• Applied Science and Convergence Technology
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• v.24 no.1
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• pp.16-21
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• 2015

The characteristics of an atmospheric pressure plasma jet (APPJ) in He discharge are measured with electrical and optical diagnostics methods. The discharge phenomenon in one cycle of the APPJ was diagnosed using intensified charge coupled device (ICCD) imaging. The gate mode images show that the propagation of plasma bullets happens only when the applied voltage on the inner conductor is positive. Moreover, the Schlieren image of the plasma jet shows that the laminar flow is changed into a turbulent flow when the plasma jet is turned on, especially when the gas flow rate increases.

• Journal of the Korean Society of Combustion
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• v.11 no.3
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• pp.1-7
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• 2006

A reaction mechanism of methane partial oxidation, which consists of thermal and plasma chemistry reaction pathways, has been investigated using with an arc-jet reactor. The reaction zone of the arc-jet reactor is spatially separated into thermal and non-thermal plasma zone. Methane conversion rates, selectivity of $H_2$ and $C_2$ chemicals in each zone are obtained, which reveals clearly different characteristics of reaction pathways depending on the temperature conditions. The conversion rates obtained in thermal plasma zone is higher than those in non-thermal plasma zone. The selectivity, however, obtained in non-thermal plasma zone is significantly higher than those in thermal plasma zone. Further parametric study on $O_2/C$ ratio, arc length and SED shows that the present process is mainly governed by thermal chemistry pathways.

• 전기의세계
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• v.26 no.2
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• pp.104-110
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• 1977

This paper investigates temperature distribution of plasma jets which used argon gas, and nitrogen gas mixed with argon as working fluids in spectroscopic method, and studies correlations between them main results are as follows; 1) The temperature at the center of plasma jet increases with are current and gas flow, and decreases with magnetic flux density along the axial direction. 2) The changing rate of temperature of plasma jet in the radial direction decreases rapidly beyond 2mm from central axis. 3) Temperature drop rate of plasma jet in the central axis direction appears most apparant beyond 13mm above the nozzle exit. 4) When argon gas mixed with a small amount of nitrogen, plasma temperature increases at same are current compared with the case of argon gas only.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.2
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• pp.96-103
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• 2003

In this paper, the heat loss to the constant volume vessel wall was investigated using instantaneous heat flux sensor, schlieren visualization, pressure rise curve. And the heat loss characteristics of plasma jet ignition were compared with conventional spark ignition. In case of plasma jet ignition, the flame kernel moves toward the center of combustion vessel in the initial period of combustion, and the flame surface spread out to the vessel wall. However, in case of conventional spark ignition, the flame surface contact with combustion vessel wall in the initial period of combustion. As a result, heat loss in the combustion duration for conventional spark ignition increase faster than that of plasma jet ignition. And the combustion enhancement rate of plasma jet ignition is higher than that of conventional spark ignition, and it was found that the heat loss rate is inversely proportional to the combustion enhancement rate.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.207-207
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• 2016

plasma group velocities of neon with oxygen admixture (ug) are obtained by intensified charge coupled device (ICCD) camera images at fixed gate width time of 5 ns. The propagation velocities outside interelectrode region are in the order of 104 m/s.The plasma ambipolar diffusion velocities are calculated to be in the order of 102 m/s. Plasma jet is generated by all fixed sinusoidal power supply, total gas flow and repetition frequency at 3 kV, 800 sccm and 40 kHz, respectively. The amount of oxygen admixture is varied from 0 to 2.75 %. By employing one dimensional convective wave packet model, the electron temperatures in non-thermal atmospheric-pressure plasma jet are estimated to be in a range from 1.65 to 1.95 eV.

• 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.

• 전기의세계
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• v.22 no.5
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• pp.19-32
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• 1973

