Journal of Electrostatics最新文献

A three-electrode hybrid volume/surface dielectric barrier discharge (V-SDBD) configuration with two plane electrodes and six grounded strips electrode was designed for enhancing the generation of discharge plasma to degrade gaseous benzene. Two plane electrodes were separately powered by a 5 kHz AC generator and a 50 Hz AC generator, respectively. Compared with the typical two-electrode volume DBD (VDBD) reactor excited by 50 Hz AC generator, the hybrid V-SDBD reactor has lower onset discharge voltage and better discharge homogeneity, and the benzene degradation efficiency of V-SDBD was 1.12 times higher than that of VDBD at a similar energy efficiency. Moreover, an increase in the voltage on HVE-II promoted benzene degradation, but decreased the energy efficiency of benzene degradation.

Antimicrobial plasma effects are promising for therapeutic applications like wound healing, cancer/tumor treatment, or pathogen-associated skin or dental diseases, but also in hygiene, food, and agriculture processing. Dielectric Barrier Discharge (DBD) reactors are the most widely used systems for antimicrobial purposes because they can use atmospheric air as a gas, do not require a vacuum, and are simple, inexpensive, and easy to use. However, when DBD plasma is applied directly to the biological sample, discharge current may pass through the biological sample, causing the plasma to transit to spark discharge and thus causing damage to the biological sample. Since Surface Dielectric Barrier Discharge (SDBD) plasmas can be generated far from the sample, they offer great advantages in the application of non-thermal plasma in extremely large volumes. While SDBD plasmas are generally generated on the lid of the container in which the sample is placed and the plasma species are expected to reach the sample, in this study, SDBD plasmas were produced on the container itself. A new SDBD reactor that can be applied to samples of various sizes and properties for antimicrobial purposes was manufactured. Gram-negative E. coli, gram-positive S. aureus and E. faecalis planktonic bacteria were placed in the reactor and inactivated for 10 min by exposure to non-thermal plasma. A plasma sterilization unit with 31.4 W power, practical, user-friendly, developed for bio-applications, with a 6.2-liter capacity.

The physics of like-charge attraction in a collinear binary system of $N$ particles has been investigated via a polarizable-ion model. It was found that like-charge attraction between an array of $(N-1)$ type-A particles on the left and a single type-B particle on the right is conditional upon a sufficient degree of dissimilarities between the two types of particles. By assuming that (1) the particles of one type are strongly polarizing (but weakly polarizable) such that the Coulomb fields they produce are dominant all over other electric fields, and that (2) the particles of the other type are strongly polarizable (but weakly polarizing) such that their Coulomb-field-induced dipoles are the only polarization effects worth considering, a good agreement between our approximate analytic theory and exact numerical solutions has been obtained. Our analytic results show that the attractive components of the electrostatic force between the two types of particles could be thought of as arising from imaginary charges induced in the polarized particle(s) by the polarizing ones, resulting in a screening of the real charge(s) in the polarized particle(s). Like-charge attraction occurs if the field contributions from the imaginary charges collectively outweigh the field contribution(s) from the real charge(s).

The Triboelectric nanogenerator (TENG) has numerous applications in biophysical health monitoring due to its small size, lightweight, and economical use. The triboelectric effect occurs when two triboelectric materials with opposite polarities come into contact or rub against each other. This paper presents the simulated output performance of a three-dimensional TENG with two opposite dielectric circular layers separated by a distance of 0.05 μm. The bottom negative layer of polytetrafluoroethylene (PTFE) with a 0.5 μm diameter and 0.1 μm thickness has a negative aluminium electrode with the same dimensions. The top of the negative layer has cylindrical surface morphology. A layer of copper serves as both a positive layer and electrode with a diameter of 1 μm and a thickness of 0.1 μm. Furthermore, for analysis, PTFE is replaced by polyvinyl chloride (PVC) and polyethylene and the results are compared. The Finite Element Analysis (FEA) was used to analyze the geometry, employing a combination of Solid mechanics and Electrostatic module of COMSOL Multiphysics 5.6 software. The result shows that a maximum output voltage of 35.9 V was observed for an applied pulse pressure of 3 kPa as input. The results indicate that the TENGs have the potential to be used for various devices and wearable healthcare monitors.

