• Title/Summary/Keyword: Gas plasma

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Characteristics of Plasma Discharge according to the Gas-flow Rate in the Atmospheric Plasma Jets (대기압 플라즈마 제트의 기체 유량에 대한 방전 특성)

  • Lee, Won Young;Jin, Dong Jun;Kim, Yun Jung;Han, Gook Hee;Yu, Hong Keun;Kim, Hyun Chul;Jin, Se Whan;Koo, Je Huan;Kim, Do Young;Cho, Guangsup
    • Journal of the Korean Vacuum Society
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    • v.22 no.3
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    • pp.111-118
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    • 2013
  • The influence of gas flow on the plasma generation in the atmospheric plasma jet is described with the theory of hydrodynamics. The plasma discharge is affected by the gas-flow streams with Reynolds number (Re) as well as the gas pressure with Bernoulli's theorem according to the gas flow rate inserted into the glass tube. The length of plasma column is varied with the flow types such as the laminar flow of Re<2,000 and the turbulent flow of Re>4,000 as it has been known in a general fluid experiments. In the laminar flow, the plasma column length is increased as the increase of flow rate. Since the pressure in the glass tube becomes low as the increase of flow velocity by the Bernoulli's theorem, the breakdown voltage of plasma discharge is reduced by the Paschen's law. Therefore, the plasma length is increased as the increasing flow rate with the fixed operation voltage. In the transition of laminar and turbulent flows, the plasma length is decreased. When the flow becomes turbulent as the flow rate is increasing, the plasma length becomes short and the discharge is shut down ultimately. In the discharge of laminar flow, the diameter of plasma beam exposed on the substrate surface is kept less than the glass diameter, since the gas flow is kept to the distinct distance from the nozzle of glass tube.

CAE Analysis of $SF_6$ Arc Plasma for a Gas Circuit Breaker Design (가스차단기 최적설계를 위한 $SF_6$ 아크 플라즈마 CAE 해석)

  • Lee Jong C.;Ahn Heui-Sub;Kim Youn J.
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.365-368
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    • 2002
  • The design of industrial arc plasma systems is still largely based on trial and error although the situation is rapidly improving because of the available computational power at a cost which is still fast coming down. The desire to predict the behavior of arc plasma system, thus reducing the development cost, has been the motivation of arc research. To interrupt fault current, the most enormous duty of a circuit breaker, is achieved by separating two contacts in a interruption medium, $SF_{6}$ gas or air etc., and arc plasma is inevitably established between the contacts. The arc must be controlled and interrupted at an appropriate current zero. In order to analyze arc behavior in $SF_{6}$ gas circuit breakers, a numerical calculation method combined with flow field and electromagnetic field has been developed. The method has been applied to model arc generated in the Aachen nozzle and compared the results with the experimental results. Next, we have simulated the unsteady flow characteristics to be induced by arcing of AC cycle, and conformed that the method can predict arc behavior in account of thermal transport to $SF_{6}$ gas around the arc, such as increase of arc voltage near current zero and dependency of arc radius on arc current to maintain constant arc current density.

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Densification and Electrical Conductivity of Plasma-Sprayed (Ca, Co)-Doped LaCrO3 Coating (플라즈마 스프레이 (Ca, Co)-Doped LaCrO3 코팅층의 치밀화 및 전기전도도)

  • Park, Hee-Jin;Baik, Kyeong-Ho
    • Korean Journal of Materials Research
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    • v.27 no.3
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    • pp.155-160
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    • 2017
  • Doped-$LaCrO_3$ perovskites, because of their good electrical conductivity and thermal stability in oxidizing and/or reducing environments, are used in high temperature solid oxide fuel cells as a gas-tight and electrically conductive interconnection layer. In this study, perovskite $(La_{0.8}Ca_{0.2})(Cr_{0.9}Co_{0.1})O_3$ (LCCC) coatings manufactured by atmospheric plasma spraying followed by heat treatment at $1200^{\circ}C$ have been investigated in terms of microstructural defects, gas tightness and electrical conductivity. The plasma-sprayed LCCC coating formed an inhomogeneous layered structure after the successive deposition of fully-melted liquid droplets and/or partially-melted droplets. Micro-sized defects including unfilled pores, intersplat pores and micro-cracks in the plasma-sprayed LCCC coating were connected together and allowed substantial amounts gas to pass through the coating. Subsequent heat treatment at $1200^{\circ}C$ formed a homogeneous granule microstructure with a small number of isolated pores, providing a substantial improvement in the gas-tightness of the LCCC coating. The electrical conductivity of the LCCC coating was consequently enhanced due to the complete elimination of inter-splat pores and micro-cracks, and reached 53 S/cm at $900^{\circ}C$.

