• 제목/요약/키워드: Electron Source

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저온 증착된 불소도핑 주석 산화 박막의 광학적·전기적 특성 (Optical and Electrical Properties of Fluorine-Doped Tin Oxide Prepared by Chemical Vapor Deposition at Low Temperature)

  • 박지훈;전법주
    • 한국재료학회지
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    • 제23권9호
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    • pp.517-524
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    • 2013
  • The electrical and optical properties of fluorine-doped tin oxide films grown on polyethylene terephthalate film with a hardness of 3 using electron cyclotron resonance plasma with linear microwave of 2.45 GHz of high ionization energy were investigated. Fluorine-doped tin oxide films with a magnetic field of 875 Gauss and the highest resistance uniformity were obtained. In particular, the magnetic field could be controlled by varying the distribution in electron cyclotron deposition positions. The films were deposited at various gas flow rates of hydrogen and carrier gas of an organometallic source. The surface morphology, electrical resistivity, transmittance, and color in the visible range of the deposited film were examined using SEM, a four-point probe instrument, and a spectrophotometer. The electromagnetic field for electron cyclotron resonance condition was uniformly formed in at a position 16 cm from the center along the Z-axis. The plasma spatial distribution of magnetic current on the roll substrate surface in the film was considerably affected by the electron cyclotron systems. The relative resistance uniformity of electrical properties was obtained in film prepared with a magnetic field in the current range of 180~200A. SEM images showing the surface morphologies of a film deposited on PET with a width of 50 cm revealed that the grains were uniformly distributed with sizes in the range of 2~7 nm. In our experimental range, the electrical resistivity of film was able to observe from $1.0{\times}10^{-2}$ to $1.0{\times}10^{-1}{\Omega}cm$ where optical transmittance at 550 nm was 87~89 %. These properties were depended on the flow rate of the gas, hydrogen and carrier gas of the organometallic source, respectively.

초소형 자유전자레이저 모듈에 있어서 위글러 구조에 따른 전자빔 특성 연구 (Study on the Characteristics of Electron Beam Dependent with the Structure of Wiggler in the Miniaturized Free Electron Laser Module)

  • 김영철;안성준;김대욱;김호섭;안승준
    • 한국산학기술학회논문지
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    • 제12권3호
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    • pp.1319-1326
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    • 2011
  • 상업용 3-D simulation tool(OPERA)을 이용하여 슬릿형 위글러가 장착된 초소형 자유전자레이저 모듈에 있어서 위글러 구조에 따른 전자빔 특성을 조사하였다. 전자렌즈의 중앙 전극에 일정한 potential을 인가하여 전자빔이 평행빔이 되도록 divergence를 줄여서 위글러에 입사시켰으며 위글러의 구조 의존성에 따른 위글러 내부에서의 전기장과 potential 분포를 계산하여 위글러에서의 전자빔 궤적의 변화를 조사하였다.

A Two-dimensional Steady State Simulation Study on the Radio Frequency Inductively Coupled Argon Plasma

  • Lee, Ho-Jun;Kim, Dong-Hyun;Park, Chung-Hoo
    • KIEE International Transactions on Electrophysics and Applications
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    • 제2C권5호
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    • pp.246-252
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    • 2002
  • Two-dimensional steady state simulations of planar type radio frequency inductively coupled plasma (RFICP) have been performed. The characteristics of RFICP were investigated in terms of power transfer efficiency, equivalent circuit analysis, spatial distribution of plasma density and electron temperature. Plasma density and electron temperature were determined from the equations of ambipolar diffusion and energy conservation. Joule heating, ionization, excitation and elastic collision loss were included as the source terms of the electron energy equation. The electromagnetic field was calculated from the vector potential formulation of ampere's law. The peak electron temperature decreases from about 4eV to 2eV as pressure increases from 5 mTorr to 100 mTorr. The peak density increases with increasing pressure. Electron temperatures at the center of the chamber are almost independent of input power and electron densities linearly increase with power level. The results agree well with theoretical analysis and experimental results. A single turn, edge feeding antenna configuration shows better density uniformity than a four-turn antenna system at relatively low pressure conditions. The thickness of the dielectric window should be minimized to reduce power loss. The equivalent resistance of the system increases with both power and pressure, which reflects the improvement of power transfer efficiency.

