scholarly journals Radiation Transfer in Arc Plasmas

2017 ◽  
Vol 4 (3) ◽  
pp. 253-256
Author(s):  
N. Bogatyreva ◽  
M. Bartlová ◽  
V. Aubrecht ◽  
P. Kloc
Keyword(s):  
Thermal Plasma ◽  
Radiation Transfer ◽  
Arc Plasma ◽  
Absorption Coefficients ◽  
Absorption Properties ◽  
Arc Plasmas

In this paper, attention has been given to the absorption properties of the arc plasma at the different pressure conditions. Calculations of the absorption coefficients for a thermal plasma have been performed as a function of the temperature and the frequency. Methods for prediction of the average absorption coefficients were described and compared in detail.

scholarly journals Approximate Determination of Radiation Properties in the Arc Plasmas With Admixtures of Copper Vapours

2019 ◽  
Vol 6 (3) ◽  
pp. 265-269
Author(s):  
N. Bogatyreva ◽  
M. Bartlová ◽  
V. Aubrecht ◽  
P. Kloc
Keyword(s):  
Spherical Harmonics ◽  
Thermal Plasma ◽  
Radiation Transfer ◽  
Approximate Determination ◽  
Absorption Coefficients ◽  
First Order ◽  
Radiation Properties ◽  
Arc Plasmas ◽  
The Way

The aim of this paper is to evaluate radiation properties of air arc plasmas with various admixtures of copper vapours. The first order of the method of spherical harmonics (P<sub>1</sub>-approximation) has been used as the way to solve the equation of radiation transfer. Calculations of the absorption coefficients for a thermal plasma have been performed as a function of the temperature and the frequency. The frequency variable in the equation of transfer was handled by means of multigroup method. Methods for prediction of the average absorption coefficients were described and compared in detail. The net emission coefficients have been determined for comparison.

scholarly journals Multigroup Approximation of Radiation Transfer in SF6 Arc Plasmas

10.14311/1719 ◽  
2013 ◽  
Vol 53 (2) ◽  
Author(s):  
Milada Bartlova ◽  
Vladimir Aubrecht ◽  
Nadezhda Bogatyreva ◽  
Vladimir Holcman
Keyword(s):  
Frequency Dependence ◽  
Spherical Harmonics ◽  
Radiation Transfer ◽  
Absorption Coefficients ◽  
Averaging Methods ◽  
First Order ◽  
Temperature Range ◽  
Cylindrical Plasma ◽  
Radiation Properties ◽  
Arc Plasmas

The first order of the method of spherical harmonics (P1-approximation) has been used to evaluate the radiation properties of arc plasmas of various mixtures of SF6 and PTFE ((C2F4)n, polytetrafluoroethylene) in the temperature range (1000 ÷ 35 000) K and pressures from 0.5 to 5 MPa. Calculations have been performed for isothermal cylindrical plasma of various radii (0.01 ÷ 10) cm. The frequency dependence of the absorption coefficients has been handled using the Planck and Rosseland averaging methods for several frequency intervals. Results obtained using various means calculated for different choices of frequency intervals are discussed.

scholarly journals Influence of metal vapours on radiation characteristics of air arc plasmas

2020 ◽  
Vol 7 (2) ◽  
pp. 30-35
Author(s):  
Milada Bartlová ◽  
Petr Kloc ◽  
Vladimír Aubrecht ◽  
Nadezda Bogatyreva
Keyword(s):  
Temperature Profile ◽  
Radiation Flux ◽  
Radiation Transfer ◽  
Plasma Temperature ◽  
Arc Plasma ◽  
Radiation Characteristics ◽  
Plasma Cylinder ◽  
Radiation Properties ◽  
Isothermal Plasma ◽  
Arc Plasmas

This paper deals with the evaluation of radiation properties of air arc plasma with various admixtures of Cu, Ag, and Fe, respectively. Under assumption of isothermal plasma cylinder, the net emission coefficients were calculated for various arc radii as a function of the plasma temperature up to 30000K. For plasma with prescribed temperature profile, the equation of radiation transfer was solved in the P1approximation, and the radiation flux and its divergence were calculated.

scholarly journals Radiative Properties and Numerical Modeling of C4F7N-CO2-O2 Thermal Plasma

2019 ◽  
Vol 6 (2) ◽  
pp. 144-147
Author(s):  
M. Gnybida ◽  
Ch. Ruempler ◽  
V. R. T. Narayanan
Keyword(s):  
Thermal Plasma ◽  
Spectral Band ◽  
Optimization Procedure ◽  
Optimal Number ◽  
Radiative Properties ◽  
Absorption Coefficients ◽  
Medium Voltage ◽  
Spectral Bands ◽  
Computational Fluid Dynamics Cfd ◽  
Low Global Warming Potential

