• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2506-2511
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• 2007

The coupled simulation is performed to find out the interaction of arc plasmas with surrounding materials in a thermal puffer plasma chamber. In order to be more realistic, PTFE nozzle ablation and Cu electrode evaporation, which are caused by high temperature of arc plasmas, are considered together. Pressure rise and temperature inside the chamber generated during the whole arcing history are investigated with the applied currents. It is very important to define how thermal flow and mass transfer are processing between the arc plasma and surrounding materials for further understanding complex physics inside the chamber. It is concluded that the result might be very useful to understand the mechanism happened inside and to design thermal puffer plasma chambers, but further experimental studies are required to verify the results for the more practical applications.

• The KSFM Journal of Fluid Machinery
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• v.11 no.4
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• pp.7-13
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• 2008

The computational investigation is performed to find out the interaction of arc plasmas with surrounding materials and the thermal flow characteristics in a PASB (Puffer-Assisted Self-Blast) chamber, which is one of new breaking concepts in $SF_6$ switchgears. It is very important to define the flow and mass transfer happened during the full arcing history for further understanding complex physics inside the chamber. In this study, we have considered two diffusion processes by the hot arc plasma, one is PTFE nozzle ablation and the other is Cu electrode evaporation, simultaneously. It was found that the principle of the pressure-rise inside the chamber is confirmed by the computational results and the increase of the electrical conductivity of the residual gas near current zero is critical to the chamber design.

• Journal of Powder Materials
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• v.20 no.6
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• pp.411-424
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• 2013

In this study, the synthesis of nickel nanoparticles and copper nanospheres for the potential applications of MLCC electrode materials has been studied by plasma arc evaporation method. The change in the broad distribution of the size of nickel and copper nanopowders is successfully controlled by manifesting proper mixture of gas ambiance for plasma generation in the size range of 20 to 200 nm in diameter. The factors affecting the mean diameter of the nanopowder was studied by changing the composition of reactive gases, indicating that nitrogen enhances the formation of larger particles compared to hydrogen gas. The morphologies and particle sizes of the metal nanoparticles were observed by SEM, and ultrathin oxide layers on the powder surface generated during passivation step have been confirmed using TEM. The metallic FCC structure of the nanoparticles was confirmed using powder X-ray diffraction method.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.6_2
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• pp.909-917
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• 2021

This study was carried out experimentally on the production and properties of silicon nanopowders characteristics using a transferred type arc plasma apparatus. To investigate the properties of silicon nanopowder, the purity of argon gas(99.999%, 99.9%) and the partial pressure ratio of nitrogen gas(0~90%) were varied. The total pressure in chamber is 400Torr and the silicon chunk amount used as raw material is 300g. The power supplied to the cathode to generate arc plasma was 9~12kW/h, and the electrode was made of tungsten and graphite with a diameter of 13mm. The particle size, impurity elements and powder evaporation rate of the silicon powder were analyzed using the XRD, FE-SEM, TEM and electronic scale. According to the purity of argon gas, the silicon evaporation rate and the particle size were similar, and impurities were generated more in the case of 99.9% purity than 99.999%. When argon gas and nitrogen gas were mixed in the chamber, the silicon evaporation rate and particle size increased as the partial pressure ratio of nitrogen gas increased. In particular, when the partial pressure ratio of nitrogen gas was 80%, the silicon evaporation rate 80g/h, and the particle size was about 80~100nm.

• Journal of the Korean Vacuum Society
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• v.12 no.2
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• pp.112-117
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• 2003

MgO films is widely used in plasma display panel (PDP) technology. In this work, structural and optical properties of the MgO films deposited by e-beam evaporation, reactive magnetron sputtering, which are commercially used, and arc deposition were compared. MgO thin films were deposited on glass substrates by vacuum arc deposition equipment using a magnesium metal target at various oxygen gas flows. In order to investigate the packing density by ellipsometer, to measure reasonable erosion-rates of the MgO protective layers, we introduced an acceleration test method, namely, Ar+ ion beam induced erosion test. Also, XPS and UV test were adopted to examine the effect of the moisture on the optical transmittance of the MgO protective layers, which showed that these of MgO films by arc deposition method sustained more 90% and were insensitive to effect of the moisture. XRD and AFM have been also used to study behaviors of the structure and surface morphology.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.565-565
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• 2013

