Electric Force Research Articles

Exploring electric field forces and polarization influence on combustion in Fe-additive fuel droplets

The application of electrical techniques such as electric field, polarization, and ionization in the field of combustion makes many positive developments possible. The electric field effect offers significant advantages in controlling flame stability and reducing soot formation during the combustion of fuels. Also, the conditioning effect can improve particle oxidation during combustion for hydrocarbon fuels containing metal particle inclusions with high calorific value. This study focuses on investigating the combustion and atomization behavior of Fe additive diesel fuel droplets at electric field strengths of E = 5 V/m, E = 6.7 V/m, and E = 10 V/m and in positive (↑) and negative (↓) electric field directions. The experiments were carried out by igniting a fuel droplet suspended on a ceramic wire with an arc at the center of the electric field between two conductive plates in a combustion chamber with optical apertures. The combustion processes were recorded with an optical system consisting of a high-speed camera and a thermal camera. Combustion and atomization behavior were characterized by sequential flame and droplet atomization images, respectively. The droplet shape change and flame behavior results were comparatively evaluated according to the d2-law. Ignition delay and extinction times were determined by processing threshold technique and maximum flame temperatures were determined by processing thermal camera images. The results showed that increasing the electric field intensity in the negative electric field direction resulted in improved soot oxidation, and Fe particles burnt efficiently. Ignition delay times showed a decreasing trend with an electric field effect and an increasing trend with the addition of Fe particles. The highest maximum flame temperature and lowest extinction time were recorded as 785 K and ∼ 578.34 ms for Diesel/Fe/100(↓) fuel droplet, respectively and Fe particles did not exhibit microexplosion phenomena at E = 10 V/m. In this study, it has been shown that an effective oxidation can be achieved for Fe particles by increasing the mobility of ionized species in the flame zone under the effect of electric field and a homogeneous thermal field can be created in the flame zone even in fuels with particle addition at increasing electric field intensities.

Effect of surface energy on the contamination characteristics of porcelain double umbrella insulators

To explore the influence of surface energy on the contamination characteristics of insulators, COMSOL Multiphysics software was used to simulate the contamination characteristics of XWP 2-160 insulators under wind tunnel conditions, and the rationality of the modified expression of the dynamic deposition model of the contaminated particles was verified. The change of contamination characteristics before and after changing the surface energy of insulators under natural conditions was simulated and analyzed. The results show that under the original surface energy (72 mJ/m 2) and low surface energy (6.7 mJ/m 2) with the increase in particle size, the contamination amount of an insulator surface area decreases first and then increases. When the wind speed is 2 m/s, the change in the particle size has the most pronounced effect on the amount of contamination. The amounts of contamination for the low surface energy are 64–75%, 60–95%, 55–91% and 54–78% lower than those for the original surface energy for particle sizes of 10, 15, 20 and 25 μm, respectively. For the same wind speed, when the size of contamination particles increases, the difference between the ratio of DC and AC contamination accumulation is gradually increasing because of the influence of the electric field force. From the perspective of the insulator preparation process, the development of low surface energy insulators can improve their anti-fouling performance.

Sisko fluid flow through a non-Darcian micro-channel: An analysis of quadratic convection and electro-magneto-hydrodynamics

Microfluidics is used in a range of applications, including conversion of energy, biological diagnostics, and chemical processes. To improve these applications, it is essential to better understand the rheology of the non-Newtonian fluid movement through micro-channels. The purpose of this paper is to examine a Sisko fluid moving through a micro-channel in the presence of electro-magneto-hydrodynamic (EMHD) forces. The Darcy-Brinkmann-Forchheimer (DBF) model is applied. In addition, quadratic convection effects are used to investigate the rehology of the Sisko fluid model. Because it can accommodate a greater range of variables that can known experimental data, the Sisko fluid model is more suited for evaluating the flow dynamics. Furthermore, it is a simple model to apply and easier to adopt for a variety of industrial applications. Other elements, such as viscosity dissipation and Joule heating, are also incorporated in the model. Since the mathematical modeling is nonlinear we adopt a shooting numerical technique to solve it. The results of the computations are given in graphs and tables for all of the parameters in the governing equations. The velocity and temperature profiles are substantially enhanced as a result of the Brinkmann number’s strong influence. The opposite effect is observed when the generation parameter (generated by the interaction of electric and magnetic forces) increases. The velocity field and temperature profiles are adversely affected by the magnetic field, but they are enhanced by the electric field.

