• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.3
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• pp.583-587
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• 2007

Corona discharge and ozone generation characteristics of a slit dielectric barrier discharge type wire-plate plasma reactor with a third electrode have been investigated. When a third electrode is installed on a slit of the slit barrier, where an intense corona discharge occurs, it is found that a significantly increased ozone output could be obtained. This, however, indicates that the third electrode can activate the corona discharges both of the discharge wire and the slit of the slit barrier in the plasma reactor. As a result, a thin stainless wire, used as the third electrode has a strong effect to influence the corona discharge of the slit and corona wire, especially to the negative corona discharge. Higher amounts of the output ozone and ozone yield, about 1.27 and 1.29 times for the negative corona discharge, can be obtained with the third electrode, which reveals the effectiveness of the third electrode.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.6
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• pp.65-71
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• 2002

Characteristics of corona discharge of the different types of the plasma reactors which are cone-hole and cone-plate is investigated experimentally. The discharge starts at lower voltage for the cathode corona than the anode corona and spark occurs at higher voltage for the cathode corona. And the cathode corona makes more stable discharge than the anode corona. The effect of the base gas in corona discharge for different O$_2$/N$_2$ concentrations is related with the gas molecular weight. The discharge for the smaller molecular weight gas occurs easier than for the high molecular weight gas. The discharge current decreases with the increase of oxygen concentration and it increases more sharply for anode corona than for cathode corona as discharge voltage increases after corona onset voltage. NO-NO$_2$ conversion increases with the energy density of corona discharge and the addition of O$_2$ in a base N$_2$ gas.

• Journal of the Korean Society of Safety
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• v.15 no.3
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• pp.66-70
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• 2000

In order to cope with environmental problems caused by harmful gases emitted from various industrial sources, a new technology which employs discharge plasma formed in ordinary atmospheric pressure has been intensively investigated in many industrialized nations. Although a plenty of useful outcomes and suggestions have been made public by scientists in this field, few commercial products which effectively decompose pollutant gases have appeared as yet. This is partly because that the energy efficiency of a most effective plasma reactor has not reached a satisfactory level in comparison with those of devices using conventional technologies. In an attempt to solve the problem mentioned above, we noticed to combine heterogeneous electrical discharges. This concepts is based on that each plasma reactor has its specific spatial region in which chemical reaction are active and by electrically affected with another reactor of different type, the activated region would increase - which may lead to cutting down the energy consumption. To prove this concept experimentally, two different discharge equipments, a plane ceramic-based surface discharge electrode and a corona electrode with tungsten needle may, are selected and combined to fabricate a hybrid plasma reactor. The results are summarized as follows; (1) Ozone concentration generated in the plasma region drastically increases when the positive corona discharge is added to the surface discharge. The rate of increase of ozone depends on the frequency of the surface discharge. The negative corona, however, does not contribute to the improvement of the ozone generation. (2) NO(nitrogen monoxide) decomposition rate also improves by simultaneously applying the surface and the positive corona discharges. The effect of the corona superposition is more evident when the level of the surface discharge is moderate. (3) By adjusting the corona level, the net energy efficiency during NO decomposition improves in comparison with the simple surface discharge reactor.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.4
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• pp.648-652
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• 2008

Corona discharge and ozone generation characteristics of a wire-plate plasma reactor, with a biased third electrode, have been investigated with an emphasis on the role of the bias voltage and frequency applied on the third electrode. It was found that the wire-plate plasma reactor, with the biased third electrode, had a switching characteristic on its I-V characteristics for negative and positive discharges, which is very different from that of a conventional wire-plate plasma reactor without the third electrode. As a result, the corona discharge and ozone generation characteristics of the proposed plasma reactor could be controlled by adjusting the bias voltage and frequency of the third electrode. The corona onset and breakdown voltages, and ozone generation and yield, were increased compared with those of without the third electrode. These, however, reveal the effectiveness of the biased third electrode.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.3
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• pp.157-161
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• 2004