Luminescence Properties of Argon and Neon Gas Using an Inductively Coupled Plasma (유도결합형 Ar, Ne 가스에서의 플라즈마 발광 특성)

  • Her, In-Sung;Lee, Young-Hwan;Lee, Jong-Chan;Choi, Yong-Sung;Park, Dae-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.07a
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    • pp.220-223
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    • 2004
  • Inductively coupled plasma is commonly used for electrodeless lamp due to its ease of plasma generation. Optical characteristics significantly depend on the RF power and gas pressure of the plasma. This paper describes the measurement of luminance as a function of RF power and gas pressure with a goal of finding optimal operating conditions of the electrodeless lamp. The gas pressure was varied from 10[mTorr] to 300[mTorr] or 500[mTorr] and the RF power was varied from 10[W] to 200[W]. It was found that the luminance tends to be decreased when argon and neon pressure is increased, and the luminance is increased as RF power is increased. It was also found that the luminance per unit RF power is high when the argon and neon pressure is low and when the RF power is in the range of $30[W]{\sim}40[W]$ or 10[W].

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Fabrication and Characterization of Gas-liquid Hybrid Reactor Equipped with Atmospheric Pressure Plasma (기-액 하이브리드 대기압 플라즈마 반응기 제작 및 특성 분석)

  • Kwon, Heoung Su;Lee, Won Gyu
    • Korean Chemical Engineering Research
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    • v.60 no.3
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    • pp.452-458
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    • 2022
  • Three types of gas-liquid hybrid horizontal, vertical and needle-to-cylinder plasma reactors were fabricated. Through these reactors, a high-efficiency, eco-friendly cleaning concept that generates reactive active species generated in atmospheric plasma discharge and gas-liquid activation reaction of cleaning components through the potential difference within the electrode was presented. As a result of comparing the efficiency for cleaning performance, the needle-to-cylinder type reactor had the best characteristics. Through this study, it was confirmed that the gas-liquid hybrid atmospheric pressure plasma reactor has the potential to be applied to ultra-precision cleaning processes such as semiconductor processes.

The Characteristics of Dust Removal in Flue Gas by the Plasma of Impulse Streamer Corona (충격식 코로나 방전 플라즈마를 이용한 배연가스로부터 먼지제거에 대한 특성)

  • 김은호
    • Journal of Environmental Science International
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    • v.12 no.12
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    • pp.1261-1267
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    • 2003
  • On the basis of the distribution of particle size measured by laser diffraction spectrometers, this research was carried out to investigate the characteristics of mist removal with the change of operating condition in the plasma reactor of impulse streamer corona. The operating parameters in this experiment were power of impulse streamer corona, gas velocity, impulse generation time, gas temperature, and SOx/NOx concentration. The collection efficiency T(d) was estimated by the distribution of particle size in the collection zone through the advanced model.

A study on the hydrogen generation's characteristics via non-thermal plasma and carrier gas (비열플라즈마에 의한 수소발생에 미치는 캐리어가스의 영향)

  • Kim, Jong-Seog;Park, Jae-Yoon;Jung, Jang-Gun;Kim, Tae-Yong;Koh, Hee-Seog;Lee, Hyun-Woo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.07a
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    • pp.215-219
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    • 2004
  • This paper is investigated about the effect of carrier gas and humidity for generating hydrogen gas. In the experimental result of generating hydrogen gas by non-thermal plasma reactor, the rate of generating hydrogen gas is different with what kind of carrier gas is. We used two types of carrier gas, such as $N_2$ and He. $N_2$ as carrier gas is more efficient to generate hydrogen gas than He because $N_2$ is reacted with $O_2$, which is made from water dissociation. In comparison with no humidity and humidity 45[%], the generation of hydrogen gas is decreased with increasing the humidity. That is the result that the energy for water dissociation is reduced on water surface because a part of plasma energy is absorbed at the small particle produced from humidifier.

