• Nuclear Engineering and Technology
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• 제23권4호
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• pp.420-425
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• 1991

SNU 1.5-MV 직렬형 반데그라프 가속기의 헬륨음이온원으로서 Rb 전하교환기를 제작하였다. 교환기의 최적운전조건을 결정하기 위해 특성실험을 수행하였다. Duoplasmatron 이온원에서 인출된 1~10 keV 에너지의 첼륨양이온빔을 Rb 증기속에 통과시킴으로써 2 단계 전하교환반응, 즉 $He^{+}\;+\;Rb\;{\rightarrow}\;He^{\circ\ast}\;+\;Rb^{+}\;과\;He^{\circ\ast}\;+\;Rb\;{\rightarrow}\;He^{-}\;+\;Rb^{+}$에 의해 헬륨음이온을 얻었다 실험결과로부터 헬륨음이온의 최대생성률이 헬륨양이온에너지가 7 keV일때 얻어짐을 알 수 있었다. Oven과 Canal의 최적온도는 각각 $370^{\circ}C{\;}와\;95^{\circ}C$로 결정되었다. 최적동작조건하에서 최대 헬륨음이온 생성률은 $2.42\pm002\;%$이었다. 본 전하교환기는 헬륨음이온생성에 효과적인 장치임이 입증되었다.

• 한국진공학회지
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• 제15권1호
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• pp.73-80
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• 2006

Si(100)에 주입된 불활성 기체 이온들의 열적 방출 특성을 열탈착(temperature-programmed desorption; TPD) 질량분석법으로 고찰하였다. 약 400K의 표면 온도 조건에서 1keV 비온빔에 시료를 노출시켜 주었을 때, He은 $500\~1100 K$의 넓은 온도 범위에서 Si(100)결정 밖으로 분출되어 나온 반면, Ne, Ar, 및 Kr은 각각 810, 860, 875 K 근처에서 매우 좁은 온도 범위에서 TPD 피크를 나타내며 급격하게 방출되었다. He+ 이온으로 처리된 Si(100)은 표면 원자 구조의 손상이 상대적으로 최소한으로 일어났지만, $Ne^+,\;Ar^+,\;Kr^+$ 등의 이온들로 처리된 경우는 질량이 클수록 표면이 원자 스케일로 더 심하게 손상되었음이 수소 흡탈착 분석 결과로 밝혀졌다. 이온빔에 의한 결정 내부의 결함 생성과 관련하여 이러한 실험적 결과가 시사하는 점들을 논의하였다

• Bulletin of the Korean Chemical Society
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• 제16권2호
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• pp.101-104
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• 1995

In an attempt to understand the nature of hyperthermal ion-surface collisions, noble gas ion beams (He+, Ne+, Ar+, and Xe+) are scattered from a Si(100) surface for collision energies of 20-300 eV and for 45°incidence angle. The scattered ions are mass-analyzed using a quadrupole mass spectrometer and their kinetic energy is measured in a time-of-flight mode. The scattering event for He+ and Ne+ can be approximated as a sequence of quasi-binary collisions with individual Si atoms for high collision energies (Ei > 100 eV), but it becomes of a many-body nature for lower energies, Ar+ and Xe+ ions undergo mutliple large impact parameter collisions with the surface atoms. The effective mass of a surface that these heavy ions experience during the collision increases drastically for low beam energies.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1999년도 춘계학술발표회요약집
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• pp.36-36
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• 1999

• 한국진공학회:학술대회논문집
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• 한국진공학회 1994년도 제7회 학술발표회 및 한·일 CVD 심포지움 논문개요집
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• pp.92-92
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• 1994

Relative intensities of photons emitted from tilted carbon foils have been measured in the wavelength region 300800 nm by 0,6-2,4 MeV $H^{+}\;and\;He^{+}$ ion impacts, Ions were directed onto target surfaces at tilt angles with respect to the sllrface normal, Experimental results support the model that the observed continuum radiation is emitted from the exited carbon foil itself. At each incident projectile energy, the photon intensities of continuum spectra for tilted carbon foi Is were compatred to the stoppi ng powers of carbon for $H^{+}\;and\;He^{+}$ ions, It was found that the photon emission intensity for $H^{+}$ ion is linearly proportional to the stopping power, whereas that for $He^{+}$ ions is proportional to a higher power of the stopping power, and that this tendency increases wi th decreasing velocity of the projectiIes[1, 2].[1, 2].

• 한국진공학회지
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• 제12권S1호
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• pp.28-32
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• 2003

Both $LiNbO_3$ and $KTiOPO_4$ samples were implanted with 350 keY $H^+$ and $He^+$ ions at different doses ranging from $1 ${\times}$\times10^{16}$ to of $5 ${\times}$\times10^{16}$ ions/$\textrm{cm}^2$. Single and multi-energy implantations were performed at room temperature. Mono-mode or a few modes in both $LiNbO_3$ and $KTiOPO_4$ waveguides were observed. The effect of temperature on the refractive index profiles of $LiNbO_3$ and $KTiOPO_4$ waveguids was studied. The temperature covered from room temperature, $200^{\circ}C$, 194.5 K (dry ice) and 77K (liquid nitrogen). Different mechanisms are needed to interpret the observed behavior. A n, increased mono-mode $LiNbO_3$ waveguide was formed by multi-energy keV $He^+$ ions.

