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| 1.
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久保田, 聖 ; 舩津, 賢人 ; 白井, 紘行 ; 高草木, 文雄
概要:
application/pdf<br />Journal Article<br />Spectroscopic measurements of micro-air plasma-jets were performed at an atmospheric pressure in the wavelength region of 280 to 420nm where N^+_21- and N_22+ bands were
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predominant. The spectra were measured at many radial and axial points to obtain its radiative characteristics in detail. Abel inversion method was applied to all the experimental data measured laterally to obtain true spectral intensity distribution at all radial points. The comparison of the experimental and Abel-inverted spectra showed that the experimental data could not be used directly to deduce temperatures without the Abel inversion except around the flow axis. Temperatures of the plasma jets were estimated by applying the spectral matching method to N^+_21- bands. Rotational temperature for N^+_21- bands was about 8000K, and was almost independent of radial positions. Vibrational temperature was about 28000K in the core region with much higher in the outermost region.
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| 2.
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HAYASHIDA, Kazuhiro ; AMAGAI, Kenji ; SATOH, Keiji ; ARAI, Masataka
概要:
application/pdf<br />Journal Article<br />Spontaneous Raman spectroscopy with KrF excimer laser was applied to obtain a fuel concentration distribution in a sooting flame. In the case of sooting flame, fluorescence from polycyclic
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aromatic hydrocarbons (PAH) and laser-induced incandescence (LII) from soot particles appeared with Raman scattering. These background emissions overlapped on the Raman scattering. In order to separate the Raman scattering and the background emissions, polarization property of laser-induced emissions was utilized. Since the background emissions were depolarized whereas the Raman scattering was highly polarized, it is possible to subtract the background emissions from the overlapping signal of the Raman scattering and the background emissions. Subtracting the emission signals for the electric vector of the laser light perpendicular and parallel to the direction of observation allows to extract the precise Raman signals. By using this technique, detailed fuel concentration distribution in sooting flames could be obtained based on Raman scattering.
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| 3.
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久保田, 聖 ; 舩津, 賢人 ; 白井, 紘行 ; 高草木, 文雄
概要:
application/pdf<br />Journal Article<br />Spectroscopic measurements of micro-air plasma-jets generated at low pressures were performed at several points on flow axis, using a spectrometer in the wavelength region of 200 to 900
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nm. The N_22+ bands and N_2^+1- bands were predominant in the region of 280 to 480nm, and atomic lines of N and O in the visible and infrared regions. Temperatures of the plasma-jets were estimated by applying a spectral matching method to N_2^+1- bands along a flow axis for low-pressure conditions. Rotational temperatures for N_2^+1- bands were 6000 to 7000K, and vibrational temperatures 25000 to 28000K, almost independent of pressures and axial positions. It was found that the rotational temperatures measured had great difference from the gas temperature based upon an empirical formula for supersonic free jets, and also the vibrational temperatures were much higher than those expected.
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| 4.
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澁澤, 健二 ; 舩津, 賢人 ; 白井, 紘行 ; 久保田, 聖
概要:
application/pdf<br />Journal Article<br />The characteristic intensity distribution in the N_2 second positive bands obs
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erved in high-temperature air plasmas generated by a micro-air plasma-jet generator was reconstructed by the theoretical spectra with predissociation and non-Boltzmann rotational population distribution. In order to construct the precise theoretical spectra, collisional transition rate coefficient that was applicable at high temperatures was proposed based upon a simple collision theory. In addition, the effect of the radiative transition from C ^3Π_u to B ^3Π_g state was included in the master equation. The theoretical spectra with non-Boltzmann rotational population distribution calculated with such factors agreed very well with the experimental ones.
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| 5.
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久保田, 聖 ; 舩津, 賢人 ; 白井, 紘行 ; 田部井, 勝稲
概要:
application/pdf<br />Journal Article<br />A micro-air plasma-jet, whose size was 3.0mm in length and about 0.7mm in diameter, was measured spectroscopically in the wavelength region of 200 to 900nm using a spectrometer. The N_2 2+ and N^+_2
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1- bands were predominant in the region of 280 to 500nm and intense atomic lines of N and O in the infrared region. Temperatures of the plasma-jet were determined by applying a spectral matching method to those band spectra. There was a very good agreement between the theoretical and experimental spectra in the main part of the measured wavelength region. It was found that the rotational temperature was 7,000 to 9.000K depending on the band, vibrational temperature about 28,000K for both the bands, and the jet was remarkably in thermal non-equilib-rium state.
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| 6.
