Dispersion properties of electromagnetic waves in a degenerate electron–ion magnetoplasma

2012 ◽  
Vol 78 (6) ◽  
pp. 683-687 ◽  
Author(s):  
A. A. MAMUN ◽  
N. ROY ◽  
P.K. SHUKLA
Keyword(s):  
Electromagnetic Waves ◽  
Fluid Model ◽  
Normal Mode Analysis ◽  
Plasma Pressure ◽  
Mode Analysis ◽  
Degenerate Plasma ◽  
Spatial And Temporal Scales ◽  
Dispersion Properties ◽  
Electrons And Ions ◽  
Linear Propagation

AbstractA theoretical investigation has been made of the linear propagation of different electromagnetic modes in a dense electron–ion magnetoplasma containing degenerate electrons and ions. The fluid model and the normal mode analysis have been employed. It has been found that the dispersion properties of the electromagnetic waves propagating in such a degenerate plasma are different (in view of both spatial and temporal scales) from those propagating in the usual electron–ion plasma because of the effects of degenerate plasma pressure, enthalpy, etc. The importance of this work has been discussed also.

Gravitational instability of partially ionized molecular clouds

2007 ◽  
Vol 73 (6) ◽  
pp. 831-838 ◽  
Author(s):  
A.C. BORAH ◽  
A.K. SEN
Keyword(s):  
Molecular Clouds ◽  
Radial Direction ◽  
Gravitational Instability ◽  
Normal Mode Analysis ◽  
Equations Of Motion ◽  
Local Approximation ◽  
Mode Analysis ◽  
Interstellar Clouds ◽  
Electrons And Ions ◽  
Partially Ionized

AbstractStars are formed as a result of the gravitational (Jeans) collapse of dense clumps in interstellar clouds. These clouds are partially ionized by nearby ionizing sources. We investigate the gravitational instability in such molecular clouds considering the non-Boltzmannian distribution for electrons and ions, which is more realistic than the Boltzmannian distribution. Assuming the perturbation (fluctuation) response in a radial direction as a mathematical analogue of the x-direction in the plane geometry approximation in the form f ∼ exp(ikx–iωt), the equations of motion for different species of the multi-fluid plasma are linearized. Jeans' swindle is used as a local approximation for the equilibrium and the dispersion relation is derived by usual normal mode analysis. Then, an analytical solution to the dispersion equation with an explanation of the effects on star formation is given.

scholarly journals Rayleigh-Bénard convection in an elastico-viscous Walters’ (model B’) nanofluid layer

2015 ◽  
Vol 63 (1) ◽  
pp. 235-244 ◽  
Author(s):  
G.C. Rana ◽  
R. Chand
Keyword(s):  
Fluid Model ◽  
Normal Mode Analysis ◽  
Sufficient Conditions ◽  
Lewis Number ◽  
Horizontal Layer ◽  
Linear Stability Theory ◽  
Mode Analysis ◽  
Physical Parameters ◽  
Onset Of Convection ◽  
The Stability

Abstract In this study, the onset of convection in an elastico-viscous Walters’ (model B’) nanofluid horizontal layer heated from below is considered. The Walters’ (model B’) fluid model is employed to describe the rheological behavior of the nanofluid. By applying the linear stability theory and a normal mode analysis method, the dispersion relation has been derived. For the case of stationary convection, it is observed that the Walters’ (model B’) elastico-viscous nanofluid behaves like an ordinary Newtonian nanofluid. The effects of the various physical parameters of the system, namely, the concentration Rayleigh number, Prandtl number, capacity ratio, Lewis number and kinematics visco-elasticity coefficient on the stability of the system has been numerically investigated. In addition, sufficient conditions for the non-existence of oscillatory convection are also derived.