One-dimensional simulation and validation of divertor detachment induced through nitrogen seeding on HL-2A

Divertor detachment is a promising method to solve the power exhaust problem in tokamak devices or even in future magnetic fusion reactors. In this work, a detachment experiment (HL-2A shot #38008) with mixed gas seeding (60% nitrogen and 40% deuterium) is simulated using the SD1D module in BOUT++. In the process from attachment to detachment, the target electron temperature and the target ion saturation current in simulations are found to be consistent with the experimental results measured by Langmuir probes on the target plate. In order to understand the underlying detachment mechanism on HL-2A, this work analyses the role of different particle species in the cases with different seeding rates. It shows that the plasma density varies little and the density of neutrals ( D and D2 ) slightly decreases with the increase of nitrogen seeding rate, such that plasma–neutral interactions cannot effectively reduce plasma energy and plasma momentum in the divertor. The case with a high seeding rate predicts that increasing seeding rate cannot reach a target temperature lower than 2.5eV , which is the required temperature for strong plasma–molecule interactions. Thus, the plasma–molecule interactions may not be important in the divertor during nitrogen seeding. This work also studies the parallel forces including (1) force due to the parallel electric field, (2) friction forces, (3) ion- and electron-thermal forces, and (4) collisional reactions (e.g. charge exchange recombination and ionisation). It is found that the friction force between nitrogen ions and other particle species (primarily D+ ) is the dominant force towards the target, while ion- and electron-thermal forces are the dominant force pushing nitrogen ions back to upstream. Parallel forces determine the parallel distribution of nitrogen impurities, and therefore decide the region of nitrogen radiation.

Dynamics of the Deformable Fluid Interface Interacting with an Approaching Solid under the Electrostatic Field.

A theoretical model was developed to describe the dynamics of a deformable fluid interface interacting with an approaching solid without contact by both the attractive electrostatic and van der Waals (i.e., vdW) interaction, analogous to the situation in the experiments by electric force microscopy (i.e., EFM) or electric-surface force apparatus (i.e., E-SFA) involved in the soft fluid interface. On the basis of this model, a numerical study of the deformation of the fluid interface, the force-vs-separation behavior, and the critical limiting conditions of contact has systematically been carried out. Our results show that the surface pressure induced by the electrostatic interaction plays a more prominent role in the deformation of the fluid interface than the vdW interaction does, and there exists a principal length scale associated with the relative strength of the electrostatic field to the surface tension, affecting the fluid interface shape under the electrostatic field. It was also shown that both the force-distance curves and the corresponding curves of fluid interface deformation peak versus distance for various electrostatic fields satisfy the universal scaling power law. Moreover, an analytical solution to the Euler-Lagrange differential equation governing the deformation of the fluid interface under the external electric field is obtained, and two extended formulas for explicitly describing the principal length scales that respectively characterize the lateral and longitudinal deformations of the fluid interface were determined.

Influence of Concentration, Surface Charge, and Natural Water Components on the Transport and Adsorption of Polystyrene Nanoplastics in Sand Columns.

Information about the influence of surface charges on nanoplastics (NPLs) transport in porous media, the influence of NPL concentrations on porous media retention capacities, and changes in porous media adsorption capacities in the presence of natural water components are still scarce. In this study, laboratory column experiments are conducted to investigate the transport behavior of positively charged amidine polystyrene (PS) latex NPLs and negatively charged sulfate PS latex NPLs in quartz sand columns saturated with ultrapure water and Geneva Lake water, respectively. Results obtained for ultrapure water show that amidine PS latex NPLs have more affinity for negatively charged sand surfaces than sulfate PS latex NPLs because of the presence of attractive electrical forces. As for the Geneva Lake water, under natural conditions, both NPL types and sand are negatively charged. Therefore, the presence of repulsion forces reduces NPL's affinity for sand surfaces. The calculated adsorption capacities of sand grains for the removal of both types of NPLs from both types of water are oscillating around 0.008 and 0.004 mg g-1 for NPL concentrations of 100 and 500 mg L-1, respectively. SEM micrography shows individual NPLs or aggregates attached to the sand and confirms the limited role of the adsorption process in NPL retention. The important NPL retention, especially in the case of negatively charged NPLs, in Geneva Lake water-saturated columns is related to heteroaggregate formation and their further straining inside narrow pores. The presence of DOM and metal cations is then crucial to trigger the aggregation process and NPL retention.

