• Nuclear Engineering and Technology
• /
• v.56 no.9
• /
• pp.3961-3968
• /
• 2024

The Korea Atomic Energy Research Institute (KAERI) is developing a novel Two-Region Arc Plasma Ion Source (TRAP) as a negative hydrogen (deuterium) ion source for a Neutral Beam Injection (NBI) system in a fusion tokamak. The TRAP ion source is based on a two-region configuration, comprising a high energy electron region that creates highly vibrationally excited molecules and a low electron temperature region that generates negative ions by attaching electrons to molecules. This configuration can be achieved by optimizing the filament position and magnetic cusp field. In order to optimize the TRAP configuration, the plasma parameters are investigated under various operating conditions, such as filament position, gas pressure, and arc power. Electron density and temperature are determined using Langmuir probe measurements. In this paper, the detailed experimental results are described and discussed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.05b
• /
• pp.1-6
• /
• 2002

Plasma processing of semiconductor materials plays a dominant role in microelectronic technology. During last century, plasma have gone a way from laboratory phenomena to industrial applications due to intensive progress in both scientific and industrial trends. Improvement and development of new experience together with development of plasma theory and plasma diagnostics methods. A most parameters (pressure, flow rate, power density) and various levels of plasma system (energy distribution, volume gas chemistry, transport, heterogeneous effects) to understand the whole process mechanism. It will allow us to choose a correct ways for processes optimization.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.08a
• /
• pp.268-268
• /
• 2012

Atmospheric pressure microwave induced plasmas are used to excite and ionize chemical species for elemental analysis, for plasma reforming, and for plasma surface treatment. Microwave plasma differs significantly from other plasmas and has several interesting properties. For example, the electron density is higher in microwave plasma than in radio-frequency (RF) or direct current (DC) plasma. Several types of radical species with high density are generated under high electron density, so the reactivity of microwave plasma is expected to be very high [1]. Therefore, useful applications of atmospheric pressure microwave plasmas are expected. The surface characteristics of SUS304 stainless steel are investigated before and after surface modification by microwave plasma under atmospheric pressure conditions. The plasma device was operated by power sources with microwave frequency. We used a device based on a coaxial transmission line resonator (CTLR). The atmospheric pressure plasma jet (APPJ) in the case of microwave frequency (880 MHz) used Ar as plasma gas [2]. Typical microwave Pw was 3-10 W. To determine the optimal processing conditions, the surface treatment experiments were performed using various values of Pw (3-10 W), treatment time (5-120 s), and ratios of mixture gas (hydrogen peroxide). Torch-to-sample distance was fixed at the plasma edge point. Plasma treatment of a stainless steel plate significantly affected the wettability, contact angle (CA), and free energy (mJ/$m^2$) of the SUS304 surface. CA and ${\gamma}$ were analyzed. The optimal surface modification parameters to modify were a power of 10 W, a treatment time of 45 s, and a hydrogen peroxide content of 0.6 wt% [3]. Under these processing conditions, a CA of just $9.8^{\circ}$ was obtained. As CA decreased, wettability increased; i.e. the surface changed from hydrophobic to hydrophilic. From these results, 10 W power and 45 s treatment time are the best values to minimize CA and maximize ${\gamma}$.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.41 no.9
• /
• pp.1085-1094
• /
• 1992

A variable-spacing cesium thermionic energy conversion test station is designed and fabricated for the study of power generation. The diode is in the form of a guard-ringed plane-parallel geometry in which a polycrystalline rhenium emitter of 2 cmS02T area faces a radiation-cooled polycrystalline rhenium collector of 1.9 cmS02T area. The emission of plasma from heated refractory electrode metal is the driving reaction in the direct conversion of heat to electricity by thermionic energy conversion. The plasma is produced from electrons and positive ions formed simultaneously by thermionic emission and surface ionization of cesium atoms incident on the hot emitter from the cesium vapor in the diode. And high plasma density causes plasma multiplication within the gap due to volume ionization that results in high power output. The variation of the saturation current of a Knudsen converter is investigated at an emitter-collector gap of 0.1 mm and an emitter temperatures. A maximum power output of 13.47 watta/cmS02T is observed at a collector temperature of 963 K and a cesium reservoir temperature of 603 K.

