scholarly journals Transport coefficients and cross sections for electrons in water vapour: Comparison of cross section sets using an improved Boltzmann equation solution

2012 ◽  
Vol 136 (2) ◽  
pp. 024318 ◽  
Author(s):  
K. F. Ness ◽  
R. E. Robson ◽  
M. J. Brunger ◽  
R. D. White
Keyword(s):  
Boltzmann Equation ◽  
Water Vapour ◽  
Cross Section ◽  
Cross Sections ◽  
Transport Coefficients ◽  
Equation Solution

scholarly journals Some Recent Studies of Electron Swarms in Gases

1992 ◽  
Vol 45 (3) ◽  
pp. 365 ◽  
Author(s):  
H Tagashira
Keyword(s):  
Boltzmann Equation ◽  
Cross Section ◽  
Electric Fields ◽  
Cross Sections ◽  
Collision Cross Section ◽  
Vibrational Excitation ◽  
Time Spectrum ◽  
Electron Collision ◽  
Electron Drift ◽  
Radio Frequency Electric Fields

Some recent studies of electron swarms in gases under the action of an electric field are introduced. The studies include a new type of continuity equation for electrons having a form in which the partial derivative of the electron density with respect to position and to time are interchanged, a method to deduce the time-of-flight and arrival-time-spectrum swarm parameters based on a Fourier-transformed Boltzmann equation, an examination of the correspondence between experimental and theoretical electron drift velocities, and an automatic technique to deduce the electron-gas molecule collision cross section from electron drift velocity data. We also briefly introduce a method for the deduction of electron collision cross sections with gas molecules having vibrational excitation cross sections greater than the elastic momentum transfer cross section by using a gas mixture technique, an integral type of method for solution of the Boltzmann equation with salient numerical stability, a quantitative analysis of the effect of Penning ionisation, and the behaviour of electron swarms under radio frequency electric fields.

Comparisons of Quantemol and Morgan LXCat cross section sets for electron-neutral scattering and rate-coefficients: Helium and water

2019 ◽  
Vol 17 (2) ◽  
pp. 145-159
Author(s):  
Zeljko Mladenovic ◽  
Sasa Gocic ◽  
Zoran Petrovic
Keyword(s):  
Distribution Function ◽  
Boltzmann Equation ◽  
Cross Section ◽  
Electron Scattering ◽  
Ground State ◽  
Electron Energy Distribution Function ◽  
Transport Coefficients ◽  
Rate Coefficients ◽  
State Water ◽  
Low Temperature Plasmas

The present work compares cross section sets for electron scattering from ground state helium and ground state water molecule, which are available at LXCat Morgan database and the new Quantemol-DB. These cross section sets are used as an input for numerical solving of Boltzmann equation by using electron Boltzmann solver BOLSIG+, in order to obtain transport coefficients, electron energy distribution function and rate coefficients for electron impact scattering processes. The calculated quantities are compared to examine the quality and completeness of the cross section sets provided by Quantemol database for modeling low-temperature plasmas and interpretation of experimental results.

scholarly journals INVESTIGATION OF ELECTRONS DIFFUSION COEFFICIENT DEPENDENCE ON TEMPERATURE IN PLASMA GAS CO2, N2, HE AND MIXTURES

2020 ◽  
pp. 31-41
Author(s):  
Nisaan Saud ORAIBI
Keyword(s):  
Experimental Data ◽  
Distribution Function ◽  
Diffusion Coefficient ◽  
Boltzmann Equation ◽  
Energy Distribution ◽  
Cross Section ◽  
Diffusion Coefficients ◽  
Equation Solution ◽  
Different Temperatures ◽  
Momentum Transfer Cross Section

The evolution of the μNth value at different temperatures was achieved through the drift velocity of electron. The results were show when the temperature was increased, the number of the electrons will be decreased because using the momentum transfer cross section for CO2 molecules through collisions. The calculation of the diffusion coefficient was used to deduce the μNth values of CO2 electrons at temperature between 288 to 573 k by utilization numerically the Boltzmann equation solution. The results were appearing the agreement with the theoretical and experimental data. Keywords: Diffusion Coefficients, Boltzmann Equation, Swarms Parameters, Energy Distribution Function.

