A porous low-density carbon composite ablator (Mono lithic Ablator, MonA) was tested in the 1.2 M... more A porous low-density carbon composite ablator (Mono lithic Ablator, MonA) was tested in the 1.2 MW inductively heated Plasmatron facility. Two different test gases were used, air and nitrogen, for heat flux levels ranging from <1.0 MW/m2 up to ˜5.0 MW/m2 . Intrusive measurement techniques were used for heat flux measurements and optical diagnostics for test sample surface and reactive boundary layer observation. The surface emissivity was addressed and time-resolved emission spectroscopy helped to identify pyrolysis and ablation products together with thermo-chemical processes in the reacting boundary layer.
... Table 1. Spectroscopic data of the O and C emission lines used in Tat determination. λair (nm... more ... Table 1. Spectroscopic data of the O and C emission lines used in Tat determination. λair (nm)Aji (s −1) Ei (cm−1) Ej (cm−1) gi gj O lines 777.194 3.69 × 107 73 768.200 86 631.454 5 7 777.417 3.69 × 107 73 768.200 86 627.778 5 5 ... Iji = nj (Tat) Aji 4π hc(Ej − Ei), (2) ...
Journal of Quantitative Spectroscopy and Radiative Transfer, 2008
... This is often the case in atmospheric entries of high-speed vehicles in the upper atmosphere ... more ... This is often the case in atmospheric entries of high-speed vehicles in the upper atmosphere (low pressure), or in applications involving fast electrical discharges. ... the electronic state, the vibrational, and rotational quantum numbers of the level. ...
IOP Conference Series: Materials Science and Engineering, 2012
The present contribution will report on the development of a Microwave Plasma Torch (MPT) at the ... more The present contribution will report on the development of a Microwave Plasma Torch (MPT) at the von Karman institute and on the characterization of subsonic plasma flow of various plasmagene gases (air, N2, CO2 and Ar) at atmospheric pressure. The aim of this work is to explore plasma flow regimes for a large envelope of operating conditions. Using a conventional arrangement for MPT, including cylindrical open-ended dielectric quartz tube, plasma generated with molecular gases have been found to be homogeneous while with argon filamentary structures have been observed. Electrical characterization of the source has been performed for some operating conditions using forwarded and reflected microwave power monitoring. Comprehensive characterization of the flow by means of high speed imaging has been performed to estimate the effect of the oscillation of the delivered power on plasma jet unsteadiness. Analysis in time and frequency domains of the light intensity recorded at 1 kHz rate is presented. Low resolution Optical Emission Spectroscopy (OES) diagnostic was performed in order to identify typical radiative signature of air, N2 and CO2 plasma jet. High resolution OES was performed on pure N2 plasma suitable for thermodynamic characterization using N2+ First Negative and N2 2nd Positive systems. Making the common assumption that the internal energy levels of molecular species are populated according to a Boltzmann distribution and making no assumption concerning the total species concentration similarly to [1], comparisons between measured and calculated radiative signature of molecular systems evidence for the achievement of thermal equilibrium and slight departure to Saha equilibrium.
ABSTRACT Emission spectroscopy measurements on a plasma representative of Titan atmosphere compos... more ABSTRACT Emission spectroscopy measurements on a plasma representative of Titan atmosphere composition were obtained in the Inductively Coupled Plasma wind tunnel facility (VKI-Minitorch) at the von Karman Institute in Belgium. Temperatures ranged from 3600 to 5000 K, pressure was fixed at 300 mbar, and the molar composition was 1.9% CH4 and 98.1% N2. The high-pressure plasma was produced to obtain conditions close to equilibrium. In conjunction, line-by-line calculations have been carried out to assess the reliability of two distinct sets of molecular electronic transition moments, recently released, by predicting the radiative signature of high-temperature N2–CH4 plasma. The radiative transfer problem was solved by considering the plasma plume at local thermodynamic equilibrium conditions in an axisymmetric configuration. Comparisons between the synthetic and experimental spectra demonstrated good agreement for the CN Violet and high-wavelength CN Red bands, while some discrepancies were observed for the C2 Swan bands and low-wavelength CN Red bands.
