http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Oxygen Behavior in High Temperature Plasma and its Applications to Hydrocarbon Fuels
엄한섭,최창호,Dong J. Kim,이주연,우상구 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.75 No.11
Oxygen molecules breakdown to atoms by impact dissociation of electrons in a microwave oxygen torch. Typical atom density of oxygen in a microwave torch is a few times of 1018/cm3 produced within millisecond time scale. Dwelling time of an oxygen fluid element in a discharge tube is longer than 10 milliseconds, which is much longer than the atom production time. The oxidation coefficient of hydrocarbon fuel in oxygen atoms is usually about one million times faster than that in oxygen molecules. As an example of applications, oxygen atoms are applied to dimethyl ether, which is relatively a large molecular structure. The initial breakdown species of DME molecules in a high-temperature reaction chamber are hydrogen, carbon monoxide and methane, which is also breakdown to CO and H2 by oxygen atoms. Abundance of water may be generated in a reaction chamber of relatively low-temperature lower than Tg = 1500K, hindering an efficient production of synthetic gas. DME disintegration in a hot chamber by a microwave oxygen torch is experimentally observed. Experimental observation is somewhat agreeing with theoretical predictions.
Hydrophobic Coating of Multi-Walled Carbon Nanotubes by Using a HMDSO Glow Plasma under Low Pressure
엄한섭,조성윤,조순천,이경하 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.2
This study demonstrates the super-hydrophobic coating of multi-waled carbon nanotube (MWCNT) powders by using a O-(Si(CH3)3)2 (HMDSO) glow discharge plasma under low pressure and investigates the hydrophobic behavior of the treated MWCNT powders. To investigate the change in the surface free energy of the MWCNT powders, we used water, PEG and glycerol as probe liquids. Their surface free energies were determined by making use of the measured contact angles (CAs) and the Owens-Wendt equation. A cushion made of the plasma-treated MWCNT powders showed super-hydrophobicity. The total surface free energies of the MWCNT powders before and after the HMDSO plasma treatment were estimated to be 82.6 and 0.1 mJ/m2, respectively.
엄한섭,홍용철,Soon Cheon Cho 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.6
Microwave discharges in argon operated at high pressure show filamentation phenomena, not filling the whole radial cross-section of the discharge tube. Such a filamentary discharge can be suppressed by introducing a small amount of molecular gas with argon. Experiments for suppressing filamentary discharges in an atmospheric-pressure argon plasma excited by using 2.45-GHz microwaves are carried out by making use of molecular gases such as N2, O2, CO2 and CH4. The in fluence of the gas's thermal conductivity on the suppression of plasma laments is also investigated.
Decay Properties of Ozone in Seawater and Its Sterilization Effects
엄한섭,Yi F. Hong,Han Y. Lee,Yun H. Park 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.1
The ozone concentration in seawater decays with a decay time that decreases as the concentration of organic contaminants increases. The ozone decay time is measured for a broad range of physical parameters, including various ethanol concentrations and pH values. The decay time of ozone increases from 1.28 minutes in natural seawater at pH 8 to 11 minutes at pH 4, indicating a possibility of sterilizing a large amount of acidic seawater in a short time. The experimental observations of sterilization agree well with results from a theoretical model.
Enhanced betatron radiation by a modulating laser pulse in laser wakefield acceleration
이승우,엄한섭,강태연,허민섭,석희용 한국물리학회 2019 Current Applied Physics Vol.19 No.4
We propose a new idea to enhance and control the betatron radiation by using a modulating laser pulse in laser wakefield acceleration. In this scheme, a high-power laser pulse is used for self-trapping and acceleration of the plasma electrons and the accelerated electron beam is modulated by a separately-propagating laser pulse for large amplitude betatron oscillations and microbunching. In this way, the relatively low power modulating laser pulse can enhance the X-ray photon flux and energy significantly. We performed two-dimensional particle-in-cell simulations to demonstrate the idea and the results show that a sub-TW laser pulse is enough for electron beam modulation and it can generate easily-controllable fs X-ray pulses with a wide range of photon energies from soft X-rays to hard X-rays.
Vanessa Ling Jen Phung,김민석,김진주,엄한섭,석희용 한국물리학회 2019 Current Applied Physics Vol.19 No.7
A preplasma plays a very important role in laser-driven proton acceleration, where it can increase the proton energy significantly. In this research, we generated a nearly planar preplasma intentionally by sending an uncompressed picosecond-long Ti:sapphire laser pulse with a large spot size onto a thin foil target (Al and mylar) and investigated the characteristics of the preplasma by using a space-time-resolved Nomarski interferometer. In this paper, a simple analytical approach employing the one-dimensional collisional plasma concept was also developed and its result is compared with the experimental results. This work reveals the detailed characteristics of the behavior of the planar preplasma, which is very important in laser-driven proton acceleration, X-ray laser, etc., employing laser-solid interactions.