scholarly journals A Swarm Experiment in He–H2 Mixtures to Examine Vibrational Excitation of H2 by Electron Impact

1987 ◽  
Vol 40 (3) ◽  
pp. 347 ◽  
Author(s):  
ZLj Petrovic ◽  
RW Crompton
Keyword(s):  
Momentum Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Vibrational Excitation ◽  
Transport Coefficients ◽  
Pure Hydrogen ◽  
Buffer Gas ◽  
Pure Helium ◽  
Momentum Transfer Cross Section ◽  
Made In

Measurements of electron drift velocities have been made in pure helium and in a helium-hydrogen mixture in order to check the available inelastic cross sections for hydrogen. Although drift velocities in mixtures with helium as the buffer gas are less,sensitive to inelastic scattering by hydrogen than those with argon, the accuracy with which the momentum transfer cross section for helium is known enables the check to be made with virtually no error arising from uncertainty in the momentum transfer cross section for the buffer gas, in contrast to the situation when argon is used. A difference techrtique has been used to minimise the effect of systematic errors in the measurements. The results support the rotational and vibrational cross sections derived from the transport coefficients measured in pure hydrogen.

scholarly journals Momentum Transfer Cross Section for e??Kr Scattering

1993 ◽  
Vol 46 (2) ◽  
pp. 249 ◽  
Author(s):  
MJ Brennan ◽  
KF Ness
Keyword(s):  
Energy Range ◽  
Momentum Transfer ◽  
Cross Section ◽  
Drift Velocity ◽  
Cross Sections ◽  
Theoretical Calculations ◽  
Transport Coefficients ◽  
Velocity Data ◽  
Experimental Errors ◽  
Momentum Transfer Cross Section

The momentum transfer cross section for electrons in krypton has been derived over the energy range Q-4 eV from an analysis of drift velocity and DT/I-' data for hydrogen-krypton mixtures. At energies in the vicinity of the Ramsauer-Townsend minimum, the present work differs significantly from derivations based on analyses of drift velocity data alone. The overall uncertainty in the derived cross section reflects the experimental errors in the transport coefficients, the uncertainty in the cross sections used to represent the hydrogen component in the mixtures, and the uncertainty associated with the X2 minimisation. The present cross section is compared with recent theoretical calculations and other experimental derivations.

Cross sections and transport coefficients for H3 + ions in water vapour

2017 ◽  
Vol 71 (11) ◽  
Author(s):  
Vladimir Stojanović ◽  
Zoran Raspopović ◽  
Jasmina Jovanović ◽  
Željka Nikitović ◽  
Dragana Marić ◽  
...  
Keyword(s):  
Water Vapour ◽  
Cross Sections ◽  
Transport Coefficients

Third-order transport coefficients for electrons in N2 and CF4: effects of non-conservative collisions, concurrence with diffusion coefficients and contribution to the spatial profile of the swarm

2021 ◽  
Author(s):  
Ilija Simonovic ◽  
Danko Bošnjaković ◽  
Zoran Lj Petrovic ◽  
Ron D White ◽  
Sasa Dujko
Keyword(s):  
Boltzmann Equation ◽  
Cross Sections ◽  
Diffusion Tensor ◽  
Transport Coefficients ◽  
Electron Attachment ◽  
Third Order ◽  
Spatial Profile ◽  
Monte Carlo Simulation Technique ◽  
The Third ◽  
The Boltzmann Equation