Free burning arcs where the work piece acts as an anode are frequently used for a number of applications. Our investigation is exclusively concerned with a simplified unified model of arcs and anode under steady state conditions at atmospheric pressure. The model is used to make predictions of arc and anode temperatures and arc voltage for a 200 A arc in argon. The computed temperatures along the axis between the cathode tip and the anode surface compare well the measured data. This knowledge of free burning arcfeatures can play a role in developing the atmospheric plasma systems, however, further investigation should include the modelling of Cu evaporation from anode and non-LTE situation near electrodes for more realistic calculations.

• Journal of computational fluids engineering
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• v.15 no.3
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• pp.9-15
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• 2010

In this study, we calculated arc discharges and flow characteristics driven by arcs in a thermal puffer chamber, which is one of most outstanding high-voltage interrupters, for understanding the complex physics and the probability of thermal breakdown. The four main parts of arc model for this virtual-reality are radiation, PTFE ablation, Cu evaporation, and turbulence. Among these important parts the turbulence model can be critical to the reliability of computation results during the whole arcing history because the plasma flow is affected by high heat energy and mass momentum. Two turbulence models, the Prandtl's mixing length model and the standard $k-\varepsilon$ model, are applied for these calculations and are compared with pressure-rise inside chamber and arc voltage between the contacts as well as flow characteristics near current zero.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.201-207
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• 2010

In this study, we calculated arc discharges happened in high-voltage circuit breakers for understanding the complex physics and the probability of thermal breakdown. The four main parts of arc model for this virtual-reality are radiation, PTFE abaltion, Cu evaporation and turbulence. Among these important parts the turbulence model can be critical to the reliability of computation results during high-current period because the plasma flow is affected by high eat energy and mass momentum. Two kinds of turbulence model, zero-equation model and two-equation model, are applied for these calculations and are compared with the measured pressure data inside a chamber.

• Journal of Powder Materials
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• v.18 no.2
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• pp.112-121
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• 2011

This study investigated the effect of solvent on the fabrication of Ni-free Fe-based alloy nano powders by employing the PWE (pulsed wire evaporation) in liquid and compared the alloy particles fabricated by three different methods (PWE in liquid, PWE in Ar, plasma arc discharge), for high temperature oxidation-resistant metallic porous body for high temperature soot filter system. Three different solvents (ethanol, acetone, distilled water) of liquid were adapted in PWE in liquid process, while X-ray diffraction (XRD), field emission scanning microscope (FE-SEM), and transmission electron microscope (TEM) were used to investigate the characteristics of the Fe-Cr-Al nano powders. The alloy powder synthesized by PWE in ethanol has good particle size and no surface oxidation compared to that of distilled water. Since the Fe-based alloy powders, which were fabricated by PWE in Ar and PAD process, showed surface oxidation by TEM analysis, the PWE in ethanol is the best way to fabricate Fe-based alloy nano powder.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.10
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• pp.832-839
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• 2007

The geometry and dimensions of an expansion chamber are decisive factors in thermal puffer plasma chamber designs. Because they together dominate the temperature and speed at which the cooling gas from the chamber flows back through a flow channel to the arcing zone for the successful interruption of fault currents. In this study, we calculated the flow and mass transfer driven by arc plasma, and investigated the effects of a flow guide installed inside a thermal puffer plasma chamber. It is found that the existing cold gas of the chamber mixes with hot gases entrained from the arcing zone and is subjected to compression due to pressure build-up in the chamber. The pressure build-up with the flow guide is larger than that without due to a vortex which rotates clockwise around the chamber center. By the reverse pressure gradient, the mixing gas of the chamber flows back out for cooling down the residual plasma near current zero. In the case with the flow guide, the temperature just before current zero is lower than that without, and the Cu concentration with high electrical conductivity is also less than that without the flow guide.