scholarly journals Calculation of Electron Swarm Parameters in Tetrafluoromethane

2020 ◽  
Vol 8 (2) ◽  
pp. 22-28
Author(s):  
Idris H. Salih ◽  
Mohammad M. Othman ◽  
Sherzad A. Taha
Keyword(s):  
Boltzmann Equation ◽  
Field Strength ◽  
Electric Field ◽  
Cross Sections ◽  
Electron Attachment ◽  
High Energy ◽  
Longitudinal Diffusion ◽  
Characteristic Energy ◽  
The Boltzmann Equation ◽  
High Energy Tail

The electron swarm parameters and electron energy distribution function (EEDF) are necessary, especially onunderstanding quantitatively plasma phenomena and ionized gases. The EEDF and electron swarm parameters including the reduce effective ionization coefficient (α-η)/N (α and η are the ionization and attachment coefficient, respectively), electron drift velocity, electron mean energy, characteristic energy, density  normalized longitudinal diffusion coefficient, and density normalized electron mobility in tetrafluoromethane (CF4) which was analyzed and calculated using the two-term approximation of the Boltzmann equation method at room temperature, over a range of the reduced electric field strength (E/N) between 0.1 and 1000 Td(1Td=10-17 V.cm2), where E is the electric field and N is the gas density of the gas. The calculations required cross-sections of the electron beam, thus published momentum transfer, vibration, electronic excitation, ionization, and attachment cross-sections for CF4 were used, the results of the Boltzmann equation in a good agreement with experimental and theoretical values over the entire range of E/N. In all cases, negative differential conductivity regions were found. It is found that the calculated EEDF closes to Maxwellian distribution and decreases sharply at low E/N. The low energy part of EEDF flats and the high-energy tail of EEDF increases with increase E/N. The EEDF found to be non-Maxwellian when the E/N> 10Td, havingenergy variations which reflect electron/molecule energy exchange processes. In addition, limiting field strength (E/N)limit has been calculated from the plots of (α-η)/N, for which the ionization exactlybalances the electron attachment, which is valid for the analysis of insulation characteristics and application to power equipment.

Production of Energetic Atoms by Multiple Collisions

1968 ◽  
Vol 9 (2-3) ◽  
Author(s):  
G. P. Wotzak ◽  
M. D. Kostin
Keyword(s):  
Boltzmann Equation ◽  
Kinetic Energy ◽  
Energy Dependence ◽  
Cross Sections ◽  
Atomic Beam ◽  
High Energy ◽  
Asymptotic Region ◽  
The Boltzmann Equation ◽  
Multiple Collisions ◽  
Collision Density

SummaryThe production of energetic atoms in the epithermal energy region by a high-energy atomic beam is considered by using the Boltzmann equation. Solutions of the Boltzmann equation show that numerous epithermal atoms may be generated as a result of scattering collisions in which an energetic atom transfers kinetic energy to a struck atom. For a system in which all the reactive and non-reactive cross sections have the same energy dependence and in which the thermal motion of the struck atoms can be neglected, numerical results obtained from a stochastic computer program confirm the analytical results for the asymptotic region and give detailed information on the energy dependence of the collision density for the non-asymptotic region near the source. Numerical calculations of reaction yields for a gaseous system containing two atomic species are also presented.

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.

scholarly journals Electric Currents Connected With the Proton Flares of 7 July and 2 September, 1966

1971 ◽  
Vol 43 ◽  
pp. 417-421
Author(s):  
A. B. Severny
Keyword(s):  
Active Region ◽  
Field Strength ◽  
Magnetic Flux ◽  
Electric Field ◽  
Electric Field Strength ◽  
Electric Conductivity ◽  
Electric Current ◽  
Current Density ◽  
High Energy ◽  
Electric Currents

It is observed that the change of the net magnetic flux associated with flares can exceed 1017 Mx/s, which corresponds according to Maxwell's equation to the e.m.f. ∼ 109 V which is specific for the high energy protons generated in flares. It is shown that this value of e.m.f. can hardly be compensated by e.m.f. of inductance which should appear due to the actually measured motions in a flare generating active region. The values of electric field strength thus found, together with measured values of electric current density (from rotH), leads to an electric conductivity which is 103 times smaller than usually adopted.

