• Journal of Electrical Engineering and information Science
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• 제3권3호
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• pp.316-321
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• 1998

In recent years, concern has been raised about the technique of controlling electrical breakdown by using laser in many fields. Especially, laser has attracted much attention in the Electro-Discharge Macining(EDM) because of its many merits. Therefore, this research has been performed to obtain fundamental data relevant to discharge processing by using a pulsed Nd:YAG laser. The experiments of laser-guided dc discharge by laser radiation have been carried out at low air pressure ranging from 0.2 to 20 torr. The minimum laser-guided dc discharge voltage V\ulcorner at the given pressures P and distances D between an anode and a cathode was measured. It is found that the minimum laser-guided dc discharge voltage is much lower than the natural discharge voltage V\ulcorner\ulcorner, and the values of V\ulcorner and V\ulcorner as a function of P.D has a similar tendency. The laser output energy Eout decreases with input pulse duration tp increasing, and the more the value of tp increases, the higher that of V\ulcorner is obtained because the number of photons during the discharge time N decreases with t\ulcorner increasing. There is the time lag frequently when the discharge by laser radiation is misguided under the condition of the applied voltage less than V_G.min.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권8호
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• pp.587-590
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• 1999

In this study, it is the purpose to develope a cheap and compact $CO_2$ laser and to apply 60 Hz AC discharges as a new exciting source. An axial and water cooledtype was adopted as the laser mode. The laser performance characteristics as various parameters, such as gas pressure and discharge current, have been investigated. And the laser output and the efficiency of DC and 60 Hz AC discharge-exciting type have been measured and compared for the different input powers at the static operational pressure. As a result, the case of 60 Hz AC discharge-exciting type, the laser oscillation began at the condition of operational pressure 6 Torr and discharge current 5 mA. A maximum laser output of about 32 W was obtained at an operational pressure of 18 Toorr and a discharge current of 30 mA. In addition, the laser output was saturated from an operational pressure of about 14 Torr and a discharge current of about 20 mA. In this $CO_2$ laser, the laser output of 60 Hz AC discharge-exciting type was slightly higher than that of DC discharge-exciting type. And the laser efficiency was about 10 to 13% for the various operational pressures and the discharge currents.

• 조명전기설비학회논문지
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• 제25권7호
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• pp.9-14
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• 2011

A spectroscopic measuring system was developed in order to determine optical gain of gas laser discharge for any optical transitions between 190[nm] and 800[nm] without laser resonator. With an image optical system and a feedback optical system emission light of laser discharge are entered in a monochromator and received at a photomultiplier. Subsequently optical gain and line intensity are measured.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계합동학술대회 논문집
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• pp.172-175
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• 2002

The technique of induced discharge by a pulsed CO2 laser is being applied to control electrical discharge path, material processing, triggered lightning for protecting the power equipments. In this paper, we have investigated about the characteristics of the induced discharge at atmospheric conditions by using a plasma channel, which is produced when a pulsed CO2 laser radiation is focused by a focusing mirror as a trigger source. A plasma channel produced by laser radiation has an effect on decreasing the threshold voltage and inducing the discharge in both needle electrodes. We have confirmed a delay time between a produced plasma channel and an electrical discharge after laser radiation. We provided the decreased voltage lower than the natural discharge voltage between electrode type of needles and was induced the discharge by forming a plasma channel between them. In this research we could understand the time delay of induced discharge by laser radiation, and the characteristics of the discharge cause by the decrease in the threshold voltage, and the polarity effect by changes of plasma channel positions between two electrodes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1905-1907
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• 1997

The experiments of laser-guided de discharge were carried out by using pulsed Nd:YAG laser radiation at low air pressure ranging from 0.3 to 20 torr. The minimum laser-guided de discharge voltages($V_{MD}$) at given pressure and distances between anode and cathode electrode were obtained. In order to generate TEM(transverse electromagnetic waves) modes, a pinhole was installed between a rod and a half mirror, and its diameter was adjusted from 6mm to 1.7mm. And then, we investigated the characteristics of laser-guided de discharge corresponding to different TEM modes. As a result, it was found that $V_{MD}$ at $TEM_{00}$ mode was lower than $V_{MD}$ at multimodes.