A porous low-density carbon composite ablator (Mono lithic Ablator, MonA) was tested in the 1.2 M... more A porous low-density carbon composite ablator (Mono lithic Ablator, MonA) was tested in the 1.2 MW inductively heated Plasmatron facility. Two different test gases were used, air and nitrogen, for heat flux levels ranging from <1.0 MW/m2 up to ˜5.0 MW/m2 . Intrusive measurement techniques were used for heat flux measurements and optical diagnostics for test sample surface and reactive boundary layer observation. The surface emissivity was addressed and time-resolved emission spectroscopy helped to identify pyrolysis and ablation products together with thermo-chemical processes in the reacting boundary layer.
... Table 1. Spectroscopic data of the O and C emission lines used in Tat determination. λair (nm... more ... Table 1. Spectroscopic data of the O and C emission lines used in Tat determination. λair (nm)Aji (s −1) Ei (cm−1) Ej (cm−1) gi gj O lines 777.194 3.69 × 107 73 768.200 86 631.454 5 7 777.417 3.69 × 107 73 768.200 86 627.778 5 5 ... Iji = nj (Tat) Aji 4π hc(Ej − Ei), (2) ...
Journal of Quantitative Spectroscopy and Radiative Transfer, 2008
... This is often the case in atmospheric entries of high-speed vehicles in the upper atmosphere ... more ... This is often the case in atmospheric entries of high-speed vehicles in the upper atmosphere (low pressure), or in applications involving fast electrical discharges. ... the electronic state, the vibrational, and rotational quantum numbers of the level. ...
IOP Conference Series: Materials Science and Engineering, 2012
The present contribution will report on the development of a Microwave Plasma Torch (MPT) at the ... more The present contribution will report on the development of a Microwave Plasma Torch (MPT) at the von Karman institute and on the characterization of subsonic plasma flow of various plasmagene gases (air, N2, CO2 and Ar) at atmospheric pressure. The aim of this work is to explore plasma flow regimes for a large envelope of operating conditions. Using a conventional arrangement for MPT, including cylindrical open-ended dielectric quartz tube, plasma generated with molecular gases have been found to be homogeneous while with argon filamentary structures have been observed. Electrical characterization of the source has been performed for some operating conditions using forwarded and reflected microwave power monitoring. Comprehensive characterization of the flow by means of high speed imaging has been performed to estimate the effect of the oscillation of the delivered power on plasma jet unsteadiness. Analysis in time and frequency domains of the light intensity recorded at 1 kHz rate is presented. Low resolution Optical Emission Spectroscopy (OES) diagnostic was performed in order to identify typical radiative signature of air, N2 and CO2 plasma jet. High resolution OES was performed on pure N2 plasma suitable for thermodynamic characterization using N2+ First Negative and N2 2nd Positive systems. Making the common assumption that the internal energy levels of molecular species are populated according to a Boltzmann distribution and making no assumption concerning the total species concentration similarly to [1], comparisons between measured and calculated radiative signature of molecular systems evidence for the achievement of thermal equilibrium and slight departure to Saha equilibrium.
ABSTRACT Emission spectroscopy measurements on a plasma representative of Titan atmosphere compos... more ABSTRACT Emission spectroscopy measurements on a plasma representative of Titan atmosphere composition were obtained in the Inductively Coupled Plasma wind tunnel facility (VKI-Minitorch) at the von Karman Institute in Belgium. Temperatures ranged from 3600 to 5000 K, pressure was fixed at 300 mbar, and the molar composition was 1.9% CH4 and 98.1% N2. The high-pressure plasma was produced to obtain conditions close to equilibrium. In conjunction, line-by-line calculations have been carried out to assess the reliability of two distinct sets of molecular electronic transition moments, recently released, by predicting the radiative signature of high-temperature N2–CH4 plasma. The radiative transfer problem was solved by considering the plasma plume at local thermodynamic equilibrium conditions in an axisymmetric configuration. Comparisons between the synthetic and experimental spectra demonstrated good agreement for the CN Violet and high-wavelength CN Red bands, while some discrepancies were observed for the C2 Swan bands and low-wavelength CN Red bands.
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