• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.209.2-209.2
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• 2016

Up to now, Plasma applications are thought as a leading technology in industrial, chemical and even medical and biological field. Especially, Due to direct discharge in liquid with reaction in ambient solution, plasma in liquid is useful plasma technology. Such as electro-surgery, water purification, radical generation for synthesis. For using those plasma applications efficiently, plasma characteristics should be understood in advance. But discharge in liquid is not much well-known about its characteristics. And plasma discharge in solution is difficult to generate and analysis due to electrolysis, vaporization and radical generation. So, We make stable plasma discharge in solution(saline 0.9%) without input gas. We also analyze new type of plasma source in thermal and electrochemical view. And we check characteristics of plasma in liquid. For example, plasma density and radical density(OH) with optical emission, thermal energy with thermometer, electrical energy with oscilloscope and so on. And we try to explain the bubble and plasma formation with circuit analysis.

• Journal of Environmental Science International
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• v.23 no.3
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• pp.369-378
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• 2014

Effect of improvement of the dielectric barrier discharge (DBD) plasma system on the inactivation performance of bacteria were investigated. The improvement of plasma reactor was performed by combination with the basic plasma reactor and UV process or combination with the basic plasma reactor and circulation system which was equipped with gas-liquid mixer. Experimental results showed that tailing effect was appeared after the exponential decrease in basic plasma reactor. There was no enhancement effect on the Ralstonia Solanacearum inactivation with combination of basic plasma process and UV process. The application of gas-liquid mixing device on the basic plasma reactor reduced inactivation time and led to complete sterilization. The effect existence of gas-liquid mixing device, voltage, air flow rate (1 ~ 5 L/min), water circulation rate (2.8 ~ 9.4 L/min) in gas-liquid mixing plasma, plasma voltage and UV power of gas-liquid mixing plasma+UV process were evaluated. The optimum air flow rate, water circulation rate, voltage of gas-liquid mixing system were 3 L/min, 3.5 L/min and 60 V, respectively. There was no enhancement effect on the Ralstonia Solanacearum inactivation with combination of gas-liquid mixing plasma and UV process.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.153-153
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• 2015

Application of the plasma is already highlighted as a new technology in the last few years. In these days, there are lots of attempt in various application with plasma in that it is known as an effective treatment to animal, plants, material and so on. Plasma in liquid, one of new plasma applications, has advantages in ability to treat bio-cell or solutions. For example, electro-surgery, water purification, radical generation and so on. Especially, plasma discharge in solutions is very useful technique and difficult to generate due to electrolysis, vaporization and something else. In this study, we have performed plasma discharge and checked sustainability of plasma in solution(saline 0.9%). And we have measured basic characteristics of plasma in liquid. Such as electrical energy and plasma density are calculated from discharging current and voltage. Also, its thermal energy is measured with IR camera.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.121.1-121.1
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• 2014

Recently, much attention has been given to plasma production under liquid and its applications [1]. However, most of plasma production techniques reported so far utilize high voltage dc, ac, rf or microwave power [2], where damage to discharge electrodes and small discharge volume are remained issues. As an alternative of plasma production method under liquid, we have proposed pulsed microwave excited plasma using slot antenna, where damage to the slot electrode can be minimized and plasma volume can be increased. We have also reported improvement of treatment efficiency with use of reduced-pressure condition during the discharge [3]. To realize low pressure conditions in liquid, various alternative technique can be considered. One possible technique is simultaneous injection of microwave power and ultrasonic wave. Ultrasonic wave induces pressure fluctuation with the wave propagation and is so far used for cavitation production in the water. We propose utilization of reduced pressure induced by ultrasonic cavitation for improvement of the plasma production. Correlation between the plasma production and the ultrasonic power will be discussed.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.17-18
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• 2011

Plasma in liquid phase has attracted great attention in the last few years by the wide domain of applications in material processing, decomposition of organic and inorganic chemical compounds and sterilization of water. The plasma in liquid is characterized by three main regions which interact each - other during the plasma operation: the liquid phase, which supply the plasma gas phase with various chemical compounds and ions, the plasma in the gas phase at atmospheric pressure and the interface between these two regions. The most complex region, but extremely interesting from the fundamental, chemical and physical processes which occur here, is the boundary between the liquid phase and the plasma gas phase. In our laboratory, plasma in liquid which behaves as a glow discharge type, is generated by using a bipolar pulsed power supply, with variable pulse width, in the range of 0.5~10 ${\mu}s$ and 10 to 30 kHz repetition rate. Plasma in water and other different solutions was characterized by electrical and optical measurements. Strong emissions of OH and H radicals dominate the optical spectra. Generally water with 500 ${\mu}S/cm$ conductivity has a breakdown voltage around 2 kV, depending on the pulse width and the repetition rate of the power supply. The characteristics of the plasma initiated in ultrapure water between pairs of different materials used for electrodes (W and Ta) were investigated by the time-resolved optical emission and the broad-band absorption spectroscopy. The deexcitation processes of the reactive species formed in the water plasma depend on the electrode material, but have been independent on the polarity of the applied voltage pulses. Recently, Coherent anti-Stokes Raman Spectroscopy method was employed to investigate the chemistry in the liquid phase and at the interface between the gas and the liquid phases of the solution plasma system. The use of the solution plasma allows rapid fabrication of the metal nanoparticles without being necessary the addition of different reducing agents, because plasma in the liquid phase provides a reaction field with a highly excited energy radicals. We successfully synthesized gold nanoparticles using a glow discharge in aqueous solution. Nanoparticles with an average size of less than 10 nm were obtained using chlorauric acid solutions as the metal source. Carbon/Pt hybrid nanostructures have been obtained by treating carbon balls, synthesized in a CVD chamber, with hexachloro- platinum acid in a solution plasma system. The solution plasma was successfully used to remove the template remained after the mesoporous silica synthesis. Surface functionalization of the carbon structures and the silica surface with different chemical groups and nanoparticles, was also performed by processing these materials in the liquid plasma.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.259.1-259.1
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• 2014