저에너지 대면적 전자빔 발생장치 개발에 관한 연구 (A Study on the Low-energy Large-aperture Electron Beam Generator)

  • 조주현;최영욱;이홍식;임근희;우성훈;이광식
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제48권12호
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    • pp.785-790
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    • 1999
  • This research has been carried out to develop a low-energy large-aperture pulsed electron beam generator (LELA), 200keV 1A, for industrial applications. One of the most important feature of this electron beam generator is large electron beam cross section of $190cm^2$. Low energy electron beam generators have been used for water cleaning, flue gas cleaning, and pasteurization, etc. In these applications the cross sectionof the e-beam is related to reaction efficiency. Another important feature of this LELA EB generator is easy maintenance because of its simple structure and relatively low vacuum operation compared to the conventional EB generators. The conventional EB generators need to be scanned because the small cross section thermal electron emitters are used in the conventional EB generators which have small EB cross section. In this research, we use the secondary electrons generated by ion bombardment on the HV cathode surface as a electron source. Therefore we can make any shape of EB cross section without scanning.

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돋보기에서 FE까지 현미경의 변천사 - 생명과학적 관점에서 - (History of Microscope from the Magnifying Glass to the Field Emission Electron Microscope)

  • 박창현;염미정;엄창섭
    • Applied Microscopy
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    • 제33권2호
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    • pp.93-104
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    • 2003
  • 본고에서는 유리의 확대력 발견으로부터 현재까지 이르는 전자현미경과 관련된 중요한 이론 및 개발 과정들을 시대별로 검토하였다. Jansen에 의한 최초의 광학현미경 제작으로부터, 분해능의 한계를 해결하려는 노력들, 짧은 광원을 찾는 노력, 그리고 보다 양질의 해상력과 확대력을 얻으려는 여러 과학자들의 부단한 노력들을 특히 전자현미경 원리 및 TEM과 SEM의 초기 개발과정에 초점을 맞추어 생명과학적 측면에서 고찰하고, 아울러 우리나라의 전자현미경 도입 과정을 살펴보았다.

상압에서 제조한 포토캐소드의 전자방출 특성에 관한 연구 (A Study on Electron Emission Characteristics of Photocathode Formed Under Condition in N2 Atmosphere)

  • 정효수
    • 한국전기전자재료학회논문지
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    • 제27권5호
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    • pp.312-316
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    • 2014
  • Photoemission is a process in which photons are converted into free electrons. Photocathodes are the typical materials for the process. They emit electrons when a light is irradiated upon. The traditional method of manufacturing photocathodes is complicated, requires specialized equipment, and is limited very small sized samples. $Cs_3Sb$ photocathode was formed on a substrate in $N_2$ atmospheric conditions. The photocathode formation was a gas phase reaction with the substrate. Vacuum devices were made to test electron emission characteristics of the formed photocathode. Visible light of wavelength 475 nm was used for the primary light source. The results showed high current density and long term stability of the photoelectron emission.

자화된 헬리칼 공진기 플라즈마 소스를 이용한 고선택비 산화막 식각에 관한 연구 (A study on the high selective oxide etching using magnetized helical resonator plasma source)

  • 이수부;임승완;이석현
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제48권5호
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    • pp.309-314
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    • 1999
  • The magnetized helical resonator plasma etcher has been built. Electron density and temperature were measured as functions of rf source power, axial magnetic field, and pressure. The results show electron density increases as the magnetic field increases and reached $2\times1012cm^{-3}$,/TEX>. The oxide etch rate and selectivity to polysilicon were investigated as the above mentioned conditions and self-bias voltage. We can obtain the much improved oxide etch selectivity to polysilicon (60 : 1) by applying the external axial weak magnetic field in magnetized helical resonator plasma etcher.