C<sub>4</sub>F<sub>7</sub>N and C<sub>4</sub>F<sub>7</sub>N-CO<sub>2</sub> mixtures are considered as alternatives to SF<sub>6</sub> for use in medium voltage gas insulated switchgear applications (GIS), due to the low global warming potential and good dielectric properties of C<sub>4</sub>F<sub>7</sub>N. Current work is focused on the calculation of radiative properties (absorption coefficients) of C<sub>4</sub>F<sub>7</sub>N-CO<sub>2</sub> thermal plasma and computational fluid dynamics (CFD) simulations of free burning C<sub>4</sub>F<sub>7</sub>N-CO<sub>2</sub> arcs that are stabilized by natural convection. Absorption coefficients of C<sub>4</sub>F<sub>7</sub>N-CO<sub>2</sub> plasma used in the CFD model are derived from spectral absorption coefficients by Planck averaging. An optimization procedure has been applied to find the optimal number of spectral bands as well as spectral band interval boundaries. Radiation and flow model results for C<sub>4</sub>F<sub>7</sub>N-CO<sub>2</sub> in comparison to SF<sub>6</sub> and air are provided and discussed.

Radiation absorption coefficients in arc plasmas

2004 ◽  
Vol 54 (S3) ◽  
pp. C759-C765 ◽  
Author(s):  
V. Aubrecht ◽  
M. Bartlová
Keyword(s):  
Radiation Absorption ◽  
Absorption Coefficients ◽  
Arc Plasmas

The Measurement of Double Decay Rates in Small Enclosures Containing Highly Absorbent Samples

1994 ◽  
Vol 1 (4) ◽  
pp. 287-297
Author(s):  
M.J. Greaves ◽  
J.L. Homer
Keyword(s):  
Decay Rate ◽  
Three Dimensional ◽  
Sound Field ◽  
Decay Rates ◽  
Experimental Results ◽  
Common Method ◽  
Absorption Coefficients ◽  
Absorption Properties ◽  
Absorbent Material ◽  
Made In

One common method of obtaining the absorption properties of a sample of material is to measure the decay of sound in an enclosure partially lined with the sample. In order to infer absorption coefficients from decay rate measurements, it is assumed that the sound field in the enclosure is diffuse. When measurements are made in enclosures which are small compared with wavelength, and contain non-uniform absorption, the diffuse field may no longer be three-dimensional in nature. Descriptions are given of measurements made in a small rectangular enclosure with one surface lined with highly absorbent material, and the results presented. Predictions are made of the decay rates in this situation and compared with the experimental results. Finally, the different field states present during the decay are explored.

Quantitative Determination of the Scattering and Absorption Coefficients from Diffuse Reflectance and Transmittance Measurements: Application to Pharmaceutical Powders

1997 ◽  
Vol 51 (3) ◽  
pp. 309-317 ◽  
Author(s):  
T. Burger ◽  
J. Kuhn ◽  
R. Caps ◽  
J. Fricke
Keyword(s):  
Particle Size ◽  
Diffuse Reflectance ◽  
Pharmaceutical Powders ◽  
Separate Determination ◽  
Absorption Coefficients ◽  
Absorption Properties ◽  
Flux Approximation ◽  
Reflectance Measurements ◽  
Made In

A measurement and data evaluation technique for the separate determination of the scattering and absorption properties of loose pharmaceutical powders is described. The equation of radiative transfer for diffuse reflectance and transmittance is analytically solved by using a three-flux approximation. Combined transmittance and reflectance measurements then allow one to derive both the scattering and the absorption coefficients. The scattering and absorption coefficients provide more information about particle size, degree of agglomeration, and chemical composition of the samples in comparison to the usual determination of only the ratio of the coefficients from diffuse reflectance measurements on optically thick samples. Furthermore, the theory of diffuse reflectance of optically thick samples according to Kubelka and Munk is compared to the three-flux approximation. The influence of the particle size on the scattering and absorption coefficient is investigated, and it is shown that the assumption of a wavelength-independent scattering coefficient, though often made in reflectance spectroscopy, is not generally valid.

High-Throughput Thermal Plasma Synthesis of FexCo1-x Nano-Chained Particles with Unusually-High Permeability, and their Electromagnetic Wave Absorption Properties at High Frequency (1-26 GHz)

Nanoscale ◽  
2021 ◽  
Author(s):  
Min-Sun Jang ◽  
Mi Se Chang ◽  
Young-tae Kwon ◽  
Sangsun Yang ◽  
Jina Gwak ◽  
...  
Keyword(s):  
Electromagnetic Wave ◽  
High Throughput ◽  
Reflection Loss ◽  
Thermal Plasma ◽  
High Frequency ◽  
Plasma Synthesis ◽  
High Permeability ◽  
Absorption Properties ◽  
Electromagnetic Wave Absorption ◽  
Thermal Plasma Synthesis

Herein, we introduce novel 1-dimensional nano-chained FeCo particles with unusually-high permeability prepared by a highly-productive thermal plasma synthesis, and demonstrate an electromagnetic wave absorber with exceptionally low reflection loss in...

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