Surface Charge Density Distribution Research Articles

Electric Susceptibility at Partial Coverage of a Circular One-Side Access Capacitive Sensor with Rigid Polyurethane Foams.

The capability of dielectric measurements was significantly increased with the development of capacitive one-side access physical sensors. Complete samples give no opportunity to study electric susceptibility at a partial coverage of the one-side access sensor's active area; therefore, partial samples are proposed. The electric susceptibility at the partial coverage of a circular one-side access sensor with cylinders and shells is investigated for polyurethane materials. The implementation of the relative partial susceptibility permitted us to transform the calculated susceptibility data to a common scale of 0.0-1.0 and to outline the main trends for PU materials. The partial susceptibility, relative partial susceptibility, and change rate of relative partial susceptibility exhibited dependence on the coverage coefficient of the sensor's active area. The overall character of the curves for the change rate of the relative partial susceptibility, characterised by slopes of lines and the ratio of the change rate in the centre and near the gap, corresponds with the character of the surface charge density distribution curves, calculated from mathematical models. The elaborated methods may be useful in the design and optimization of capacitive OSA sensors of other configurations of electrodes, independent of the particular technical solution.

Phenolics from Polygonatum cyrtonema Hua extracted using natural deep eutectic solvents combined with auxiliary techniques: Composition, bioactivity, and mechanistic elucidation

This study investigated the natural extraction of polyphenolic compounds from Polygonatum cyrtonema Hua (P. cyrtonema). Employing the combination of natural deep eutectic solvents (NADESs) and auxiliary extraction techniques, we mainly focused on yield, total phenolics, total flavonoids, antioxidant capacity, and enzyme inhibition efficiency. Compared to hot reflux extraction (HRE), the NADES extract using a 1:2 ratio of choline chloride-lactic acid (ChCl-Lac) significantly increased the total phenolic content (TPC), total flavonoid content (TFC), and α-glucosidase inhibition (p < 0.05). The HPLC-MS-MS identified the five most abundant phenolic compounds. Quantitative analysis showed that these compounds had the highest leaching rates in the ultrasonic-assisted extraction (UAE) combined with lactic acid-based NADES system, followed by microwave-assisted extraction (MAE), requiring less than 4 min. Notably, rutin exhibited the highest extraction rate of 281.1 μg/g in the UAE-ChCl-Lac system, 9.82 times higher than conventional methods. The extraction mechanism was elucidated from the perspectives of surface charge density distribution and interaction energy. Therefore, ultrasound or microwave-assisted NADES extraction aligns with sustainable development principles, offering a green approach to enrich polyphenolic compounds in P. cyrtonema.

Method for Measuring Surface Charge on Insulating Materials Based on the Vibrating Capacitor Method

The phenomenon of surface charging, known as contact electrification or tribocharging, has wide-ranging applications but also notable hazards. Precisely measuring surface charge density in insulating materials is crucial for optimizing tribocharging and mitigating adverse effects. Although the vibrating capacitor method is commonly used for this purpose, its principle, designed for conductive materials, limits direct application to insulating surfaces, leaving the relationship between measured surface potential and surface charge density unclear. To address this issue, this study simulated the process of measuring the surface potential of insulating materials using Comsol simulations. It analyzed the effects of charged area size, probe height, and probe position, and utilized the spatial distribution of potential measurement values of surface point charges to derive an integral relationship between the distribution of measured surface potential values and the distribution of surface charge density. The integral relationship of surface potential distribution under different forms of surface charge density distributions calculated from this formula largely matches the numerical simulation results. Based on this, a relationship between the distribution of surface charge density and surface potential measurement values was further derived. This relationship can be used for measuring the surface charge density of insulating materials.