Droplet coalescence in coupled shear and electric fields: A molecular dynamics study

Water droplet coalescence in coupled flow and electric fields is a phenomenon extensively observed in petrochemical, microfluidic, and chemical synthesis processes; however, the existing research in this domain lacks the necessary depth. This paper employs a molecular dynamics approach to elucidate the microscopic mechanisms governing droplet aggregation in water-in-oil emulsions. The investigation spans various shear rates and droplet angles, considering droplet morphology and molecular interactions. The study reveals an interrelation between shear rate and droplet angle effects on droplet coalescence, both seeking to understand the impact of the flow field's shear effect on the electrocoalescence of water droplets. Increasing the shear rate proves advantageous to droplet aggregation up to a certain threshold; however, complete coalescence is hindered beyond the critical shear rate, γ = 7.5 × 109 s−1. Augmenting the droplet angle amplifies the shear force exerted by the flow field on the droplets, while diminishing the radial electric field force. Consequently, an optimal droplet angle of θ = 25° facilitates comprehensive droplet merging. The analysis of the coalescence process, interaction energy, charge density and radial distribution function shows that the approximate process of droplet motion is as follows: the shear effect drives the droplets to approach, and then the directional migration of charge and electrostatic attraction between water molecules drive the coalescence. The existence of a moderate shear effect enables complete droplet coalescence. This study offers theoretical guidance for the exploration of dynamic electrocoalescence technology.

Enhancing pool boiling in microgravity using micro-fins and an electrostatic field under different liquid subcooling

Despite boiling heat transfer is an effective way to remove heat and its performances comply with the high requirements of the electronics cooling and aerospace devices, in reduced gravity levels environments a decrease of the Critical Heat Flux (CHF) occurs. In the past decades, several techniques were developed to enhance the performances of a boiling system, such as external force fields and surface modification. Adding micro-structures on a boiling surface can delay the CHF occurrence, due to capillarity. As capillary forces are independent of gravity, this technique is potentially useful in microgravity. In the present study, micro-finned surfaces of new geometry were tested during parabolic flights in microgravity conditions under the action of an electric field and at different subcooling levels ranging from 5 to 35 K. The experimental results, reported here for the first time, showed that the micro-fins alone (whose characteristic length ranges from 30 to 120 µm) were not effective to increase CHF in microgravity, even if the heat transfer coefficients were higher with respect to the smooth surface tested for comparison. The addition of an external electric field enhanced the CHF due to its vapor removal capability and the bubble breaking effect. Moreover, the combined effect of micro-fins and electric field showed a synergic effect, increasing the CHF value up to 2.2 times. The CHF increased linearly with the subcooling level. The results indicate that micro-fins enhancing action can be severely reduced by the accumulation of vapor in the proximity of the surface, due to lack of buoyancy. However, if vapor is removed with an alternative action (e.g., electric forces) the fin enhancement is restored.

Unraveling Partial Coalescence Between Droplet and Oil-Water Interface in Water-in-Oil Emulsions under a Direct-Current Electric Field via Molecular Dynamics Simulation.

When the electric field strength (E) surpasses a certain threshold, secondary droplets are generated during the coalescence between water droplets in oil and the oil-water interface (so-called the droplet-interface partial coalescence phenomenon), resulting in a lower efficiency of droplet electrocoalescence. This study employs molecular dynamics (MD) simulations to investigate the droplet-interface partial coalescence phenomenon under direct current (DC) electric fields. The results demonstrate that intermolecular interactions, particularly the formation of hydrogen bonds, play a crucial role in dipole-dipole coalescence. Droplet-interface partial coalescence is categorized into five regimes based on droplet morphology. During the contact and fusion of the droplet with the water layer, the dipole moment of the droplet exhibits alternating increases and decreases along the electric field direction. Electric field forces acting on sodium ions and the internal interactions within droplets promote the process of droplet-interface partial coalescence. High field strengths cause significant elongation of the droplet, leading to its fragmentation into multiple segments. The migration of hydrated ions has a dual impact on the droplet-interface partial coalescence, with both facilitative and suppressive effects. The time required for droplet-interface partial coalescence initially decreases and subsequently increases as the field strength increases, depending on the competitive relationship between the extent of droplet stretching and the electric field force. This work provides molecular insights into the droplet-interface coalescence mechanisms in water-in-oil emulsions under DC electric fields.

