Plasma Ignition Research Articles

On the ignition kernel formation and propagation: an experimental and modeling approach

The next generation of advanced combustion devices is being developed to operate under ultra-high-pressure conditions. However, under such extreme conditions, flame tends to become unstable and measurement of fundamental properties such as the laminar flame speed becomes challenging. One potential method to resolve this issue is measuring the ignition-affected region during spherically expanding flame experiments. The flame in this region is more resistant to perturbations and remains smooth due to the high stretch rates (i.e. small radii). Stable flame propagation allows for improved flame measurement, however, the experimentally observed kernel propagation is a function of both inflammation and ignition plasma. Therefore, the goal of the present study is to better understand the plasma formation and propagation during the ignition process, which would allow for reliable laminar flame speed measurements. To accomplish this goal, thermal plasma operating at high pressures is studied with emphasis on the spark energy effects on the formation of the ignition kernel. The thermal effect of the plasma is experimentally observed using a high-speed Schlieren imaging system. The energy dissipated within the plasma is measured with the use of voltage and current probes with a measurement of plasma sheath voltage drop as an input to numerical modeling. The measured kernel propagation rate is used to assess the accuracy of the model. The experiments and modeling are conducted in dry air at 1, 3, and 5 atm as well as in CH4-N2 mixtures at 1 atm, and kernel radius, temperature, and mass are reported. The voltage-drop (as a non-thermal loss) is measured to be approximately 330 5 V (dry air at 1 atm) for glow plasma with a large dependency on pressure, gas composition, electrode surface quality, electrode geometry, electrode shape, and current density. The same loss within the arc plasma is measured to be 15 5 V, however the arc phase loss which agrees with arc propagation is significantly higher (∼45 V) which suggest additional unaccounted for phenomena occurring during the arc phase. With these losses, the modeling results are shown to predict the final kernel radius within 10%–20% of the observed kernel size. The difference found between the modeling and experimental results is determined to be a result of assuming that the primary loss mechanism (voltage drop across sheath formation) remains constant for the duration of glow discharge. The discrepancy for arc discharge is discussed with several potential sources, however, additional studies are required to better understand how the arc formation affects the kernel propagation.

Increased Plasma Ignition Distance Practice may Prevent the Obturator Reflex Occurrences and Compare of its Effectiveness Versus Obturator Block: A Prospective, Randomized, Controlled Study

ObjectiveTo compare the ability of the obturator nerve block (ONB) and increased plasma ignition distance practice (IPDP) techniques to inhibit obturator nerve reflex (ONR) occurring with bipolar transurethral resection of the bladder. MethodsSixty patients who had a tumor placed at the lateral sidewall or had a tumor in another part of the bladder along with the lateral wall were randomly enrolled. Cystoscopic and ultrasonographic examinations and a computerized tomography scanning of the urinary bladder were used to determine the ONB side. Group 1 consisted of patients who had the ONB procedure. Group 2 consisted of patients who had IPIDP. The severity of the ONR was classified as severe, mild, and very mild. The study's primary endpoint was ONR occurrences and successful completion of the surgery. The secondary endpoints were bleeding and bladder perforation. ResultsThere was a significant difference in the occurrence of ONR between the two groups (P = 0.0011). However, there was no significant difference between the two groups in the ability to resect the tumor and complete the surgery (P = .764). There was no correlation between the ONR and the tumor size (P = 0.478). ConclusionOur study concluded that both ONB and IPIDP have comparable results, especially in resecting tumors and completing the operation. IPIDP has some advantages over ONB, such as shorter operative time, lower total costs, and less trained personnel requirements.

Plasma ignition of solid fuels at thermal power plants. Part 2. 3D modeling of the furnace of a pulverized coal boiler

Plasma ignition of solid fuels at thermal power plants. Part 2. 3D modeling of the furnace of a pulverized coal boiler

Characterization of a Gliding Arc Igniter from an Equilibrium Stage to a Non–Equilibrium Stage Using a Coupled 3D–0D Approach

A gliding arc plasma source designed for high efficient ignition has been studied with the help of numerical simulation and experiments. A coupled 3D–0D approach has been proposed to model the gliding arc from ignition (the equilibrium stage) to extinguish (the non–equilibrium stage). The model takes the measured discharge morphology, voltage, current, and velocity as inputs, and has been validated by comparing the calculated temperature with experimental results from an independent group. The temporal evolution of the temperature as well as active species, and the effective penetration length of the gliding arc has been studied; the influence of the gliding arc-based plasma igniter on the ignition delay time of a premixed pentane-air gas has also been theoretically analyzed.