Recently non-thermal plasma has been frequently applied to various research fields. The liquid plasma have received much attention lately because of interests in surgical and nanomaterial synthesis applications. Especially, intensive researches have been carried out for non-thermal plasma in liquid by using various electrode configurations and power supplies. We have developed a bioplasma source which could be used in a liquid, in which outer insulator has been covered onto the outer electrode. Also we have also put an insulator between the inner and outer electrode. Based on the surface discharge mode, the nonthermal bioplasma has been generated inside a liquid by using an alternating current voltage generator with peak voltage of 12 kV under driving frequency of 22 KHz. Here the discharge voltage and current have been measured for electrical characteristics. Especially, We have measured discharge and optical characteristics under various liquids of deionized (DI) water, tap water, and saline by using monochromator. We have also observed nitric oxide (NO), hydrogen peroxide (H2O2), and hydroxyl (OH) radical species by optical emission spectroscopy during the operation of bioplasma discharge inside various kinds of DI water, tap water, and saline. Here the temperature has been kept to be $40^{\circ}C$ or less when discharge in liquid has been operated in this experiment. Also we have measured plasma temperature by high speed camera image and density by using either H-alpha or H-beta Stark broadening method.

• Journal of Environmental Health Sciences
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• v.39 no.3
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• pp.289-299
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• 2013

Objectives: For the field application of the dielectric barrier discharge plasma reactor, scale-up of the plasma reactor is needed. This study investigated the possibility of inactivation of microorganisms in sewage using pilot multi-plasma reactor. We also considered the possibility of degradation of total organic carbon (TOC) and nonbiodegradable matter ($UV_{254}$) in sewage. Methods: The pilot plasma reactor consists of plasma reactor with three plasma modules (discharge electrode and quartz dielectric tube), liquid-gas mixer, high voltage transformers, gas supply equipment and a liquid circulation system. In order to determine the operating conditions of the pilot plasma reactor, we performed experiments on the operation parameters such as gas and liquid flow rate and electric discharge voltage. Results: The experimental results showed that optimum operation conditions for the pilot plasma reactor in batch experiments were 1 L/min air flow rate), 4 L/min liquid circulation rate, and 13 kV electric discharge voltage, respectively. The main operation factor of the pilot plasma process was the high voltage. In continuous operation of the air plasma process, residual microorganisms, $UV_{254}$ absorbance and TOC removal rate at optimal condition of 13 kV were $10^{2.24}$ CFU/mL, 56.5% and 8.6%, respectively, while in oxygen plasma process at 10 kV, residual microorganisms, $UV_{254}$ absorbance and TOC removal rate at optimal conditions were $10^{1.0}$ CFU/mL, 73.3% and 24.4%, respectively. Electric power was increased exponentially with the increase in high voltage ($R^2$ = 0.9964). Electric power = $0.0492{\times}\exp^{(0.6027{\times}lectric\;discharge\;voltage)}$ Conclusions: Inactivation of microorganisms in sewage effluent using the pilot plasma process was done. The performance of oxygen plasma process was superior to air plasma process. The power consumption of oxygen plasma process was less than that of air plasma process. However, it was considered that the final evaluation of air and oxygen plasma must be evaluated by considering low power consumption, high process performance, operating costs and facility expenses of an oxygen generator.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.642-644
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• 1999

We have prepared the plasma-polymerized membrane for pervaporation of organic-liquid mixtures by the plasma polymerization technique. Plasma polymerization techniques were utilized in the development of hydrophilic composite membranes having high hydrogen ion permeability and excellent dimensional stability. To develop an organic liquid permselective Membrane, suppressing membrane swearing as well as enhancing the solubility difference is impotant. the objectives of the present study are to disign a suitable membrane for an organic-mixture system by the control of the plasma-polymer solubility.

• Applied Chemistry for Engineering
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• v.33 no.2
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• pp.229-233
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• 2022

In this study, a gas-liquid hybrid atmospheric pressure plasma reactor of the dielectric barrier discharge method was fabricated and characterized. The solubility of copper oxide in the organic acid solution was increased when argon having a larger atomic weight than helium was used during plasma discharge. There was no significant effect of mixing organic acid solutions under plasma discharge treatment on the variation of copper oxide's solubility. As the applied voltage for plasma discharge and the concentration of the organic acid solution increased, the dissolution and removal power of the copper oxide layer increased. Solubility of copper oxide was more affected by the concentration in organic acid solution rather than the variation of plasma applied voltage. The usefulness of hybrid plasma reactor for the surface cleaning process was confirmed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.335-340
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• 2004

On a liquid propellant PPT, the discharge processes that discharge was initiated and plasma was accelerated was observed by using a ultra high speed camera. Liquid propellant PPT is a pulsed plasma thruster using liquid as propellant. Our past study showed the successful operation of liquid propellant PPT and the thruster showed high specific impulse. However, its acceleration mechanism has not been clarified. In this study we observed the plasma acceleration processes in order to deepen our understanding of the acceleration mechanism.