Effect Of Corona Discharge Research Articles

Effect of corona discharge on formation of holographic diffraction gratings in the Cu–As2Se3 thin-film structure

Application of negative corona discharge in the course of recording leads to an increase in the holographic sensitivity of the Cu–As2Se3 structure and diffraction efficiency of the recorded holographic gratings and the relief gratings fabricated with the aid of chemical etching. Positive corona discharge impedes the recording of holographic gratings in the Cu–As2Se3 structure. The Cu–As2Se3 structure exhibits the properties of a negative photoresist under irradiation in the presence of the negative corona discharge. In addition, the dissolution selectivity substantially increases due to the corona discharge.

Corona Discharge: A Novel Approach To Fabricate Three-Dimensional Electrospun Nanofibers for Bone Tissue Engineering.

The electrospinning process produces dense two-dimensional (2D) nanofiber (NF) sheets with small pore size that limits cell infiltration and proliferation. This study aims to fabricate three-dimensional (3D) NF sheets by designing a NF collector mounted with multiple movable needles. The corona discharge effect leads to continuous deposition of 3D polycaprolactone (PCL) NF matrices on the surface of the NF collector. The increase of the pore size, pore volume, and pore interconnectivity of the formed 3D NF sheet was confirmed by scanning electron microscopy, 3D confocal laser scanning microscopy, and micro-computerized tomography, respectively. An increased crystallinity of 3D NFs was observed by thermal and rheological analysis. Furthermore, cell growth on the 3D NF matrices was evaluated using murine pre-osteoblastic MC3T3 cells. When compared with 2D NF matrices, 3D NF matrices demonstrated enhanced cell infiltration, proliferation, and differentiation. We believe that a corona discharge-based NF collector design represents a promising approach to fabricate 3D NF matrices with desirable geometry, and microstructure. This simple, controllable, one-step process may help move forward the clinical translation of electrospun NFs in regenerative medicine.

Effect of corona discharge on the stability of the adhesion of thin silicone-organic coating to polyamide fiber surface made by the sol\u2013gel method

This paper presents the effect of pretreatment of polyamide (PA6) nonwoven with corona discharge on the stability of the adhesion of thin hydrophobic silicone-organic coating based on vinyltriethoxysilane, made by the sol–gel method. This pretreatment with corona discharge causes a change in the physicochemical properties of the PA6 fiber surface. These changes include, among others, an increase in the fiber surface roughness, wettability, and surface free energy. At the same time, XPS and EDS investigations have shown an increase in the degree of oxidation and the formation of functional polar groups on the fiber surface (C–O–, C–OH, and O=C–O–). As a result of the changes in the surface properties of pretreated PA6 fibers, a higher degree of the sol deposition was obtained compared with that for untreated nonwoven surface. The assessment of the stability of the adhesion of thin hydrophobic coating to the fiber surface was carried out on the basis of changes in the content of silica deposited on fibers and the kinetics of water contact angle after washing and abrasion processes. In the end, the PA6 nonwoven, pretreated with corona discharge, shows a higher stability of the adherence of the thin silicone-organic coating and a higher degree of hydrophobicity than the untreated nonwoven.

Agglomeration and capture of fine particles in the coupling effect of pulsed corona discharge and acoustic wave enhanced by spray droplets

Fine particles from industrial processes are considered to be potentially harmful to humans and environment, and massive amounts of fine particles are continuously emitted into the air due to the low removal efficiency of current conventional dust capture devices. A novel pretreatment process using the coupling effect of pulsed corona discharge and acoustic waves enhanced by spray droplets for fine particle agglomeration and capture was investigated in this study. The application of pulsed corona discharge in an acoustic field led to an increase in the efficiency of fine particle agglomeration to 74.7%, and the improvement was much more obvious for low frequency acoustic waves. The spray flow rate delivered by the spray nozzles with a size of 0.30mm or 0.40mm was incrementally increased. Furthermore, the penetration efficiency initially decreased, then increased, and finally decreased when droplets were sprayed in either a pulsed corona discharge field or an acoustic wave field. The penetration efficiency of fine particles substantially decreased to 10% with the enhancement of spray droplets coupled with both a pulsed corona discharge and an acoustic wave, both at their most efficient settings. The penetration efficiency further decreased with the addition of sodium dodecyl sulfonic salt surfactant to the spray droplets, in particular, at a concentration of 0.3%.