COSMO-RS guided screening of ionic liquids for the separation of fluorinated greenhouse gases R-410A: Delving into anion, cation effects, and hydrogen bond dynamics

Reclamation of high-GWP near-azeotropic refrigerant R-410A (50 wt% R-32 (difluoromethane) + 50 wt% R-125 (pentafluoroethane)) can be an effective way to mitigate the greenhouse effect and achieve a circular economy. Efficient ionic liquids (ILs) as extractants needed to be found for the extractive distillation (ED) separation process of R-410A. Given the numerous combinations of cations and anions in ILs, the discovery of an efficient IL via experimental methods proves to be an exceedingly complex task. In this work, the solubilities of R-32, and R-125 in 840 conventional ILs (comprised of 20 cations and 42 anions) were analyzed based on infinite dilution activity coefficient. The absorption mechanisms of R-32 and R-125 in ILs were elucidated by analyzing excess enthalpy (HE), excess Gibbs free energy (GE)) and surface charge density distribution through COSMO-RS (Conductor-like Screening Model for Real Solvents). Results revealed that HE and GE of the mixture formed by R-125 and most ILs surpassed those of R-32, resulting in higher solubility of R-32 in most ILs compared to R-125. Structural changes of anions and cations had a greater effect on the solubility of R-125 in ILs. It is found for the first time that the existence of a strong hydrogen bond donor region in cations/anions generated intense repulsion with the hydrogen atom in R-125. Furthermore, a large area of weak polarity on the surface of cations/anions was difficult to form an effective charge shield with fluorine atoms in R-125, thus inhibiting the dissolution of R-125. Finally based on the identified interaction sites, combined with melting point and viscosity, some novel functional ILs with high selectivity for R-32 + R-125 were designed and determined for actual separation process. These findings significantly enrich the understanding of the solubility mechanism and provide theoretical guidance for designing new ILs for R-410A reclamation.

Theoretical modeling approach for adsorption of fibronectin on the nanotopographical implants.

The success of orthopedic implants depends on the sufficient integration between tissue and implant, which is influenced by the cellular responses to their microenvironment. The conformation of adsorbed extracellular matrix is crucial for cellular behavior instruction via manipulating the physiochemical features of materials. To investigate the electrostatic adsorption mechanism of fibronectin on nanotopographies, a theoretical model was established to determine surface charge density and Coulomb's force of nanotopography - fibronectin interactions using a Laplace equation satisfying the boundary conditions. Surface charge density distribution of nanotopographies with multiple random fibronectin was simulated based on random number and Monte Carlo hypothesis. The surface charge density on the nanotopographies was compared to the experimental measurements, to verify the effectiveness of the theoretical model. The model was implemented to calculate the Coulomb force generated by nanotopographies to compare the fibronectin adsorption. This model has revealed the multiple random quantitative fibronectin electrostatic adsorption to the nanotopographies, which is beneficial for orthopedic implant surface design.Significance: The conformation and distribution of adsorbed extracellular matrix on biomedical implants are crucial for directing cellular behaviors. However, the Ti nanotopography-ECM interaction mechanism remains largely unknown. This is mostly because of the interactions that are driven by electrostatic force, and any experimental probe could interfere with the electric field between the charged protein and Ti surface. A theoretical model is hereby proposed to simulate the adsorption between nanotopographies and fibronectin. Random number and Monte Carlo hypothesis were applied for multiple random fibronectin simulation, and the Coulomb's force between nanoconvex and nanoconcave structures was comparatively analyzed.

Temperature-Dependent Surface Charge Accumulation for Vertical and Horizontal HVDC GIL

