• Applied Science and Convergence Technology
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• 제27권4호
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• pp.65-69
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• 2018

We studied the critical pressure characteristics of an anode type ion beam source driven by both charge repulsion and diffusion mechanism. The critical pressure $P_{crit}$ of the diffusion type ion beam source was linearly decreased from 2.5 mTorr to 0.5 mTorr when the gas injection was varied in 3~10 sccm, while the $P_{crit}$ of the charge repulsion ion beam source was remained at 3.5 mTorr. At the gas injection of 10 sccm, the range of having normal beam shape in the charge repulsion ion beam source was about 6.4 times wider than that in the diffusion type ion beam source. An impurity of Fe 2p (KE = 776.68 eV) of 12.88 at. % was observed from the glass surface treated with the abnormal beam of the charge repulsion type ion beam source. The body temperature of the diffusion type ion beam source was observed to increase rapidly at the rate of $1.9^{\circ}C/min$ for 30 minutes and to vary slowly at the rate of $0.1^{\circ}C/min$ for 200 minutes for an abnormal beam and normal beam, respectively.

• Nuclear Engineering and Technology
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• 제56권1호
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• pp.70-77
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• 2024

A low energy ion irradiation system based on the deuterium arc ion source with a high perveance of 1 µP for a single extraction aperture has been successfully developed for the investigation of ion irradiation on plasma-facing components including the first mirror of plasma optical diagnostics system. Under the optimum operating condition for mirror testing, the ion source has a beam energy of 200 eV and a current density of 3.7 mA/cm². The ion source comprises a magnetic cusp-type plasma source, an extraction system, a target system with a Faraday cup, and a power supply control system to ensure stable long time operation. Operation parameters of plasma source such as pressure, filament current, and arc power with D₂ discharge gas were optimized for beam extraction by measuring plasma parameters with a Langmuir probe. The diode electrode extraction system was designed by IGUN simulation to optimize for 1 µP perveance. It was successfully demonstrated that the ion beam current of ~4 mA can be extracted through the 10 mm aperture from the developed ion source. The target system with the Faraday cup is also developed to measure the beam current. With the assistance of the power control system, ion beams are extracted while maintaining a consistent arc power for more than 10 min of continuous operation.

• 한국세라믹학회지
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• 제40권10호
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• pp.967-972
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• 2003

직경 5 cm cold hollow cathode 이온원을 박막의 이온보조증착법 또는 이온보조반응법에 사용하기에 적합한 이온빔으로 넓은 면적을 균일하게 조사할 수 있는 이온원을 설계, 제작하기 위한 방안으로 연구하게 되었다. 이온원은 글로우 방전을 위한 음극과 이온화 효율의 증가를 위한 자석, 플라즈마 챔버, 그리드 전극으로 이루어진 이온광학시스템, 직류전원공급장치로 이루어진다. 전자인출전극의 구조 및 형태로 구분하여 한개의 노즐로 이루어진 (I) 형태와 복수개의 노즐로 변형된 (II) 형태로 제작하였다. 서로 다른 구조의 전자인출전극 (I)형태와 (II) 형태를 부착한 이온원에 beam profile을 측정한 결과 (I) 형태의 전자인출전극을 부착한 경우에는 이온원의 중심에서 140 $\mu\textrm{A}$/$\textrm{cm}^2$으로 측정되어 졌으며, 외곽으로 멀어질수록 급격히 전류밀도가 감소하여 균일한 영역(최대값의 90%)은 직경 5 cm로 측정되어졌다. (II) 형태로 변형되어진 이온원의 경우 중심에서 65 $\mu\textrm{A}$/$\textrm{cm}^2$으로 (I) 형태와 비교하여 상대적으로 낮은 전류밀도가 측정되었지만 외각으로 멀어졌을 경우에도 전류밀도는 완만하게 감소하여 균일한 영역은 직경 20 cm로 측정되었으며, 본 연구목적에 부합되는 특성이 측정되었다. 이온빔 균일도가 증가한 (II) 형태의 전자인출전극을 부착한 이온원으로 주입하는 아르곤 가스량의 변화, 이온광학시스템의 플라즈마 그리드 전극과 가속 그리드 전극 간격의 조절, 이온빔 에너지 변화에 따른 beam profile 및 특성을 괸찰하였다.