Effect of corona discharge on the structure and photoluminescence properties of nanocomposites based on polypropylene (PP) and zirconium dioxide (ZrO2) nanoparticles

ABSTRACTThe influence of corona discharge on the structure and photoluminescence properties of nanocomposites based on polypropylene and zirconium dioxide nanoparticles has been studied. It is shown that after the polarization under the influence of corona discharge surface roughness of polarized sample was for 40–60 nm whereas for unpolarized compositions it was 80–120 nm, i.e. the grinding of structural element took place. It was found that, after the polarization, the intensity of the photoluminescence increases depending the concentration. In order to determine the cause of the increase in the intensity of the luminescence by TSD method the stored charge at the interface between the components of the nanocomposite was studied. It has been shown that the polarization process led to accumulation of sufficiently large amount of electric charges at the interface between the components of the nanocomposite PP + ZrO2. The intensity of the internal local field of charges was calculated, and it was found that it creates a high internal local field due to the border charges. As a result, the luminescence intensity rose after increasing the value of the polarization.

Improvement of aluminum/polyethylene adhesion through corona discharge

Polyethylene (PE) is often used in several industrial applications including the building, packaging and transport industries. Aluminum (Al) is widely used in different applications in the automotive, railway, aeronautic, and naval industries because of its excellent mechanical and chemical properties. Laminates prepared from Al and PE lead to an enhancement in physical and mechanical properties. These materials play a main role in the packaging and building sectors, such as in TetraPak containers and aluminum composite panels. The main problem observed is associated with the adhesion between polymers and metals. This research focused on investigating the enhancement in the adhesion of the PE/Al laminate using the corona discharge. The corona treatment of the surfaces led to a significant increase in the adhesion of the PE/Al laminate as a result of improved surface properties confirmed by peel test measurements. Moreover, the positive effect of the corona treatment in combination with a primer on the improvement of adhesion characteristics was observed too. Different analytical techniques were employed to characterize the effect of the corona treatment on the improvement in adhesion of PE/Al. A significant increase in wettability was confirmed by the measurement of contact angles. Changes in the surface morphology of the PE and Al surface, after the corona treatments at different operating conditions, were observed using atomic force microscopy (AFM) and scanning electron microscopy (SEM). In addition, x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) were used to analyze changes in chemical composition after the corona discharge effect on PE and Al surfaces.

Destructive effect of atmospheric pressure pulsed corona discharge plasma in air on biofilms of opportunistic bacteria

Импульсный коронный разряд (ИКР) средней частоты в воздухе способен оказывать бактерицидное и бактериостатическое действие на культуру Escherichia сoli М17 как на клеточном, так и на популяционном уровне. Действие ИКР препятствует формированию микробного сообщества и приводит к деструкции уже образованных биопленок. В работе представлены данные электронно-микроскопических исследований ультраструктуры клеток и биопленок после их обработки ИКР в течение 90 секунд. Изменения морфологических свойств клеток E. сoli M17, вызванные обработкой ИКР, подобны изменениям после сублетального и летального теплового воздействия. Библиогр. 32 назв. Ил. 6.

Negative DC corona discharge effects on the ultraviolet photon count in rod to plane air gaps

In order to investigate the effects of negative DC corona discharge on ultraviolet (UV) photon count, a corona discharge measurement system based on rod to plane air gaps was established. The variations of positive ion, negative ion, and electron densities were calculated with a fluid model, and the generation process of photons during negative corona discharge was investigated. The differences of photon count and the variation of charged particles between negative and positive corona were also compared. The corona current, Trichel pulses, and corona‐generated photons were measured with increasing applied voltage. An approximate parabolic relationship found to exist between the photon count and the corona current, and also an ideal quadratic function was found to exist between the photon count and the frequency of Trichel pulses. These results provide a solid foundation in the application of UV imaging detection of negative DC corona discharge in power equipment. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Effects of corona discharges on a turbulent air flow: Simulation on a high-lift system

Abstract In this work, the effects of corona discharges on a wing and flap system are studied through numerical simulation. The mathematical model, which is used, reproduces the overall phenomenon of boundary layer acceleration and does not intend to model the plasma itself. The model integrates an electro hydrodynamic force, which is a function of the electric charge density of the plasma to the Navier–Stocks equations. The CFD code FLUENT associated with a UDF module is used to solve the equations associated with the mathematical model and perform the simulations. Computations are validated through the turbulent air flow over a flat plate system. Numerical results of the high lift system show a significant increase of the lift coefficients between the angles of attack of 1.8° and 6° and a delay of the boundary layer separation.