• 전기학회논문지P
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• 제67권4호
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• pp.214-220
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• 2018

Light sources induced by gas discharge using rare gases have been widely used in the thin film deposition, the surface modification and the polymer etching. A dielectric barrier discharge (DBD) has been developed in order to consistently emit light and control the wavelength of the emission light. However, much research on the characteristics of the movement of discharge particles is required to improve the efficiency of the light lamp and the life-time of the light apparatus in detail. In this paper, we developed a He DBD discharge simulation tool and investigated the characteristics of discharge particles which were electrons, two positive ions ($He^+$, $He_2^+$) and 5 excited particles ($He^*(1S)$, $He^*(3S)$, $He^*$, $He^{**}$, $He^{***}$). The discharge currents showed the transition from pulse mode to continuous mode with the increase of power. With the accumulated charges on the barrier walls, the discharge current was rapidly increased and caused oscillation of the discharge voltage. As the gas pressure increased, $He_2^+$ and $He^*(3S)$ became the dominant activated particles. The input power was mostly consumed by electrons and $He_2^+$ ion. And the change curve showed that power consumption by electrons increased more with gas pressure than with source voltage or frequency.

• Nuclear Engineering and Technology
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• 제52권12호
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• pp.2860-2866
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• 2020

Oxide dispersion-strengthened materials W-1wt%Pr₂O₃ and W-1wt%La₂O₃ were synthesized by wet chemical method and spark plasma sintering. The field emission scanning electron microscopy (FE-SEM) analysis, XRD and Vickers microhardness measurements were conducted to characterize the samples. The irradiations were carried out with a 5 keV helium ion beam to fluences up to 5.0 × 10²¹ ions/m² under 600 ℃ using the low-energy ion irradiation system. Transmission electron microscopy (TEM) study was performed to investigate the microstructural evolution in W-1wt%Pr₂O₃ and W-1wt%La₂O₃. At 1.0 × 10²⁰ He⁺/m², the average loops size of the W-1wt%Pr₂O₃ was 4.3 nm, much lower than W-1wt% La₂O₃ of 8.5 nm. However, helium bubbles were not observed throughout in both doped W materials. The effects of pre-irradiation with 1.0 × 10²¹ He⁺/m² on trapping of injected deuterium in doped W was studied by thermal desorption spectrometry (TDS) technique using quadrupole mass spectrometer. Compared with the samples without He⁺ pre-irradiation, deuterium (D) retention of doped W materials increased after He⁺ irradiation, whose retention was unsaturated at the damage level of 1.0 × 10²²D₂⁺/m². The present results implied that irradiation effect of He⁺ ions must be taken into account to evaluate the deuterium retention in fusion material applications.

• 한국진공학회지
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• 제10권2호
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• pp.241-246
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• 2001

투명한 폴리에틸렌 테레프탈레이트(Polyethylene terephtalate : PET) 막에 100 keV 이하의 에너지 범위에서 단독 또는 두 이온을 주입하여 표면의 경도 및 광투과도의 변화를 측정하였다. Nano-indentation방법을 사용하여 표면의 경도를 측정한 결과, 표면에서 50 nm 깊이에서 최고 경도가 형성되었고 최고경도를 기준으로 질소 이온 단독으로 주입하였을 때 표면 경도는 약 3배 이상 향상됨과 동시에 광투과도는 550 nm(가시광선 영역) 이상의 파장에서 85％ 이상, 300 nm 이하(자외선 영역)의 파장에서는 95％ 이상의 빛을 차단하여 투명성 유지와 동시에 자외선 차단 효과가 있었다. 두 이온, 즉 He과 N, N와 C 이온들을 PET에 주입하였을 때 질소 단독으로 주입하였을 때보다도 표면의 경도는 훨씬 더 상승하였으며 N과 C 이온을 주입하였을 경우 가장 높았으며 약 5배 이상 더 상승하였다. 이 결과는 이온 주입에 의한 경도 향상은 일반적으로 고분자 재의 경우 교차결합(cross linking)이 기구로 고려되나 이중 이온 주입의 경우 교차결합 뿐만 아니라 주입이온간 또는 이온과 matrix 원소들간의 반응에 의한 경한 게재물 형성도 고려될 수 있음을 보여준다. N 및 C 이온을 주입하였을 경우 경도의 향상이 가장 컸는 이유는 교차결합 뿐만 아니라 주입이온간의 반응으로 매우 경한 C-N화합물의 형성에 기인된 것으로 고려된다.

• 천문학회지
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• 제41권6호
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• pp.163-172
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• 2008

Using the spectral data in the 3700 to $10050{\AA}$ wavelength range secured with the Hamilton Echelle Spectrograph (HES) at the Lick observatory, we have investigated the expansion velocities and the physical conditions of the elliptical planetary nebula NGC 6803. Various forbidden and permitted lines, e.g. HI, HeI, HeII, [OIII], [NII], [ArIII], and [SII], indicate complicated but systematic physical conditions variation: electron temperatures $T_{\varepsilon}\;{\sim}\;9000$ - 11000 K and electron number densities $N_{\varepsilon}\;{\sim}\;2000$ - $9000\;cm^{-3}$. The line profile analysis of these ions also indicates the systematic change or the acceleration of the expansion velocities in the range of 10 - $22\;km\;s^{-1}$. We show that the velocity gradient and physical condition found in various ions are closely related to the prolate ellipsoidal structure of NGC 6803. The expansion velocity and the ionic abundance of $O^{2+}$ were derived based on the OII and [OIII] lines. In spite of the discrepancy of ionic abundances derived by the two cases and their line profiles, the expansion velocities of them agree well. We find that the ratios of the red to blue line component of the HeII & OII lines are different from those of the [OIII] or other forbidden lines that indicates a possible involvement of emission of HeII & OII lines. This subtle difference and the different physical condition of the lines are likely to be caused by the elongated geometry and the latitude dependence of the emission zone.