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Gonho Kim - One of the best experts on this subject based on the ideXlab platform.

  • determination of electron energy probability function in low temperature plasmas from current voltage characteristics of two langmuir probes filtered by savitzky golay and Blackman Window methods
    Current Applied Physics, 2015
    Co-Authors: Hyunjoon Roh, Namkyun Kim, Sangwon Ryu, Seolhye Park, Seokhwan Lee, Sungryul Huh, Gonho Kim
    Abstract:

    Abstract Acceptable data for electron energy probability function (EEPF) measurement in low-pressure plasmas require a small depletion in near-zero electron energy and a large dynamic range in the high-energy regime. The voltage drop across internal resistance and noise from the data acquisition system cause a rounding of the EEPF near the zero electron energy and a reduction in the dynamic range due to a low signal-to-noise ratio of the high-energy regime, respectively, leading to erroneous interpretation in the EEPF measurement. A digital smoothing filter can be employed to reduce the noise signal, but it can also cause additional depletion near the zero energy. In order to obtain reliable EEPF data, a novel technique is proposed using two Langmuir probes with differing collecting areas and the Savitzky–Golay and Blackman Window methods. The technique enables the internal resistance effect to be removed using a slope of the current – voltage characteristic taken from the probes. In addition, the Savitzky–Golay and Blackman Window methods in the technique apply separately to two regimes of the EEPF, i.e., the near-zero energy regime and the inelastic energy regime, because appropriate smoothing methods that minimize loss and distortion of information differ for the two regimes. This allows one to decrease the noise signal, minimizing the additional depletion near the zero energy. This technique improves the dynamic range of the EEPF from 30 to 55 dB to 65–105 dB and provides more accurate electron density and effective electron temperature from the EEPF, compared to those of the conventional technique.

  • improvement of dynamic range of electron energy probability function from two asymmetrical collecting area probe data filtered by savitzky golay and Blackman Window methods
    International Conference on Plasma Science, 2015
    Co-Authors: Hyunjooh Roh, Namkyun Kim, Sangwon Ryu, Seokhwan Lee, Sungryul Huh, Gonho Kim
    Abstract:

    The electron energy probability function (EEPF) measured by Langmuir probe is required to be reasonable in low energy regime and have large dynamic range (DR) in high energy regime to investigate the kinetics of low pressure plasma.1 However the internal resistance (R int ) in bias circuit of probe and the adaption of digital smoothing filter to increase DR destruct these requirements by distorting the EEPF in low energy regime.1,2 R int is sum of the resistances due to the chamber wall sheath and surface of chamber wall. The existence of R int gives distortion of measured EEPF in low energy regime by overestimating measured probe voltage. Adapting digital smoothing filter gives additional distortion of EEPF in low energy regime since it flattens the peak shape near zero electron energy. A new method is proposed to acquire EEPF which has reasonable value in low energy regime and large DR in high energy regime. The overestimated probe voltage is corrected by removing the effect of R int which is determined from two sets of plasma potential (V p ) and electron saturation current (I pe ∗). The Savitzky-Golay and Blackman Window filters are adapted to the I-V characteristics of larger collecting area probe, which has larger signal-to-noise ratio. The two digital smoothing filters are optimized to maximize the strengths of each filter by considering the property of EEPF in low and high energy regime. The verification and capability evaluation of the proposed method are performed by comparing the EEPF measured from optical emission spectroscopy (OES) and conventional method based on single Langmuir probe. The method enhances DR of measured EEPF about 35 ∼ 40 dB in comparison with the EEPF from conventional method, especially at two energy regions near zero electron energy and high energy. There are two requirements for proposed method. The distance between two probes is small enough to maintain that ΔV p due to the difference of measurement position is smaller than ΔV p due to R int where ΔV p is the difference of V p between two probes. Also signal-to-noise ratio of larger collecting area probe should be larger than 55 dB to ensure the performance of Savitzky-Golay method in low energy regime.

Hyunjoon Roh - One of the best experts on this subject based on the ideXlab platform.