We present a simple analytical expression of plasma density by making use of the electron density equation to study the dynamic behavior of the corona discharge plasma. It assumes that a specified voltage profile is fed through the inner conductor of the reactor chamber consisting of two coaxial conducting cylinders. The analytical description is based on the electron continuity equation with ionization and attachment by electrons. It is found that the electron density profile calculated between two coaxial cylindrical electrodes depends very sensitively on the Profile of applied voltage. The analytical expression of plasma density and its generation will provide important scaling laws in the corona discharge plasma.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.1061-1064
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• 2001

Deep Interests have been paid on the application of non-thermal plasma technique to solve the environmental pollution problems. $CO_2$, is one of the severe pollutants which cause the acid rain and global warming. In this study, in order to improve the conversion efficiency of $CO_2$, the streamer corona discharge plasma and barrier discharge plasma reactors were made, and the conversion characteristics of $CO_2$by the corona discharge plasma and some discharge characteristics of these discharge chambers are studied experimentally.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.1
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• pp.151-155
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• 2007

A compact discharge plasma system with a photocatalyst has been proposed and investigated experimentally for application to air conditioners. It was found that there was intense ultra violet radiation with high energy of 3.2 eV from the corona discharge due to the DC-biased pulse voltage applied on a wire. An electrophotochemical reaction took place apparently on the surfaces of the photocatalyst of $TiO_2$ irradiated ultra violet front the discharge plasma in the proposed plasma system. The proposed discharge plasma system with the photocatalyst of $TiO_2$ showed very high removal efficiency of VOCs by tile additional electrophotochemical reactions on the photocatalyst. The proposed discharge plasma system also showed very high removal efficiency of particles such as smokes, suspended bacteria, and pollen and mite allergens by the electrostatic precipitation part. This type of corona discharge plasma system with a photocatalyst can be used as an effective means of removing both indoor pollutant gases and particles including suspended allergens.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.5
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• pp.921-925
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• 2007

Gas removal characteristics of an air clean system, consisted of a filter and a nonthermal discharge plasma reactor with a magnetic field, have been investigated with emphasis on the enhancing gas removal efficiency of the applied magnetic field. It is found that the magnetic field influenced significantly to the corona discharge characteristics, decreasing the corona onset voltage and increasing the corona current. As a result, the proposed air clean system with the magnetic field showed the higher removal efficiency of the gas (e.g., trimethlyamine) than that of without the magnetic field. This would be because the magnetic field applied to the discharge plasma reactor of the air clean system can elevate the corona characteristics, and activate the generation of ozone, thus the removal efficiency of the gas was concurrently enhanced. This reveals that the proposed air clean system with the magnetic field could be used as an effective means of removal an indoor pollutant gas.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.5
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• pp.933-937
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• 2007

A point plate type nonthermal plasma reactor, with a grounded cylindrical third electrode which closely- encompasses the needle point, have been investigated with an emphasis on the role of the third electrode. It was found that the point plate airgap, with the grounded third electrode, had a switching characteristic on its I V characteristics for negative and positive discharges, which is very different from that of a conventional point plate airgap without a third electrode. The corona discharge and ozone generation characteristics of the plasma reactor with the grounded cylindrical third electrode, such as the corona onset voltage. the breakdown voltage. the corona current. and the amount of output ozone, were influenced significantly by the height of the third electrode. and these characteristics can be controlled by adjusting the height of the third electrode.

• The Korean Journal of Ceramics
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• v.5 no.3
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• pp.245-249
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• 1999

A new type of nonthermal plasma reactor utilizing ferroelectric pellets is proposed to generate nonthermal plasma efficiently, which is used for simultaneous control of various pollutant gases. Electric charges stored on ferroelctric pellets by corona discharge between a corona tip and a mesh electrode provide partial electrical discharges among ferroelectric pellets. These partial electrical discharges can enhance partial discharges around the surface of ferroelectric pellets. This method utilizes wide reacting area of ferroelectric pellets and partial discharge. Positive and negative dc voltage are applied to the corona tip to generate partial discharges, and corona currents are estimated to investigate charge storage on ferroelectric pellets as function of time and charge relaxation time constants of ferroelectric pellects. As a result, charge relaxationtime, dielectric constants of ferroelectric pellets, polarity of applied voltage and applied time influence partial discharges among ferroelectric pellect.