In this paper, the heat transfer process of DC gas-insulated transmission line (GIL) is comprehensively considered, including thermal conduction, thermal convection and thermal radiation. An electric-thermal field coupling model is established to characterize the surface charge accumulation characteristics of insulators. The temperature and insulator surface charge density distribution of a 3-D GIL model under different GIL installation ways (i.e. vertical and horizontal GIL) are obtained by finite element software. The results show that: under the identical load current, a large temperature difference (up to 5.7 °C) is shown between both surfaces of vertical GIL insulator, and the temperature on the insulator surface is distributed symmetrically along the center of the insulator. However, the temperature on both surfaces of the horizontal GIL is basically the same, but the temperature distribution varies greatly along the different radial directions of the insulator (up to 5.3 °C). By comparing the surface charge density distribution of insulators under both GIL installation ways, it is found that the surface charge density of horizontal GIL is more than 20% higher than that of vertical GIL. In addition, the volume conductivity distribution of insulator varies greatly under different GIL installation ways. The volume conductivity is positively correlated with the temperature distribution, while the normal electric field on the insulator surface is negatively correlated with volume conductivity distribution. It is hoped that this study can serve as a reference for the design and safe operation of DC GIL.

A new method of Ionic Fragment Contribution-Gradient Boosting Regressor for predicting the infinite dilution activity coefficient of dichloromethane in ionic liquids

Ionic liquids (ILs) have shown huge potential advantages as solvents to absorb and recover dichloromethane (DCM) from waste gases. The infinite dilution activity coefficient ( γ ∞ ) of DCM in ILs is an important parameter, which can be used to predict the vapor-liquid equilibrium of DCM-IL systems. In this work, a new model of calculating the γ ∞ of DCM in ILs is established based on ionic fragments contribution (IFC) and gradient boosting regressor (GBR) algorithm. IFC is used to obtain the surface charge density distribution area of ILs (S σ-profile ) that is the input of GBR. GBR is used to learn the mapping relationship between input feature and γ ∞ of DCM in ILs. The database of the γ ∞ of DCM in ILs composed of 29 cations and 22 anions includes 72 experimental data and 421 COSMO calculation data, which was employed to establish the IFC-GBR model and predict the γ ∞ of DCM in ILs. The coefficient of determination (R 2 ) and mean absolute error (MAE) of the IFC-GBR model test set are 0.9703 and 0.0519, respectively. Also, this model has excellent generalization capability of predicting evidenced by high 10-fold cross-validation coefficients of determination in the range 0.9474–0.9481. These results indicate that the proposed model can accurately predict γ ∞ of DCM in ILs, then provide the important data for developing a new process of absorbing and desorbing DCM by IL-based technologies.

Temperature Dependence of Surface Charge Accumulation on DC-GIS Insulating Spacer

Surface charge accumulation on an insulating spacer is a critical issue that causes electric field distortion and flashover voltage reduction in DC-GIS. In the operating environment, high-voltage electrode is heated by Joule heat, and the surface charge accumulation is strongly affected by the temperature. This study reports the temperature dependence of surface charge accumulation on DC-GIS insulating spacer and its impact on electric field distortion. Surface charge density distribution is measured on a downsized epoxy spacer under isothermal conditions at room temperature, 40 °C, and 70 °C. Special care is taken to realize a low-moisture and low-dust environment. We obtain the saturation tendency of homo-charge accumulation with less random charges and its temperature dependence. Homo-charge accumulation develops more rapidly and more extensively on the spacer at the higher temperatures. Our results indicate that the surface charge accumulation cannot be explained by a conventional resistive field calculation, and that an explanation based on charge trapping is reasonable. They also show that the homo-charge accumulation significantly contributes to the electric field enhancement after the polarity reversal in our experimental system, especially at high temperatures.

Characterisation of surface charge density and net electric field during parallel-plate dielectric barrier discharge generated in atmospheric-pressure air