Numerical investigation of heat transfer enhancement in dielectric fluids through electro-thermo-capillary convection

In this study, a 2D numerical analysis was conducted to investigate electro-thermo-capillary convection in a 2D enclosure filled with a dielectric fluid. The enclosure had a free top surface and was subjected to buoyancy and electrical forces. The study considered a strong unipolar injection of electric charge (C = 10), a mobility number (M = 10), and a Prandtl number (Pr = 10). Calculations were performed for various thermal Rayleigh numbers (Ra) ranging from 5000 to 50,000, Marangoni numbers (Ma) varying from −5000 to 5000 and electric Rayleigh numbers (T) ranging from 100 to 800. The coupled equations governing the electro-thermo-convection problem (Navier-Stokes, energy, charge density transport, and the Maxwell-Gauss equations) were established and solved numerically using the FVM. This study involved mathematical modelling of complex and coupled phenomena, considering viscous, thermal, thermocapillary, and electrical instabilities. The findings showed a significant improvement in heat transfer with higher electrical and thermal Rayleigh numbers. Furthermore, the control of different forces led to an increase in the Nusselt number. Specifically, the application of thermal forces resulted in a 70% increase, while the use of thermocapillary forces led to a remarkable 169% increase. Additionally, electrical forces resulted in an impressive 224% increase. Multi-parameter correlations were established to estimate the Nusselt number as a function of the Marangoni, thermal and electrical Rayleigh numbers.

Influences of electric guitar pickup magnetic force on string vibrations

The design of a magnetic pickup has a significant impact on the tone of an electric guitar. In particular, the magnetic force from the pickup can influence the string vibrations and cause a beating effect, depending on the strength of the magnetic force and the amplitude of the string vibrations. To understand this behavior, we performed experiments and simulations. We measured and modeled the transversal string restoring force at various displacements from the magnetic pickup in directions both parallel and perpendicular to the guitar body. We observed that the magnetic force distribution is asymmetric in the perpendicular direction but symmetric in the parallel direction, which distorts the frequency of vibrations in opposite ways for the two directions and causes a resultant beating. This effect increases with larger string amplitudes or greater magnetic force and also varies over the duration of a plucked tone.

Investigation of the role of charge injection and Coulomb force during the melting of phase-change materials under constant temperature boundary conditions

This paper presents an investigation of the melting of dielectric material in a rectangular cavity under the effect of electrohydrodynamics (EHD). First, phase-change modeling is implemented to simulate the melting performance of paraffin wax without EHD under constant temperature boundary conditions until a steady-state condition is achieved. Next, the whole set of coupled EHD equations is introduced to the model, with the Coulomb force using a Heaviside function for charge injection being the only electrical body force considered. Finally, the numerical model is implemented using the finite element method to solve for the electric field, flow field, temperature field, and charge transport. The numerical results show that, under the effect of EHD, melting continues due to the generation of electroconvection cells in the liquid phase-change material and the flow field manifests as two symmetric rotational cells generated between every two successive electrodes. The flow field causes the redistribution of the temperature field in the liquid bulk, which enhances the heat transfer. Melting continues until a steady-state condition is almost reestablished after about one hour. The enhancement factor, defined as the ratio of the EHD melt thickness to the steady-state melt thickness without EHD, is 2.33 at 6 kV applied voltage.

Development of a Monte Carlo tool for simulating electron transport in noble liquids

This study presents a Monte Carlo simulation tool for modeling the transportation processes of thermal electrons in noble liquids, specifically focusing on liquid argon and liquid xenon. The study aims to elucidate the microscopical mechanisms governing the drift and diffusion of electrons within the context of time projection chambers (TPCs), with detailed considerations of coherent electron-atom scattering and electric field force. The simulation tool is implemented in the Geant4 framework, allowing for the exploration of electron transport parameters, including drift velocity, longitudinal diffusion coefficient, and transverse diffusion coefficient. The simulation is validated by comparing its results for drift velocity and diffusion coefficients with experimental measurements, revealing reasonable agreement in the low to moderate electric field ranges. Discrepancies between the simulation and experimental measurements are discussed, emphasizing the necessity for enhanced cross-section calculations and high-precision sampling. Despite certain limitations, the simulation tool provides valuable insights into electron transport in noble liquids, establishing a foundation for future enhancements and applications in various research areas