Finite-Larmor-radius effects on z–pinch stability

1989 ◽  
Vol 41 (3) ◽  
pp. 427-439 ◽  
Author(s):  
Jan Scheffel ◽  
Mostafa Faghihi
Keyword(s):  
Particle Density ◽  
Fluid Model ◽  
Normal Mode Analysis ◽  
Plasma Boundary ◽  
Alpha Particles ◽  
Constant Current ◽  
Mode Analysis ◽  
Larmor Radius ◽  
Poloidal Magnetic Field ◽  
Finite Larmor Radius

The effect of finite Larmor radius (FLR) on the stability of m = 1 small-axial-wavelength kinks in a z–pinch with purely poloidal magnetic field is investigated. We use the incompressible FLR MHD model; a collisionless fluid model that consistently includes the relevant FLR terms due to ion gyroviscosity, Hall effect and electron diamagnetism. With FLR terms absent, the Kadomtsev criterion of ideal MHD, 2r dp/dr + m2B2/μ0 ≥ 0 predicts instability for internal modes unless the current density is singular at the centre of the pinch. The same result is obtained in the present model, with FLR terms absent. When the FLR terms are included, a normal-mode analysis of the linearized equations yields the following results. Marginally unstable (ideal) modes are stabilized by gyroviscosity. The Hall term has a damping (but not absolutely stabilizing) effect – in agreement with earlier work. On specifying a constant current and particle density equilibrium, the effect of electron diamagnetism vanishes. For a z–pinch with parameters relevant to the EXTRAP experiment, the m = 1 modes are then fully stabilized over the crosssection for wavelengths λ/a ≤ 1, where a denotes the pinch radius. As a general z–pinch result a critical line-density limit Nmax = 5 × 1018 m–1 is found, above which gyroviscous stabilization near the plasma boundary becomes insufficient. This limit corresponds to about five Larmor radii along the pinch radius. The result holds for wavelengths close to, or smaller than, the pinch radius and for realistic equilibrium profiles. This limit is far below the required limit for a reactor with contained alpha particles, which is in excess of 1020 m–1.

Stimulated scattering of electromagnetic waves in a two-electron plasma

2002 ◽  
Vol 67 (5) ◽  
pp. 363-369 ◽  
Author(s):  
P. K. SHUKLA ◽  
M. A. HELLBERG
Keyword(s):  
Electromagnetic Waves ◽  
Modulational Instability ◽  
Normal Mode Analysis ◽  
Mode Analysis ◽  
Stimulated Scattering ◽  
Temperature Plasma ◽  
Coupled Equations ◽  
Laboratory Plasmas ◽  
General Dispersion ◽  
Electron Acoustic

The nonlinear interaction between large-amplitude electromagnetic waves and electron-acoustic (EA) waves in a two-electron-temperature plasma is considered, taking into account the combined effects of the radiation pressure and the thermal force involving the differential Joule heating of the electrons caused by the electromagnetic waves. By employing a fluid approach, we derive a system of coupled equations for the electromagnetic waves and the EA waves; the latter are nonlinearly driven by the radiation and thermal forces. We have carried out a normal mode analysis of our nonlinearly coupled equations, and have derived a general dispersion relation that is useful for studying different types of parametric instabilities. A new class of modulational instability in the collision-dominated regime is identified. The implications for space and laboratory plasmas are pointed out.

Application of the ESMACS Binding Free Energy Protocol to a Highly Varied Ligand Dataset: Lactate Dehydogenase A

2019 ◽  
Author(s):  
David Wright ◽  
Fouad Husseini ◽  
Shunzhou Wan ◽  
Christophe Meyer ◽  
Herman Van Vlijmen ◽  
...  
Keyword(s):  
Free Energy ◽  
Surface Area ◽  
Binding Free Energy ◽  
Normal Mode Analysis ◽  
Binding Mode ◽  
Accessible Surface Area ◽  
Solvent Accessible Surface Area ◽  
Mode Analysis ◽  
Energy Calculation ◽  
Accessible Surface

<div>Here, we evaluate the performance of our range of ensemble simulation based binding free energy calculation protocols, called ESMACS (enhanced sampling of molecular dynamics with approximation of continuum solvent) for use in fragment based drug design scenarios. ESMACS is designed to generate reproducible binding affinity predictions from the widely used molecular mechanics Poisson-Boltzmann surface area (MMPBSA) approach. We study ligands designed to target two binding pockets in the lactate dehydogenase A target protein, which vary in size, charge and binding mode. When comparing to experimental results, we obtain excellent statistical rankings across this highly diverse set of ligands. In addition, we investigate three approaches to account for entropic contributions not captured by standard MMPBSA calculations: (1) normal mode analysis, (2) weighted solvent accessible surface area (WSAS) and (3) variational entropy. </div>

