• Title/Summary/Keyword: optogalvanic signal

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Measurement of Optogalvanic Signal in Hollow Cathode Discharge Tube (Hollow Cathode Discharge Tube에서의 광검류 신호 측정)

  • Lee, Jun-Hoi;Yoon, Man-Young;Kim, Song-Kang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.07b
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    • pp.874-877
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    • 2002
  • The optogalvanic signals were measured using hollow cathode discharge tube with argon as buffer gas at change of discharge currents. A change of ionization rate due to electron collision causes an increase or decrease of the electric conductivity. This change in electric conductivity generates the optogalvanic signal. We conclude that optogalvanic signal has close relation with the lowest metastable atoms density at low current.

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Observation of Penning ionization using the optogalvanic effect

  • Jeong, Kee-Ju;Lee, Jun-Hoi
    • Journal of Korean Vacuum Science & Technology
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    • v.7 no.1
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    • pp.18-22
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    • 2003
  • The optogalvanic effect is proposed and demonstrated as a technique for Penning ionization in a discharge of mixtures of metal vapors and rare gases. The gadolinium and argon mixture is used as a prototype. The lowest metastable of argon, 3P$_2$ (ls$\_$5/ in Paschen notation) at 93144 cm$\^$-1/, is within kT from the excited states of Gd ion. Thus Penning ionization occurs to an excited states of the ion. This process strongly alters the optogalvanic signal and has its own signatures.

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Laser Induced Impedance Changes in Hollow Cathode Lamps

  • Byung Chul Cha;Jae Jung Lee;Ki Beom Lee;Hyo Jin Kim;Gae Ho Lee;Hasuck Kim
    • Bulletin of the Korean Chemical Society
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    • v.14 no.5
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    • pp.610-614
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    • 1993
  • Laser induced impedance changes in hollow cathode lamps containing sputtered metal atoms have been employed to measure the spectroscopic properties of metal. This technique, known as optogalvanic spectroscopy, has been shown to be a powerful and inexpensive technique for the investigation of atomic and molecular species. Characteristic optogalvanic signals from hollow cathode lamps (HCL) made of different metal species and induced with a pulsed dye laser were observed, and the dependence of the optogalvanic signal on the discharge current and wavelength of laser was measured. Based on the results obtained, the mechanisms involved in evoking the optogalvanic signals were consisted of single-photon absorption, multi-photon absorption, and photoionization. Moreover the current dependence of the optogalvanic signal indicates that the optogalvanic technique could be one of the most sensitive optical methods of detecting atomic species.

Measurement of Optogalvanic Signal in Hollow Cathode Discharge Tube (Hollow cathode discharge tube에서의 광검류 신호 측정)

  • 이준회;정기주
    • Journal of the Korean Vacuum Society
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    • v.11 no.2
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    • pp.119-126
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    • 2002
  • The optogalvanic signals were measured using hollow cathode discharge tube with argon as buffer gas at change of discharge currents. A change of ionization rate due to electron collision causes an increase or decrease of the electric conductivity, This change in electric conductivity generates the optogalvanic signal. We conclude that optogalvanic signal has close relation with change of the lowest metastable atoms density at low current.

Changes in the Optogalvanic Signal Amplitude in a Hollow Cathode Discharge

  • Lee, Jun-Hoi;Koo, Kyung-Wan;Lee, Ki-Sik
    • Transactions on Electrical and Electronic Materials
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    • v.10 no.6
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    • pp.212-216
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    • 2009
  • The spatial distribution of the optogalvanic (OG) signal in argon at the 801.489 nm ($1s_5-2p_8$ transition at the metastable level in Paschen notation) was investigated in the radial direction of a hollow cathode discharge tube. The results of this experiment showed that the OG signal amplitude decreases in accordance with the following two conditions; first, the level of discharge current and second, the distance from the cathode dark space. These results can be quantified by analyzing the electron density profile along the discharge regions, which can directly influence the collisional ionization induced by electron impact.

Observation of Negative Resistance Region in Voltage-current Curve of Hollow Cathode Discharge (속이 빈 원통형음극 방전의 전압-전류 곡선에서 음 저항 영역 관찰)

  • Lee, Jun-Hoi;Lee, Sung-Jik
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.9
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    • pp.870-875
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    • 2005
  • We measured the optogalvanic signal and discharge voltage-current(V-I) curve under the two different discharge conditions with different buffer gases, Ar, and Ne. When the Gd was used as a cathode material at low discharge current less than 10mA, a significant change was observed in the current-voltage curve. Time resolved optogalvanic signal measurement were measured by the diode laser of which wavelengths correspond to metastable transition line of these gases (Ar, Ne). From these measurements, we found that the characteristics of the V-I curve strongly depend on the Penning ionization process.

