WAVE PROPAGATION IN MAGNETOPLASMAS

1966 ◽  
Vol 44 (1) ◽  
pp. 255-264 ◽  
Author(s):  
S. R. Sharma
Keyword(s):  
Magnetic Field ◽  
Wave Propagation ◽  
Momentum Transfer ◽  
Transverse Wave ◽  
Energy Exchange ◽  
Dispersion Relations ◽  
Longitudinal Waves ◽  
Temperature Relaxation ◽  
The Magnetic Field

Wave propagation in a fully ionized unbounded magnetoplasma is considered taking into account the momentum transfer and energy exchange due to collisions. Dispersion relations are examined for wave propagation along and perpendicular to the magnetic field. It is found that there is no additional damping due to temperature relaxation for pure transverse wave propagation. For longitudinal waves dispersion relations are presented which include damping due to temperature relaxation and momentum transfer due to collisions.

WAVE PROPAGATION IN A PLASMA WITH ANISOTROPIC PRESSURE

1967 ◽  
Vol 45 (10) ◽  
pp. 3189-3198 ◽  
Author(s):  
S. R. Sharma
Keyword(s):  
Magnetic Field ◽  
Wave Propagation ◽  
Resonant Frequency ◽  
Transverse Wave ◽  
Anisotropy Parameter ◽  
Anisotropic Pressure ◽  
Electrostatic Forces ◽  
Pressure Anisotropy ◽  
Component Plasma ◽  
The Magnetic Field

Wave propagation in an unbounded, magnetoactive, one-component plasma is considered with the help of modified Burgers equations. The pressure is assumed to be anisotropic and the effect of collisions on the wave propagation is examined. New modes of propagation have been reported in which the magnetic field and pressure anisotropy play an important role, while the electrostatic forces are comparatively less important. For the collisionless case, under certain conditions, new resonances appear in the transverse wave propagation, the resonant frequency being dependent upon the anisotropy parameter β. Cases have been pointed out where spatial instabilities may occur for certain values of β and the collision frequencies. It is further shown that the collisions may also offset the velocity–space instabilities which occur in a plasma with anisotropic pressure.

The magnetoplasma dispersion function: some mathematical properties

1974 ◽  
Vol 12 (1) ◽  
pp. 51-59 ◽  
Author(s):  
J. P. M. Schmitt
Keyword(s):  
Magnetic Field ◽  
Wave Propagation ◽  
Computational Methods ◽  
Dispersion Relations ◽  
Dispersion Function ◽  
Mathematical Properties ◽  
Image Position ◽  
The Magnetic Field

The magnetoplasma dispersion function is defined asIt is found in all the dispersion relations for wave propagation perpendicular to the magnetic field in hot plasmas. We review the properties of fω(z), and present several new expansions, which may be of interest in the study of properties of waves in plasmas, or may suggest computational methods for calculating fω(z).

scholarly journals Inferring the chromospheric magnetic topology through waves

2007 ◽  
Vol 3 (S247) ◽  
pp. 78-81
Author(s):  
S. S. Hasan ◽  
O. Steiner ◽  
A. van Ballegooijen
Keyword(s):  
Magnetic Field ◽  
Wave Propagation ◽  
Energy Density ◽  
Acoustic Wave ◽  
Acoustic Waves ◽  
Phase Speed ◽  
Time Correlation ◽  
Propagation Time ◽  
Fast Mode ◽  
The Magnetic Field

AbstractThe aim of this work is to examine the hypothesis that the wave propagation time in the solar atmosphere can be used to infer the magnetic topography in the chromosphere as suggested by Finsterle et al. (2004). We do this by using an extension of our earlier 2-D MHD work on the interaction of acoustic waves with a flux sheet. It is well known that these waves undergo mode transformation due to the presence of a magnetic field which is particularly effective at the surface of equipartition between the magnetic and thermal energy density, the β = 1 surface. This transformation depends sensitively on the angle between the wave vector and the local field direction. At the β = 1 interface, the wave that enters the flux sheet, (essentially the fast mode) has a higher phase speed than the incident acoustic wave. A time correlation between wave motions in the non-magnetic and magnetic regions could therefore provide a powerful diagnostic for mapping the magnetic field in the chromospheric network.

A Proposed Experiment of Direct Detecting of the Vector Potential within Classical Electrodynamics

1997 ◽  
Vol 11 (12) ◽  
pp. 531-540
Author(s):  
V. Onoochin
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Field ◽  
Charged Particle ◽  
Vector Potential ◽  
Energy Exchange ◽  
Short Pulse ◽  
Classical Electrodynamics ◽  
Direct Influence ◽  
Ultra Short Pulse ◽  
The Magnetic Field

An experiment within the framework of classical electrodynamics is proposed, to demonstrate Boyer's suggestion of a change in the velocity of a charged particle as it passes close to a solenoid. The moving charge is replaced by an ultra-short pulse (USP), whose characteristics should depend on the current in the coil. This dependence results from the exchange of energy between the electromagnetic field of the pulse and the magnetic field within the solenoid. This energy exchange could only be explained, by assuming that the vector potential of the solenoid has a direct influence on the pulse.