We measured the surface charge density in a parallel-plate dielectric barrier discharge (DBD) using the Pockels effect, and the axial and lateral components of the net electric field were evaluated for different gap lengths and applied voltages. The DBD was driven by a 5 kHz sinusoidal voltage in gap lengths of 0.5, 0.3, and 0.1 mm at atmospheric pressure with Bi4Ge3O12 crystal as a dielectric. Typical microdischarges (MDs) were observed for every gap length, and the number of MDs increased with the increasing applied voltage. As the gap length decreased, the spot radius of a single MD decreased, whereas the peaks of charge density were almost the same, indicating that the amount of charge transported per unit MD is limited for short gaps. The spatial memory effect, in which MDs occur at the same position in successive cycles, was not always observed under the experimental conditions, and it was evaluated considering the surface charge density distributions. Whether the memory effect works is determined by the surface charge density, and it is likely to occur under a balance between positive and negative charges across successive half-cycles. The net electric field was estimated from surface charge measurements. The axial component of the net electric field strength increased up to 150–170 Td before the MD occurred, and it decreased below 100 Td by the surface charge deposited by MD, being approximately 50%–60% of the external field amplitude. The maximum value of the lateral component of the electric field was approximately 150 Td at the edge of the MD spot with a gap length of 0.5 mm, and it decreased as the gap length decreased. As a negative surface charge generated a weaker lateral field than a positive one, the electric field distribution differed between anodic and cathodic dielectrics.

Economic, environmental, exergy (3E) analysis and multi-objective genetic algorithm optimization of isopropyl acetate production with hybrid reactive-extractive distillation

Isopropyl acetate (IPAC) is an important fine chemical intermediate with a great demand for industrial production. In view of the high energy consumption in the traditional reactive distillation (RD) process of IPAC production, this study further proposed three enhanced processes of reactive-extractive distillation (RED), reactive-extractive dividing wall column (REDWC) and reactive-extractive distillation coupled pervaporation (REDPV) process. Firstly, the surface charge density distribution between components is calculated by COSMO-SAC model to screen a variety of potential solvents. Combined with the empirical screening method, relative volatility is used to determine the optimal solvent. Then, the conceptual design of RD, RED and REDWC three processes are completed based on reaction kinetics, and the operating conditions of processes are optimized by multi-objective genetic algorithm. Furthermore, REDPV process using pervaporation module instead of solvent recovery column is proposed. Finally, the total annual cost (TAC), gas emissions and exergy efficiency are used to evaluate the proposed process. The results show that compared with RD process, the TAC and gas emission of RED process are reduced by 42.69% and 49.82%. While those of REDWC process are reduced by 45.06% and 52.93%. The thermodynamic efficiency of these two processes is increased by 63.28% and 62.67%. Compared with RED process, REDPV process further reduces the cost by 14.45% and the gas emissions by 34.55%, but obtain the lowest thermodynamic efficiency.

Streamer–surface interaction in an atmospheric pressure dielectric barrier discharge in argon

An atmospheric-pressure dielectric barrier discharge (DBD) in argon is investigated using a time-dependent and spatially two-dimensional fluid-Poisson model in axisymmetric geometry. The focus is on the streamer–surface interaction and the cathode-layer formation during the first discharge event in the single-filament DBD driven by sinusoidal voltage. A characteristic structure consisting of a volume streamer propagating just above the dielectric and simultaneous development of an additional surface discharge near the cathode is observed. The analysis of the electric field, electron production and loss rates, and surface charge density distribution shows that the radial deflection of the volume streamer is driven by free electrons remaining in the volume from the Townsend pre-phase and guided by the radial component of the electric field. The surface discharge occurring between the deflected volume streamer, which acts as virtual anode, and the dielectric surface is governed by ion-induced secondary electron emission and the surface charges accumulated on the dielectric.

Molecular mechanism, liquid–liquid equilibrium and process design of separating octane-n-butanol system by ionic liquids

The development of clean and green separation technologies has become a key scientific issue in the chemical industry. Because of the wide applicability of ionic liquids (ILs) as green and recyclable extractants, their abilities to extract and separate n-butanol from octane were explored in this work. Based on quantum chemical methods and the COSMO-SAC model, the surface charge density distributions of 22 cations, 19 anions, octane, and n-butanol were calculated. Moreover, the infinite dilution activity coefficients of octane-n-butanol-IL systems were calculated. The distribution coefficients and separation coefficients were also determined. ILs with strong extraction effects (i.e., [Bmim][HSO4], [Bmim][NO3], and [Bmim][OTf]) were used to explore the separation mechanism at the molecular scale; this was conducted by analyzing charge density, bond energy, and bond length of intermolecular interactions. The liquid–liquid equilibrium data of octane-n-butanol-ILs systems were measured, and the distribution coefficients and separation coefficients of each system were calculated. The experimental data were regressed using the NRTL model to obtain the corresponding binary interaction parameters. A process for separating the azeotropic octane and n-butanol systems using ILs was proposed. This process was simulated and optimized using the Aspen Plus 11 software. In addition, the total annual cost was calculated. This work lays the foundation for the screening of green and clean separation solvents.