• Proceedings of the Korean Vacuum Society Conference
• /
• 1998.02a
• /
• pp.77-77
• /
• 1998

Present silicon dioxide (SiOz) 떠m as intennetal dielectridIMD) layers will result in high parasitic c capacitance and crosstalk interference in 비gh density devices. Low dielectric materials such as f f1uorina뼈 silicon oxide(SiOF) and f1uoropolymer IMD layers have been tried to s이ve this problem. I In the SiOF ftlm, as fluorine concentration increases the dielectric constant of t뼈 film decreases but i it becomes unstable and wa않r absorptivity increases. The dielectric constant above 3.0 is obtain어 i in these ftlms. Fluoropolymers such as polyte$\sigma$따luoroethylene(PTFE) are known as low dielectric c constant (>2.0) materials. However, their $\alpha$)Or thermal stability and low adhesive fa$\pi$e have h hindered 야1리ru뚱 as IMD ma따"ials. 1 The concept of a plasma processing a찌Jaratus with 비gh density plasma at low pressure has r received much attention for deposition because films made in these plasma reactors have many a advantages such as go여 film quality and gap filling profile. High ion flux with low ion energy in m the high density plasma make the low contamination and go어 $\sigma$'Oss피lked ftlm. Especially the h helicon plasma reactor have attractive features for ftlm deposition 야~au똥 of i앙 high density plasma p production compared with other conventional type plasma soun:es. I In this pa야Jr, we present the results on the low dielectric constant fluorocarbonated-SiOF film d밑JOsited on p-Si(loo) 5 inch silicon substrates with 00% of 0dFTES gas mixture and 20% of Ar g gas in a helicon plasma reactor. High density 띠asma is generated in the conventional helicon p plasma soun:e with Nagoya type ill antenna, 5-15 MHz and 1 kW RF power, 700 Gauss of m magnetic field, and 1.5 mTorr of pressure. The electron density and temperature of the 0dFTES d discharge are measUI벼 by Langmuir probe. The relative density of radicals are measured by optic허 e emission spe따'Oscopy(OES). Chemical bonding structure 3I피 atomic concentration 따'C characterized u using fourier transform infrared(FTIR) s야3띠"Oscopy and X -ray photonelectron spl:’따'Oscopy (XPS). D Dielectric constant is measured using a metal insulator semiconductor (MIS;AVO.4 $\mu$ m thick f fIlmlp-SD s$\sigma$ucture. A chemical stoichiome$\sigma$y of 야Ie fluorocarbina$textsc{k}$영-SiOF film 따~si야영 at room temperature, which t the flow rate of Oz and FTES gas is Isccm and 6sccm, res야~tvely, is form려 야Ie SiouFo.36Co.14. A d dielec$\sigma$ic constant of this fIlm is 2.8, but the s$\alpha$'!Cimen at annealed 5OOt: is obtain려 3.24, and the s stepcoverage in the 0.4 $\mu$ m and 0.5 $\mu$ m pattern 킹'C above 92% and 91% without void, res야~tively. res야~tively.

• The Bulletin of The Korean Astronomical Society
• /
• v.39 no.1
• /
• pp.74.1-74.1
• /
• 2014

We have investigated a supra-arcade structure associated with an M1.6 flare, which occurred on the south-east limb in the 4th of November 2010. It is ob- served in extreme ultraviolet (EUV) with the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO), microwaves at 17 and 34 GHz with the Nobeyama Radioheliograph (NoRH), and soft X-rays of 8-20 keV with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). Interestingly, we found exceptional properties of the supra-arcade thermal plasma from the AIA 131 A and the NoRH: 1) plasma upflows along large coronal loops and 2) enhancing microwave emission. RHESSI detected two soft X-ray sources, a broad one in the middle of supra-arcade structure and a bright one just above the flare-arcade. We estimated the number density and thermal energy for these two source regions during the decay phase of the flare. In the supra-arcade source, we found that there were increases of the thermal energy and the density at the early and the last stages, respectively. On the contrary, the density and thermal energy of the source on the top of the flare-arcade decreases throughout. The observed upflows imply that there is continuous energy supply into the supra- arcade structure from below during the decay phase of the flare. It is hard to be explained by the standard flare model in which the energy release site is located high in corona. Thus, we suggest that the potential candidate as the energy source for the hot supra-arcade structure is the flare-arcade which has exhibited a predominant emission throughout.