  • determination of electron energy probability function in low temperature plasmas from current voltage characteristics of two langmuir probes filtered by savitzky golay and Blackman Window methods
    Current Applied Physics, 2015
    Co-Authors: Hyunjoon Roh, Namkyun Kim, Sangwon Ryu, Seolhye Park, Seokhwan Lee, Sungryul Huh, Gonho Kim
    Abstract:

    Abstract Acceptable data for electron energy probability function (EEPF) measurement in low-pressure plasmas require a small depletion in near-zero electron energy and a large dynamic range in the high-energy regime. The voltage drop across internal resistance and noise from the data acquisition system cause a rounding of the EEPF near the zero electron energy and a reduction in the dynamic range due to a low signal-to-noise ratio of the high-energy regime, respectively, leading to erroneous interpretation in the EEPF measurement. A digital smoothing filter can be employed to reduce the noise signal, but it can also cause additional depletion near the zero energy. In order to obtain reliable EEPF data, a novel technique is proposed using two Langmuir probes with differing collecting areas and the Savitzky–Golay and Blackman Window methods. The technique enables the internal resistance effect to be removed using a slope of the current – voltage characteristic taken from the probes. In addition, the Savitzky–Golay and Blackman Window methods in the technique apply separately to two regimes of the EEPF, i.e., the near-zero energy regime and the inelastic energy regime, because appropriate smoothing methods that minimize loss and distortion of information differ for the two regimes. This allows one to decrease the noise signal, minimizing the additional depletion near the zero energy. This technique improves the dynamic range of the EEPF from 30 to 55 dB to 65–105 dB and provides more accurate electron density and effective electron temperature from the EEPF, compared to those of the conventional technique.

Namkyun Kim - One of the best experts on this subject based on the ideXlab platform.

  • determination of electron energy probability function in low temperature plasmas from current voltage characteristics of two langmuir probes filtered by savitzky golay and Blackman Window methods
    Current Applied Physics, 2015
    Co-Authors: Hyunjoon Roh, Namkyun Kim, Sangwon Ryu, Seolhye Park, Seokhwan Lee, Sungryul Huh, Gonho Kim
    Abstract:

    Abstract Acceptable data for electron energy probability function (EEPF) measurement in low-pressure plasmas require a small depletion in near-zero electron energy and a large dynamic range in the high-energy regime. The voltage drop across internal resistance and noise from the data acquisition system cause a rounding of the EEPF near the zero electron energy and a reduction in the dynamic range due to a low signal-to-noise ratio of the high-energy regime, respectively, leading to erroneous interpretation in the EEPF measurement. A digital smoothing filter can be employed to reduce the noise signal, but it can also cause additional depletion near the zero energy. In order to obtain reliable EEPF data, a novel technique is proposed using two Langmuir probes with differing collecting areas and the Savitzky–Golay and Blackman Window methods. The technique enables the internal resistance effect to be removed using a slope of the current – voltage characteristic taken from the probes. In addition, the Savitzky–Golay and Blackman Window methods in the technique apply separately to two regimes of the EEPF, i.e., the near-zero energy regime and the inelastic energy regime, because appropriate smoothing methods that minimize loss and distortion of information differ for the two regimes. This allows one to decrease the noise signal, minimizing the additional depletion near the zero energy. This technique improves the dynamic range of the EEPF from 30 to 55 dB to 65–105 dB and provides more accurate electron density and effective electron temperature from the EEPF, compared to those of the conventional technique.

  • improvement of dynamic range of electron energy probability function from two asymmetrical collecting area probe data filtered by savitzky golay and Blackman Window methods
    International Conference on Plasma Science, 2015
    Co-Authors: Hyunjooh Roh, Namkyun Kim, Sangwon Ryu, Seokhwan Lee, Sungryul Huh, Gonho Kim
    Abstract:

    The electron energy probability function (EEPF) measured by Langmuir probe is required to be reasonable in low energy regime and have large dynamic range (DR) in high energy regime to investigate the kinetics of low pressure plasma.1 However the internal resistance (R int ) in bias circuit of probe and the adaption of digital smoothing filter to increase DR destruct these requirements by distorting the EEPF in low energy regime.1,2 R int is sum of the resistances due to the chamber wall sheath and surface of chamber wall. The existence of R int gives distortion of measured EEPF in low energy regime by overestimating measured probe voltage. Adapting digital smoothing filter gives additional distortion of EEPF in low energy regime since it flattens the peak shape near zero electron energy. A new method is proposed to acquire EEPF which has reasonable value in low energy regime and large DR in high energy regime. The overestimated probe voltage is corrected by removing the effect of R int which is determined from two sets of plasma potential (V p ) and electron saturation current (I pe ∗). The Savitzky-Golay and Blackman Window filters are adapted to the I-V characteristics of larger collecting area probe, which has larger signal-to-noise ratio. The two digital smoothing filters are optimized to maximize the strengths of each filter by considering the property of EEPF in low and high energy regime. The verification and capability evaluation of the proposed method are performed by comparing the EEPF measured from optical emission spectroscopy (OES) and conventional method based on single Langmuir probe. The method enhances DR of measured EEPF about 35 ∼ 40 dB in comparison with the EEPF from conventional method, especially at two energy regions near zero electron energy and high energy. There are two requirements for proposed method. The distance between two probes is small enough to maintain that ΔV p due to the difference of measurement position is smaller than ΔV p due to R int where ΔV p is the difference of V p between two probes. Also signal-to-noise ratio of larger collecting area probe should be larger than 55 dB to ensure the performance of Savitzky-Golay method in low energy regime.