Study on Characteristics of Plasma in Hollow Cathode Discharge (Hollow Cathode Discharge에서 플라즈마 특성에 관한 연구)

  • Yoon, Man-Young;Shin, Jong-Soon
    • Journal of the Korean Graphic Arts Communication Society
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    • v.23 no.2
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    • pp.93-101
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    • 2005
  • The measured plasma temperature of Ar hollow cathode discharge for several metal cathodes are about $620\;{\sim}\;780K$ at discharge current of $7\;{\sim}\;10mA$. The optogalvanic signals were measured using hollow cathode discharge tube with argon as buffer gas at change of discharge currents. A change of ionization rate due to electron collision causes an increase or decrease of the electric conductivity. This change in electric conductivity generates the optogalvanic signal. We conclude that optogalvanic signal has close relation with the lowest metastable atoms density at low current.

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Optogalvanic Spectroscopy of U, Th and Rb using Diode Lasers (반도체 다이오드 레이저를 사용한 U, Th 및 Rb 의 Optogalvanic Spectroscopy 에 관한 연구)

  • Lee, Sang Cheon
    • Journal of the Korean Chemical Society
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    • v.38 no.1
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    • pp.34-40
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    • 1994
  • First observation of uranium using a diode laser was published recently. The experiment was performed by the optogalvanic spectroscopy using diode lasers. A laser source causes the current change in a hollow cathode discharge lamp when metal atoms in plasma absorb the diode laser light. The optogalvanic signal is collected by detecting the current change. This work is the extended investigation of our previous research, the uranium detection using a diode laser. New electronic transitions of uranium and thorium in 775∼850 nm were investigated using diode lasers. In addition, the Rb(Ⅰ) optogalvanic spectra at 780.02 nm and 794.76 nm were studied. The Rb(Ⅰ) spectrum at 780.02 nm showed the isotopic features and hyperfine splittings. This work provides a key idea that the diode lasers are useful in the specrochemical analysis of the radioactive actinides that have a rich spectrum with transitions which can be easily reached with AlGaAs diode lasers. Also, this study shows that the diode lasers can be an important tool to find the spectroscopic parameters of actinides and rare earth elements which have not known.

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Observation of spontaneous oscillation of optogalvanic signal in a hollow cathode discharge (Hollow cathode discharge에서 자발적 진동의 광검류 신호 측정)

  • 이준회
    • Journal of the Korean Vacuum Society
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    • v.12 no.1
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    • pp.51-54
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    • 2003
  • The spontaneous oscillations in the optogalvanic signals are observed in negative glow region of Ar hollow cathode discharge. The spontaneous oscillations in the optogalvanic signals are observed at low discharge currents less than about 3 mA. Based on the simultaneous measurements of both the density variation of metastable atoms and emission intensities of the 1s-2p transitions, one of the possible mechanisms for the spontaneous oscillation is considered to be related to the stepwise ionization of the metastable atoms due to collisions with slow electrons in the discharge.

High-Density Hollow Cathode Plasma Etching for Field Emission Display Applications

  • Lee, Joon-Hoi;Lee, Wook-Jae;Choi, Man-Sub;Yi, Joon-Sin
    • Journal of Information Display
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    • v.2 no.4
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    • pp.1-7
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    • 2001
  • This paper investigates the characteristics of a newly developed high density hollow cathode plasma(HCP) system and its application for the etching of silicon wafers. We used $SF_6$ and $O_2$ gases in the HCP dry etch process. This paper demonstrates very high plasma density of $2{\times}10^{12}cm^{-3}$ at a discharge current of 20 rna, Silicon etch rate of 1.3 ${\mu}m$/min was achieved with $SF_6/O_2$ plasma conditions of total gas pressure of 50 mTorr, gas flow rate of 40 seem, and RF power of200W. This paper presents surface etching characteristics on a crystalline silicon wafer and large area cast type multicrystlline silicon wafer. We obtained field emitter tips size of less than 0.1 ${\mu}m$ without any photomask step as well as with a conventional photolithography. Our experimental results can be applied to various display systems such as thin film growth and etching for TFT-LCDs, emitter tip formations for FEDs, and bright plasma discharge for PDP applications. In this research, we studied silicon etching properties by using the hollow cathode plasma system.

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