This paper treats with some of plasma jet behaviors under magnetic field for the purpose of controlling important characteristics of plasma jet in the practices of material manufacturings. Under the existence and non-existence of magnetic field, the pressure distribution, flame length, stability and noise of plasma jet are comparatively evaluated in respect of such parameters as are current, gap of electrode, quantity of argon flow, magnetic flux density, diameter and length of nozzle. The results are as follows: 1) the pressure, the length and the noise of plasma jet rise gradually with the increase of are current, and have high values under identical arc current as the diameter of nozzle increases, but reverse phenomenon tends to appear in the noise. 2) The pressure, the flame length and the noise increase with the increased quantity of argon flow, and the rising slope of noise is particularly steep. Under magnetic field, the quantity of argon flow in respect of flame length has the critical value of 80(cfh). 3) The pressure and length of flame decrease with small gradient value as the length of gap increases, but the noise tends to grow according to the increase of nozzle diameter. 4) The pressure and the length of jet flame decrease inversly with the increase of magnetic flux density, which have one critical value in the 100 amps of arc current and two values in 50 amps. The pressure of jet flame can be below atomospher pressure in strong magnetic field. 5) "The constriction length of nozzle has respectively the critical value of 6(mm) for pressure and 23(mm) for the length of flame. 6) Fluctuations in the wave form of voltage become greater with the increase of argon flow and magnetic flux density, but tends to decrease as arc current increases, having the frequency range of 3-8KHz. The wave form of noise changes almost in parallel with that of voltage and its changing value increases with argon flow, arc current and magnetic flux density, having the freuqency range of 6-8KHz. The fluctuation of jet presurre is reduced with the increase of argon flow and magnetic flux density and grows with arc current.rent.

• 전기의세계
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• v.22 no.2
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• pp.57-69
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• 1973

The aim of this study was to investigate the behaviors of plasma jet under coaxial magnetic field in paralled with it for controlling optical characteristics and input power of plasma jet without impurity and instability of arc plasma column. Because the discharge characteristics of plasma jet were so distinctively different according to the existence or non-existence of magnetic field, the input power, luminous intensity of plasma jet and thermal efficiency were comparatively studied in respect of such variables as arc current, gap of electrode, quantity of argon flow, magnetic flux density, diameter and length of nozzle, with the use of several materials which were different in diameter and length of nozzel. The results were as follows; 1) The voltage tends to show a drooping characteristic at law current and then rises gradually. The luminous intensity of plasma jet increases exponentially with arc current. 2) Arc voltage increases and luminous intensity tends to decrease gradually as gap of electrode increases. 3) Arc voltage and luminous intensity tends to decrease gradually as gap of electrode increases. 3) Arc voltage and luminous intensity increase in accordance with the quantity of argon flow. 4) At first step, arc voltage increases to maximum value with the growth of flux density and then tends to show a gradual decrease. Luminous intensity decreases with the growth flux density. 5) Arc voltage decreases as the constriction length of nozzle increases, maximum decrease is shown at the constriction length of 20(mm) and it increases beyond that value. The luminous intensity decreases as the constriction length grows. 6) Arc voltage and luminous in tensity increase with the growth of diameters of nozzle. 7) Thermal efficiency has values between 50% and 75%, being influenced by arc current, the quantity of argon flow, flux density, the length of electrode gap and the constriction length of nozzle.

• 전기의세계
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• v.24 no.1
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• pp.75-85
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• 1975

In order to develop the commercial frequency (60Hz) plasma torch of small capacity for material cutting, welding and other industrial heating, the A.C plasma jet generator of non-transfered type is made domestically and the electrode configurations of plasma torch are composed of two kinds of electrodes W-C and W-Cu, combined by thermal emission and field emission electrode materials. In this paper, the characteristics of input power, thermal efficiency, electrode consumption, the flame and forms of arc voltage and arc current for A.C plasma torch are investigated in relation to such variables as arc current, argon flow and magnetic field intensity to obtain the basic design data necessary to A.C plasma jet generator. The result are as follows; (1)The input power, thermal efficiency and electrode consumption are influenced greatly by argon flow, magnetic field intensity and nozzle materials. (2)A.C arc voltage and current are non-symmetrial, involving D.C Component. Due to this current of D.C Component, transformer core is saturated and a large abnormal current flows into the primary winding coil. In order to prevent this abnormal current flow, a condenser must be connected in series to the main discharge circuit. (3)The stability and sharpness of jet flame are improved more in the torch of W-C electrode configuration than in the torch of W-Cu electrode configuration.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.198.2-198.2
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• 2016

Reactive oxygen and nitrogen species (RONS) can be generated by using non-thermal atmospheric pressure plasma jet which have profound biomedical applications [1, 2]. In this work, reactive oxygen species like hydroxyl radical (OH) are generated by using non-thermal direct plasma jet above water surface using Ar gas and their properties have been studied using ultraviolet absorption spectroscopy. OH radicals are found to be generated simultaneously with the discharge current with concentration of $2.7{\times}1015/cm3$ at 7mm above water surface while their persistence time have been measured to be $2.8{\mu}S$. In addition, it has been shown that plasma initiated ultraviolets play a major role to generate RONS inside water. Further works are going on to measure the temporal behavior of OH and $O2^*-$.