Anomalous temperature relaxation and particle transport in a strongly non-unifrom, fully in ionized Plasma in a stromg mangnetic field

1995 ◽  
Vol 53 (1) ◽  
pp. 31-48 ◽  
Author(s):  
Alf H. Øien
Keyword(s):  
Magnetic Field ◽  
Particle Transport ◽  
Transport Theory ◽  
Debye Length ◽  
Larmor Radius ◽  
Collision Integrals ◽  
Ion Interactions ◽  
Electrons And Ions ◽  
Temperature Relaxation ◽  
The Magnetic Field

In classical kinetic and transport theory for a fully ionized plasma in a magnetic field, collision integrals from a uniform theory without fields are used. When the magnetic field is so strong that electrons may gyrate during electron—electron and electron—ion interactions, the form of the collision integrals will be modified. Another modification will stem from strong non-uniformities transverse to the magnetic field B. Using collision terms that explicitly incorporate these effects, we derive in particular the temperature relaxation between electrons and ions and the particle transport transverse to the magnetic field. In both cases collisions between gyrating electrons, which move along the magnetic field, and non-gyrating ions, which move in arbitrary directions at a distance transverse to B from the electrons larger than the electron Larmor radius but smaller than the Debye length, give rise to enhancement factors in the corresponding classical expressions of order In (mion/mel).

Magneto-thermo-elastic plane waves

1965 ◽  
Vol 61 (4) ◽  
pp. 939-944 ◽  
Author(s):  
C. M. Purushothama
Keyword(s):  
Magnetic Field ◽  
Wave Propagation ◽  
Shear Wave ◽  
Wave Velocity ◽  
Compression Wave ◽  
Thermal Field ◽  
Plane Waves ◽  
Elastic Plane ◽  
Magnetic Diffusivity ◽  
The Magnetic Field

AbstractThe combined effects of uniform thermal and magnetic fields on the propagation of plane waves in a homogeneous, initially unstressed, electrically conducting elastic medium have been investigated.When the magnetic field is parallel to the direction of wave propagation, the compression wave is purely thermo-elastic and the shear wave is purely magneto-elastic in nature. For a transverse magnetic field, the shear waves remain elastic whereas the compression wave assumes magneto-thermo-elastic character due to the coupling of all the three fields—mechanical, magnetic and thermal. In the general case, the waves polarized in the plane of the direction of wave propagation and the magnetic field are not only coupled but are also influenced by the thermal field, once again exhibiting the coupling of the three fields. The shear wave polarized transverse to the plane retains its magneto-elastic character.Notation.Hi = primary magnetic field components,ht = induced magnetic field components,To = initial thermal field,θ = induced thermal field,C = compression wave velocity.S = shear wave velocity,ui = displacement components,cv = specific heat at constant volume,k = thermal conductivity,η = magnetic diffusivity,μe = magnetic permeability,λ, μ = Lamé's constants,β = ratio of coefficient of volume expansion to isothermal compressibility.

Waves in a cold plasma with spatially periodic sheared fields

1989 ◽  
Vol 42 (1) ◽  
pp. 153-164 ◽  
Author(s):  
D. A. Diver ◽  
E. W. Laing ◽  
C. C. Sellar
Keyword(s):  
Magnetic Field ◽  
Wave Propagation ◽  
Cold Plasma ◽  
Density Fluctuations ◽  
Rotating Magnetic Field ◽  
Physical Parameters ◽  
Order Ordinary Differential Equation ◽  
Spatially Periodic ◽  
Constant Magnitude ◽  
The Magnetic Field

We have studied wave propagation in a cold plasma, in the presence of a spatially rotating magnetic field of constant magnitude. New features introduced by this variation include streaming velocities and a plasma current in equilibrium and density fluctuations. We present only the case of wave propagation along the axis of rotation of the magnetic field. A set of ordinary differential equations for the electric field components is obtained, which may be combined into a single fourth-order ordinary differential equation with periodic coefficients. Solutions are obtained in closed form and their nature is determined in terms of the physical parameters of the System, magnetic field strength, number density and wave frequency.

Wave propagation in a moving plasma. Part 1. Wave propagation normal to the magnetic field and motion of the plasma along the magnetic field

1974 ◽  
Vol 11 (3) ◽  
pp. 389-395 ◽  
Author(s):  
D. N. Srivastava
Keyword(s):  
Magnetic Field ◽  
Wave Propagation ◽  
Dispersion Relation ◽  
Magnetic Fields ◽  
Plasma Frequency ◽  
Electron Plasma ◽  
Ordinary Wave ◽  
Moving Plasma ◽  
The Magnetic Field

The dispersion relation for a collisionless moving electron plasma, when the direction of motion is along the magnetic field, and that of the wave propagation normal to the magnetic field, is analysed. It is shown that in small magnetic fields the ordinary wave develops a new band of backward waves below the plasma frequency. When the frequency of the wave is higher than the plasma frequency, the effect of the motion of the plasma is identical to a deviation of the direction of propagation.

Growing plasma oscillations for symmetrical double-humped velocity distributions

1970 ◽  
Vol 4 (2) ◽  
pp. 297-300 ◽  
Author(s):  
S. W. H. Cowley
Keyword(s):  
Magnetic Field ◽  
Vlasov Equation ◽  
Zero Order ◽  
Sufficient Condition ◽  
Necessary And Sufficient Condition ◽  
Plasma Oscillations ◽  
Longitudinal Waves ◽  
Hot Plasma ◽  
Necessary And Sufficient ◽  
The Magnetic Field

The problem considered here is that of growing longitudinal waves which propagate in a hot plasma parallel to any magnetic field which may be present (i.e. the magnetic field is neglected in the Vlasov equation). The necessary and sufficient condition for stability was obtained by Penrose (1960) and growth rates for plasmas obeying a Maxwell zero-order velocity distribution were computed by Fried & Conte (1961).

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