Electromagnetic enhanced ignition of octogen explosive at subnormal temperatures: A numerical study

The thermal decomposition and ignition of high-performance high explosives occur via a mechanism where the solid phase sublimes and the parent molecules decompose rapidly in the gas phase to form unstable and charged intermediates. These intermediates continue to react and form the final products to release energy and do work. We have observed that the presence of electromagnetic energy significantly reduces the ignition temperature of a common high explosive, and data suggest that this occurs via electromagnetic interactions with the charged gas-phase intermediates. Here, we modified the thermal decomposition kinetic expressions for octogen (High Melt eXplosive, HMX) to couple the effects of an incident microwave (MW) field. This modified kinetic model is used to investigate our previous experimental work which showed that the surface temperature at ignition of HMX powder is reduced by the MW field. The Fridman–Macheret α-model is a common approach in plasma chemistry and was incorporated into the Henson/Smilowitz HMX kinetics; this effectively reduces the activation energy (Ea) by vibronically excited charged reactive intermediates. A modified kinetic model was implemented into the COMSOL Multiphysics Software. The thermal time to ignition was validated; as a result, plasma formation reduced the surface temperature by ∼23 °C compared to thermal ignition. With a validated kinetic model that can simulate both pure thermal ignition and mixed thermal/plasma ignition, we are able to simulate our previous experimental work showing that plasma ignition reduces the surface temperature at ignition compared to thermal initiation.

Effects of a Cylindrical Metallic Cavity on the Radiation of Longitudinally Polarized Limited-Diffractive Bessel Beams

This letter deals with the problem of evaluating the effect of a cylindrical metallic cavity on the radiation of a planar longitudinally polarized Bessel beam launcher, as it could arise in applications related to microwave heating or plasma ignition. A full analytical model is developed to extract fundamental physics insight of the problem at hand. Full-wave numerical simulations by COMSOL multiphysics are used to validate the proposed model, showing fair agreement between simulations and theoretical predictions.

Advanced combustion strategies for improving ic engine efficiency and emissions

The growing need for higher fuel efficiency and compliance with increasingly stringent emission regulations has prompted significant advancements in internal combustion (IC) engine technology. Traditional combustion methods, while widely utilized, face inherent challenges such as limited thermal efficiency and the production of harmful emissions like nitrogen oxides (NOx), particulate matter (PM), carbon monoxide (CO), and unburned hydrocarbons (HC). To address these concerns, researchers and engineers have developed a range of advanced combustion strategies that offer the potential to drastically improve engine efficiency while minimizing environmental impact.This paper provides a comprehensive analysis of cutting-edge combustion techniques, with a focus on strategies that balance the trade-off between fuel efficiency and emission reduction. Prominent among these strategies is Homogeneous Charge Compression Ignition (HCCI), which utilizes a lean, premixed air-fuel mixture to achieve spontaneous ignition at low temperatures, significantly reducing NOx and PM emissions. Another promising technique, Reactivity-Controlled Compression Ignition (RCCI), leverages the controlled use of two fuels with different reactivity levels, enabling precise control over the combustion process and enhancing both fuel efficiency and emission control. In contrast, Gasoline Direct Injection (GDI) technology improves fuel atomization and combustion control by injecting fuel directly into the combustion chamber, leading to higher efficiency and power output, albeit with challenges related to particulate emissions.In addition to these combustion strategies, this paper explores the role of Low-Temperature Combustion (LTC), which operates at reduced in-cylinder temperatures to mitigate the formation of NOx and soot, as well as the potential of advanced ignition systems like plasma or laser-based ignition to improve lean-burn combustion processes. Furthermore, the paper examines the integration of renewable fuels, such as hydrogen and biofuels, with advanced combustion techniques to support the global transition toward cleaner energy.The analysis also considers technological enablers such as variable valve timing (VVT), turbocharging, and sophisticated exhaust after-treatment systems that complement these advanced combustion strategies. Moreover, the application of simulation and optimization tools, including computational fluid dynamics (CFD) and machine learning (ML), is highlighted as essential for refining engine design and optimizing combustion processes.Despite the notable progress, challenges remain in terms of system complexity, control precision, and expanding the operational range of these advanced combustion techniques. As the automotive industry moves towards electrification and hybridization, advanced IC engine combustion strategies will continue to play a crucial role in improving vehicle performance and sustainability. This paper concludes by outlining the future prospects for further optimizing combustion efficiency and integrating renewable fuels in next-generation IC engines, thereby contributing to a cleaner, more efficient transportation sector.

