity of the material of internal semiconducting screen should exceed 10–6 S/m and its thickness should be at least 1.5 mm in order to obtain the uniform electric field in the basic insulation of the cable at the boundary with the screen. The paper also considers the effect of various types of the surface and volumetric defects in the semiconducting screen on the electric field inhomogeneity in cable insulation. It is shown that the defects in the screen can lead to a significant increase of the electric field in the local zones of their location (up to 5 times as compared to the field without defects) and therefore contribute to the formation and development of treeing structures in the insulation. The revealed results explain the reasons for the micro- and macro-level degradation of power cable insulation and confirm the need to ensure the uniform structure, smooth surface of both semiconducting screen and core during the technological process of manufacturing the power cables with cross-linked polyethylene insulation. References 23, figures 8, table 1.

Nonlinear wave propagation in large extra spatial dimensions and the blackbody thermal laws

Abstract Nonlinear wave propagation in large extra spatial dimensions (on and above d = 2) is investigated in the context of nonlinear electrodynamics theories that depend exclusively on the invariant F ( = − ( 1 / 4 ) F μ ν F μ ν ) . In this vein, we consider propagating waves under the influence of external uniform electric and magnetic fields. Features related to the blackbody radiation in the presence of a background constant electric field such as the generalization of the spectral energy density distribution and the Stefan–Boltzmann law are obtained. Interestingly enough, anisotropic contributions to the frequency spectrum appear in connection to the nonlinearity of the electromagnetic field. In addition, the long wavelength regime and Wien’s displacement law in this situation are studied. The corresponding thermodynamics quantities at thermal equilibrium, such as energy, pressure, entropy, and heat capacity densities are contemplated as well.

Mitigating Zn Dendrite Growth and Enhancing the Utilization of Zn Electrode in Aqueous Zn-Ion Batteries.

In spite of extensive research and appreciable progress, in aqueous zinc-ion batteries, Zn metal anode is struggling with low Zn utility and poor cycling stability. In this study, a 3D "electrochemical welding" composite electrode is designed by introduction of ZnO/C nanofibers film to copper foils as an anode according to pre-electrodeposition active Zn (Zn@ZnO/C-Cu). The flow of Zn2+ through carbon fiber layer is regulated by zincophilic ZnO, promoting homogeneous diffusion of Zn2+ to Cu foil. In subsequent Zn deposition/stripping processes, the hydrophobicity of ZnO/C fiber layer reduces water at the interface of Zn@ZnO/C-Cu and results in uniform electric field significant suppressing growth of Zn dendritic and side reactions. Thus, pre-electrodeposition active Zn electrochemical welds ZnO/C nanofibers and Cu foil collectively provide stable charge/electron transfer and stripping/plating of Zn with low polarization and excellent cycling performance. The assembled symmetrical batteries exhibit stable cycling performance for over 470 h under 20% utilization of Zn at 5mA cm-2, and an average coulombic efficiency of 99.9% at low negative/positive capacity ratio (N/P = 1) after 1000 cycles in the Zn@ZnO/C-Cu||Na2V6O16·1.5H2O full cell.

Boron-Doped Carbon Scaffold Hosts for Li Metal Batteries

Lithium metal anodes offer the promise of higher energy density batteries. However, the formation of lithium dendrites due to non-uniform plating and stripping of the lithium metal has proven to be a major hurdle for this technology, decreasing the lifetime of the device and causing safety hazards. Utilizing a carbon scaffold host for the lithium metal anode can limit dendrite formation by providing a more uniform electric field and numerous lithium nucleation sites to encourage uniform plating and stripping. In this poster, we present our work developing carbon scaffold hosts for lithium metal anodes. We synthesized scaffolds with various architectures and microstructures using different carbon materials. Our atomistic simulations demonstrated that the addition of boron to the carbon results in stronger binding of lithium to the carbon surface, further improving the lithiophilicity. Therefore, we also prepared boron-doped carbon scaffolds to test this experimentally. Boron was introduced using boric acid and incorporated into the carbon structure during carbonization under nitrogen, and these samples were characterized by XPS, SEM, and BET to try and correlate scaffold properties with performance. In addition, we are investigating other dopants (such as nitrogen), which have also been reported to increase the lithiophilicity of carbon materials. Utilizing these doped carbon scaffolds can help increase the lifetime of lithium metal batteries by improving the cycling uniformity.This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344

