Dielectric Barrier Discharge (DBD) plasma actuators with an asymmetric, straight edge electrode configuration generate a wall-bounded jet without moving parts. Mechanistic description of the interaction between the Coulombic forces and fluid motion as a function of DBD parameters remains unclear. This paper presents an experimental investigation of DBD actuator, including electrical current associated with microdischarges, plasma volume, and the wall jet momentum over a range of AC frequencies (0.5 - 2 kHz) and peak-to-peak voltages up to 19.5 kV. Discharge current is measured with a high temporal resolution, and plasma volume is characterized optically, and the momentum induced by the DBD wall jet is computed based on the axial velocities measured downstream of the actuator using a custom-built pitot tube. Discharge current analysis demonstrated asymmetry between the positive and negative semi-cycle; both currents yielded a power-law relationship with empirical fitting coefficients. Plasma length varies linearly and volume quadratically with voltage. Although plasma length reached an asymptotic value at a higher frequency, the plasma volume grows due to the increasing height of the ionization region. In a simple 2D configuration, the DBD wall jet momentum shows near-linear dependency with discharge current in the range of voltages and frequencies considered in this work. The presented empirical model characterizes the DBD wall jet momentum and the discharge current based only on the AC inputs. With the estimation of plasma volume, the model can be applied for determining more realistic boundary conditions in numerical simulations.
A complete investigation of the discharge behavior of dielectric barrier discharge device using ZnO-coated dielectric layer in atmospheric pressure is made. Highly conductive ZnO film was deposited on the dielectric surface. Discharge characteristic of the dielectric barrier discharge are examined in different aspects. Experimental result shows that discharge uniformity is improved definitely in the case of ZnO-coated dielectric barrier discharge. And relevant theoretical models and explanation are presented to describing its discharge physics.
The processes of injection of a sputtered-and-ionized working material into the pulsed reflex discharge plasma have been considered at the initial stage of dense gas-metal plasma formation. A calculation model has been proposed to estimate the parameters of the sputtering mechanism for the required working material to be injected into the discharge. The data obtained are in good accordance with experimental results.
This paper reports on experimental measurements of the gas temperature in a dielectric barrier discharge reactor powered by a high voltage pulsed signal. It is shown that the thermal behavior of the reactor follows a first order model. However, an unexpected runaway phenomenon was observed at a frequency of 300Hz. A sudden increase in the power source and consequently in reactor temperature which reaches 170°C is observed. This behavior is discussed in terms of input power variation with temperature, possibly due to a resonance phenomenon.
We report on the first observation of white-eye pattern in an air dielectric barrier discharge. The patterned discharges undergo a development as following: random spots - quasihexagonal pattern - hexagonal pattern (type I) - hexagonal pattern (type II) - white-eye pattern - chaos as the voltage is increased. The spatiotemporal characteristics of patterned discharges are investigated by using an optical method. Results show that the two discharge modes, uniform mode and filamentary mode, are actually two different spatial presentations of the same origin: the microdischarge. From the viewpoint…
Dielectric barrier discharge (DBD) plasma actuators are an attractive option for separation control, lift enhancement, and drag reduction. Some plasma actuators feature optimized electrode shapes, electrical waveforms to maximize the aerodynamic forces at higher angles of attack. Here, we analyze the performance of a direct current augmented DBD (DBD - DCA) actuator with a sawtooth shape exposed electrode. The active electrode was positioned at 18% chord and the electrode at 48% chord of NACA 0012 airfoil. Wind tunnel experiments were conducted at wind speeds of 15 - 25 m/s, corresponding to R…
MCPlas is introduced as a powerful tool for automated fluid model generation with application to the analysis of dielectric barrier discharges operating in different regimes. MCPlas consists of a number of MATLAB\textsuperscript{\textregistered} scripts and uses the COMSOL Multiphysics\textsuperscript{\textregistered} module LiveLink\textsuperscript{\texttrademark} for MATLAB\textsuperscript{\textregistered} to build up equation-based COMSOL Multiphysics\textsuperscript{\textregistered} models from scratch. The present contribution highlights how MCPlas is used to implement time-dependent mode…
Discharge characteristics and parameter diagnosis of dielectric barrier discharge patterns in double-gap configuration
College of Physics Science and Technology, Hebei University（河北大学物理科学与技术学院）；Engineering Research Center of Zero-carbon Energy Buildings and Measurement Techniques, Ministry of Education（教育部零碳能源建筑及测量技术工程研究中心）
A combination of experiments and extensive modelling, including a chemical kinetics analysis, was performed for a CO$_2$/H$_2$O plasma in a dielectric barrier discharge. This provides a better understanding of the mechanisms related to the reactivity of the plasma and of the conversions into value-added products, such as methanol.