Treatment of hepatocellular carcinoma with in situ generated plasma‐activated air‐driven water mist

AbstractSince the development of cold atmospheric plasma (CAP), substantial and significant usage of CAP applications was introduced in medicine. Here, we developed two combined sources of plasma to produce in situ plasma‐activated air‐driven water mist (PAAWM). The first is generated using air as a feed gas, while the second is plasma‐activated water generated by the ignition of plasma within the air‐driven water mist. Both contribute to the plasma jet generation of PAAWM. The antitumor efficacy of PAAWM was evaluated against two hepatocellular carcinoma cell lines (SNU‐449 and SNU‐475). The generated PAAWM was efficient in the treatment of both chemosensitive and chemoresistant hepatocellular carcinoma cells. These results may support using PAAWM alone or in combination with other treatment modalities.

Review on Plasma-Assisted Ignition Systems for Internal Combustion Engine Application

Due to the depletion of conventional petroleum-based fuels and increasing environmental concerns, industries have been developing new combustion technologies with acceptable cost ranges and minimum system modifications for consumers. Among many approaches, the utilization of plasma ignition systems is considered as a promising pathway to achieve greener transportation while maintaining conventional internal combustion engine systems. Plasma contains highly reactive radicals, and those have a great potential of enhancing chemical reactions that are beneficial for reducing carbon emissions. The primary objective of this paper is to provide an overview of currently available plasma-assisted combustion systems including recent achievements in research and development, and technical challenges for successfully implementing a new ignition system. This review will introduce various plasma-assisted combustion approaches from worldwide projects, covering non-thermal and thermal plasma systems in internal combustion engines.

Comparison of the 3-Fluid Dynamic Model with Experimental Data

The article considers a way to compare large bulks of experimental data with theoretical calculations, in which the quality of theoretical models is clearly demonstrated graphically. The main idea of the method consists in grouping physical observables, represented by experiment and theoretical calculation, into samples, each of which characterizes a certain physical process. A further choice of a convenient criterion for comparing measurements and calculations, its calculation and averaging within each sample and then over all samples, makes it possible to choose the best theoretical model in the entire measurement area. Published theoretical data of the three-fluid dynamic model (3FD) applied to the experimental data from heavy-ion collisions at the energy range $\sqrt{s_{NN}}\,=\,2.7 - 63$ GeV are used as example of application of the developed methodology. When analyzing the results, the quantum nature of the fireball, created at heavy ion collisions, was taken into account. Thus, even at energy $\sqrt{s_{NN}}\,=\,63$ GeV of central collisions of heavy ions, there is a nonzero probability of fireball formation without ignition of the quark-gluon plasma (QGP). At the same time, QGP ignition at central collision energies above at least $\sqrt{s_{NN}}\,=\,12 GeV occurs through two competing processes, through a first-order phase transition and through a smooth crossover. That is, in nature, these two possibilities are realized, which occur with approximately the same probabilities.

Thermal Energy and Luminosity Characterization of an Advanced Ignition System Using a Non-Intrusive Methodology in an Optically Accessible Calorimeter

To restrain the environmental impact of modern SI engines, igniters must guarantee stable combustions with low cycle-to-cycle variability in extreme operating conditions (high EGR, ultra-lean), via high energy release in the combustion chamber. The direct measurement of this energy is not trivial and requires a controlled environment. Luminosity detection is a non-intrusive diagnostic technique to indirectly measure the thermal energy released by the discharge on optically accessible apparatus. This work compares energy and luminosity produced by a plasma igniter in a constant volume vessel at realistic working conditions (ignition at 8 bar and air as a medium). A calibration factor can be defined to describe the thermal energy behavior as a function of the discharge luminosity and to give an assessment of such approach for its use in optically accessible engine. This study shows that thermal energy and luminosity are influenced by the gas type and related by a linear relationship for both air and nitrogen. The presence of oxygen resulted in discharges with reduced energy delivery to the medium and a lower discharge luminosity compared to nitrogen. This work outcome could improve the use of a non-intrusive methodology, based on luminosity detection, to characterize the igniter performance, exploitable for 3D-CFD.