Effect of unipolar corona discharges on properties of pulp-and-paper materials

The possibility of producing pulp-and-paper materials with improved performance characteristics via exposing paper to the field of a unipolar corona discharge has been explored. It has been shown that the improvement of the physicomechanical properties of a pulp-and-paper material under the action of an electric field is associated with the orientation of the structural elements of the material and the strengthening of the bonds between the mutually approaching cellulose fibers. The enhancement of the barrier characteristics of the paper exposed to a unipolar corona discharge is attributed to the formation of an energy barrier, which is overcome at the expense of the driving force of the spreading of the liquid over the surface of the material.

SPR gas sensor with corona discharge

Surface plasmon resonance (SPR)-based sensors are widely used today for express analysis of liquid biological mediums in microbiology, medicine and genetic engineering. They are also used for detecting different contaminants in gaseous mediums. In this case, the main problem of such sensors development is choosing of selective sorbents applied to the sensor surface of for detecting a specific contaminant. Sorbent properties in combination with SPR high sensitivity define the achievable sensor parameters. At nanometer thicknesses of sorbents, the surface condition defines the main contribution to the sensor properties. The impact of the positive corona discharge plasma leads to an effective desorption of extraneous contaminants that block active adsorption centers. Furthermore, the sensor surface is exposed to radicals generated in the discharge plasma under ionization of contaminants. In the present paper, we discuss the possibility of using the corona discharge effects for developing SPR sensors, allowing one to detect trace contaminants in gaseous mediums.

The Effect of Corona Discharge on Leader Initiation in Long Air Gaps

In this paper, the effect of the corona space charge on the leader initiation is experimentally and theoretically investigated. The critical corona charge for the stem-leader transition is reviewed and a more proper charge criterion is recommended based on the experimental measurements and theoretical analysis. It is shown that the chocking effect of the corona space charge for the second corona inception should not be ignored, which decreases the electric field strength of the stem tip and hinders the initiation of the leader. A simple physical model is proposed to calculate the leader initiation time, which can consider the thermodynamic mechanism for stem-leader transition and the chocking effect of the corona space charge, and a good agreement with the experimental results was obtained.

Wplyw wyladowan koronowych na wlasciwosci warstwy wierzchniej polilaktydu

The paper investigates the effect of corona discharge (CD) treatment on the properties of surface layer (SL) of polylactide (PLA) film. The modification of PLA was carried out in the air and helium atmosphere and the results were compared on the basis of the assessment of wettability, surface free energy (SFE) calculated using Owens–Wendt method as well as the degree of oxidation (O/C) of the modified SL, determined by photoelectron spectroscopy.

Normalization of working conditions in premises of special purpose methods of artificial airionization

The paper deals with solving important scientific and technical problem of ensuring safe working conditions for the personnel of departments of the State Emergency Service of Ukraine, which is to normalize working conditions in special-purpose premises using artificial bipolar air ionization of working environment.It is shown that using modern ventilation and conditioning systems deionize air in the working areas of premises, depriving it of natural ionic composition. This negatively affects the general personnel condition of departments and their efficiency as a whole. Herewith, normative concentration level of light air ions in specialpurpose premises can be achieved using artificial air ionization methods, the implementation of which requires specific data on the air ion concentration field formation mechanism in the air of working areas.The design of adjustable bipolar corona air ionizer was developed, and relations, allowing to determine its design and operating parameters were defined. The analytical relations, the adequacy of which was confirmed experimentally, reveal the air ion concentration field formation mechanism in supply jets of ionized air that allows to estimate the working area air ion mode parameters under their direct influence.Using the developed device in special-purpose premises will ensure the implementation of occupational safety air ionization requirements and guaranteed safety of their operation, as well as high efficiency of artificial air ionization measures with their implementation cost reduction that is caused by the possibility of using engineering calculation methods in the design and manufacture of devices, based on the corona discharge effect.

Effects of Positive Corona Discharge on PH Value of Tap and Distilled Waters in Liquid system

In this paper, the effect of positive corona discharge on the PH values of tap and distilled waters are studied in water liquid system. The photographs of the results show that the shape of water drop that formed in the end of capillary tube is extended into a cone as well as a blue glow appears at the end of capillary tube. The size of cone decreases with increases of applied voltage and because of the change distance between the liquid electrode and the surface of liquid, the cone diameter at the end of capillary tube oscillates with period approximately 1 Sec. In addition, the PH values of both tested waters are constant when the applied voltage is less than 5 KV, while when the exterinal applied voltage is equal to or greater than 5KV, the PH value of both water types are increases rapidly where the tap water shows increases rate larger than that for distilled water.