The plasma-liquid interaction is an important issue in plasma technology. The simulation of discharge in spherical bubbles in the water that produced plasma-activated water (PAW) is investigated using finite element methods (FEM) for a simulated 2D dielectric barrier discharge in three different geometries. The electron density changes with voltage, frequency, dielectric thickness, and bubble radius are investigated in different time duration. The results show that electron density increases linearly by increasing voltage, frequency and bubble radius, while it is vice versa for dielectric thic…
The use of dielectric barrier discharge (DBD) plasmas has become a practical way to carry out surface treatment and one seeks to do it in a more efficient way, which requires to have control of the plasma parameters like rotational and vibrational temperatures (T_rot and T_vib). Since the T_vib of an atmospheric pressure plasma jet is an important parameter related to improvement of surface treatments, in this work it was analyzed two methods to increase the values of T_vib in the DBD plasma. One of the methods is to reduce the exit size of the DBD reactor, and the other is to change the gas f…
Dynamics of an impulse dielectric barrier discharge in pure ammonia gas using electrical characteristics and imaging analysis
Institut Jean Lamour, Université de Nancy（让·拉缪尔研究所，南锡大学）；Groupe de Recherches sur l’Énergétique des Milieux Ionisés, Université d’Orléans（离子介质能源研究组，奥尔良大学）
We use a pin-grid electrode to introduce a corrugated electrical potential into a planar dielectric-barrier discharge (DBD) system, so that the amplitude of the applied electric field has the profile of a two-dimensional square lattice. The lattice potential provides a template for the spatial distribution of plasma filaments in the system and has pronounced effects on the patterns that can form. The positions at which filaments become localized within the lattice unit cell vary with the width of the discharge gap. The patterns that appear when filaments either overfill or under-fill the latti…
This paper present a model of dielectric barrier discharge DBD describe and simulate the electrical breakdown at atmospheric pressure in pure oxygen using Comsol Multiphysics for the better understanding and explanation of physical behaviours of the existing species in gap. For this model, we prefer to simulate using the 1D geometry using physics-based kinetic methods. DBD have a several applications, such as ozone generation, surface treatment, light source and other environmental industries. This model include a numerical and chemical model. Courant and voltage characteristics presented in t…
Packed bed plasma reactors (PBPRs) inherently have complex geometries where the volume between the electrodes is filled with dielectric/catalytic pellets to form an array of voids and cavities. This design generates multiple length scales i.e. the dimension of the plasma region (of the order of centimeters), of the dielectric/catalytic pellets (of the order of millimeters) and of the void between the dielectrics (or cavities) and/or surface pores that can reach micrometer dimensions. The plasma is formed as an array of connected or segmented microdischarges. The understanding of plasma propaga…
We investigate the dynamics of negative surface discharges in air through numerical simulations with a 2D fluid model. A geometry consisting of a flat dielectric embedded between parallel-plate electrodes is used. Compared to negative streamers in bulk gas, negative surface streamers are observed to have a higher electron density, a higher electric field and higher propagation velocity. On the other hand, their maximum electric field and velocity are lower than for positive surface streamers. In our simulations, negative surface streamers are slower for larger relative permittivity. Negative c…
The influence of charge trap states in the dielectric boundary material on capacitively coupled radio frequency plasma discharge is investigated with theory and Particle in cell/Monte Carlo Collision simulation. It is found that the trap states of the wall material manipulated discharge properties mainly through the varying ion induced secondary electron emission (SEE) coefficient in response to dynamic surface charges accumulated within solid boundary. A comprehensive SEE model considering surface charging is established first, which incorporates the valence band electron distribution, electr…
Prediction of Re-Ignition Times in Dielectric Barrier Discharges
Leibniz Institute for Plasma Science and Technology (INP)（莱布尼兹等离子体科学与技术研究所）；Department of Plasma Physics and Technology, Masaryk University（马萨里克大学等离子体物理与技术系）；Institute of Physics, University of Greifswald（格赖夫斯瓦尔德大学物理研究所）
The propagation mechanisms of plasma streamers have been observed and investigated in a surface dielectric barrier discharge (SDBD) using 2D particle in cell simulations. The investigations are carried out under a simulated air mixture, 80\% N$_2$ and 20\% O$_2$, at atmospheric pressure, 100$\,$kPa, under both DC conditions and a pulsed DC waveform that represent AC conditions. The simulated geometry is a simplification of the symmetric and fully exposed SDBD resulting in the simultaneous ignition of both positive and negative streamers on either side of the Al$_2$O$_3$ dielectric barrier. In …