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Multilevel acceleration of scattering-source iterations with application to electron transport

  • Drumm, Clif;Fan, Wesley
    • Nuclear Engineering and Technology
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    • 제49권6호
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    • pp.1114-1124
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    • 2017
  • Acceleration/preconditioning strategies available in the SCEPTRE radiation transport code are described. A flexible transport synthetic acceleration (TSA) algorithm that uses a low-order discrete-ordinates ($S_N$) or spherical-harmonics ($P_N$) solve to accelerate convergence of a high-order $S_N$ source-iteration (SI) solve is described. Convergence of the low-order solves can be further accelerated by applying off-the-shelf incomplete-factorization or algebraic-multigrid methods. Also available is an algorithm that uses a generalized minimum residual (GMRES) iterative method rather than SI for convergence, using a parallel sweep-based solver to build up a Krylov subspace. TSA has been applied as a preconditioner to accelerate the convergence of the GMRES iterations. The methods are applied to several problems involving electron transport and problems with artificial cross sections with large scattering ratios. These methods were compared and evaluated by considering material discontinuities and scattering anisotropy. Observed accelerations obtained are highly problem dependent, but speedup factors around 10 have been observed in typical applications.

황산염환원균을 이용한 폐광폐수의 중금속 제거 (Removal of Heavy Metals from Acid Mine Drainage Using Sulfate Reducing Bacteria)

  • 백병천;김광복
    • 상하수도학회지
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    • 제13권2호
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    • pp.47-54
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    • 1999
  • SRB(Sulfate Reducing Bacteria) converts sulfate into sulfide using an organic carbon source as the electron donor. The sulfide formed precipitates the various metals present in the AMD (Acid Mine Drainage). This study is the fundamental research on heavy metal removal from AMD using SRB. Two completely mixed anaerobic reactors were operated for cultivation of SRB at the temperature of $30^{\circ}C$ and anaerobic batch reactors were used to evaluate the effects of carbon source, COD/sulfate($SO_4^=$) ratio and alkalinity on sulfate reduction rate and heavy metal removal efficiency. AMD used in this study was characterized by low pH 3.0 and 1000mg/l of sulfate and dissolved high concentration of heavy metals such as iron, cadmium, copper, zinc and lead. It was found that glucose was an organic carbon source better than acetate as the electron donor of SRB for sulfate reduction in AMD. Amount of sulfate reduction maximized at the COD(glucose)/sulfate ratio of 0.5 in the influent and then removal efficiencies of heavy metals were 97.5% of Cu, 100% of Pb, 100% of Cr, 49% of Mn, 98% of Zn, 100% Cd and 92.4% of Fe. Although sulfate reduction results in an increase in the alkalinity of the reactor, alkalinity of 1000mg/1 (as $CaCo_3$) should be should be added continuously to the anaerobic reactor in order to remove heavy metals from AMD.

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Efficiency of an SCM415 Alloy Surface Layer Implanted with Nitrogen Ions by Plasma Source Ion Implantation

  • Lyu, Sung-Ki;He, Hui-Bo;Lu, Long;Youn, Il-Joong
    • International Journal of Precision Engineering and Manufacturing
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    • 제7권4호
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    • pp.47-50
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    • 2006
  • SCM415 alloy was implanted with nitrogen ions using plasma source ion implantation (PSII), at a dose range of $1{\times}10^{17}\;to\;6{\times}10^{17}\;N^+cm^{-2}$ Auger electron spectrometry (AES) was used to investigate the depth profile of the implanted layer. Friction and wear tests were carried out on a block-on-ring wear tester. Scanning electron microscopy (SEM) was used to observe the micro-morphology of the worn surface. The results revealed that after being implanted with nitrogen ions, the frictional coefficient of the surface layer decreased, and the wear resistance increased with the nitrogen dose. The tribological mechanism was mainly adhesive, and the adhesive wear tended to become weaker oxidative wear with the increase in the nitrogen dose. The effects were mainly attributed to the formation of a hard nitride precipitate and a supersaturated solid solution of nitrogen in the surface layer.