Research of biocidal effect of corona discharges on poly(lactic acid) packaging films

Investigation of the effect of corona discharges on the mortality of the strains of bacteria and fungus: Salmonella enteritidis, Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, and Penicillium chrysogenum is presented. The microorganisms were placed onto a polylactide (PLA) packaging film. The surface layer of that film, with the microorganisms deposited on it, was subjected to modification by the corona treatment in the air, using the modifying unit energy (Ej) ranging from 1 to 20kJ/m2, and then the count of dead bacteria was determined. Microscopic images were taken to show the effect of the corona discharges on the individual microorganisms.

Steady-State Corona Discharges in Atmospheric Air for Cleaning and Decontamination

It is shown that high-voltage corona discharges in atmospheric air have significant potential for bacterial inactivation. Neutral reactive oxygen and nitrogen species and ions generated by the corona discharges act upon the target liquid or solid surfaces and produce chemical or biological effects. The concentration of ions and reactive species including ozone generated by these discharges defines the efficiency of the corona treatment. In this paper, the chemical (oxidation) effect of direct corona discharges (where ions act upon the target surface) and indirect corona discharges (where ions are screened by a grounded metallic mesh) in atmospheric air is studied by measuring the degree of decolorization of a blue dye dissolved in water. The biological effects of the direct and indirect discharges are studied by observing the degree of bacterial inactivation of gram-negative and gram-positive microorganisms, Escherichia coli and Staphylococcus aureus, seeded on agar plates. The relationship between the ozone concentration and biological efficiency of the corona treatment is evaluated. The obtained results can be used for optimization of cleaning and inactivation treatment processes based on the use of nonthermal plasma produced under dc energization conditions.

Experimental Investigation of the Induced Airflow of Corona Discharge

In order to improve the acceleration effect of corona discharge acting on air, we present an experimental study on the induced airflow produced by corona discharge between two parallel electrodes. The parameters investigated are the type of electrodes, actuation voltage and the distance in the absence of free airflow. The induced flow velocity is measured directly in the accelerated region using the particle image velocimetry technology. The results show that if corona discharge is not developed into arc discharge, the induced airflow velocity increases nearly linearly with the applied voltage and the maximum induced airflow velocity near the needle electrode reaches 36 m/s. It is expected that in the future, the result can be referred to in the research about effect of active flow control to reach much higher induced airflow speed.

Enhanced electrical conductivity of polyaniline films by postsynthetic DC high-voltage electrical field treatment

New approach of chemical bath deposition combined with drying of freshly polymerized PANI films in DC high-voltage static electrical field 0.6–2.7kV/cm has been applied in present work. AFM and SEM microscopy revealed the significant changes of structure and morphology of PANI films, however the most important result of high-voltage treatment was the strong increase of conductivity of PANI films from 88S/m for the reference sample untreated in high-voltage field up to 374S/m for samples dried in the electric field (1.0kV/cm). The dependence of PANI conductivity on the intensity of high-voltage field showed the maximum conductivity for 1.0kV/cm. Effects of corona discharge observed for high-voltage field intensity above 2.0kV/cm on the samples are also presented. Results showed the possibility to change the nanostructure, morphology and conductivity using high-voltage electrical field.

FDTD Simulation of Insulator Voltages at a Lightning-Struck Tower Considering Ground-Wire Corona

In this paper, a simplified model of corona discharge for the finite-difference time-domain (FDTD) computations has been applied to the analysis of transient voltages across insulators of a transmission line struck by lightning. In the simulation, three 60-m towers, separated by 200 m, with one overhead ground wire and three-phase conductors are employed. The progression of corona streamers from the ground wire is represented as the radial expansion of cylindrical conducting region around the wire. On the basis of the computed results, the effect of corona discharge at the ground wire on transient insulator voltages is examined. The insulator voltages are reduced by corona discharge on the ground wire. The reduction of insulator-voltage peak due to the ground-wire corona is not very significant: the upper-, middle-, and lower-phase-voltage peaks are reduced by 15, 14, and 13% for a positive stroke with 50-kA-peak and 3-μs-risetime current, and those for the negative stroke with the same current waveform parameters are reduced by 10, 9, and 8%, respectively.