Experimental Investigation on Gliding Arc Plasma Ignition and Assisted Combustion Actuator

In a scramjet engine, the viscosity of kerosene increases, the oxygen content decreases, the atomization evaporation rate and chemical reaction rate of kerosene decrease significantly, and the flame propagation speed decreases significantly under the condition of low total temperature, leading to the difficulty of ignition. Therefore, it is urgent to innovate the repeatable ignition method suitable for ramjet from the source. Gliding arc plasma has the advantages of both thermal equilibrium and nonequilibrium plasma. It can be used as a stable high-temperature heat source and chemical reaction source to strengthen the whole process from ignition to flame combustion, which has a critical application prospect in broadening the ignition boundary of scramjet engines at low total temperature and improving flame stability. In this article, a gliding arc plasma igniter is designed and developed. The research of gliding arc plasma ignition technology in scramjet combustor is carried out from two aspects of the discharge characteristics of gliding arc plasma igniter and kerosene cracking characteristics experiment. The results show that the average power of the gliding arc igniter in the air environment is higher than that in the nitrogen environment. With the increase of flow rate, the average power of the igniter increases first and then decreases. The maximum average power of the igniter with nitrogen is 193.56 W, and the maximum average power in the air environment is 323.49 W. The cracking products of kerosene are mainly hydrogen, methane, ethylene, acetylene, and other hydrocarbons below C3. The concentration of the product was positively correlated with the excitation voltage and channel length, and the concentration of hydrogen was the largest. The concentration of cracking products is higher in air, where hydrogen is three times higher than that in nitrogen. The main flow ignition of scramjet was successfully achieved under the condition of 2-Ma inlet velocity and 1000 K inlet temperature.

Degradation of diclofenac and 4-chlorobenzoic acid in aqueous solution by cold atmospheric plasma source

In this study, cold atmospheric plasma (CAP) was explored as a novel advanced oxidation process (AOP) for water decontamination. Samples with high concentration aqueous solutions of Diclofenac sodium (DCF) and 4-Chlorobenzoic acid (pCBA) were treated by plasma systems. Atmospheric pressure plasma jets (APPJs) with a 1 pin-electrode and multi-needle electrodes (3 pins) configurations were used. The plasma generated using argon as working gas was touching a stationary liquid surface in the case of pin electrode-APPJ while for multi-needle electrodes-APPJ the liquid sample was flowing during treatment. In both configurations, a commercial RF power supply was used for plasma ignition. Measurement of electrical signals enabled precise determination of power delivered from the plasma to the sample. The optical emission spectroscopy (OES) of plasma confirmed the appearance of excited reactive species in the plasma, such as hydroxyl radicals and atomic oxygen which are considered to be key reactive species in AOPs for the degradation of organic pollutants. Treatments were conducted with two different volumes (5 mL and 250 mL) of contaminated water samples. The data acquired allowed calculation of degradation efficiency and energy yield for both plasma sources. When treated with pin-APPJ, almost complete degradation of 5 mL DCF occurred in 1 min with the initial concentration of 25 mg/L and 50 mg/L, whereas 5 mL pCBA almost degraded in 10 min at the initial concentration of 25 mg/L and 40 mg/L. The treatment results with multi-needle electrodes system confirmed that DCF almost completely degraded in 30 min and pCBA degraded about 24 % in 50 min. The maximum calculated energy yield for 50 % removal was 6465 mg/kWh after treatment of 250 mL of DCF aqueous solution utilizing the plasma recirculation technique. The measurements also provided an insight to the kinetics of DCF and pCBA degradation. Degradation products and pathways for DCF were determined using LC-MS measurements.

Optical study of the effects arising from the interaction of a CO2-laser with the powder in a coaxial nozzle for laser cladding

Experimental studies of the NiCr powder interaction with the CO2-laser radiation in the conditions of free jets of a coaxial nozzle for laser cladding are carried out. Optical diagnostics is used with the video recording of moving particles and registration of the radiation spectrum. The influence of the type of working gas, i.e., air and argon, as well as laser operation modes – the continuous CW and pulse-periodic PP on plasma ignition – is studied. An increase in the average particle velocity from 3 m/s in a cold flow to 10 m/s, when exposed to a laser, was found and the maximum velocity values at the level of 50-60 m/s were registered. The phenomena of particle break-up and plasma plume formation on their surface are described. It is shown that particles rotating with a frequency of 30-40 kHz are present in the powder flow. The continuous thermal radiation of particles and the spectral lines of plasma radiation in the range of 400-900 nm are analyzed.