Reconstruction methods for super-resolution imaging with PSF modulation

Recently, a super-resolution imaging method called the PSF (point spread function) modulation method was developed (Lu, IEEE TUFFC 2024). In this method, the amplitude, phase, or both of the PSF of a linear shift-invariant (LSI) imaging system is modulated so that the modulated PSF has a higher spatial frequency than that of the original PSF to reconstruct super-resolution images. The modulator can be produced and manipulated remotely by methods such as radiation force or it can be a physical particle such as micro- or nano-particle manipulated by an external force such as electrical and electromagnetic force. In principle, the super-resolution imaging method can be applied to any LSI imaging system, such as ultrasound, optical, photoacoustic, electromagnetic, underwater, nondestructive evaluation (NDE), and magnetic resonance imaging (MRI) system. These include pulse-echo ultrasound imaging, transmission imaging, wave source/field imaging, acoustical camera, and optical bright-field microscope. To optimize the quality of the images, methods for the reconstruction of pulse-echo and wave source/field super-resolution images are studied and the results will be presented. These methods include the uses of an analytic envelope of radio-frequency (RF) signals with and without windowing, “I” (in-phase) and “Q” (quadrature) signals, and the DC (direct current) component removal.

Transient electrophoresis of a conducting cylindrical colloidal particle suspended in a Brinkman medium

The time-dependent electrophoresis of an infinitely cylindrical particle in an electrolyte solution, saturated in a charged porous medium after the sudden application of a transverse or tangential step electric field, is investigated semi-theoretically with an arbitrary double-layer thickness in an arbitrary direction relative to the cylinder. The time-dependent modified Brinkman equation with an electric force term, which governs the fluid flow field, is used to model the porous medium and is solved by using the Laplace transform technique. Explicit formulas, for the time-dependent electrophoretic velocity of the cylindrical particle in Laplace’s transform domain, have been derived for both axially and transversely when the uniform electric fields are imposed. They can also be linearly superimposed for an arbitrarily oriented relative to the electric field. Semi-analytical results for the electrophoretic velocities are presented as functions of the dimensionless elapsed time, the ratio of the particle radius to the Debye length, the particle-to-medium density ratio, and the permeability parameter of the porous medium. The results demonstrate, in general, that the growth of the electrophoretic velocities with the time scale are more slower for high permeability, and the effect of the relaxation time for unsteady electrophoresis is found to be negligible, regardless of the thickness of the double layer, the relative mass density or the permeability of the medium. The normalized transient electrophoretic velocities exhibit a consistent upward trend as the ratio of the particle radius to the Debye screening length increases. Conversely, they display a consistent downward trend as the particle-to-fluid density ratio increases, while all other parameters remain constant. The effect of the relaxation time for the transient electrophoresis is much more important for a cylindrical particle than for a spherical particle due to its smaller specific surface area.

Electric field control of magnetic anisotropy and model for oriented Co/graphene design

Electric field controlled magnetic devices have attracted interest in the area of magnetic recording research, owing to their lower power consumption and high stability. While heterostructures composed of Co and carbon materials exhibit unique properties, our understanding of the magnetic properties of Co on graphene with a wavelike structure and related electric field-controlled phenomena remains limited. Here, we demonstrate the preparation of a customized Co/graphene structure, in which the controllability of the coercive force is enhanced. Taking the coercive force and geometric factor of Co into consideration, a shape-dependent magnetic anisotropy is proposed, which sufficiently explains the correlation between the coercive force and the aspect ratios of the Co stripes. For the magnetic field perpendicular to the bottom lines of canyons, the adjustment capability of the coercive force is enhanced under conditions of a more negatively charged surface. Based on the large electric field and related magnetic anisotropy energy, a ferro-ionic control (FeIC) model is proposed, which describes the relationship between the electric potential and coercive force in electrified conditions. Based on a FeIC model with a preferred orientation, we propose a design of an integrated FeIC inductor with field tunability that could strongly impact the field of integrated-circuit design, resulting in wider applications and functionalities of chips.