Sangwon Ryu - One of the best experts on this subject based on the ideXlab platform.

  • determination of electron energy probability function in low temperature plasmas from current voltage characteristics of two langmuir probes filtered by savitzky golay and Blackman Window methods
    Current Applied Physics, 2015
    Co-Authors: Hyunjoon Roh, Namkyun Kim, Sangwon Ryu, Seolhye Park, Seokhwan Lee, Sungryul Huh, Gonho Kim
    Abstract:

    Abstract Acceptable data for electron energy probability function (EEPF) measurement in low-pressure plasmas require a small depletion in near-zero electron energy and a large dynamic range in the high-energy regime. The voltage drop across internal resistance and noise from the data acquisition system cause a rounding of the EEPF near the zero electron energy and a reduction in the dynamic range due to a low signal-to-noise ratio of the high-energy regime, respectively, leading to erroneous interpretation in the EEPF measurement. A digital smoothing filter can be employed to reduce the noise signal, but it can also cause additional depletion near the zero energy. In order to obtain reliable EEPF data, a novel technique is proposed using two Langmuir probes with differing collecting areas and the Savitzky–Golay and Blackman Window methods. The technique enables the internal resistance effect to be removed using a slope of the current – voltage characteristic taken from the probes. In addition, the Savitzky–Golay and Blackman Window methods in the technique apply separately to two regimes of the EEPF, i.e., the near-zero energy regime and the inelastic energy regime, because appropriate smoothing methods that minimize loss and distortion of information differ for the two regimes. This allows one to decrease the noise signal, minimizing the additional depletion near the zero energy. This technique improves the dynamic range of the EEPF from 30 to 55 dB to 65–105 dB and provides more accurate electron density and effective electron temperature from the EEPF, compared to those of the conventional technique.

  • improvement of dynamic range of electron energy probability function from two asymmetrical collecting area probe data filtered by savitzky golay and Blackman Window methods
    International Conference on Plasma Science, 2015
    Co-Authors: Hyunjooh Roh, Namkyun Kim, Sangwon Ryu, Seokhwan Lee, Sungryul Huh, Gonho Kim
    Abstract:

    The electron energy probability function (EEPF) measured by Langmuir probe is required to be reasonable in low energy regime and have large dynamic range (DR) in high energy regime to investigate the kinetics of low pressure plasma.1 However the internal resistance (R int ) in bias circuit of probe and the adaption of digital smoothing filter to increase DR destruct these requirements by distorting the EEPF in low energy regime.1,2 R int is sum of the resistances due to the chamber wall sheath and surface of chamber wall. The existence of R int gives distortion of measured EEPF in low energy regime by overestimating measured probe voltage. Adapting digital smoothing filter gives additional distortion of EEPF in low energy regime since it flattens the peak shape near zero electron energy. A new method is proposed to acquire EEPF which has reasonable value in low energy regime and large DR in high energy regime. The overestimated probe voltage is corrected by removing the effect of R int which is determined from two sets of plasma potential (V p ) and electron saturation current (I pe ∗). The Savitzky-Golay and Blackman Window filters are adapted to the I-V characteristics of larger collecting area probe, which has larger signal-to-noise ratio. The two digital smoothing filters are optimized to maximize the strengths of each filter by considering the property of EEPF in low and high energy regime. The verification and capability evaluation of the proposed method are performed by comparing the EEPF measured from optical emission spectroscopy (OES) and conventional method based on single Langmuir probe. The method enhances DR of measured EEPF about 35 ∼ 40 dB in comparison with the EEPF from conventional method, especially at two energy regions near zero electron energy and high energy. There are two requirements for proposed method. The distance between two probes is small enough to maintain that ΔV p due to the difference of measurement position is smaller than ΔV p due to R int where ΔV p is the difference of V p between two probes. Also signal-to-noise ratio of larger collecting area probe should be larger than 55 dB to ensure the performance of Savitzky-Golay method in low energy regime.