Dielectric barrier discharge (DBD) in air is characterized applying current measurement, numerical simulation and optical emission spectroscopy (OES). For OES, a non-calibrated spectrometer is used. This diagnostic method is applicable when cross-sectional area of the active plasma volume and current density can be determined. The nitrogen emission in the spectral range of 380 nm- 406 nm is used for OES diagnostics. Electric field in the active plasma volume is determined applying the measured spectrum, well-known Frank-Condon factors for nitrogen transitions and numerically- simulated electro…
In this work we studied processing of poly(dimethylsiloxane) (PDMS) surfaces using dielectric barrier discharge (DBD) plasma in two different assemblies, one using the primary plasma jet obtained from a conventional DBD and the other using a DBD plasma jet transfer. The evolution of water contact angle (WCA) in function of plasma processing time and in function of aging time as well as the changes in the surface roughness of PDMS samples for both plasma treatments have been studied. We also compared vibrational and rotational temperatures for both plasmas and for the first time the vibrational…
We use various electrode layouts to tailor the profile of the electric field in a two-dimensional (2D) dielectric-barrier-discharge system, thereby creating spatial templates for the lateral distribution of discharge filaments. Our discussion focuses on the formation of patterns and the interactions between filaments in several template configurations. Hexagonal and square lattice templates produce patterns reminiscent of the surface phases of adatoms on crystal surfaces. For the square lattice, a lateral displacement between opposing lattice electrodes modifies the pattern-forming behavior of…
Major sterilization mechanisms are related to atoms and radicals, charged parti-cles, excited molecules, ozone, and UV radiation. The ROS (Reactive Oxygen Species) are well known as evildoers. These species are easily created in ambient air and water and they live long enough to reach the cell and attack the organic matter. Test molecules conversion in dry and wet air is studied using Dielectric Barrier Discharge (DBD) and Gliding Arc Reactors (GAR). The effects of tem-perature and energy deposition into the media on the active species production and then on the organic compounds degradation a…
We show that the spatio-temporal ElectroHydroDynamic (EHD) force production in surface AC-Dielectric Barrier Discharge (AC-DBD) actuators is strongly influenced by both the streamer regime during the positive phase and the micro-discharge regime during the negative phase. Focusing on the spatial EHD force profiles, we demonstrate that the ionic wind spatial distribution can only be explained by the positive contribution of the streamer regime. The location of maximum ionic wind is found to be directly linked with the maximum elongation of the streamers at several millimeters from the exposed e…
In this manuscript we present an in vitro model based on agarose gel that can be used to simulate a dirty, oily, bloody, and morphologically complex surface of, for example, an open wound. We show this models effectiveness in simulating depth of penetration of reactive species generated in plasma deep into tissue of a rat and confirm the penetration depths with agarose gel model. We envision that in the future such a model could be used to study plasma discharges (and other modalities) and minimize the use of live animals: plasma can be optimized on the agarose gel wound model and then finally…
In this work, the effect of flashing corona enhancement by introducing Teflon dielectric enclosure in vicinity to the electrode assembly was studied. The discharge operating in air without the dielectric was able to operate within a very narrow voltage range of approximately 200 V. The pulsing frequency was below 1.2 kHz and current peaks were below 14 mA. Increasing the applied voltage onto the positive electrode beyond this range would result in sparks between the electrodes. When the Teflon tube enclosure surrounding the high voltage electrode was used, the window of stable flashing corona …
Dielectric barrier discharge (DBD) plasma actuators can generate a wall jet without moving parts through interaction between ionized and neutral molecules in an electric field. The coupling between electro-hydrodynamic, turbulence, and viscous effects in the flow boundary layer remains unclear and deserves careful investigation. We present an experimental investigation of momentum injection by DBD actuators in a U_external = 5 m/s and U_external = 11 m/s co-flow and counter-flow configuration over a range of VAC = 12 kV - 19.5 kV peak-to-peak at a frequency of 2 kHz. In the co-flow configurati…
We use numerical simulations to study the dynamics of surface discharges, which are common in high-voltage engineering. We simulate positive streamer discharges that propagate towards a dielectric surface, attach to it, and then propagate over the surface. The simulations are performed in air with a two-dimensional plasma fluid model, in which a flat dielectric is placed between two plate electrodes. Electrostatic attraction is the main mechanism that causes streamers to grow towards the dielectric. Due to the net charge in the streamer head, the dielectric gets polarized, and the electric fie…
