Temporal evolution of reactive and resistive nonlinear instabilities

1987 ◽  
Vol 38 (3) ◽  
pp. 473-481 ◽  
Author(s):  
D. B. Melrose
Keyword(s):  
Electron Number Density ◽  
Temporal Evolution ◽  
Random Phase ◽  
Low Frequency ◽  
Rate Of Change ◽  
Number Density ◽  
Wave Instability ◽  
Langmuir Waves ◽  
Secular Evolution ◽  
Coherent Wave

A kinetic theory for nonlinear processes involving Langmuir waves, developed in an earlier paper, is extended through consideration of three aspects of the temporal evolution, (i) Following Falk & Tsytovich (1975). the dynamic equation for the rate of change of one amplitude at t is expressed as an integral over T of the product of two amplitudes at t – T and a kernel functionf(T); two generalizations of Falk & Tsytovich's form (f(T) ∝ T) that satisfy the requirement f(∞) = 0 are identified, (ii) It is shown that the low-frequency or beat disturbance may be described in terms of fluctuations in the electron number density, and that its time evolution involves an operator that is essentially the inverse of f(t). (iii) The transition from oscillatory evolution in the reactive or ‘coherent-wave’ version of the three-wave instability to the secular evolution of the resistive or ‘random-phase’ version is discussed qualitatively.

Jeans-Alfvén instability in quantum dusty magnetoplasmas

2017 ◽  
Vol 83 (1) ◽  
Author(s):  
M. Jamil ◽  
A. Rasheed ◽  
M. Amir ◽  
G. Abbas ◽  
Young-Dae Jung
Keyword(s):  
Significant Contribution ◽  
Electron Number Density ◽  
Fluid Model ◽  
Low Frequency ◽  
Momentum Balance ◽  
Number Density ◽  
Electron Number ◽  
Momentum Balance Equation ◽  
Quantum Plasmas ◽  
Jeans Instability

The Jeans instability is examined in quantum dusty magnetoplasmas due to low-frequency magnetosonic perturbations. The fluid model consisting of the momentum balance equation for quantum plasmas, Poisson’s equation for the gravitational potential and Maxwell’s equations for electromagnetic magnetosonic perturbations is solved. The numerical analysis elaborates the significant contribution of magnetic field, electron number density and variable dust mass to the Jeans instability.

Some Aspects in Recombining Transient Nitrogen Plasmas Some Aspects in Recombining Transient Nitrogen Plasmas Some Aspects in Recombining Transient Nitrogen Plasmas Some Aspects in Recombining Transient Nitrogen Plasmas Some Aspects in Recombining Transient Nitrogen Plasmas Some Aspects in Recombining Transient Nitrogen Plasmas Some Aspects in Recombining Transient Nitrogen Plasmas Some Aspects in Recombining Transient Nitrogen Plasmas

1978 ◽  
Vol 33 (8) ◽  
pp. 895-902 ◽  
Author(s):  
C. Gorse ◽  
M. A. Cacciatore ◽  
M. Capitelli
Keyword(s):  
Electron Number Density ◽  
Temporal Evolution ◽  
Coupled System ◽  
Nitrogen Plasma ◽  
Number Density ◽  
Population Densities ◽  
Order Of Magnitude ◽  
Nitrogen Plasmas ◽  
Stationary Conditions ◽  
The Times

The temporal evolution of the population densities of a monatomic Nitrogen plasma has been studied in the electron temperature range 0.5 eV ≦ kTe ≦ 1 eV and in the electron number density interval 1012 cm-3 ≦ ne ≦1014 cm-3 by solving a coupled system of m aster equations. The results show that the times necessary to achieve quasi-stationary conditions for the population densities can be as long as 10-5 sec. in the optically thick plasma, and two order of magnitude shorter in the optically thin case. The possibility of population inversions during the recombination of a completely ionized Nitrogen plasma (ne ≃ 1015 cm-3, kTe = 0.5 eV) is then shown.

scholarly journals Influence of water vapour on the height distribution of positive ions, effective recombination coefficient and ionisation balance in the quiet lower ionosphere

2014 ◽  
Vol 32 (3) ◽  
pp. 207-222 ◽  
Author(s):  
V. Barabash ◽  
A. Osepian ◽  
P. Dalin
Keyword(s):  
Water Vapour ◽  
Electron Density ◽  
Electron Number Density ◽  
Lower Ionosphere ◽  
Recombination Coefficient ◽  
Height Distribution ◽  
Number Density ◽  
Electron Number ◽  
Water Vapour Concentration ◽  
Vapour Concentration