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2MHz, 2kW RF Generator (2MHz, 2kW RF 전원장치)

  • Lee J.H.;Choi D.K.;Choi S.D.;Choi H.Y.;Won C,Y.;Kim S.S
    • Proceedings of the KIPE Conference
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    • 2003.07a
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    • pp.260-263
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    • 2003
  • When ICP(Inductive Coupled Plasma type etching and wafer manufacturing is being processed in semiconductor process, a noxious gas in PFC and CFC system is generated. Gas cleaning dry scrubber is to remove this noxious gas. This paper describes a power source device, 2MHz switching frequency class 2kW RF Generator, used as a main power source of the gas cleaning dry scrubber. The power stage of DC/DC converter is consist of full bridge type converter with 100kHz switching frequency Power amplifier is push pull type inverter with 2MHz switching frequency, and transmission line transformer. The adequacy of the circuit type and the reliability of generating plasma in various load conditions are verified through 50$\Omega$ dummy load and chamber experiments result.

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ABLATION OF PTFE NOZZLE DRIVEN BY ARC PLASMA (아크 플라즈마에 의한 PTFE 노즐 용삭현상)

  • Lee J.C.;Kim Y.J.
    • 한국전산유체공학회:학술대회논문집
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    • 2005.10a
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    • pp.311-317
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    • 2005
  • It has been the most progressive interruption technique to use the ablation gas from the surface of PTFE nozzle driven by arc plasma during switching process in $SF_6$ gas circuit breakers. This advanced interruption technique can reduce the required mechanical energy to compress and blow the gas for extinguishing the arc plasma between the electrodes due to using the ablation effect instead. In order to consider the phenomena during calculation of switching process, it is required to confirm the principles of ablation from PTFE nozzle as well as of arc plasma during switching process. In this study, we have calculated the switching process considered the ablation of PTFE nozzle driven by arc plasma using multidisciplinary simulation technique and compared the results with the data without the ablation effect. More $50\%$ difference of pressure rise inside expansion chamber has been found from the results and it should be indispensable for this type of computational work to consider and include the ablation effect of PTFE nozzle. Further study on turbulence and radiation will be followed.

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An Investigation of Selective Etching of GaAs to Al\ulcornerGa\ulcornerAs Using BCI$_3$SF\ulcorner Gas Mixture in ECR Plasma (ECR 플라즈마에서 $BCI_3/SF_6$ 혼합 가스를 이용한 $Al_{0.25}Ga_{0.75}As$에 대한 GaAs의 선택적 식각에 대한 연구)

  • 이철욱;이동율;손정식;배인호;박성배
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.11 no.6
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    • pp.447-452
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    • 1998
  • The selective dry etching of GaAs to Al\ulcornerGa\ulcornerAs using $BCI_3/SF_6$ gas mixture in electron cyclotron resonance(ECR) plasma is investigated. A selectivity of GaAs to AlGaAs of more than 100 and maximum etch rate of GaAs are obtained at a gas ratio $SF_6/BCI_3+SF_6$ of 25%. We verified the formation of $AlF_3$ on $Al_{0.25}Ga_{0.75}As$from the Auger spectra which enhanced the etch selectivity. In order to investigate surface damage of AlGaAs caused by ECR plasma, we performed a low temperature photoluminescence(PL) measurement as a function of RF power. As the RF power. As the RF power increases, the PL intensity decreases monotonically from 50 to 100 Wand then repidly decreases until 250 W. This behavior is due to surface damage by plasma treatment. This dry etching technique using $BCI_3/SF_6$ gas mixture in ECR plasma is suitable for gate recess formation on the GaAs based pseudomorphic high electron mobility transistor(PHEMT)

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