Modulation of ionic current behaviors based on a dual-channel micro/nano-pipette with ternary-form-charged model

• Ternary-Formed-Charged model is proposed for simulation of ionic behaviors of a dual-channel pipette such as a resistor, diodes, and a bipolar junction transistor. • The uneven distribution and location of surface charge density are confirmed to cause asymmetric bipolar junction transistor behavior and pseudo-bipolar junction transistor behavior. • Scale ratio of radius of the pipette to liquid bridge and the effect of surface charge at the interface between liquid bridge and air is evaluated. Dual-channel micro- or nanopipettes can be used to perform various ionic current behaviors such as a resistor, diodes, and a bipolar junction transistor (BJT) via chemical modification. These ionic current devices could be modulated by charge pattern of modification, pH, size and scale ratio of pipette to the liquid bridge, whose intrinsic mechanism is indistinct. Herein, a universal Ternary-Form-Charged (TFC) model is proposed, in which the pipettes contain three individual tunable regions with different scale, location, surface charge density while ions can flux across the charged liquid bridge connected with them. Based on the TFC model, we could obtain three basic ionic behaviors mentioned above of dual-channel pipettes and demonstrate that these basic ionic behaviors of dual-channel pipette are dependent on the number of transition zone. Transformation from the BJT behavior to a pseudo-BJT behavior is attributed to a narrow middle charged region or a thick liquid bridge. Asymmetric BJT behavior is also observed under asymmetric distribution of location and quantity of surface charge density. Furthermore, we provide the approximate size of liquid bridge: 5–8 nm and 15–20 nm for dual-channel nanopipette and micropipette, respectively. In short, the TFC model and our simulation results shed light on the mechanism of dual-channel pipette based ionic circuits and provide a useful guide to design, modify and develop novel applications of dual-channel pipettes in nanofluidic sensors.

Molecular mechanism and extraction performance evaluation of diethylene glycol-based DES for extraction desulfurization process of fuel oil

From July 1, 2020, China has fully implemented the most stringent National VI emission standards for automobiles. Thiophenes (TPs) are main form of sulfur compounds in China crude oil. More than 80% of TPs is composed of dibenzothiophene (DBT). The upgrade of emission regulations will drive technological upgrades. Deep eutectic solvent (DESs) has great potential for industrial application because of its simple preparation, low cost and high extraction rate. Based on the quantum chemistry (QC), this work proposed a screening method for DESs to extract DBT from Heptane + DBT mixtures. Through quantum chemical (QC) calculation, the probability distribution of surface charge density σ (σ-profile) was obtained, and suitable DES was selected as the extractant. Molecular dynamics (MD) simulation of the microscopic behavior of the involved DESs and mixtures was carried out, and the diffusion and aggregation behavior of sulfides in DES were studied. Through the analysis of intermolecular interaction energy, radial distribution function, spatial distribution function and self-diffusion coefficient, the formation of DESs and the extraction mechanism of DBT as well as the influence of hydrogen bond acceptors (HBA)/ hydrogen bond donors (HBD) type and molar ratio were explained. The effects of process parameters and thiophene compounds on desulfurization were studied.

