scholarly journals On the Amplitude Equation of Approximate Surface Waves on the Plasma-Vacuum Interface

2016 ◽  
pp. 181-201 ◽  
Author(s):  
Paolo Secchi
Keyword(s):  
Surface Waves ◽  
Amplitude Equation ◽  
Vacuum Interface

On the generation of waves by wind

1980 ◽  
Vol 298 (1441) ◽  
pp. 451-494 ◽  
Keyword(s):  
Surface Waves ◽  
Linear Stability ◽  
Small Amplitude ◽  
Nonlinear Effects ◽  
Amplitude Equation ◽  
Basic Flow ◽  
Parallel Plates ◽  
Cubic Nonlinearity ◽  
Linear Effects ◽  
Layer Flow

The fully developed laminar flow of air over water confined between two infinite parallel plates was used to study nonlinear effects in the generation of surface waves. A linear stability analysis of the basic flow was made and the conditions at which small amplitude surface waves first begin to grow were determined. Then, following Stewartson & Stuart (1971), the nonlinear stability of the flow was examined and the usual parabolic equation with cubic nonlinearity obtained for the amplitude of the disturbances. The calculation of the linear stability characteristics and the coefficients appearing in the amplitude equation was a lengthy computational task, with most interest centred on the coefficient of the nonlinear terms in the amplitude equation. In two profiles, used as crude models of a boundary layer flow of air over water, the calculations indicated that, over a range of parameters, the non-linear effects would reduce the growth rate of the surface waves and hence lead to equilibrium amplitude waves.

scholarly journals Collisionless Damping of Fast and Ion?Cyclotron Surface Waves

1993 ◽  
Vol 46 (2) ◽  
pp. 271 ◽  
Author(s):  
GW Rowe
Keyword(s):  
Surface Waves ◽  
Short Wavelength ◽  
Mode Conversion ◽  
Low Frequency ◽  
Wave Mode ◽  
Alfven Wave ◽  
Field Boundary ◽  
First Order ◽  
Vacuum Interface ◽  
Ion Cyclotron

A recently developed general kinetic theory of surface waves is used to calculate the collisionless damping of low frequency fast and ion-cyclotron surface waves on a magnetised plasma-vacuum interface. In particular, the possibility of Cherenkov (Landau and transit-time magnetic) absorption by electrons is accounted for, assuming a bi-Maxwellian distribution of electrons in velocity space. It is shown that in general the surface waves are damped via mode conversion to a short-wavelength mode, such as the kinetic Alfven wave, which is subsequently Landau absorbed within the plasma. For high temperatures this short-wavelength mode can also be radiated into the plasma without being completely absorbed. It is also shown that the related ion-sound surface wave mode and instability identified by Alexandrov et al. (1984) are unphysical, and are the result of neglecting the gas pressure in the first-order magnetic field boundary condition.

The effect of neutral-gas friction on Alfvén surface waves propagating along a plasma–vacuum interface

1998 ◽  
Vol 60 (4) ◽  
pp. 731-742 ◽  
Author(s):  
NAGENDRA KUMAR ◽  
KRISHNA M. SRIVASTAVA
Keyword(s):  
Dispersion Relation ◽  
Surface Waves ◽  
Mode Structure ◽  
Astrophysical Plasmas ◽  
Interstellar Clouds ◽  
The Real ◽  
Viscosity Parameter ◽  
Neutral Gas ◽  
Vacuum Interface ◽  
Coefficient Of Viscosity

The effect of neutral-gas friction on Alfvén surface waves propagating along an infinitely conducting viscous plasma–vacuum interface has been investigated. A dispersion relation is obtained for such waves. For different values of the neutral-gas friction parameter S=νc/ω (where νc is the collisional frequency between two components of the composite plasma), the variations of the real and imaginary parts kr and ki of the wavenumber k with the viscosity parameter vp= μlω/ρ01v2A1 (where μl and ρ01 are the coefficient of viscosity and the density of plasma media 1) are shown graphically. It is concluded that a three-mode structure of Alfvén surface waves results flowing to neutral-gas friction. It is suggested that our results are useful for both laboratory and astrophysical plasmas (e.g. photospheres, chromospheres and cool interstellar clouds).

Alfvén Surface Waves in a Partially Ionized Resistive Medium

2011 ◽  
Vol 110-116 ◽  
pp. 867-873
Author(s):  
Nagendra Kumar ◽  
Vinod Kumar ◽  
Himanshu Sikka
Keyword(s):  
Surface Waves ◽  
Wave Number ◽  
Space Plasmas ◽  
Mode Structure ◽  
Viscosity Parameter ◽  
Neutral Gas ◽  
Vacuum Interface ◽  
Partially Ionized ◽  
Friction Parameters ◽  
Resistive Medium

We study the joint effects of viscosity, resistivity and ion-neutral collisions on Alfvén surface waves propagating along a partially ionized plasma - vacuum interface. Applying boundary conditions at plasma-vacuum interface, we obtain the dispersion relation for Alfvén surface waves and solve it numerically. For different values of resistivity and neutral gas friction parameters, the variation of real and imaginary parts of wave number with viscosity parameter are shown graphically. It is found that two-mode structure of Alfvén surface waves results due to the combined effects of resistivity, viscosity and ion-neutral collisions. These results might be useful for studying the behavior of Alfvén surface waves in laboratory and space plasmas.