This study sets out to describe the interaction of charged confined particles with a gravitational field. The system consisted of charged particles interacting electrostatically between themselves and with a confining box whose walls have a linear charge distribution. We studied numerically several configurations including the introduction of a tilt, that takes into account the Earth’s gravitational field. In our analysis, we included the $\alpha$ parameter for describing the position of the center of mass and its evolution according to the influence of the box size. We also studied in detail the competition between the gravitational field and electrostatic forces over the system. Such a competition determines the shape and size of the distributed charges. When the electrostatic force is dominant, the charges are distributed almost symmetrically. Whereas, when the gravitational field is preponderant, the distribution of particles tends to have a hive-like shape and then as the tilt angle increases the distribution is flattened. This effect is exacerbated when the particles have bigger masses and the inclination is higher. From a physical analysis, we obtained an expression to determine the center of mass of the distributed particles, depending on the box’s size and other physical parameters. Finally, based on the data analysis, we obtained fitting equations for the gravitational (logarithmic) and electrostatic (exponential) energies as a function of the enveloping area.

An EHD flow has complex characteristics with superimposed characteristic structures of various scales due to the coupling effect of the electric and flow fields. This paper provides a new research perspective on active control techniques of EHD flows by unraveling the large-scale dynamic structure of the dominant electroconvection from the manifold of the jet. The SVD-based POD technique in our work marks the first comprehensive investigation of modal analysis for EHD jets, aiming at extracting reduced-order modes that capture the main features and exploring the mechanisms that govern these jets through a deeper understanding of dynamic physics. The findings indicate that large-scale coherent structures that determine the EHD flows regularly emerge in the low-order modes, and fine-scale vortex structures typically appear in the high-order modes. In addition, the POD-based flow field recovery technique can effectively remove the spurious vectors from the PIV dataset by simply excluding the high-order modes from the expansion during reconstruction.

In this work, the coalescence motion characteristics of two droplets under the chaotic pulse position modulation (CPPM) electric field and the influence of electric field parameters on the coalescence motion of the droplets were studied. The numerical results show that the coalescence motion of the droplets under the action of CPPM electric field is related to the deformation relaxation time. The pulse width mainly affects the droplet movement process, and has little effect on the droplet coalescing time. The electric field strength affects the droplet coalescence efficiency, and the greater the electric field strength, the shorter the droplet coalescing time. This study provides a theoretical basis for the application of CPPM electric field in practice.

We have investigated the potentialities of dielectric barrier discharges (DBD) for aerosol electro-processing with a special focus on ion production and aerosol charging for deposition (filtration and materials) and aerosol measurement tools. The advantages and drawbacks of aerosol injection downstream or upstream of the discharge are compared according to the application. The main parameters that control ion production and transport are investigated based on post-discharge ion current measurements. Post-DBD aerosol chargers are compared for submicron particle size measurements based on aerosol bipolar charging and electrical mobility analysis. Finally, the principle of counterflow extraction of bipolar ion from an atmospheric pressure DBD is established from upstream measurements of positive and negative ion fluxes in air, without neither ozone (<0.1 ppmv) nor nanoparticles.

Materials with triboelectric properties are critical to boosting the efficiency of triboelectric nanogenerators (TENG) by gathering power from waste force and mechanical movement. In this study, we explored tin-oxide (SnO₂) thin films with silver (Ag) seed layer properties for friction surfaces at TENGs. Investigation of the triboelectric behavior of semi-conductor/polymer coupling structured TENGs formed by thin films with and without Ag seed layer after heat treatment was explored by X-ray diffraction (XRD), electron microscopy (SEM), atomic force microscopy (AFM), and semi-logarithmic current-voltage measurements. Similar structural characterization studies were carried out in indium tin oxide coated polyethylene terephthalate film (PET/ITO) for the polymer friction layer. Semiconductor/polymer coupling structured TENG efficiency was evaluated in contact-separation mode and the output voltage-current was enhanced to 80 V, 4 μA, and 210 μW of output power calculated by depositing a SnO₂ thin film on an Ag seed layer, respectively. Our findings offer a different perspective for synthesizing the semi-conductor/polymer coupling structured TENGs for promising applications in a range of application technologies.

Aiming at the current wet plume problem, we present a novel technique to integrate electrostatic precipitator (ESP) and heat exchanger in order to simultaneously increase heat exchange efficiency, collect water and control particle emission from flue gases. Unlike the conventional ESP, a lab-scale wire–cylinder type ESP with the collection electrode cooling by water is used for investigations in this paper. Our research indicates that the heat transfer coefficient of the ESP rises with reducing gaseous velocity, increasing applied voltage, corona current or gas temperature. The maximum improvement of the total heat transfer coefficient of 271% was achieved at 0.15 m/s, 80 °C and 16 kV of the negative discharge. Moreover, the presence of Particle matters can enhance the heat transfer coefficient by 9%–16%. The ionic wind, which is quantitatively expressed by electro-hydrodynamic number, plays a key role in modifying the gas flow patterns and consequently improving the heat exchange coefficient. For lowering the overall energy consumption, it is suggested that the ESP should be operated at a specific mode of low voltage and high current.