• 한국연소학회:학술대회논문집
• /
• 2013.06a
• /
• pp.99-101
• /
• 2013

The equivalence ratio is measured by LIBS(Laser-induced Breakdown spectroscopy) in hydrocarbon flame and high temperature (${\sim}3200^{\circ}C$) oxyhydrogen flame, where a stoichiometric mixture of hydrogen and oxygen is produced from water through electrolysis. The ratio of the hydrogen and oxygen (H/O) atomic lines intensities is used for quantitatively determining the quivalence ratio. laser energy is evaluated for determining the optimal condition for plasma diagnostics. The minimum laser energy for generating plasma in a laminar premixed hydrocarbon flame was about 70 mJ, whereas oxyhydrogen flame. consequently the irradiated spot of a lower density in high temperature oxyhydrogen flame gave rise to bigger plasma in size, thus limiting the spatial resolution of the LIBS measurement.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.11 no.5
• /
• pp.231-237
• /
• 2001

Etch rates up to 120 nm/min for $Ta_{2}O_{5}$ were achieved in both $SF_{6}/Ar$ and $Cl_{2}/Ar$ discharges. The effect of ultraviolet (UV) light illumination during ICP etching on $Ta_{2}O_{5}$ etch rate in those plasma chemistries was examined and UV illumination was found to produce significant enhancements in $Ta_{2}O_{5}$ etch rates most likely due to photoassisted desorption of the etch products. The effects of ion flux, ion energy, and plasma composition on (Ba, Sr)$TiO_3$ etch rate were examined and maximum etch rate ~90 nm/min was achieved in $Cl_{2}/Ar$ ICP discharges while $CH_{4}/H_{2}/Ar$ chemistry produced extremely low etch rates (${\leq}10\;nm/min$) under all conditions.

• Korean Journal of Community Nutrition
• /
• v.10 no.1
• /
• pp.91-100
• /
• 2005

This study was conducted to investigate the effects of smoking on nutrition intake, bone mineral density and blood mineral status. The subjects were composed of two groups: 100 smokers and 100 non-smokers was used along with a questionnaire. Anthropometric measurements, dietary intakes using 24-hours recall method were compared. At twenty subjects from each group were selected, bone mineral density were measured by quantitative ultrasound and plasma mineral levels were analyzed by ICP spectrometer. The average ages of smokers and non-smokers were 23.9 and 22.8 years old, respectively. The height, weight and BMI of the smokers were no significant difference. The average numbers of smoked cigarettes were 11.8/d and the average packyear was 3.1 in the smokers. About $97\%$ of the smokers drank alcoholic beverages, while $85\%$ of the non-smokers did. The smokers tended to eat less meals and dinner meal, but drink coffee more often compared to the non-smokers. The mean daily energy intake and CPF energy intake ratio were 2184. 9 kcal and 57.2 : 13.7 : 26.4 in the smokers and 2262.6 kcal and 55.8 : 13.1 : 28.6 in the non-smokers. The smokers consumed significantly lower intake of $\beta$-carotene. There were no significant differences in bone mineral density of BUA, SOS and QUI. There were no significant differences in plasma levels of Ca, Mg, Fe and Zn. However, plasma Cu level of the smokers was significantly higher than that of the non-smokers. In conclusion, the smokers of this study showed a more undesirable dietary intake in the light of their low ,B -carotene and high alcoholic beverages, and coffee. The plasma Cu level of the smokers was higher than that of the non-smokers, showing that Cu is involved in smoking. Therefore, it could be suggested that more systematic research be conducted with respect to Cu and smoking and that increased nutrition education and guidelines for smokers are required.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.11
• /
• pp.2236-2241
• /
• 2009

In this study, the electron behavior was investigated numerically in order to obtain guidelines for design and operation of a new plasma source by a magnetic neutral loop discharge (NLD). The optimum plasma production was investigated by using a 3-dimensional simulation model which enables the electron behavior calculation from source region to downstream region. The results showed that the high-density plasma produced around the magnetic neutral loop (NL) is transferred from the NL region to the downstream region along magnetic force lines. Also the avaraged electron energy is increased with the normalized RF electric field (F), which can be used to characterize the plasma production efficiency of NLD system. Considering the relation between F and plasma production, in-depth plasma control can be achieved at a given specific process condition.