scholarly journals On the role of ‘hot’ atoms in plasma-assisted ignition

2015 ◽  
Vol 373 (2048) ◽  
pp. 20140343 ◽  
Author(s):  
Andrey Yu Starikovskiy
Keyword(s):  
Initial Distribution ◽  
Translational Energy ◽  
Collisional Quenching ◽  
Active Components ◽  
Temperature Oxidation ◽  
Electronically Excited ◽  
Ignition Threshold ◽  
Kinetics Of ◽  
Non Equilibrium

This paper discusses the processes leading to the formation of ‘hot’ atoms and radicals possessing excessive translational energy in high-voltage NS pulse discharges. It is shown that the formation of such ‘hot’ atoms occurs efficiently both in the dissociation of molecules by direct electron impact, and in the collisional quenching of electronically excited states. Depending on the magnitude of the reduced electric field in the discharge, reactions of these ‘hot’ atoms increase the initial concentration of radicals in the discharge afterglow two to three times when compared with the values calculated without effects of translational non-equilibrium. The role of thermally non-equilibrium excitation has been demonstrated in the formation of the initial distribution of the chemically active components in the mixture and its influence on the kinetics of ignition initiation at low and high temperatures. It was found that in undiluted mixtures the presence of ‘hot’ atoms can significantly decrease an ignition threshold and accelerate a low-temperature oxidation.

The linear mixture formula in non-equilibrium chemical kinetics

1977 ◽  
Vol 55 (5) ◽  
pp. 802-811 ◽  
Author(s):  
Robert K. Boyd
Keyword(s):  
Chemical Kinetics ◽  
Ideal Gas ◽  
Eigenvalue Approximation ◽  
Mixture Formula ◽  
Collision Partner ◽  
Recombination Reactions ◽  
Kinetics Of ◽  
Equilibrium Chemical ◽  
Non Equilibrium

The recent extensions of the 'eigenvalue approximation' of non-equilibrium kinetics proposed by Bartis and Widom to explain in a direct qualitative sense some general features of phenomenological chemical kinetics in ideal gas systems, have been used to investigate the problem of the 'linear mixture formula' applied to non-equilibrium kinetics of reactions proceeding in mixtures. For isomerization reactions in mixtures dilute in reactant, the model of Bartis and Widom, without further embellishment, has been shown to justify such an equation. Extrapolation of this result to account for recent empirical successes of a linear mixture formula in dissociation–recombination reactions of diatomic molecules X2 is not straightforward; the physical implications of the mathematical approximations employed are examined, and the non-linear recombination term is accounted for in the present purely qualitative context by an appropriate linearization. However, the appreciable contributions from X2–X2 collisions, under the conditions of the experiments cited, introduce inescapable non-linearities if vibration–vibration exchange, for example, is important. Problems associated with the role of the free atom X as a collision partner seem likely to be less important.

scholarly journals The simulation of vibrational populations of electronically excited N2and O2molecules in the middle atmosphere of the Earth during precipitations of high-energetic particles.

2020 ◽  
Author(s):  
A.S. Kirillov ◽  
◽  
R. Werner ◽  
V. Guineva ◽  
◽  
...  
Keyword(s):  
Molecular Oxygen ◽  
Electronic Excitation ◽  
Middle Atmosphere ◽  
Molecular Nitrogen ◽  
Inelastic Collisions ◽  
Transfer Processes ◽  
The Earth ◽  
Electronically Excited ◽  
Kinetics Of

We study the electronic kinetics of molecular nitrogen and molecular oxygen in the middle atmosphere of the Earth during precipitations of high-energetic protons and electrons.The role of molecular inelastic collisions in intermolecularelectron energy transfer processes is investigated.It is shown that inelastic molecular collisions influence on vibrational populations of electronically excited molecular oxygen. It is pointed out on very important role of the collisions of N2(A3u+) with O2molecules on the electronic excitation of Herzberg states of molecular oxygenat the altitudes of the middle atmosphere.