Electro-Magnetic and Stress Analysis of a −400 T2/m High-Field Gradient Magnet with a Room-Temperature Bore Size of 200 mm

High-field-strength gradient superconducting magnets have been widely used in many fields. With advancements in technology, the demand for large-aperture magnets is gradually increasing, but there is relatively little research on the design and stress–strain of large-aperture gradient magnets. This article presents the design and analysis of a superconducting magnet characterized by a high field strength of 10 T, a strong gradient of −400 T2/m, and a large room-temperature bore of 200 mm. The aim of this project is to establish an experimental setup for the growth of Ga1−xInxSb crystals. The study starts with an overview of the development process and applied research related to strong-gradient magnets. The study employs a magneto–electric force coupling method based on generalized stretching to theoretically optimize the gradient coil pre-stress parameters through orthogonalization parameter scanning. In addition, an analysis of the stress distribution in both the magnet coil and the mandrel is carried out. The results indicate that the stress and strain values for both the gradient coils and the frame are within the allowable range of their respective materials. The magnets can be designed to operate stably in theory. This article may provide a reference for designers in related fields in optimizing the design and stress–strain analysis of large, strong-gradient magnets.

Probing the nanomechanics of interfacial interactions between hydrophobic surfaces

Hydrophobic interactions are widely applied in diverse fields, yet the effect of the degree of hydrophobicity on the interactions between hydrophobic surfaces is still unaddressed, limiting the development of functional hydrophobic surfaces. In this study, the interfacial interactions and configuration of hydrophobic chains on surfaces with ranging hydrophobicity are surveyed by surface forces apparatus. Our findings revealed that with partial hydrophobicity, a long-range electrical double-layer repulsive force pertains between surfaces, while between fully hydrophobized surfaces, only steric hindrance is observed, and the hydrophobic chains maintain configuration even after long time compression. Our findings provide useful implications for understanding hydrophobic interactions.

An environment-friendly capacitive deionization recovery strategy for rare-earth (La/Nd/Ce/Pr) ions based on nickel foam

Rare earth (RE) is a non-renewable strategic resource widely used in many high-tech fields, it is crucial to develop clean and efficient separation technologies for RE elements. In this work, the RE ions (RE=La, Nd, Ce and Pr) in single or mixed simulated solution are recovered using nickel foam (NF) as an adsorptive electrode by capacitive deionization (CDI) technology. The adsorption capacity of NF from solution of the studied RE is amounted to 1347.7 mg g−1 for La(NO3)3, 841.9 mg g−1 for Nd(NO3)3, 810.7 mg g−1 for Ce(NO3)3 and 1082.0 mg g−1 for Pr(NO3)3 within 300 min, indicating the strong effect of an electric field force on the mobility of RE ions. The obtained products are designated as La(OH)3, CeO2, Pr(OH)3 and Nd(OH)3, respectively. Changes in pH and conductivity occur due to the adsorption of RE ions and water hydrolysis. The respective precipitates are deposited on the ribs and in the void of NF electrode, leading to an increase in reaction impedance and reducing the adsorption rate. By monitoring the adsorption, La, Ce, and Pr are indicated to follow the second order kinetics, while Nd follows the first order kinetics. Furthermore, the RE elements are simultaneously adsorbed from mixed solutions, and the electrode can be reused for several times without Ni corrosion. RE3+ ions can be recovered rapidly within a few minutes without any other chemical agents, making this an inexpensive and environment-friendly way to recover or enrich RE elements.

Simulation analysis on the synergistic effect of vegetation ashes and charged particles on the gap electric field distortion

Hill fires, a sort of ultra-natural disaster that poses a severe threat to the safe and stable operation of transmission lines, have become more frequent in recent years. Currently, the modeling research on the transmission line gap electric field distortion under hill fire conditions does not consider the synergistic effect of charged particles and ash particles, which would lead to the imperfect gap electric field distortion mechanism. Herein, a coupled multi-physics field simulation model of electric, thermal, fluid, chemical field and particle motion was constructed to analyze the electric field distribution and particle motion. Compared to the related simulation models, this study improves the simulation accuracy by around 407% by optimizing the structure and parameters of the simulation model. The FEM software COMSOL Multiphysics simulation results show that the percentage of ash entering the examined region of the AC conductor was 34.1% higher, and the percentage of connected ash was 45% higher, increasing the likelihood of gap breakdown compared to the DC conductor; the charge of ash (10−14 to 10−11) is significantly less than the saturation charge of ash (⩾10−3). Therefore, the charged particles change the motion characteristics of the ash primarily through the electric field force and dielectrophoresis force, while the ash-induced distortion of the electric field affects the spatial distribution of the charged particles, eventually, the background electric field undergoes significant distortion by the synergistic effect of the two. The results examine the inherent mechanism of gap electric field distortion at the microscopic level, which can provide theoretical support for understanding the transition phase of transmission line gaps from insulation to break down under hill fire conditions.