Generation and evolution of laser-induced shock waves under martian atmospheric conditions

SuperCam on NASA's Mars 2020 mission is the first laser-induced breakdown spectroscopy (LIBS) instrument on Mars that also employs a microphone to help with the evaluation of the LIBS spectra. When a LIBS measurement is performed in an atmosphere, an acoustic signal is emitted that can be recorded and used, for example, as a normalization standard to help in the interpretation of spectral data. The investigation of this pressure wave in Martian atmospheric conditions is important to better understand the relation between the acoustic signals and the LIBS spectra that are measured by SuperCam. However, the mechanisms involved in the generation of the pressure wave in Martian atmospheric conditions have not been studied in detail yet. To improve our understanding of how the acoustic signal is generated and how it can be used to aid in the analysis of the spectroscopic data, we developed an experimental setup combining different experimental methods to study the pressure waves generated during LIBS measurements in a simulated Martian atmosphere. It incorporates a schlieren imaging system for shock wave analysis, a plasma imaging setup for spatially and temporally resolved plasma analysis and a microphone to study the acoustic signal generated by the shock wave. The schlieren system is used to investigate the shock wave's density structure and expansion dynamics. The system was designed to record schlieren images in low-pressure Mars-analogue atmosphere with a high temporal resolution. We present first measurements including schlieren images of the laser-induced shock wave expanding from an iron target in a simulated Martian atmosphere. The measurements confirm numerical simulations of the density structure of laser-induced shock waves for the first time. Furthermore, we find that the Taylor-Sedov model gives a good estimate of the shock wave dynamics up until sonic speeds, when a linear model is appropriate. By comparing the dynamics of the shock wave to the expansion of the plasma, we find that the shock wave decouples from the luminous plasma between 400 ns and 500 ns after plasma ignition. We demonstrate the capabilities of this new setup by giving a detailed description of how the acoustic signal is generated from the expanding plasma. In future studies, the presented setup will be used to investigate the influence of material properties and experimental parameters on the generation of the shock wave and the acoustic signal to support the analysis of SuperCam measurements on Mars.

Schlieren imaging and spectroscopic approximation of the rotational-vibrational temperatures of a microwave discharge igniter with a resonating cavity.

A microwave discharge igniter (MDI) with a resonating cavity was developed and optimized for practical applications in an internal combustion engine. In contrast to the typical microwave ignition, the resonating cavity of the MDI induces a discharge through dielectric resonance. Its source of microwave (MW) is a 2.45GHz semiconductor oscillator that is capable of numerous oscillation patterns. To verify and demonstrate the optimum ignition performance and combustion, we varied the oscillation parameters (signal factors) of the MW to optimize the performance of the MDI using the Taguchi method. Plasma spectroscopy was used for ignition condition analysis. Two sets of microwave pulses, a first pulse followed by a second set of pulse bursts, were used to ignite a propane-air fuel. The flame kernel growth rate and O I species generation were used as the response outputs, which were obtained, respectively from Schlieren imaging and emission spectroscopy experiments. The extended pulse periods and higher MW pulse numbers of the second set of pulses improved the response outputs of the MDI. To further analyze the effect of MW oscillation patterns on plasma properties and performance, measurements were done on MW superimposed operation with the high-voltage ignition from spark plugs. The MW transmission on a typical spark plug enhanced the air plasma ignition. Higher input MW energy and more extended MW pulse widths results in increased spectral intensity and radical generation of OH, O, and N 2. An inverse relation between the temperature and spectral intensity functions of the MW pulse width was observed, which was attributed to the cutoff density of the MW-enhanced plasma.