Seokhwan Lee - One of the best experts on this subject based on the ideXlab platform.

  • determination of electron energy probability function in low temperature plasmas from current voltage characteristics of two langmuir probes filtered by savitzky golay and Blackman Window methods
    Current Applied Physics, 2015
    Co-Authors: Hyunjoon Roh, Namkyun Kim, Sangwon Ryu, Seolhye Park, Seokhwan Lee, Sungryul Huh, Gonho Kim
    Abstract:

    Abstract Acceptable data for electron energy probability function (EEPF) measurement in low-pressure plasmas require a small depletion in near-zero electron energy and a large dynamic range in the high-energy regime. The voltage drop across internal resistance and noise from the data acquisition system cause a rounding of the EEPF near the zero electron energy and a reduction in the dynamic range due to a low signal-to-noise ratio of the high-energy regime, respectively, leading to erroneous interpretation in the EEPF measurement. A digital smoothing filter can be employed to reduce the noise signal, but it can also cause additional depletion near the zero energy. In order to obtain reliable EEPF data, a novel technique is proposed using two Langmuir probes with differing collecting areas and the Savitzky–Golay and Blackman Window methods. The technique enables the internal resistance effect to be removed using a slope of the current – voltage characteristic taken from the probes. In addition, the Savitzky–Golay and Blackman Window methods in the technique apply separately to two regimes of the EEPF, i.e., the near-zero energy regime and the inelastic energy regime, because appropriate smoothing methods that minimize loss and distortion of information differ for the two regimes. This allows one to decrease the noise signal, minimizing the additional depletion near the zero energy. This technique improves the dynamic range of the EEPF from 30 to 55 dB to 65–105 dB and provides more accurate electron density and effective electron temperature from the EEPF, compared to those of the conventional technique.

  • improvement of dynamic range of electron energy probability function from two asymmetrical collecting area probe data filtered by savitzky golay and Blackman Window methods
    International Conference on Plasma Science, 2015
    Co-Authors: Hyunjooh Roh, Namkyun Kim, Sangwon Ryu, Seokhwan Lee, Sungryul Huh, Gonho Kim
    Abstract:

    The electron energy probability function (EEPF) measured by Langmuir probe is required to be reasonable in low energy regime and have large dynamic range (DR) in high energy regime to investigate the kinetics of low pressure plasma.1 However the internal resistance (R int ) in bias circuit of probe and the adaption of digital smoothing filter to increase DR destruct these requirements by distorting the EEPF in low energy regime.1,2 R int is sum of the resistances due to the chamber wall sheath and surface of chamber wall. The existence of R int gives distortion of measured EEPF in low energy regime by overestimating measured probe voltage. Adapting digital smoothing filter gives additional distortion of EEPF in low energy regime since it flattens the peak shape near zero electron energy. A new method is proposed to acquire EEPF which has reasonable value in low energy regime and large DR in high energy regime. The overestimated probe voltage is corrected by removing the effect of R int which is determined from two sets of plasma potential (V p ) and electron saturation current (I pe ∗). The Savitzky-Golay and Blackman Window filters are adapted to the I-V characteristics of larger collecting area probe, which has larger signal-to-noise ratio. The two digital smoothing filters are optimized to maximize the strengths of each filter by considering the property of EEPF in low and high energy regime. The verification and capability evaluation of the proposed method are performed by comparing the EEPF measured from optical emission spectroscopy (OES) and conventional method based on single Langmuir probe. The method enhances DR of measured EEPF about 35 ∼ 40 dB in comparison with the EEPF from conventional method, especially at two energy regions near zero electron energy and high energy. There are two requirements for proposed method. The distance between two probes is small enough to maintain that ΔV p due to the difference of measurement position is smaller than ΔV p due to R int where ΔV p is the difference of V p between two probes. Also signal-to-noise ratio of larger collecting area probe should be larger than 55 dB to ensure the performance of Savitzky-Golay method in low energy regime.