Abstract. Mesospheric water vapour concentration effects on the ion composition and electron density in the lower ionosphere under quiet geophysical conditions were examined. Water vapour is an important compound in the mesosphere and the lower thermosphere that affects ion composition due to hydrogen radical production and consequently modifies the electron number density. Recent lower-ionosphere investigations have primarily concentrated on the geomagnetic disturbance periods. Meanwhile, studies on the electron density under quiet conditions are quite rare. The goal of this study is to contribute to a better understanding of the ionospheric parameter responses to water vapour variability in the quiet lower ionosphere. By applying a numerical D region ion chemistry model, we evaluated efficiencies for the channels forming hydrated cluster ions from the NO+ and O2+ primary ions (i.e. NO+.H2O and O2+.H2O, respectively), and the channel forming H+(H2O)n proton hydrates from water clusters at different altitudes using profiles with low and high water vapour concentrations. Profiles for positive ions, effective recombination coefficients and electrons were modelled for three particular cases using electron density measurements obtained during rocket campaigns. It was found that the water vapour concentration variations in the mesosphere affect the position of both the Cl2+ proton hydrate layer upper border, comprising the NO+(H2O)n and O2+(H2O)n hydrated cluster ions, and the Cl1+ hydrate cluster layer lower border, comprising the H+(H2O)n pure proton hydrates, as well as the numerical cluster densities. The water variations caused large changes in the effective recombination coefficient and electron density between altitudes of 75 and 87 km. However, the effective recombination coefficient, αeff, and electron number density did not respond even to large water vapour concentration variations occurring at other altitudes in the mesosphere. We determined the water vapour concentration upper limit at altitudes between 75 and 87 km, beyond which the water vapour concentration ceases to influence the numerical densities of Cl2+ and Cl1+, the effective recombination coefficient and the electron number density in the summer ionosphere. This water vapour concentration limit corresponds to values found in the H2O-1 profile that was observed in the summer mesosphere by the Upper Atmosphere Research Satellite (UARS). The electron density modelled using the H2O-1 profile agreed well with the electron density measured in the summer ionosphere when the measured profiles did not have sharp gradients. For sharp gradients in electron and positive ion number densities, a water profile that can reproduce the characteristic behaviour of the ionospheric parameters should have an inhomogeneous height distribution of water vapour.

Characteristics of a resonant iris microwave-induced nitrogen plasma

2016 ◽  
Vol 31 (5) ◽  
pp. 1097-1104 ◽  
Author(s):  
Daniel A. Goncalves ◽  
Tina McSweeney ◽  
George L. Donati
Keyword(s):  
Electron Number Density ◽  
Nitrogen Plasma ◽  
Number Density ◽  
Electron Number ◽  
Temperature Electron ◽  
Mip Oes

Temperature, electron number density and robustness profiles of a N2 plasma contribute for more sensitive and accurate MIP OES determinations.

scholarly journals Excitation and analytical characteristics of an ethanol loaded U-shaped arc

2003 ◽  
Vol 68 (2) ◽  
pp. 109-118 ◽  
Author(s):  
Marija Raskovic ◽  
Ivanka Holclajtner-Antunovic ◽  
Mirjana Tripkovic ◽  
Dragan Markovic
Keyword(s):  
Spectral Line ◽  
Electron Number Density ◽  
Ethanol Solution ◽  
Number Density ◽  
Electron Number ◽  
Plasma Parameters ◽  
Line Intensities ◽  
Ethanol Addition ◽  
Plasma Characteristics ◽  
Dc Arc

The effect of the ethanol load on the discharge and analytical parameters of an argon stabilized U-shaped DC arc has been recorded. Measurements of the radial distribution of the apparent temperatures and the electron number density of the DC plasma showed that ethanol addition causes a decrease in both plasma parameters. The changes in the plasma characteristics, as well as in transport and atomisation processes of the analyte cause a general change in the spectral line intensities, which depends on the physical characteristics of the analyte and the quantity of ethanol loaded into the plasma. Improved detection limits were obtained for V and Mn when a 10%(v/v) water?ethanol solution was nebulized into the plasma.

Calculated electron number density profiles for the aeroassist flight experiment

1992 ◽  
Vol 29 (5) ◽  
pp. 621-626 ◽  
Author(s):  
Robert B. Greendyke ◽  
Peter A. Gnoffo ◽  
R. Wes Lawrence
Keyword(s):  
Electron Number Density ◽  
Number Density ◽  
Electron Number ◽  
Density Profiles ◽  
Flight Experiment

scholarly journals Atomic physics for beam-target interactions

1984 ◽  
Vol 2 (4) ◽  
pp. 449-465 ◽  
Author(s):  
C. Deutsch
Keyword(s):  
Electron Number Density ◽  
Accurate Determination ◽  
Projectile Energy ◽  
Stark Broadening ◽  
Number Density ◽  
Compact Formulation ◽  
Electron Contribution ◽  
Hot Matter ◽  
Special Relevance

This survey is devoted to a few basic atomic problems associated with the stopping of nonrelativistic pointlike ions in dense and hot matter, and also to the Stark broadening diagnostics of the resulting beam-produced plasmas.First, we consider the free electron contribution, taken in the RPA approximation with an exact dynamic dielectric function, valid at any temperature. Therefore, we obtain stopping power and straggling for any projectile velocity. The temperature dependence is of special relevance for a projectile energy smaller than 5 MeV/a.m.u.Next, we revise the Barkas effect (Z3 corrections) through a novel and compact formulation, which is based on an analogy with electron impact broadening theory. It facilitates inclusion of the non hydrogenic and electronic structure of the target ions, in a more selective way. The results may increase the usual Z2-stopping by 15 to 30 per cent corrections.Then, we show how the Stark broadening diagnostics of the compressed D + T fuel, seeded with high Z species, arising from the surrounding envelopes, may provide accurate determination of the electron number density ne. In this connection, it should be appreciated that the relatively long compression times (≃ 20 nsec) suggested by the HIBALL numerical simulation allow for a nearly Local Thermodynamic Equilibrium (LTE) state in the target, with Te ≃ Ti. As a consequence, spectroscopic measurements are expected to be easier to implement in HIF targets, than in laser ones.A tentative proposal for the use of Stark broadening diagnostics of inflight excited and highly stripped ion projectiles is displayed in § 5.Experiments involving an HIB produced by a standard accelerator, and interacting with an independently produced coronal plasma are finally outlined.

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