Investigation of irradiation-induced nucleation processes in silicon and germanium

1995 ◽  
Vol 53 ◽  
pp. 224-225
Author(s):  
Harry A. Atwater ◽  
C.M. Yang ◽  
K.V. Shcheglov
Keyword(s):  
Room Temperature ◽  
Crystal Size ◽  
Initial Distribution ◽  
Engineering Control ◽  
Size Evolution ◽  
Silicon And Germanium ◽  
Ge Quantum Dot ◽  
And Control ◽  
Germanium Quantum Dots ◽  
Kinetics Of

Studies of the initial stages of nucleation of silicon and germanium have yielded insights that point the way to achievement of engineering control over crystal size evolution at the nanometer scale. In addition to their importance in understanding fundamental issues in nucleation, these studies are relevant to efforts to (i) control the size distributions of silicon and germanium “quantum dots𠇍, which will in turn enable control of the optical properties of these materials, (ii) and control the kinetics of crystallization of amorphous silicon and germanium films on amorphous insulating substrates so as to, e.g., produce crystalline grains of essentially arbitrary size.Ge quantum dot nanocrystals with average sizes between 2 nm and 9 nm were formed by room temperature ion implantation into SiO2, followed by precipitation during thermal anneals at temperatures between 30°C and 1200°C[1]. Surprisingly, it was found that Ge nanocrystal nucleation occurs at room temperature as shown in Fig. 1, and that subsequent microstructural evolution occurred via coarsening of the initial distribution.

Optical analysis of ink and other contaminants in process waters

TAPPI Journal ◽  
2012 ◽  
Vol 11 (8) ◽  
pp. 51-58
Author(s):  
ANTTI HAAPALA ◽  
MIKA KÖRKKÖ ◽  
ELISA KOIVURANTA ◽  
JOUKO NIINIMÄKI
Keyword(s):  
Optically Active ◽  
Process Water ◽  
Paper Machine ◽  
Optical Analysis ◽  
Direct Process ◽  
Active Components ◽  
Water Contaminants ◽  
Dependent Measurement ◽  
Measurement Methodology

Analysis methods developed specifically to determine the presence of ink and other optically active components in paper machine white waters or other process effluents are not available. It is generally more interest¬ing to quantify the effect of circulation water contaminants on end products. This study compares optical techniques to quantify the dirt in process water by two methods for test media preparation and measurement: direct process water filtration on a membrane foil and low-grammage sheet formation. The results show that ink content values obtained from various analyses cannot be directly compared because of fundamental issues involving test media preparation and the varied methodologies used to formulate the results, which may be based on different sets of assumptions. The use of brightness, luminosity, and reflectance and the role of scattering measurements as a part of ink content analysis are discussed, along with fine materials retention and measurement media selection. The study concludes with practical tips for case-dependent measurement methodology selection.

Modelling of impregnation of γ-alumina with cobalt and molybdenum salts. CoCl2-(NH4)2MoO4-γ-Al2O3 (aluminate type) system

1987 ◽  
Vol 52 (3) ◽  
pp. 663-671 ◽  
Author(s):  
Jiří Hanika ◽  
Vladimír Janoušek ◽  
Karel Sporka
Keyword(s):  
Effective Diffusion ◽  
Type System ◽  
Catalyst Particle ◽  
Ammonium Molybdate ◽  
Active Components ◽  
Model Set ◽  
Cobalt Dichloride ◽  
Set Up ◽  
Electron Microanalysis ◽  
Kinetics Of

Adsorption data for the impregnation of alumina with an aqueous solution of cobalt dichloride and ammonium molybdate were treated in terms of the Langmuir adsorption isotherm and compared with a mathematical model set up to describe the kinetics of simultaneous impregnation of a support by two components. The effective diffusion coefficients of the two components at 25 °C in a cylindrical particle of alumina were obtained. The validity of the model used was verified qualitatively by comparing the numerical results with the experimental time dependent concentration profiles of the active components in a catalyst particle, measured by electron microanalysis technique.

Thermodynamic and Kinetic Investigation of the Solvent Effect on the Oxidation of [Co(en)2SCH2COO]+ with S2O82- In Water-Methanol and Water-tert-Butyl Alcohol Mixtures

1993 ◽  
Vol 58 (5) ◽  
pp. 1001-1006 ◽  
Author(s):  
Oľga Vollárová ◽  
Ján Benko
Keyword(s):  
Transfer Functions ◽  
Activation Parameters ◽  
Butyl Alcohol ◽  
Oxidation Of Co ◽  
Kinetics Of Oxidation ◽  
Tert Butyl ◽  
Tert Butyl Alcohol ◽  
Alcohol Mixtures ◽  
Kinetics Of

The kinetics of oxidation of [Co(en)2SCH2COO]+ with S2O82- was studied in water-methanol and water-tert-butyl alcohol mixtures. Changes in the reaction activation parameters ∆H≠ and ∆S≠ with varying concentration of the co-solvent depend on the kind of the latter, which points to a significant role of salvation effects. The solvation effect on the reaction is discussed based on a comparison of the transfer functions ∆Ht0, ∆St0 and ∆Gt0 for the initial and transition states with the changes in the activation parameters accompanying changes in the CO-solvent concentration. The transfer enthalpies of the reactant were obtained from calorimetric measurements.

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