MAGNETOPLASMA OSCILLATIONS OF A TWO-DIMENSIONAL, TWO-COMPONENT PLASMA

1996 ◽  
Vol 10 (16) ◽  
pp. 737-744
Author(s):  
NGUYEN QUOC KHANH
Keyword(s):  
Random Phase Approximation ◽  
Random Phase ◽  
Three Dimensional ◽  
Collective Modes ◽  
Two Dimensional ◽  
Long Wavelength ◽  
Effective Masses ◽  
Two Component ◽  
Component Plasma ◽  
The Individual

We investigate the magnetoplasma excitations in a system comprised of two parallel two-dimensional conducting layers separated by a distance 2d>0. The individual layers are assumed to have, in general, different effective masses, particle densities and charges. The dispersion equations are derived quantum mechanically within the random phase approximation and the spectrum of the long wavelength collective modes is calculated. We also investigate the mutual phase of two-dimensional magnetoplasma oscillations and show that this mutual phase is similar to that in the three-dimensional case and does not depend on the interlayer distance.

The Structure Factor of Expanded Liquid Alkali Metals at the Long-Wavelength Limit

1986 ◽  
Vol 41 (6) ◽  
pp. 823-825 ◽  
Author(s):  
K. N. Khanna ◽  
G. Shanker
Keyword(s):  
High Temperatures ◽  
Structure Factor ◽  
Random Phase Approximation ◽  
Alkali Metals ◽  
Random Phase ◽  
Phase Approximation ◽  
Long Wavelength ◽  
Wavelength Limit ◽  
Component Plasma ◽  
Liquid Alkali Metals

S (0 ) values of expanded alkali metals are calculated in random phase approximation. The results reproduce positive values of S (0) at sufficiently high temperatures showing the validity of RPA in one-component plasma systems.

Surface excitations in the random phase approximation

1970 ◽  
Vol 48 (21) ◽  
pp. 2592-2605 ◽  
Author(s):  
John Harris ◽  
Allan Griffin
Keyword(s):  
Random Phase Approximation ◽  
Short Range ◽  
Function Method ◽  
Wigner Distribution ◽  
Random Phase ◽  
Density Fluctuations ◽  
Wigner Distribution Function ◽  
Surface Modes ◽  
Inhomogeneous Systems ◽  
Two Component

Density fluctuations in inhomogeneous systems are treated in the RPA using the Kadanoff–Baym Green's function method. In our analysis, the Wigner distribution function plays an important role. Well-known results for surface plasmons in one- and two-component plasmas are very easy to derive. A brief discussion is given of surface modes in systems for which the interaction is of short range.

Stability of flow in a channel with longitudinal grooves

2014 ◽  
Vol 757 ◽  
pp. 613-648 ◽  
Author(s):  
H. V. Moradi ◽  
J. M. Floryan
Keyword(s):  
Reynolds Number ◽  
Small Amplitude ◽  
Arbitrary Shape ◽  
Critical Reynolds Number ◽  
Critical Role ◽  
Three Dimensional ◽  
Travelling Wave ◽  
Two Dimensional ◽  
Wave Instability ◽  
Long Wavelength

AbstractThe travelling wave instability in a channel with small-amplitude longitudinal grooves of arbitrary shape has been studied. The disturbance velocity field is always three-dimensional with disturbances which connect to the two-dimensional waves in the limit of zero groove amplitude playing the critical role. The presence of grooves destabilizes the flow if the groove wavenumber $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}\beta $ is larger than $\beta _{tran}\approx 4.22$, but stabilizes the flow for smaller $\beta $. It has been found that $\beta _{tran}$ does not depend on the groove amplitude. The dependence of the critical Reynolds number on the groove amplitude and wavenumber has been determined. Special attention has been paid to the drag-reducing long-wavelength grooves, including the optimal grooves. It has been demonstrated that such grooves slightly increase the critical Reynolds number, i.e. such grooves do not cause an early breakdown into turbulence.

Bhatia-Young Model Calculations of the Thermodynamic Properties of TKEBS-Based Binary Liquid Mixtures

1989 ◽  
Vol 44 (9) ◽  
pp. 793-800 ◽  
Author(s):  
L. J. Gallego ◽  
J. A. Somoza ◽  
M. Silbert
Keyword(s):  
Random Phase Approximation ◽  
Random Phase ◽  
Pair Potential ◽  
Liquid Mixtures ◽  
Binary Liquid Mixtures ◽  
Temperature Derivative ◽  
Phase Approximation ◽  
Model Calculations ◽  
Long Wavelength ◽  
Binary Liquid

Abstract The simplified random phase approximation Bhatia-Young model has been used to evaluate the properties of mixing and the concentration fluctuations of the binary liquid mixtures of TKEBS with cyclohcxane. carbon tetrachloride and benzene. At this level of description the details of the potentials are not important; only the values of the long-wavelength limit of the average effective ordering pair potential and its temperature derivative are required. In the three mixtures the constituent molecules are assumed to be globular in shape.

scholarly journals TDDFT WITH SKYRME FORCES: EFFECT OF TIME-ODD DENSITIES ON ELECTRIC GIANT RESONANCES

2008 ◽  
Vol 17 (01) ◽  
pp. 89-99 ◽  
Author(s):  
V. O. NESTERENKO ◽  
W. KLEINIG ◽  
J. KVASIL ◽  
P. VESELY ◽  
P.-G. REINHARD
Keyword(s):  
Ground State ◽  
Random Phase Approximation ◽  
Random Phase ◽  
Galilean Invariance ◽  
Giant Resonances ◽  
Nd Isotopes ◽  
Effective Masses ◽  
Self Consistent ◽  
A Chain

Time-odd densities and their effect on electric giant resonances are investigated within the self-consistent separable random-phase-approximation (SRPA) for a variety of Skyrme forces (SkT6, SkO, SkM*, SIII, SGII, SLy4, SLy6, SkI3). Time-odd densities are essential for maintaining the Galilean invariance of the Skyrme functional. Their contribution is determined by the values and signs of the isovector and isoscalar effective-mass parameters of the force. In even-even nuclei these densities are not active in the ground state but can affect the dynamics. As a particular case, we explore the role of the current density in the description of isovector E1 and isoscalar E2 giant resonances in a chain of spherical and deformed Nd isotopes with A=134-158. The relation of the current to the effective masses and relevant parameters of the Skyrme functional is analyzed. It is shown that the current contributes substantially to E1 and E2 and the contribution is the same for all the isotopes along the chain, i.e. for both standard and exotic nuclei.

Three-Dimensional Scour Below Pipelines

1988 ◽  
Vol 110 (4) ◽  
pp. 373-379 ◽  
Author(s):  
J. Fredso̸e ◽  
E. A. Hansen ◽  
Y. Mao ◽  
B. M. Sumer
Keyword(s):  
Three Dimensional ◽  
Essential Element ◽  
Laboratory Model ◽  
Span Length ◽  
Two Dimensional ◽  
Practical Application ◽  
Field Situation ◽  
Scour Holes ◽  
The Individual ◽  
A Current

This paper deals with the scour below pipelines exposed to a current. In a typical field situation, the scour pattern along a pipeline is not uniform; the scour holes are interrupted with the reaches where the pipeline is partially or totally buried. This paper focuses on the longitudinal extent of the individual scour holes. A simplified picture of the process is given to describe the longitudinal dimension of a scour hole. The sagging of the pipeline is an essential element of the process. The effect of sagging on the final scour depth is investigated, using a two-dimensional laboratory model. A simple equation to calculate the length of individual scour holes (the span length) is developed. The practical application of the equation is demonstrated by an example.

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