Nonlinear charge regulation for the deposition of silica nanoparticles on polystyrene spherical surfaces

HypothesisWe describe the deposition behavior of monodispersed silica nanoparticles on polystyrene spherical particles by using modified pairwise DLVO (Derjaguin-Landau-Verwey-Overbeek) interaction force profiles at pH values between two and twelve. Our modified model contains a new nonlinear charge regulation parameter that considers redistribution of ions, which allows us to realistically express the electrical double layer (EDL) interaction forces. ExperimentsSilanol-terminated silica nanoparticles (7.6 ± 0.4 nm), l-lysine-covered silica nanoparticles (7.8 ± 0.4 nm), and polyallylamine hydrochloride-covered polystyrene (PAH/PS) particles (348 ± 1 nm) were synthesized. Then, each type of silica nanoparticle was deposited on the PAH/PS particles at a range of pH values. FindingsOur new regulation parameter describes the realistic redistribution of charges governed by pH, total salt concentration, ionic strength of solution, and separation distance of particles. We find that this regulation parameter can be roughly approximated from the absolute values of theoretically calculated surface charge density and potential distributions, as well as experimentally measured ζ-potentials. Morphological analysis using electron microscopy of the experimental systems shows that the modified pairwise DLVO interaction forces exceptionally describe the deposition behavior of the silica nanoparticles physically adsorbed on the PAH/PS particle substrates.

Effects of pulse voltage rising edge on discharge evolution of He atmospheric pressure plasma jet in dielectric tube

In this work, we employ pulse voltage to drive an atmospheric pressure plasma jet (APPJ) in Helium, and consider mainly the evolution of discharge inside tube. Specifically, the effects of rising edge on the discharge evolution are studied through the simulation and experiment. The spatiotemporal evolution of electron density, ionization source, electron temperature and excited helium atom are evaluated. Besides, the mechanism affecting the rise time is analyzed by the parameters such as discharge current, sheath thickness and surface charge density distribution. In the considered cases, the ionization wave propagates to the ground electrode and downstream of the active electrode in the dielectric tube. The plasma with faster rising edge has larger electron temperature, discharge current, electron density and electric field strength. With the change of voltage rising edge, there occur two discharge modes: hollow mode and solid mode in dielectric barrier discharge (DBD) area. When the rising edge is of nanosecond and sub microsecond, it develops into hollow mode, and changes into solid mode after the rising edge has continued to increase. Both discharge modes are essentially affected by the sheath thickness, the electric field distribution, and the surface charge density inside the tube. When the sheath thickness is less than 1.8 mm, the plasma usually propagates in hollow mode, and when the sheath thickness is equal to 1.8 mm, the radial propagation range of the plasma is limited and changes into solid propagation. In the DBD region, when the electric field is mainly axial component, the plasma propagates in the mode at the beginning of discharge; inside the ground electrode, owing to the fact that the applied electric field is deviated from the radial direction, and that the positive charge deposited on the tube wall forms a radial self-built electric field, the strong radial electric field formed by the superposition of the two fields causes the discharge to propagate in hollow mode.

Effect of grain boundaries on the work function of hafnium: A first-principles investigation

Hafnium (Hf) has been used as a cathode material for thermionic emission in high temperature environments for a long time. However, the effect of grain boundaries (GBs) on its work function has not been reported. In this work, by using first-principles calculations, we find that the introduction of GBs would reduce the work function of Hf surface as compared with that of the perfect crystal, and by increasing the distance between two grain boundaries, the work function converges gradually to the value of monocrystalline Hf. By analyzing the surface atomic structure and charge density distribution, we find that the reduced work function of GB-containing structures originates from the increase of atomic distance and the changes of atomic coordination environments at the GB region, which results in redistribution of electrons and enhances the electronic density of states at the Fermi level.

