• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.156.1-156.1
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• 2015

Neon and argon plasma group velocities (ug) are obtained by intensified charge coupled device (ICCD) camera images at fixed gate width time of 5 ns. The propagation velocities in upstream and downstream region are in the order of 104-105 m/s. The plasma ambipolar diffusion velocities are calculated to be in the order of 101-102 m/s. Plasma jet is generated by sinusoidal power supply in varying voltages from 1 to 4 kV at repetition frequency of 40 kHz. By employing one dimensional convective wave packet model, the neon and argon electron temperatures in non-thermal atmospheric-pressure plasma jet are estimated to be 1.95 and 1.18 eV, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2008.08a
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• pp.295-295
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• 2008

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.550-551
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• 2013

Large-area RF-driven ion source is being developed at Germany for the heating and current drive of ITER plasmas. Negative hydrogen (deuterium) ion sources are major components of neutral beam injection systems in future large-scale fusion experiments such as ITER and DEMO. RF ion sources for the production of positive hydrogen ions have been successfully developed at IPP (Max-Planck- Institute for Plasma Physics, Garching) for ASDEX-U and W7-AS neutral beam injection (NBI) systems. In recent, the first NBI system (NBI-1) has been developed successfully for the KSTAR. The first and second long-pulse ion sources (LPIS-1 and LPIS-2) of NBI-1 system consist of a magnetic bucket plasma generator with multi-pole cusp fields, filament heating structure, and a set of tetrode accelerators with circular apertures. There is a development plan of large-area RF ion source at KAERI to extract the positive ions, which can be used for the second NBI (NBI-2) system of KSTAR, and to extract the negative ions for future fusion devices such as ITER and K-DEMO. The large-area RF ion source consists of a driver region, including a helical antenna (6-turn copper tube with an outer diameter of 6 mm) and a discharge chamber (ceramic and/or quartz tubes with an inner diameter of 200 mm, a height of 150 mm, and a thickness of 8 mm), and an expansion region (magnetic bucket of prototype LPIS in the KAERI). RF power can be transferred up to 10 kW with a fixed frequency of 2 MHz through a matching circuit (auto- and manual-matching apparatus). Argon gas is commonly injected to the initial ignition of RF plasma discharge, and then hydrogen gas instead of argon gas is finally injected for the RF plasma sustainment. The uniformities of plasma density and electron temperature at the lowest area of expansion region (a distance of 300 mm from the driver region) are measured by using two electrostatic probes in the directions of short- and long-dimension of expansion region.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.05a
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• pp.138-140
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• 1994

Plasma polymerized thin film was prepared using an interelectrod inductively coupled gas-flow-type reactor. Styrene was chosen as the monomer to be used. This thin films were also delineated by the electron-beam apparatus with an acceleration voltage 30kV, and the pattern in the resist was developed with RIE 80 with argon gas mixture ratio, pressure and RF power. The effect of charge of discharge power on growth rate and etching rate of the thin films were studied. The molecular structure of thin films were investigated by FIR and then was discussed in relation to its quality as a resist. In the case of Plasma polymerization, thickness of resist could be controlled by discharge duration and power. Also etch rate is increased as to growing argon gas and RF power with RIE 80.

• Applied Science and Convergence Technology
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• v.24 no.5
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• pp.162-166
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• 2015

Linear ion beams have been introduced for the ion beam treatments of flexible substrates in roll-to-roll web coating systems. Anode layer linear ion sources (300 mm width) were used to make the linear ion beams. Oxygen ion beams having an ion energy from 200 eV to 800 eV used for the adhesion improvement of Cu thin films on PET substrates. The Cu thin films deposited by a conventional magnetron sputtering on the oxygen ion beam treated PET substrates showed Class 5 adhesion defined by ASTM D3359-97 (tape test). Argon ion beams with 1~3 keV used for the ion beam sputtering deposition process, which aims to control the initial layer before the magnetron sputtering deposition. When the discharge power of the linear ion source is 1.2 kW, static deposition rate of Cu and Ni were 7.4 and $3.5{\AA}/sec$, respectively.

• Korean Journal of Materials Research
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• v.12 no.1
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• pp.27-35
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• 2002

In laser materials processing, localized heating, melting and evaporation caused by focused laser radiation forms a vapor on the material surface. The plume is generally an unstable entity, fluctuating according to its own dynamics. The beam is refracted and absorbed as it traverses the plume, thus modifying its power density on the surface of the condensed phases. This modifies material evaporation and optical properties of the plume. A laser-produced plasma plume simulation is completed using axisymmetric, high-temperature gas dynamic model including the laser radiation power absorption, refraction, and reflection. The physical properties and velocity profiles are verified using the published experimental and numerical results. The simulation results provide the effect of plasma plume fluctuations on the laser power density and quantitative beam radius changes on the material surface. It is proved that beam absorption, reflection and defocusing effects through the plume are essential to obtain appropriate mathematical simulation results. It is also found that absorption of the beam in the plume has much less direct effect on the beam power density at the material surface than defocusing does and helium gas is more efficient in reducing the beam refraction and absorption effect compared to argon gas for common laser materials processing.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.141-141
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• 2013