EQUAL VELOCITY RULE IN HEAVY HADRON PRODUCTION AT HIGH ENERGY

1989 ◽  
Vol 04 (02) ◽  
pp. 369-387 ◽  
Author(s):  
T. KITAZOE ◽  
H. INAZAWA ◽  
T. MORII
Keyword(s):  
Cross Sections ◽  
Particle Production ◽  
Production Cross ◽  
Heavy Particle ◽  
Bound State ◽  
High Energy ◽  
Wave Functions ◽  
Characteristic Energy ◽  
Heavy Particles ◽  
Heavy Hadron

A production mechanism of heavy particles in e+e− annihilations is studied on a field theoretical basis using the bound state wave functions. The requirement that wave functions of hadrons overlap maximally with each other leads to the conclusion that (1) the model predicts a 2-jet structure in a one-loop diagram and (2) heavy hadrons in a jet have an equal velocity. Heavy particle production cross sections and their characteristic energy distributions are calculated for some typical reactions.

scholarly journals Quantemol Electron Collisions (QEC): An Enhanced Expert System for Performing Electron Molecule Collision Calculations Using the R-Matrix Method

Atoms ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 97 ◽  
Author(s):  
Bridgette Cooper ◽  
Maria Tudorovskaya ◽  
Sebastian Mohr ◽  
Aran O’Hare ◽  
Martin Hanicinec ◽  
...  
Keyword(s):  
Expert System ◽  
Cross Sections ◽  
Electron Attachment ◽  
Dissociative Recombination ◽  
Biological Tissues ◽  
Reaction Rates ◽  
High Energy ◽  
Electron Collision ◽  
Low Energy Electrons ◽  
Ionization Cross Sections

Collisions of low energy electrons with molecules are important for understanding many aspects of the environment and technologies. Understanding the processes that occur in these types of collisions can give insights into plasma etching processes, edge effects in fusion plasmas, radiation damage to biological tissues and more. A radical update of the previous expert system for computing observables relevant to these processes, Quantemol-N, is presented. The new Quantemol Electron Collision (QEC) expert system simplifyies the user experience, improving reliability and implements new features. The QEC graphical user interface (GUI) interfaces the Molpro quantum chemistry package for molecular target setups, and the sophisticated UKRmol+ codes to generate accurate and reliable cross-sections. These include elastic cross-sections, super elastic cross-sections between excited states, electron impact dissociation, scattering reaction rates, dissociative electron attachment, differential cross-sections, momentum transfer cross-sections, ionization cross sections, and high energy electron scattering cross-sections. With this new interface we will be implementing dissociative recombination estimations, vibrational excitations for neutrals and ions, and effective core potentials in the near future.

scholarly journals The determination of low energy electron-molecule cross sections via swarm analysis

2008 ◽  
Vol 6 (1) ◽  
pp. 57-69 ◽  
Author(s):  
S. Dujko ◽  
R.D. White ◽  
Z.Lj. Petrovic
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Boltzmann Equation ◽  
Electron Transport ◽  
Cross Sections ◽  
Low Energy ◽  
Energy Electron ◽  
The Boltzmann Equation ◽  
Low Energy Electron

In this paper we discuss the swarm physics based techniques including the Boltzmann equation analysis and Monte Carlo simulation technique for determination of low energy electron-molecule cross sections. A multi term theory for solving the Boltzmann equation and Monte Carlo simulation code have been developed and used to investigate some critical aspects of electron transport in neutral gases under the varying configurations of electric and magnetic fields when non-conservative collisions are operative. These aspects include the validity of the two term approximation and the Legendre polynomial expansion procedure for solving the Boltzmann equation, treatment of non-conservative collisions, the effects of a magnetic field on the electron transport and nature and difference between transport data obtained under various experimental arrangements. It was found that these issues must be carefully considered before unfolding the cross sections from swarms transport data.