RAMAN SPECTRA OF TITANIUM DI-, TRI-, AND TETRA-CHLORIDES

2001 ◽  
Vol 15 (28n30) ◽  
pp. 3865-3868 ◽  
Author(s):  
H. MIYAOKA ◽  
T. KUZE ◽  
H. SANO ◽  
H. MORI ◽  
G. MIZUTANI ◽  
...  
Keyword(s):  
Force Constant ◽  
Raman Spectra ◽  
Normal Mode ◽  
Raman Band ◽  
Normal Mode Analysis ◽  
Force Constants ◽  
Mode Analysis ◽  
Oxidation Number

We have obtained the Raman spectra of TiCl n (n= 2, 3, and 4). Assignments of the observed Raman bands were made by a normal mode analysis. The force constants were determined from the observed Raman band frequencies. We have found that the Ti-Cl stretching force constant increases as the oxidation number of the Ti species increases.

scholarly journals Normal mode analysis of spectral density of FMO trimers: Intra- and intermonomer energy transfer

2020 ◽  
Vol 153 (21) ◽  
pp. 215103
Author(s):  
Alexander Klinger ◽  
Dominik Lindorfer ◽  
Frank Müh ◽  
Thomas Renger
Keyword(s):  
Energy Transfer ◽  
Spectral Density ◽  
Normal Mode ◽  
Normal Mode Analysis ◽  
Mode Analysis

scholarly journals Normal-mode analysis for scalar fields in BTZ black-hole background

2009 ◽  
Vol 60 (2) ◽  
pp. 169-173 ◽  
Author(s):  
Sayan K. Chakrabarti ◽  
Pulak Ranjan Giri ◽  
Kumar S. Gupta
Keyword(s):  
Black Hole ◽  
Normal Mode ◽  
Normal Mode Analysis ◽  
Scalar Fields ◽  
Mode Analysis ◽  
Btz Black Hole ◽  
Black Hole Background

Electrostatic oscillations in cold inhomogeneous plasma I. Differential equation approach

1971 ◽  
Vol 5 (2) ◽  
pp. 239-263 ◽  
Author(s):  
Z. Sedláček
Keyword(s):  
Differential Equation ◽  
Green Function ◽  
Normal Mode Analysis ◽  
Inhomogeneous Plasma ◽  
Mode Analysis ◽  
Complex Frequency ◽  
Plasma Oscillations ◽  
The Laplace Transform ◽  
Collective Oscillations ◽  
The Green Function

Small amplitude electrostatic oscillations in a cold plasma with continuously varying density have been investigated. The problem is the same as that treated by Barston (1964) but instead of his normal-mode analysis we employ the Laplace transform approach to solve the corresponding initial-value problem. We construct the Green function of the differential equation of the problem to show that there are branch-point singularities on the real axis of the complex frequency-plane, which correspond to the singularities of the Barston eigenmodes and which, asymptotically, give rise to non-collective oscillations with position-dependent frequency and damping proportional to negative powers of time. In addition we find an infinity of new singularities (simple poles) of the analytic continuation of the Green function into the lower half of the complex frequency-plane whose position is independent of the spatial co-ordinate so that they represent collective, exponentially damped modes of plasma oscillations. Thus, although there may be no discrete spectrum, in a more general sense a dispersion relation does exist but must be interpreted in the same way as in the case of Landau damping of hot plasma oscillations.

scholarly journals Rapid Characterization of Allosteric Networks with Ensemble Normal Mode Analysis

2016 ◽  
Vol 120 (33) ◽  
pp. 8276-8288 ◽  
Author(s):  
Xin-Qiu Yao ◽  
Lars Skjærven ◽  
Barry J. Grant
Keyword(s):  
Normal Mode ◽  
Normal Mode Analysis ◽  
Mode Analysis ◽  
Rapid Characterization
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