Surface waves on the inhomogeneous interface between radiative electron–ion plasma and vacuum

2021 ◽  
Vol 87 (4) ◽  
Author(s):  
N. Maryam ◽  
Ch. Rozina ◽  
B. Arooj ◽  
A. Asma ◽  
I. Kourakis
Keyword(s):  
Dispersion Relation ◽  
Surface Waves ◽  
Energy Balance Equation ◽  
Surface Instability ◽  
Temperature Inhomogeneity ◽  
Magnetic Field Effects ◽  
Surface Mass ◽  
Ion Plasma ◽  
Vacuum Interface ◽  
The Impact

The impact of temperature inhomogeneity, surface charge and surface mass densities on the stability analysis of charged surface waves at the interface between dense, incompressible, radiative, self-gravitating magnetized electron–ion plasma and vacuum is investigated. For such an incompressible plasma system, the temperature inhomogeneity is governed by an energy balance equation. Adopting the one-fluid magnetohydrodynamic (MHD) approximation, a general dispersion relation is obtained for capillary surface waves, which takes into account gravitational, radiative and magnetic field effects. The dispersion relation is analysed to obtain the conditions under which the plasma–vacuum interface may become unstable. In the absence of electromagnetic (EM) pressure, astrophysical objects undergo gravitational collapse through Jeans surface oscillations in contrast to the usual central contraction of massive objects due to enhanced gravity. EM radiation does not affect the dispersion relation much, but actually tends to stabilize the Jeans surface instability. In certain particular cases, pure gravitational radiation may propagate on the plasma vacuum interface. The growth rate of radiative dissipative instability is obtained in terms of the wavevector. Our theoretical model of the Jeans surface instability is applicable in astrophysical environments and also in laboratory plasmas.

Surface waves in a plasma flow

2000 ◽  
Vol 63 (5) ◽  
pp. 489-493 ◽  
Author(s):  
E. BENOVA ◽  
S. T. IVANOV ◽  
A. A. RUKHADZE
Keyword(s):  
Boundary Conditions ◽  
Surface Waves ◽  
Flow Velocity ◽  
Plasma Flow ◽  
Relativistic Velocity ◽  
Lorentz Transformations ◽  
Electron Motion ◽  
Dispersion Characteristics ◽  
Vacuum Interface ◽  
Bulk Waves

Dispersion characteristics of surface waves in a semibounded plasma flow with relativistic velocity u0 parallel to the plasma–vacuum interface are presented. The plasma is considered to be cold and collisionless, which allows us to take into account only the electron motion. It is shown that – in contrast to the bulk waves, which are invariant with respect to Lorentz transformations and whose spectrum is independent of the flow velocity – the surface waves are not invariant, which leads to a dependence of their spectrum on the flow velocity and, correspondingly, to non-reciprocity. The latter peculiarity is due to the fact that the boundary conditions are not invariant.

scholarly journals General Dispersion Relation for Surface Waves on a Plasma?Vacuum Interface: Application to Magnetised Plasmas

1992 ◽  
Vol 45 (1) ◽  
pp. 55 ◽  
Author(s):  
GW Rowe
Keyword(s):  
Dispersion Relation ◽  
General Theory ◽  
Surface Waves ◽  
Low Frequency ◽  
Surface Currents ◽  
Ion Plasma ◽  
Vacuum Interface ◽  
Slight Extension ◽  
Infinite Conductivity ◽  
General Dispersion

The general dispersion relation for electromagnetic surface waves on a plasma-vacuum interface, recently derived by Rowe (1991), is applied to the case of a cold magnetised plasma bounded by a vacuum. It is illustrated how the dispersion relation and the surface wave fields may be determined in practice, and some general results are given. It is remarked that a plasma of this type satisfies the consistency conditions which were derived for the general theory by Rowe. These general results are then used to reproduce the dispersion relation of Cramer and Donnelly (1983) for low frequency surface waves in an electron-ion plasma. This example illustrates the general principles of the theory. A major difference between the derivation in their paper and the calculation of this paper is that in the former the plasma was assumed to be infinitely conducting whereas here the plasma is strictly assumed to have finite conductivity.The transition to infinite conductivity, which involves a slight extension of the general theory to include surface currents, is thus also discussed.

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