Drug resistant bacteria, prions and nosocomial infections underline the need of more effective sterilizing technologies. The cold plasma technology is expected to bring a benefit in this context. Six different plasma sources, based on printed circuit boards, were evaluated fourfold. This include measurements of the power consumption, the ignition behavior by an ICCD-camera and ozone formation by absorption spectroscopy at 254 nm. To evaluate the biocidal effect, four bacterial test series were performed with Escherichia coli. The entirety of the tests analyze the plasma inactivation process fr…
Nanosecond Surface Dielectric Barrier Discharge (ns-SDBDs) are a class of plasma actuators that utilize a high-voltage pulse of nanosecond duration between two surface-mounted electrodes to create an electrical breakdown of air, along with rapid heating. These actuators usually produce multiple filaments when operated at high pulse frequencies, and the rapid heating leads to the formation of shock waves and complex flow fields. In this work we replicate a single filament of the ns-SDBDs and characterize the induced flow using velocity measurements from particle image velocimetry and density me…
Spectroscopic investigations of the properties of a plasma produced by a flashboard plasma source, commonly used in pulsed plasma experiments, are presented. The plasma is used to prefill a planar 0.4-ms-conduction time plasma opening switch (POS). A novel gas-doping technique and a secondary surface flashover plasma source are used to locally dope the plasma with gaseous and solid materials, respectively, allowing for spatially-resolved measurements. The electron density, temperature, and plasma composition are determined from spectral line intensities and line profiles. Detailed collisional-…
Demonstration of the etching cobalt oxide grown on the stainless steel as a base metal surface using F2/He dielectric barrier discharge plasma in atmospheric pressure
From plasma to pattern: observation and characterization of periodic structure formation in dielectric breakdown channels of electron-irradiated insulators
Saskatchewan Torus-Modified (STOR-M) is a small tokamak, well known for various fusion related basic experimental studies such as edge turbulent heating, different instabilities, AC (alternating current) tokamak operation, Ohmic H-mode triggering by the electrode biasing, fueling and momentum injection by Compact Torus (CT) injection, and effects of Resonance Magnetic Perturbations (RMP), among others. Some of those experiments require real time visualization of magnetic surface reconstructions either through EFIT or quick analyses and visualization of experimental data during experiments. Rec…
In the present work, the significance of various components (ground electrode material and its surface (knurling pitch size), power electrode material and type, and dielectric material) of dielectric barrier discharge plasma device (DBD-PD) on plasma and plasma-activated water (PAW) properties are studied. The characterization of plasma is performed by studying voltage-current waveform and plasma discharge power. In addition, the characterization of PAW is performed by studying the physicochemical properties (PP) and reactive oxygennitrogen species (RONS) concentration. The results of plasma c…
For ITER-relevant runaway electron studies, such as suppression, mitigation, termination and/or control of runaway beam, obtaining the runaway electrons after the disruption is important. In this paper we report on the first achieved discharges with post-disruptive runaway electron beam, entitled "runaway plateau", in the COMPASS tokamak. The runaway plateau is produced by massive gas injection of argon. Almost all of the disruptions with runaway electron plateaus occurred during the plasma current ramp-up phase. Comparison between the Ar injection discharges with and without plateau has been …
The plasma parameters such as electron distribution function and electron density of three atmospheric-pressure transient discharges namely filamentary and homogeneous dielectric barrier discharges in air, and the spark discharge of argon plasma coagulation (APC) system are determined. A combination of numerical simulation as well as diagnostic methods including current measurement and optical emission spectroscopy (OES) based on nitrogen emissions is used. The applied methods supplement each other and resolve problems, which arise when these methods are used individually. Nitrogen is used as …
Applications of dielectric barrier discharge (DBD) based atmospheric pressure plasma jets are often limited by the relatively small area of treatment due to their 1D configuration. This letter describes the first results demonstrating generation of 2D plasma bullets and 2D plasma jets permitting fast treatment of large targets. Imaging of pulsed DBD in He and ionization wave propagation along the dielectric surface show that DBD evolution starts with formation of transient anode glow, and only then continues with development of cathode-directed streamers. The anode glow can propagate as an ion…
Full cycle, self-consistent, two-dimensional analysis of a packed bed DBD reactor for plasma-assisted $\mathrm{CO_{2}}$ splitting: spatiotemporal inhomogeneous, glow to streamer to surface discharge transitions