DUAL SPHERICAL ELECTRIC FIELD VOLTAGE SENSOR

2021 ◽  
pp. 85-91
Author(s):  
С.В. Бирюков ◽  
А.В. Тюкин ◽  
Л.В. Тюкина
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Electric Fields ◽  
Electrical Energy ◽  
High Energy ◽  
Measurement Range ◽  
Field Source ◽  
Dual Sensor ◽  
Spatial Measurement

Мы живем в мире высоких энергетических технологий, способных передавать электрическую энергию на большие расстояния. Эту энергию невозможно сосредоточить только внутри передающих энергетических систем. Она выплескивается наружу в виде электрических полей. Эти электрические поля неблагоприятно воздействуют на окружающую среду, технические и биологические объекты. В связи с этим необходимо контролировать уровни электрических полей, важной характеристикой которых является напряженность электрического поля. Для восприятия электрического поля необходимы датчики напряженности электрического поля. Существующие датчики неудобны в эксплуатации и имеют высокую погрешность восприятия напряженности электрического поля, достигающую ± 20%. Bыдвигается идея создания универсального датчика нового вида, относящeгося к виду сдвоенных датчиков. Его универсальность заключается в том, что он воплощает в себе все виды известных датчиков - одинарные, сдвоенные и теперь еще двойные. Погрешность восприятия напряженности неоднородного электрического поля сдвоенных датчиков не превышает +5 % во всем пространственном диапазоне измерения 0£ a £1. При этом расстояние d до источника поля ограничено только радиусом сферического основания датчика, т.е. d » R , в то время как для датчиков, входящих в состав сдвоенного датчика, в том же пространственном диапазоне измерение погрешности составляет ± 35 %. Используя сдвоенный датчик, можно добиться значительного повышения точности измерения напряженности неоднородных электрических полей в широком пространственном диапазоне измерений по сравнению с известными датчиками We live in a world of high energy technologies capable of transmitting electrical energy over long distances. This energy cannot be concentrated only within the transmitting energy systems. It spills out in the form of electric fields. These electric fields adversely affect the environment, technical and biological objects. In this regard, it is necessary to control the levels of electric fields, an important characteristic of which is the strength of the electric field. Sensors of the electric field strength are required to sense the electric field. The existing sensors are inconvenient in operation and have a high error in the perception of the electric field strength, reaching ± 20%. In the work under consideration, the idea of creating a universal sensor of a new type, related to the type of dual sensors, is put forward. Its versatility lies in the fact that it embodies all types of known sensors - single, twin, and now dual. The error in the perception of the intensity of the inhomogeneous electric field of the dual sensors does not exceed + 5% in the entire spatial measurement range 0£ a £1. In this case, the distance d to the field source is limited only by the radius of the spherical base of the sensor, i.e. d » R . At the same time, for sensors that are part of a dual sensor in the same spatial measurement range, the error is ± 35%. Using a dual sensor, it is possible to achieve a significant increase in the accuracy of measuring the strength of inhomogeneous electric fields in a wide spatial measurement range in comparison with known sensors.

scholarly journals Cross Sections for Electron?Carbon Monoxide Collisions in the Range 1?4 eV

1983 ◽  
Vol 36 (4) ◽  
pp. 473 ◽  
Author(s):  
GN Haddad ◽  
HB Milloy
Keyword(s):  
Boltzmann Equation ◽  
Energy Range ◽  
Drift Velocity ◽  
Cross Sections ◽  
Velocity Distribution Function ◽  
Gas Mixtures ◽  
Transport Parameter ◽  
Velocity Data ◽  
The Boltzmann Equation ◽  
Term Approximation

The scattering of electrons from CO molecules has been studied over the energy range from 1 to 4 eV by analysing drift velocity data for pure CO and CO-inert gas mixtures at 294 K. The validity of using the so-called 'two term approximation' for the velocity distribution function in the solution of the Boltzmann equation to analyse drift velocity data for the pure gas (and thus also for the gas mixtures) has been established. The momentum transfer cross section for CO has been determined in the energy range 1-4 eV, and the measurements of the vibrational cross sections by Ehrhardt et al. (1968) have been renormalized. By using a solution of the Boltzmann equation which avoids the two term approximation, these cross sections have been shown to be consistent with previous measurement.s of the transport parameter D 1.1 fl in pure CO.

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