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 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 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 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.

Consecutive reactions in the thermal decomposition of phenylalkyldiazirines

1977 ◽  
Vol 55 (20) ◽  
pp. 3596-3601 ◽  
Author(s):  
Michael T. H. Liu ◽  
Barry M. Jennings
Keyword(s):  
Thermal Decomposition ◽  
Kinetic Parameters ◽  
Diazo Compounds ◽  
First Order ◽  
Temperature Range ◽  
Decomposition Reactions ◽  
Consecutive Reactions ◽  
Rate Processes ◽  
Subsequent Decomposition

The thermal decomposition of phenyl-n-butyldiazirine and of phenylmethyldiazirine in DMSO and in HOAc have been investigated over the temperature range 80–130 °C. The intermediate diazo compounds, 1-phenyl-1-diazopentane and 1-phenyldiazoethane respectively have been detected and isolated. The decomposition of phenyl-n-butyldiazirine and the subsequent decomposition of its product, 1-phenyl-1-diazopentane, are an illustration of consecutive reactions. The kinetic parameters for the isomerization and decomposition reactions have been determined. The isomerization of phenylmethyldiazirine to 1-phenyldiazoethane is first order and probably unimolecular but the kinetics for the subsequent reactions of 1-phenyldiazoethane are complicated by several competing rate processes.

THE THERMAL DECOMPOSITION OF PERACETIC ACID IN AROMATIC SOLVENTS

1963 ◽  
Vol 41 (7) ◽  
pp. 1826-1831 ◽  
Author(s):  
F. W. Evans ◽  
A. H. Sehon
Keyword(s):  
Thermal Decomposition ◽  
Rate Constant ◽  
Peracetic Acid ◽  
First Order ◽  
Aromatic Solvents ◽  
Temperature Range ◽  
Polymeric Compounds

The thermal decomposition of peracetic acid in toluene, benzene, and p-xylene was studied over the temperature range 75–95°C. The main products of decomposition were found to be CH4, CO2, CH3COOH; small amounts of methanol, phenols, and polymeric compounds were also detected.The rate of the overall decomposition was first order with respect to peracetic acid, and the results could be explained by postulating the participation of the two simultaneous reactions:[Formula: see text] [Formula: see text]The rate constant of reaction (1) was independent of the solvent, whereas k2 was dependent on the solvent. The ratio k2/k1 was about 10.

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

Ultrasonic Relaxation in Phase Transition Region in Ferroelectric Semiconductors of Sn2P2S6 Family

2012 ◽  
Vol 184 ◽  
pp. 345-350
Author(s):  
Vytautas Samulionis ◽  
Juras Banys ◽  
Yulian Vysochanskii
Keyword(s):  
Phase Transition ◽  
Ultrasonic Velocity ◽  
Thermal Hysteresis ◽  
Ultrasonic Attenuation ◽  
Landau Theory ◽  
Velocity Change ◽  
First Order ◽  
Temperature Range ◽  
Large Hysteresis ◽  
Relative Change

The paper presents recent results of ultrasonic investigation of Sn2P2S6 family ferroelectric crystals and their solid solutions in the temperature range 100-300 K. It was shown that in Sn2P2(S,Se)6 crystals the critical ultrasonic velocity slowing down for longitudinal waves propagating along main crystallographic directions is quite sharp and large. The relative change of longitudinal ultrasonic velocity along z-axis at the phase transition gradually increased from 10 % in pure Sn2P2S6 till 25 % for sample with 0.4 content of Se. Such large velocity change causes the large ultrasonic attenuation anomaly. The increase of relaxation time: τ=τ0/(TC-T) leads to the increase of attenuation. Prefactor τ0 was shown to be very small and the critical attenuation anomaly arises in the narrow temperature range close to phase transition. In the 0.4 Se sample the phase transition is of the first order because small thermal hysteresis exists. The ultrasonic velocity behaviour in the ferroelectric phase was described using Landau theory and free energy expansion including sixth order terms. For (Sn,Pb)2P2S6 system the critical ultrasonic anomalies were smaller and the phase transition temperature substantially decreased (for 0.45 Pb sample the phase transition point was at Tc =140 K). The ultrasonic anomalies at phase transition in (PbxSn1-x)2P2S6 have large hysteresis showing that transition is of the first order, far from the critical point.

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