Designing Better Li Metal Anodes for Next-Generation Batteries

Li metal batteries have the potential to significantly advance battery technology due to their substantially higher energy densities. However, robust high-capacity Li metal anodes are necessary to realize this approach, and current Li metal anode designs suffer from significant degradation over time due to non-uniform Li plating/stripping during cycling, which can lead to dead Li and/or Li dendrite growth. Carbon scaffold hosts can help mitigate this problem by creating a uniform electric field and providing abundant Li nucleation sites, but the relationship between the host architecture and performance is not well understood. We investigated the effect of scaffold architecture and chemistry on the resulting Li morphology and electrochemical performance using a combined experiment/theory approach. Carbon scaffolds with well-controlled geometries and varied porosities were fabricated using 3D printing and then characterized by SEM, Raman, and XPS before cycling in cells to evaluate their performance as hosts for uniform Li plating/stripping with both liquid and solid electrolytes. Atomistic and mesoscale modeling were used to predict how scaffold chemistry and microstructure affect Li nucleation probability and the formation of current density/stress hotspots that can lead to dendrite growth, and these results were used to help guide scaffold design. This work provides further insight into the relationship between anode architecture and Li metal cycling stability, which will facilitate the development of high-energy-density batteries in the future.Lawrence Livermore National Laboratory is operated by Lawrence Livermore National Security, LLC, for the U.S. Department of Energy, National Nuclear Security Administration under Contract DE-AC52-07NA27344.

Customizing Pore Structure and Lithiophilic Sites Dual-Gradient Free-Standing 3D Lithium-Based Anode to Enable Excellent Lithium Metal Batteries.

Developing 3D hosts is one of the most promising strategies for putting forward the practical application of lithium(Li)-based anodes. However, the concentration polarization and uniform electric field of the traditional 3D hosts result in undesirable "top growth" of Li, reduced space utilization, and obnoxious dendrites. Herein, a novel dual-gradient 3D host (GDPL-3DH) simultaneously possessing gradient-distributed pore structure and lithiophilic sites is constructed by an electrospinning route. Under the synergistic effect of the gradient-distributed pore and lithiophilic sites, the GDPL-3DH exhibits the gradient-increased electrical conductivity from top to bottom. Also, Li is preferentially and uniformly deposited at the bottom of the GDPL-3DH with a typical "bottom-top" mode confirmed by the optical and SEM images, without Li dendrites. Consequently, an ultra-long lifespan of 5250h of a symmetrical cell at 2mA cm-2 with a fixed capacity of 2 mAh cm-2 is achieved. Also, the full cells based on the LiFePO4, S/C, and LiNi0.8Co0.1Mn0.1O2 cathodes all exhibit excellent performances. Specifically, the LiFePO4-based cell maintains a high capacity of 136.8 mAh g-1 after 700 cycles at 1C (1C = 170mA g-1) with 94.7% capacity retention. The novel dual-gradient strategy broadens the perspective of regulating the mechanism of lithium deposition.

Water structures in tip-charged carbon nanotubes.

Carbon nanotubes (CNTs) have potential applications in separation membranes and nanofluidic devices. It is well known that the behavior of water molecules confined in CNTs is affected by surface functional groups and external electric fields, leading to structural changes. The understanding of these structural changes of water within various CNTs is crucial, particularly in the context of material separation. While there have been many investigations into the effects of individual specific functional groups, a comprehensive understanding of the effect of these functional groups and the electric fields they generate on water molecules remains elusive. In this study, we investigate the properties of water molecules in tip-charged CNTs of (8,8), (10,10), and (12,12) chiral vectors with positive charges at one tip and negative charges at the other tip. Abstraction of ionized functional groups as tip charges enables a comprehensive understanding that is independent of individual functional groups. The symmetrically arranged tip-charges spontaneously generate a strong and symmetric electric field in the CNTs. However, the strength and directionality of the electric field are non-uniform and complex. In the interiors of (8,8) and (10,10) tip-charged CNTs, helical and square structures, which have disturbances caused by the non-uniformity of the electric field, are observed. The properties of the water molecules differed significantly in the center of the CNTs and near positive and negative charges, despite the electric field symmetry. In (12,12) tip-charged CNTs with 12 charges, a local ring structure is observed in the vicinity of negative charges but not in the vicinity of positive charges. It is concluded that the water structures in tip-charged CNTs have different characteristics from those in plain CNTs under a uniform electric field.