We have generated the needle-typed nonthermal plasma jet by using an Ar gas flow at atmospheric pressure. Diagnostics of electron temperature anddensity is critical factors in optimization of the atmospheric plasma jet source in accordance with the gas flow rate. We have investigated the electron temperature and density of plasma jet by selecting the four metastable Ar emission lines based on the atmospheric collisional radiative model and radial profile characteristics of current density, respectively. The averaged electron temperature and electron density for this plasma jet are found to be ~1.6 eV and ~$3.2{\times}10^{12}cm^{-3}$, respectively, in this experiment. The densities of OH radical species inside the various bio-solutions are found to be higher by about 4~9 times than those on the surface when the argon bioplasma jet has been bombarded onto the bio-solution surface. The densities of the OH radicalspecies inside the DI water, DMEM, and PBS are measured to be about $4.3{\times}10^{16}cm^{-3}$, $2.2{\times}10^{16}cm^{-3}$, and $2.1{\times}10^{16}cm^{-3}$, respectively, at 2 mm downstream from the surface under optimized Ar gas flow 250 sccm.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.5
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• pp.802-808
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• 1994

The purpose of this paper is to describe an application of plasma polymerized thin film as an electron beam resist. Plasma polymerized thin film was prepared using an interelectrode capacitively coupled gas-flow-type reactor, and chosen methylmethacrylate(MMA)and methylmethacrylate-tetrameth-yltin(MMA-TMT) as a monomer. This thin films were also delineated by the electron-beam apparatus with an acceleration voltage of 30kV and an expose dose ranging from 20 to 900$\mu$C/cmS02T. The delineated pattern in the resist was developed with the same reactor which is used for polymerization using an argon as etching gas. The growth rate and etching rate of the thin film is increased with increasing of discharge power. Thin films by plasma polymerization show polymerization rate of 30~45($\pm$3) A/min, and etching rate of 440($\pm$30) A/min during Ar plasma etching at discharge power of 100W. In apparently lower than that of conventional PMMA, but the plasma-etching rate of PP(MMA-TMT) was higher than that of PPMMA.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.223-223
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• 2012

Surface engineering plays a significant role in fabricating highly functionalized materials applicable to industrial and biomedical fields. Surface wrinkles and folds formed by ion beam or plasma treatment are buckling-induced patterns and controlled formation of those patterns has recently gained considerable attention as a way of creating well-defined surface topographies for a wide range of applications. Surface wrinkles and folds can be observed when a stiff thin layer attached to a compliant substrate undergoes compression and plasma treatment is one of the techniques that can form stiff thin layers on compliant polymeric substrates, such as poly (dimethylsiloxane) (PDMS). Here, we report two effective methods using plasma modification techniques for controlling the formation of surface wrinkles and folds on flat or patterned PDMS substrates. First, we show a method of creating wrinkled diamond-like carbon (DLC) film on grooved PDMS substrates. Grooved PDMS substrates fabricated by a molding method using a grooved master prepared by photolithography and a dry etching process were treated with argon plasma and subsequently coated with DLC film, which resulted in the formation of wrinkled DLC film aligning perpendicular to the steps of the pre-patterned ridges. The wavelength and the amplitude of the wrinkled DLC film exhibited variation in the submicron- to micron-scale range according to the duration of argon plasma pre-treatment. Second, we present a method for controlled formation of folds on flat PDMS substrates treated with oxygen plasma under large compressive strains. Flat PDMS substrates were strained uniaxially and then treated with oxygen plasma, resulting in the formation of surface wrinkles at smaller strain levels, which evolved into surface folds at larger strain levels. Our results demonstrate that we can control the formation and evolution of surface folds simply by controlling the pre-strain applied to the substrates and/or the duration of oxygen plasma treatment.

• Journal of the Korean Ceramic Society
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• v.47 no.6
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• pp.618-622
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• 2010

Cost-effective purification methods of silicon were carried out in order to replace the conventional Siemens method for solar grade silicon. Firstly, acid leaching which is a hydrometallurgical process was preceded with grinded silicon powders of metallurgical grade (~99% purity) to remove metallic impurities. Then, plasma treatments were performed with the leached silicon powders of 99.94% purity by argon plasma at 30 kW power under atmospheric pressure. Plasma treatment was specifically efficient for removing Zr, Y, and P but not for Al and B. Another purification step by EB treatment was also studied for the 99.92% silicon lump which resulted in the fast removal of boron and aluminum. That means the two methods are effective alternative tools for removing the doping elements like boron and phosphor.