• Applied Science and Convergence Technology
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• 제27권3호
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• pp.47-51
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• 2018

We fabricated an anode-type ion beam source and studied its driving characteristics of the initial extraction of ions using two driving mechanisms: a diffusion phenomenon and a charge repulsion phenomenon. For specimen exposed to the ion beam in two methods, the surface impurity element was investigated by using X-ray photoelectron spectroscopy. Upon Ar gas injection for plasma generation the ion beam source was operated for 48 hours. We found a Fe 2p peak 5.4 at. % in the initial ions by the diffusion mechanism while no indication of Fe in the ions released in the charge repulsion mechanism. As for a long operation of 200 min, the temperature of ion beam sources was measured to increase at the rate of ${\sim}0.1^{\circ}C/min$ and kept at the initial value of $27^{\circ}C$ for driving by diffusion and charge repulsion mechanism, respectively. In this study, we confirmed that the ion beam source driven by the charge repulsion mechanism was very efficient for a long operation as proved by little electrode damage and thermal stability.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.269-269
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• 2012

A new ion source has been designed, fabricated, and installed at the NBTS (Neutral Beam Test Stand) at the KAERI (Korea Atomic Energy Research Institute) site. The goalis to provide a 100 keV, 2MW deuterium neutral beam injection as an auxiliary heating of KSTAR (Korea Super Tokamak Advanced Research). To cope with power demand, an ion current of 50 A is required considering the beam power loss and neutralization efficiency. The new ion source consists of a magnetic cusp bucket plasma generator and a set of tetrode accelerators with circular copper apertures. The plasma generator for the new ion source has the same design concept as the modified JAEA multi-cusp plasma generator for the KSTAR prototype ion source. The dimensions of the plasma generator are a cross section of $59{\times}25cm^2$ with a 32.5 cm depth. The anode has azimuthal arrays of Nd-Fe permanent magnets (3.4 kG at surface) in the bucket and an electron dump, which makes 9 cusp lines including the electron dump. The discharge properties were investigated preliminarily to enhance the efficiency of the beam extraction. The discharge of the new ion source was mainly controlled by a constant power mode of operation. The discharge of the plasma generator was initiated by the support of primary electrons emitted from the cathode, consisting of 12 tungsten filaments with a hair-pin type (diameter = 2.0 mm). The arc discharge of the new ion source was achieved easily up to an arc power of 80 kW (80 V/1000 A) with hydrogen gas. The 80 kW capacity seems sufficient for the arc power supply to attain the goal of arc efficiency (beam extracted current/discharge input power = 0.8 A/kW). The accelerator of the new ion source consists of four grids: plasma grid (G1), gradient grid (G2), suppressor grid (G3), and ground grid (G4). Each grid has 280 EA circular apertures. The performance tests of the new ion source accelerator were also finished including accelerator conditioning. A hydrogen ion beam was successfully extracted up to 100 keV /60 A. The optimum perveance is defined where the beam divergence is at a minimum was also investigated experimentally. The optimum hydrogen beam perveance is over $2.3{\mu}P$ at 60 keV, and the beam divergence angle is below $1.0^{\circ}$. Thus, the new ion source is expected to be capable of extracting more than a 5 MW deuterium ion beam power at 100 keV. This ion source can deliver ~2 MW of neutral beam power to KSTAR tokamak plasma for the 2012 campaign.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.807-814
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• 2004

Land seismic reflection survey has been increasingly demanded in various civil engineering works because of its own ability to delineate layers, water table, to detect cavities or fracture zones, to estimate seismic velocities of each layer. However, our shallow subsurface structures are very complex. The relatively thin layer(mostly soil) to the wavelength directly followed by a basic rock with high impedance used to generate complicated surface waves, kind of channel waves with high amplitude that is dominate in entire seismograms and hence the useful reflection events will be almost hopelessly immersed in the undesired surface waves. Thus, it would seem that the use of traditional seismic survey could not be likely to provide in itself a satisfactory information about our exploration targets. This paper hence introduces an efficient measuring strategy illustrating a properly controlled arrangement of the vertical single force sources commonly used, yielding a very sharply elongated form of P-energy with a minimum of S radiation energy, what we call, P-beam source. Abundant experiments of physical modeling showed that in that way the surface waves could be enormously reduced and the reflection events would be additive and thus reinforced. Examples of field data are also illustrated. The contribution of P-beam source will be great in civil engineering area as well as in general geological exploration area.