Computational Fluid Dynamics Modeling of Low Temperature Ignition Processes From a Nanosecond Pulsed Discharge at Quiescent Conditions

Abstract Recent interest in nonequilibrium plasma discharges as sources of ignition for the automotive industry has not yet been accompanied by the availability of dedicated models to perform this task in computational fluid dynamics (CFD) engine simulations. The need for a low-temperature plasma (LTP) ignition model has motivated much work in simulating these discharges from first principles. Most ignition models assume that an equilibrium plasma comprises the bulk of discharge kernels. LTP discharges, however, exhibit highly nonequilibrium behavior. In this work, a method to determine a consistent initialization of LTP discharge kernels for use in engine CFD codes like converge is proposed. The method utilizes first principles discharge simulations. Such an LTP kernel is introduced in a flammable mixture of air and fuel, and the subsequent plasma expansion and ignition simulation is carried out using a reacting flow solver with detailed chemistry. The proposed numerical approach is shown to produce results that agree with experimental observations regarding the ignitability of methane-air and ethylene-air mixtures by LTP discharges.

Low-temperature filamentary plasma for ignition-stabilized combustion

In this work, an experimental study investigating dielectric barrier discharge (DBD) plasma-assisted ignition in methane-air flows at near-atmospheric pressure is presented. Discharges are produced using 10 ns duration high voltage pulses at maximum 3 kHz pulse repetition rate. The goal is to check the feasibility of plasma as an ignition source for ignition-stabilized combustion in a wide range of equivalence ratio, pressure, and flow speed conditions. To that end, four important characteristics are investigated: 1) Ignition dynamics, 2) Minimum number of pulses required for ignition, 3) Plasma energy per pulse, gas temperature, and the effective reduced electric field, and 4) Plasma NOx production. In continuous plasma mode, we observe an elongated flame outside of the discharge region when a methane-air mixture flows through the discharge. The elongated flame is due to repetitively ignited kernels moving downstream with the flow. High-speed intensified imaging is used to explore plasma morphology and ignition dynamics. Plasma has a filamentary nature which is perceived as moving with the flow due to pulse-to-pulse memory effects. For fuel-air mixtures, ignition is followed by kernel expansion and splitting, flame propagation, and consecutive ignition. The time delay between consecutive ignition events is found to be a function of flow speed, because ignition is achieved only when a previously ignited kernel moves out of the plasma region, which happens faster at higher flow speeds. We performed optical emission spectroscopy in burst mode to further characterise plasma and ignition parameters. In air, plasma gas temperature and hence the reduced electric field increases because of pulse-to-pulse effects. By comparing the air plasma temperature with the methane auto-ignition temperature, we conclude that the observed ignition is low-temperature ignition. Parametric studies of NOx measurements suggest that plasma NOx emissions are higher for low flow speeds, high pulse repetition rates, and low-pressure conditions. Overall, our DBD filamentary plasma is found to be a fast, repetitive, and low-temperature ignition source that can be used for ignition-stabilized combustion at near atmospheric conditions.

In situ monitoring of plasma ignition step during photoresist stripping using O2/N2 and O2/Ar

In situ monitoring of plasma ignition step during photoresist stripping using O2/N2 and O2/Ar

Water Surface Plasma Source for Large Area Water Treatment by Using Volume Dielectric Barrier Discharge

The concept of a water surface plasma source (WSPS) was proposed to directly interact plasmas with water for large area water treatment, which is the type of volume dielectric barrier discharge (vDBD) with plate-to-plate. One electrode is submerged in water, while the other is floated in air, which is covered with a dielectric material. The characteristics of the WSPS were investigated by using a complementary metal–oxide–semiconductor (CMOS) camera, voltage and current probes, and optical emission spectroscopy (OES). The electrochemical parameters of plasma-activated water (PAW, 2 L) after plasma treatment times of 3 min by the WSPS were analyzed by using a multiparameter meter. As results, the formation of the water wave due to plasma generation, caused by the effect of the induced polarization forces, was observed at the WSPS. By comparison with the tap water, the applied voltage of the distilled water required higher than 130% for stable operation of the WSPS due to lower electrical conductivity (EC). As gap distance between dielectric plate and water surface increased, the applied voltage increased. In addition, an increase of 2 mm in the water level from the lower electrode required an approximately 5% increase in applied voltages for the ignition and stable plasma generation of the WSPS. The dominant peaks that were for N2 species system in the spectrum of plasmas at the WSPS were analyzed by using the OES. In the case of distilled water, the pH values decreased from 6.25 to 4.24 and the EC increased from 2.00 to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$22.33 ~\mu \text{S} \cdot $ </tex-math></inline-formula> cm by using multiparameter meter during plasma treatment, whereas in the case of tap water, the effects on the pH and EC were insignificant.