Abstract Using a multi-term solution of the Boltzmann equation and Monte Carlo simulation technique we study behaviour of the third-order transport coefficients for electrons in model gases, including the ionisation model of Lucas and Saelee and modified Ness-Robson model of electron attachment, and in real gases, including N2 and CF4. We observe negative values in the E/n 0-profiles of the longitudinal and transverse third-order transport coefficients for electrons in CF4 (where E is the electric field and n 0 is the gas number density). While negative values of the longitudinal third-order transport coefficients are caused by the presence of rapidly increasing cross sections for vibrational excitations of CF4, the transverse third-order transport coefficient becomes negative over the E/n 0-values after the occurrence of negative differential conductivity. It is found that the accuracy of the two-term approximation for solving the Boltzmann equation is sufficient to investigate the behaviour of the third-order transport coefficients in N2, while for electrons in CF4 it produces large errors and is not even qualitatively correct . The influence of implicit and explicit effects of electron attachment and ionisation on the third-order transport tensor is investigated. In particular, we discuss the effects of attachment heating and attachment cooling on the third-order transport coefficients for electrons in the modified Ness-Robson model, while the effects of ionisation are studied for electrons in the ionisation model of Lucas and Saelee, N2 and CF4. The concurrence between the third-order transport coefficients and the components of the diffusion tensor, and the contribution of the longitudinal component of the third-order transport tensor to the spatial profile of the swarm are also investigated. For electrons in CF4 and CH4, we found that the contribution of the component of the third-order transport tensor to the spatial profile of the swarm between approximately 50 Td and 700 Td, is almost identical to the corresponding contribution for electrons in N2. This suggests that the recent measurements of third-order transport coefficients for electrons in N2 may be extended and generalized to other gases, such as CF4 and CH4.

Electron Irradiation Effects in Polyoxymethylene Crystals Grown Inside Trioxane Crystals

1971 ◽  
Vol 29 ◽  
pp. 78-79
Author(s):  
J. P. Colson ◽  
D. H. Reneker
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Detailed Examination ◽  
The Other ◽  
Electron Micrograph ◽  
Irradiation Effects ◽  
Threefold Axis ◽  
Typical Sample ◽  
Polymer Crystals ◽  
Chain Axis

Polyoxymethylene (POM) crystals grow inside trioxane crystals which have been irradiated and heated to a temperature slightly below their melting point. Figure 1 shows a low magnification electron micrograph of a group of such POM crystals. Detailed examination at higher magnification showed that three distinct types of POM crystals grew in a typical sample. The three types of POM crystals were distinguished by the direction that the polymer chain axis in each crystal made with respect to the threefold axis of the trioxane crystal. These polyoxymethylene crystals were described previously.At low magnifications the three types of polymer crystals appeared as slender rods. One type had a hexagonal cross section and the other two types had rectangular cross sections, that is, they were ribbonlike.

A quantitative approach to inner shell losses

1978 ◽  
Vol 36 (1) ◽  
pp. 526-527 ◽  
Author(s):  
R.D. Leapman ◽  
P. Rez ◽  
D.F. Mayers
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Background Intensity ◽  
Core Excitation ◽  
Quantitative Basis ◽  
Cross Section Differential ◽  
Bound Electrons

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

Oxygen K near edge structures studied with multiple scattering calculations

1988 ◽  
Vol 46 ◽  
pp. 504-505
Author(s):  
Xudong Weng ◽  
Peter Rez
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Partial Cross Section ◽  
Energy Window ◽  
Edge Structure ◽  
Fine Structures ◽  
Hydrogenic Model ◽  
Electron Energy Loss ◽  
Quantitative Chemical

In electron energy loss spectroscopy, quantitative chemical microanalysis is performed by comparison of the intensity under a specific inner shell edge with the corresponding partial cross section. There are two commonly used models for calculations of atomic partial cross sections, the hydrogenic model and the Hartree-Slater model. Partial cross sections could also be measured from standards of known compositions. These partial cross sections are complicated by variations in the edge shapes, such as the near edge structure (ELNES) and extended fine structures (ELEXFS). The role of these solid state effects in the partial cross sections, and the transferability of the partial cross sections from material to material, has yet to be fully explored. In this work, we consider the oxygen K edge in several oxides as oxygen is present in many materials. Since the energy window of interest is in the range of 20-100 eV, we limit ourselves to the near edge structures.

Sign in / Sign up

Export Citation Format

Share Document