• 한국재료학회지
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• 제9권9호
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• pp.861-864
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• 1999

다중 음극 전자빔을 이용한 새로운 플라즈마 소스를 설계하고 제작하였다. 대면적의 플라즈마를 발생시키기 위해 다중 음극을 채택하였다. 다중 음극 전자빔 플라즈마 소스(multi-cathode electron beam plasma source, MCEBPS)를 이용하여 300mm 또는 그 이상의 직경을 가진 웨이퍼에 안정한 플라즈마를 생성시킬 수 있었다. 텅스텐 필라멘트를 음극으로 사용하였다. 직경 320mm의 넓이에서, plasma potential $V_p$와 floating potential $V_f$ 모두 균일하게 유지되었고 $V_p와 V_f$의 차이도 낮은 값으로 나타났다. 플라즈마 밀도는 약 $10^{10} cm^{-3}$ 정도로 측정되었고 반경걸에 따른 편차는 작게 나타났다.

• 전자공학회논문지A
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• 제30A권9호
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• pp.24-29
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• 1993

The 607 nm GaInP/AlInP distributed bragg reflector (DBR) lasers using the second order gratings period of 184.7 nm were fabricated by gas source molecular beam epitaxy (GSMBE) and the conventional holographic method. GaInP/AlInP DBR lasers show single mode operations up to 1.8 times the threshold currents with a wavelength of 607 nm at 140 K and a wavelength shift of 0.033 nm/K is observed. No mode hopping was found in the temperature ranging from 120 to 165K.

• 한국산학기술학회논문지
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• 제7권6호
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• pp.1047-1055
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• 2006

필드이온빔(FIB) 가공기를 써서 초고강도의 벌크다이아몬드를 가공하기 위해 이온 소오스의 종류와 가공 조건에 따른 나노급 미세 선폭의 최적조건을 알아보고 이에 근거한 2차원적인 텍스트의 가공과 3차원적인 박막요소의 가공을 시도하였다. 다이아몬드 기판과 실리콘 기판을 Ga과 $H_2O$ 소오스를 이용하는 FIB를 써서 30 kV 빔 전류를 10 pA $\sim$ 5 nA로 변화시키면서 패터닝하고 이때 각각 20 ${\mu}m$ 길이로 생성되는 선형 패턴의 선폭, 깊이, 에치속도, 에치형상, 깊이선폭비 (aspect ratio)를 확인하였다. 다이아몬드도 실리콘 기판과 마찬가지로 나노급 패턴의 형성이 가능하였다. $H_2O$ 소오스를 채용한 경우가 에치 깊이가 2배 정도 증가하였으며 동일한 가공 조건에서는 실리콘에 비해 다이아몬드의 에치 선폭이 감소는 경향이 있었다. 특히 다이아몬드는 절연성 때문에 차지가 축적되어 가공 중 이온빔이 불안정해지는 문제가 있었으나 차지 중화 모드를 이용하여 성공적으로 sub-100 nm급 선폭의 미세 가공이 가능하였다. 확인된 선폭가공 조건에 근거하여 2차원적으로 0.3carat의 보석용 다이아몬드의 거들부에 300여개의 글자를 FIB를 활용하여 선폭 240 nm정도로 명확히 기록하는 것이 가능하였다. $Ga^+$이온과 30 eV-30 pA로 조건에서 비교적 넓은 선폭과 Z축 depth 고정범위에서 많은 개인정보의 기록이 영구적으로 가능하였으며 전자현미경으로 재생이 가능하였다. 3차원적으로 두께 $1{\mu}m$의 박막요소를 FIB가공과 백금 용접으로 떼어낸 후 FIB가공으로 두께가 100 nm가 되도록 한 후 투과전자현미경을 이용하여 성분 분석을 하는 것이 성공적으로 수행될 수 있었다.

• 한국진공학회지
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• 제4권S2호
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• pp.75-78
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• 1995

Gas source molecular beam epitaxy have been used in the growth of InAlAsAnGaAs MSM-PD structure, in which InAlAs ultra thin layer was used as Schottky barrier enhancement material. High performance MSM-PDs have been constructed on the grown wafer. High breakdown voltage of >30V, low dark current density of $3pA/\mu \textrm{cm}^2$ at 10V bias and fast transient response of <20ps rise time / <40ps FWHM have been measured, which confirm the results that GSMBE is a superior method for the growth of materials with high layer and interfacial quality, especially for InP based InAIAdInGaAs system.