Collision Frequency and Axial Inhomogeneity Effects on Average Plasma Conductivity by rf Probes

1969 ◽  
Vol 40 (13) ◽  
pp. 5394-5396 ◽  
Author(s):  
M. Ciampi ◽  
N. Talini
Keyword(s):  
Collision Frequency ◽  
Plasma Conductivity

Effective coffision frequency and electron temperature in a weakly ionized argon plasma

1980 ◽  
Vol 23 (2) ◽  
pp. 271-282
Author(s):  
C. P. Schneider
Keyword(s):  
Electron Temperature ◽  
High Frequency ◽  
Collision Frequency ◽  
Argon Plasma ◽  
Angular Frequency ◽  
Weak Electric Field ◽  
Hard Sphere Model ◽  
Plasma Conductivity ◽  
Gas Plasma ◽  
Weakly Ionized

Herein is described a calculation of the effective coffision frequency νeffof a low- density, shock-heated argon plasma under the influence of a weak electric field which oscillates harmonically with angular frequency ω. It is shown that, for the high frequency case ω >whereis the collision frequency in a Maxwellian gas plasma, one has νeff⋍ 2, provided that the imaginary part of the argon plasma conductivity is negligibly small in comparison to the real part. The influence of the theoretical model used to calculate νeffon the values of the electron temperatureTederived from measurements is compared with the results obtained in a data reduction for which the hard-sphere model for particle encounters was utilized.

scholarly journals Quantitative Ship Collision Frequency Estimation Models: A Review

2021 ◽  
Vol 9 (5) ◽  
pp. 533
Author(s):  
Mirko Čorić ◽  
Sadko Mandžuka ◽  
Anita Gudelj ◽  
Zvonimir Lušić
Keyword(s):  
Risk Assessment ◽  
Collision Frequency ◽  
Frequency Estimation ◽  
Cost Effective ◽  
Future Improvement ◽  
Ship Collision ◽  
Estimation Models

Ship collisions are one of the most common types of maritime accidents. Assessing the frequency and probability of ship collisions is of great importance as it provides a cost-effective and practical way to mitigate risk. In this paper, we present a review of quantitative ship collision frequency estimation models for waterway risk assessment, accompanied by a classification of the models and a description of their main modelling characteristics. Models addressing the macroscopic perspective in the estimation of ship collision frequency on waterways are reviewed in this paper with a total of 29 models. We extend the existing classification methodology and group the collected models accordingly. Special attention is given to the criteria used to detect potential ship collision candidates, as well as to causation probability and the correlation of models with real ship collision statistics. Limitations of the existing models and future improvement possibilities are discussed. The paper can be used as a guide to understanding current achievements in this field.

Studies on the ionization produced by metallic salts in flames I. The determination of the collision frequency of electrons in coal-gas/air flames

1950 ◽  
Vol 201 (1067) ◽  
pp. 480-488 ◽  
Keyword(s):  
Conversion Factor ◽  
Collision Frequency ◽  
Metal Salt ◽  
Alkali Metal Salt ◽  
Electron Content ◽  
Radio Waves ◽  
Coal Gas ◽  
Flame Ionization ◽  
Metallic Salts

As an introduction to the study of reactions contingent on ionization in flames, an experimental measurement has been made of the collision frequency of electrons with molecules in coal-gas/air flames, containing added alkali metal salt. This quantity is an important parameter in the expression relating the electron content of a flame with the attenuation of centimetric radio waves by it. This attenuation has been chosen as a convenient method of investigating flame ionization. The form of the results obtained agree well with the predictions of theory, a uniform difference of about 20 % between measured collision frequency and that calculated on a very simple gas kinetic hypothesis being obtained. A suitable conversion factor has been evolved for proceeding from attenuation of 3 cm. waves to electron concentration/cm. 3 .

Attenuation of longitudinal electro-acoustic waves in a plasma

1974 ◽  
Vol 11 (1) ◽  
pp. 37-49
Author(s):  
R. J. Papa ◽  
P. Lindstrom
Keyword(s):  
Dispersion Relation ◽  
Electric Field ◽  
Acoustic Waves ◽  
Collision Frequency ◽  
Wave Dispersion ◽  
Signal Frequency ◽  
Variable Theory ◽  
Longitudinal Waves ◽  
Confluent Hypergeometric Functions ◽  
Linearized Boltzmann Equation

There are several practical situations in partially ionized plasmas when both collisionless (Landau) damping and electron-neutral collisions contribute to the attenuation of longitudinal waves. The longitudinal-wave dispersion relation is derived from Maxwell's equations and the linearized Boltzmann equation, in which electron-neutral collisions are represented by a Bhatnagar–Gross–Krook model that conserves particles locally. (The dispersion relation predicts that, for a given signal frequency ώ), an infinite number of complex wavenumbers kn can exist. Using Fourier–Laplace transform techniques, an integral representation for the electric field of the longitudinal waves is readily derived. Then, using theorems from complex variable theory, a modal expansion of the electric field can be made in terms of an infinite sum of confluent hypergeometric functions, whose arguments are proportional to the complex wavenumbers kn. It is demonstrated numerically that the spatial integral of the square of the electric field amplitude decreases as the electron-neutral collision frequency increases. Also, the amount of energy contained in the first few (lowest) modes, and the coupling between the modes, is examined as a function of plasma frequency, signal frequency and collision frequency.

Effects of temperature and electron collision frequency on the elastic electron–ion collisions in a collisional plasma

2013 ◽  
Vol 79 (5) ◽  
pp. 553-558 ◽  
Author(s):  
YOUNG-DAE JUNG ◽  
WOO-PYO HONG
Keyword(s):  
Phase Shift ◽  
Temperature Effect ◽  
Cross Section ◽  
Collision Frequency ◽  
Electron Collision ◽  
Elastic Electron ◽  
Dynamic Temperature ◽  
Electron Collision Frequency ◽  
Dynamic Screening ◽  
Ion Collision

AbstractThe effects of dynamic temperature and electron–electron collisions on the elastic electron–ion collision are investigated in a collisional plasma. The second-order eikonal analysis and the velocity-dependent screening length are employed to derive the eikonal phase shift and eikonal cross section as functions of collision energy, electron collision frequency, Debye length, impact parameter, and thermal energy. It is interesting to find out that the electron–electron collision effect would be vanished; however, the dynamic temperature effect is included in the first-order approximation. We have found that the dynamic temperature effect strongly enhances the eikonal phase shift as well as the eikonal cross section for electron–ion collision since the dynamic screening increases the effective shielding distance. In addition, the detailed characteristic behavior of the dynamic screening function is also discussed.

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