Surface streamer patterns induced by a strong vertical electric field under impulse voltages

Discharge across an insulation surface is an important factor leading to insulation failure. Better understanding of surface discharge phenomenon is beneficial to the optimal design of insulation structures. In this letter, we report surface streamer propagation characteristics induced by a strong vertical electric field under impulse voltages. Surface charge density and electric field distribution are calculated on the basis of measurement of surface potential distribution, the correctness of which is verified by dust figure after surface discharge. The current signal during surface discharge is recorded as well, which achieves excellent agreement with surface streamer patterns. The difference in surface streamer patterns between positive and negative impulse voltages application is discussed in detail. It is found that under negative impulse voltages, surface discharge shows single-current pulse and multi-current pulse modes. The formation of the latter is closely related to the accumulated surface charges, electric field distribution and the discharge energy accumulated by the first streamer. The findings in this letter are helpful to better understand surface discharge phenomenon as well as to inspire new ideas for the optimal design of insulation structures.

Numerical simulation of dielectric barrier discharge with asymmetrical electrode in atmospheric helium

The characteristics of the dielectric barrier discharge (DBD) equipped with asymmetrical electrode (ring electrode on the upper and disk electrode on the lower) in atmospheric helium are investigated by a two-dimensional self-consistent fluid model. Simulation results show that as the applied voltage increases, the discharge enhances and the onset of discharge advances, which is similar to the results of traditional DBD. However, with the applied voltage increasing, the symmetry of the discharge current pulses in the positive and negative half cycles disappears because of the asymmetric electrode configuration. In addition, only the spatial distribution of the electron density at the peak moments of the first and second current pulses satisfies the complementary characteristics, while the spatial distribution at other peak moments does not meet the complementary characteristics. Moreover, the electric field, near the upper dielectric barrier surface, presents a curtain-like distribution with considerable radial electric field components, which results from the non-uniform radial surface charge distribution and the ring electrode configuration. The relative variation of the radial distribution of surface charge density is largely determined by the geometry of the opposite electrode.

РЕШЕНИЕ ОБРАТНОЙ ЗАДАЧИ НАХОЖДЕНИЯ ПОВЕРХНОСТНОЙ ПЛОТНОСТИ ЗАРЯДА ПО ИЗВЕСТНОМУ ЭЛЕКТРИЧЕСКОМУ ПОТЕНЦИАЛУ СРЕДСТВАМИ COMSOL MULTIPHYSICS

Relevance Polymer materials capable of electric charge accumulation on their surface and in volume have wide application in a great number of applied problems of electrophysics and high-voltage engineering due to their excellent dielectric property. This property can be both an advantage (in electret manufacture), and a disadvantage (when using polymers as an isolating medium). Fundamentally important here is the need to characterize and control the degree of charge using the value of surface charge density which, however, can be determined indirectly through the electric potential only. When measuring the potential using a capacitive probe, difficulties arise in solving an inverse problem of converting the potential into surface charge density, since the relationship between these values largely depends on the geometry of the charged body and the capacitive probe. An effective and universal conversion method will greatly simplify the measurement of the surface charge density that will be helpful in practical tasks of electrical technology and operation of high-voltage equipment with elements made of polymer materials. Aim of research Aim of the research is to develop a technique for restoring surface charge density distribution according to a given measured distribution of electric potential created by the surface charge; give recommendations on how to achieve an optimal balance between accuracy and labor intensity of numerical calculations. Methods The problem is solved using numerical modeling in finite element method based software Comsol Multiphysics. With the help of the created 3D model containing the reproduced design of the capacitive probe and the charged examined material, the principle of the weight coefficients matrix formation is explained, through which the relationship between a discrete set of measured potentials and the unknown distribution of the surface charge density is subsequently established. Results An effective method has been developed to recalculate the known distribution of the electric potential from a charged surface into its surface charge density. The principle of constructing and setting the boundary conditions in the 3D model required for recalculation is shown. On the example of one given distribution of electric potential, the high efficiency of the method for obtaining the distribution of the charge density was shown. It has been established that the accuracy of the method increases with a finer partition of the charged surface into elementary charged areas. Recommendations are given on the use of methods for solving the arising systems of linear algebraic equations. It was also shown how to simplify the technique used in the presence of an axisymmetric distribution of the charge density.