• 조명전기설비학회논문지
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• 제20권1호
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• pp.19-26
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• 2006

용량결합고주파(ccrf)방전은 홀로우음극방전이나, 직류방전에 비해서 방전관의 구조가 간단하고 균질한 플라즈마를 발생시키는 장점을 가지고 있다. 본 논문에서는 ccrf-방전을 기체레이저의 여기에 적용하기 위한 목표를 가지고 방전시스템을 선계, 제작하여 연속운전의 균질한 방전을 실현하였다. 13.56[MHz]의 rf-전력을 방전 내부로 효율적으로 결합하기 위해서 내부직경 5[mm]의 레이저방전관에 특수하게 제작된 rf-전극을 사용하였다. 또한 방전관의 임피던스가 rf-발생기의 풀력저항 50[$\Omega$]에 정합을 이루는 임피던스 정합회로를 개발하였다.

• 조명전기설비학회논문지
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• 제13권1호
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• pp.1-8
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• 1999

최근 들어 레이저를 이용한 방전 제어 기술에 대한 관심이 여러 분야에서 고조되고 있다. 특히, 레이저의 우수한 특성 때문에 Electro-Discharge Machining(EDM)분야에서 각광을 받고 있다. 본 연구에서는 펄스형 Nd:TAG 레이저를 이용해서 방전 가공 장치에 적용될 수 있는 방전 유도 기술에 관한 기초 데이터의 확보를 위한 실험이 수행되었다. 레이저에 의한 직류 발전 유도 실험의 동작 압력의 범위는 0.2~20 torr였다. 진공조 내의 압력 P와 전극간의 거리 d에 따른 최소 직류 레이저 방전 유도 전압 $V_{G.min}$을 측정하였으며, $V_{G.min}$이 자연 방전전압 VND보다 훨씬 낮고 P.d값에 따른 $V_{G.min}$이 $V_{ND}$와 유사한 경향을 가짐을 확인하였다. 그리고 레이저 출력 에너지 $E_{out}$은 플래쉬램프의 전류 펄스폭 $t_p$가 증가함에 따라 감소하고 $t_p$값이 증가할수록 $V_{G.min}$은 방전 지속 시간 동안에 조사되는 광자량이 감소하기 때문에 더 높아짐을 알 수 있었다. 또한 레이저에 의한 방전 유도 가능범위와 레이저 출력에 따른 방전 유도 특성을 조사하였다.

• 한국광학회지
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• 제16권5호
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• pp.450-455
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• 2005

본 논문에서는 기존의 TE(transverse excitation) 방식과 달리 LE(longitudinal excitation) 방식을 사용하여 유전체 표면을 따라 발생하는 미끄럼 방전에 의해서도 질소레이저 발진이 가능함을 보였다. 이는 방전여기 방식인 엑시머 레이저 등의 기체 레이저에서도 미끄럼 방전을 이용한 레이저 발진이 가능함을 의미한다. 또한, 레이저빔의 형상이 공진기의 원둘레를 따라 발진이 되어 빔이 환 모양으로 출력이 됨을 보임에 따라 직사각형이나 타원형의 빔 등 폐곡선을 이루는 어떤 특정한 형태의 질소레이저 빔도 만들어 낼 수 있다는 가능성을 보였다. 레이저의 동작특성인 출력과 안정성은 TE 방식에 비해서도 뒤떨어지지 않는 다는 것을 알 수 있었으며, 공진기의 지름이 2배 증가하면 미끄럼 방전이 일어나는 표면이 2배, 체적은 4배 증가하여 그에 따른 방전간극과 유동률이 비례관계에 있음을 알 수 있었다.

• 한국전기전자재료학회논문지
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• 제15권6호
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• pp.551-557
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• 2002

Carbon nitride films have been deposited on Si(100) substrate by a high voltage discharge plasma combined with laser ablation in a nitrogen atmosphere. The films were grown both with the without the presence of an assisting focused Nd:YAG laser ablation. The laser ablation of the graphite target leads to vapor plume plasma expending into th ambient nitrogen arc discharge area. X-ray photoelectron spectroscopy and Auger electron spectroscopy were used to identify the binding structure and the content of the nitrogen species in the deposited films. The nitrogen content of the films was found to increase drastically with an increase of nitrogen pressure. The surface morphology of the films was studied using a scanning electron microscopy. Data of infrared spectroscopy and x-ray photoelectron spectroscopy indicate the existence of carbon-nitrogen bonds in the films. The x-ray diffraction measurements have also been taken to characterize the crystal properties of the obtained films.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권12호
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• pp.568-572
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• 2003

A longitudinal discharge heated copper vapor laser with internal diameter 28 mm and discharge length 1.3 m has been constructed and tested. At the discharging voltage 15.2 kV, pulse repetition rate 10 kHz, buffer gas pressure 40 mbar, and internal temperature of the laser plasma tube $1520^{\circ}C$, it delivers more than 30 W average laser outputs.