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林田, 和宏 ; 天谷, 賢児 ; 佐藤, 桂司 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Raman scattering technique with KrF excimer laser was applied to obtain a fuel concentration distribution in a sooting flame. In the case of sooting flame, fluorescence from polycyclic
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aromatic hydrocarbons (PAH) and laser-induced incandescence (LII) from soot particles appeared with Raman scattering. These background emissions overlappped on the Raman scattering. In order to separate the Raman scattering and the background emissions, polarization property of laser-induced emissions was utilized. Since the background emissions were depolarized whereas the Raman scattering was highly polarized, it is possible to subtract the background emissions from the overlapping signal of the Raman scattering and the background emissions. Subtracting the emission signals for the electric vector of the laser light perpendicular and parallel to the direction of observation allows to extract the precise Raman signals. By using this technique, detailed fuel concentration distribution in sooting flames could be obtained based on Raman scattering.
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| 7.
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澁澤, 健二 ; 舩津, 賢人 ; 白井, 紘行 ; 久保田, 聖
概要:
application/pdf<br />Journal Article<br />The N_2 second positive bands observed in high-temperature air plasmas are con
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sidered to be useful to determine internal states of high-temperature plasmas. In the experiments with a microair plasma-jet, the N_2 second positive bands with higher vibrational levels (v'≧2) were found to show a characteristic intensity distribution. The intensity distribution could not be explained by a usual equilibrium radiation theory. In order to investigate the phenomenon, theoretical spectra were calculated by taking account of two effects, that is, predissociation of N_2 C 3^II_u state through C' 3^II-u state and non-Boltzmann rotational population distribution. This calculated spectra with such effects agreed very well with the experiments.
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| 8.
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林田, 和宏 ; 天谷, 賢児 ; 白井, 紘行 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />LIF thermometry in a sooting diffusion flame was newly proposed based on a spe
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ctral matching method. A tunable ArF excimer laser was used to excite the several absorption lines in the D^2Σ^+←X^2II(0, 1) band system of NO. In the case of sooting diffusion flame, emission spectrum consisted of NO and O_2 fluorescence, and off-resonance emissions related to the soot. The O_2 fluorescence and the off-resonance emissions overlapped on the NO fluorescence. However, the offresonance emissions near the vacuum ultraviolet region (VUV) were weaker than the NO fluorescence, and the ε(0, 3) band of the NO fluorescence, which appeared near the VUV region, was free from the O_2 fluorescence. Therefore, NO rotational temperature in a sooting diffusion flame could be measured by the spectral matching method using the ε(0, 3) band. By using this technique, NO rotational temperature in a propane diffusion flame could be measured.
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| 9.
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舩津, 賢人 ; 渡辺, 泰夫 ; 白井, 紘行 ; 伊藤, 健 ; 石田, 清道
概要:
application/pdf<br />Journal Article<br />Spectroscopic measurements were made of a shock layer generated by a flat-head body in high-enthalpy air and nitrogen plasma flows of NAL 750kW arc-jet wind tunnel. In the wavelength region of 350nm
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to 450nm, N_2^+ 1- band was predominant in the nitrogen jets and the N_2^+ 1- and CN violet bands in the air jets. These bands were analyzed in detail by using synthetic spectra calculated theoretically. Temperature determination of the shock layer was tried by applying a spectral matching method to these band systems. In case of the nitrogen plasma jet, axial temperature distribution across the shock layer was measured and compared with the flow calculation based upon the modified fully-merged shock layer theory. It was found that the rotational temperature in the shock layer for both the arc jets was about 7000K, and the tempeature of a free stream in the nitrogen plasma jets was much higher than that expected.
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| 10.
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HAYASHIDA, Kazuhiro ; SHIRAI, Hiroyuki ; AMAGAI, Kenji ; ARAI, Masataka
概要:
application/pdf<br />Journal Article<br />Rotational temperature of NO molecule in methane/air premixed flame was estima
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ted by a spectral matching method. A tunable narrow band ArF excimer laser was used to excite the D^2Σ^+ ← X^2∏(0,1) band system of NO. Laser beam was introduced in a flame, and the laser-induced fluorescence was resolved into a spectrum by using a spectrograph. On this spectrum, e and δ bands of upper vibrational level of v'=0 were analyzed. In order to use a spectral matching method, profiles of ε and δ band spectra were calculated theoretically in detail with reliable molecular constants and exact equations, and they were modulated by an experimental slit function. Since the profile of band spectrum was determined as a function of a rotational temperature, a rotational temperature could be estimated using the temperature where the profile of every band spectrum obtained theoretically is fitted to that of experimentally obtained. Applying a spectral matching method on the ε(0,3), ε(0,4) and δ(0,2) band of NO, it was obtained that the rotational temperature is about 1000 K. The obtained rotational temperature is almost agreed with the thermocouple temperature.
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