Freestreaming mode excited by a pulse

1986 ◽  
Vol 64 (7) ◽  
pp. 768-772
Author(s):  
Ludwig Schott
Keyword(s):  
Acoustic Waves ◽  
Voltage Pulse ◽  
Velocity Distribution Function ◽  
Density Perturbation ◽  
Zeroth Order ◽  
Ion Acoustic Waves ◽  
Ion Acoustic Wave ◽  
Ion Acoustic ◽  
Analytic Expressions ◽  
Applied Voltage Pulse

When a voltage pulse is applied to an exciter (probe or grid) immersed in a plasma, both an ion-acoustic wave and a freestreaming (ballistic) signal are excited. It is shown that the density perturbation produced by the freestreaming signal is independent of the shape of the applied-voltage pulse for times that are large compared with the temporal width of the pulse and at distances that are large compared with the size of the sheath at the exciter, but it depends on the second derivative of the zeroth-order velocity-distribution function. Analytic expressions that are valid for all times and positions are derived for a simple sheath model. Criteria are presented that enable the experimentalist to distinguish freestreaming modes from ion-acoustic waves.

scholarly journals Effects of Boundary and Electron Inertia on the Ion Acoustic Wave in a Plasma: A Pseudopotential Approach

1998 ◽  
Vol 51 (1) ◽  
pp. 113 ◽  
Author(s):  
K. K. Mondal ◽  
S. N. Paul ◽  
A. Roy Chowdhury
Keyword(s):  
Acoustic Waves ◽  
Finite Geometry ◽  
Cylindrical Domain ◽  
Plasma Parameters ◽  
Ion Acoustic Waves ◽  
Ion Acoustic Wave ◽  
Electron Inertia ◽  
Ion Acoustic ◽  
Pseudopotential Approach ◽  
Range Of Values

A pseudopotential approach is used to analyse the propagation of ion-acoustic waves in a plasma bounded by a cylindrical domain. The effect of the finite geometry is displayed both analytically and numerically. The phase velocity of the wave is determined and its variation is studied with respect to the plasma parameters. It is observed that the pseudopotential shows a wide variation of shape due to the imposition of a finite boundary condition. It is shown that if the other parameters are kept within a certain range of values, then the trapping of particles is favoured when the presence of the boundary is taken into account.

Nonlinear interaction of slow Alfvén wave with ion acoustic wave and applications to space plasma

2013 ◽  
Vol 79 (5) ◽  
pp. 833-836 ◽  
Author(s):  
B. K. DAS ◽  
R. P. SHARMA ◽  
N. YADAV
Keyword(s):  
Acoustic Waves ◽  
Analytical Study ◽  
Pump Wave ◽  
Modulational Instability ◽  
Solar Wind Plasma ◽  
Alfven Wave ◽  
Ion Acoustic Waves ◽  
Ion Acoustic Wave ◽  
Ion Acoustic ◽  
Model Equations

AbstractThe paper is concerned with the analytical study of nonlinear coupling of slow Alfvén wave (SW) with ion acoustic waves (IAWs) in high-β and low-β plasmas. Here the pump wave (SW) number density gets perturbed in the presence of IAW. The model equations of IAW and SW turn out to be the modified Zakharov system of equations when the ponderomotive nonlinearities are incorporated in the IAW and SW dynamics. Growth rate of modulational instability has been calculated. The relevance of these investigations for solar wind plasma and solar coronal plasma has also been discussed.

Propagation of Ion Acoustic Waves from and to a Spherical or Cylindrical Conductor

1972 ◽  
Vol 50 (5) ◽  
pp. 506-512 ◽  
Author(s):  
L. Schott
Keyword(s):  
Phase Velocity ◽  
Acoustic Waves ◽  
Fluid Model ◽  
Debye Length ◽  
Plasma Boundary ◽  
Ion Acoustic Waves ◽  
Ion Acoustic ◽  
Analytic Expressions ◽  
Consistent Solution ◽  
Two Fluid Model

Analytic expressions for the spatial variation of the phase velocity and amplitude of ion acoustic waves propagating radially through the plasma boundary layer at a conducting sphere or cylinder are derived using the two-fluid model. The Debye length is assumed to be small compared with any relevant dimension of the problem and the wavelength small compared with the radius of the conductor. The limits of ion mean free paths small and large compared with the radius of the sphere are considered. In the cylindrical case only the collisionless limit has a self-consistent solution. It is found that both the converging and the diverging waves are damped and that the phase velocity of the wave is approximately equal to the sum of the ion acoustic velocity in a homogeneous plasma and the ion drift velocity. The contribution of Landau damping to the total damping is estimated.

scholarly journals Effect of Negative Ions on the Instability of Ion-acoustic Waves in a Relativistic Plasma

1997 ◽  
Vol 50 (2) ◽  
pp. 319 ◽  
Author(s):  
K. K. Mondal ◽  
S. N. Paul ◽  
A. Roychowdhury
Keyword(s):  
Dispersion Relation ◽  
Acoustic Wave ◽  
Acoustic Waves ◽  
Negative Ions ◽  
Ion Concentration ◽  
Negative Ion ◽  
Relativistic Velocity ◽  
Ion Acoustic Waves ◽  
Ion Acoustic Wave ◽  
Ion Acoustic

The dispersion relation of an ion-acoustic wave propagating through a collisionless, unmagnetised plasma, having warm isothermal electrons and cold positive and negative ions has been derived. It is seen that the ion-acoustic wave will be unstable in the presence of streaming of ions. Instability of the wave is graphically analysed for the plasma having (H+, O¯) ions, (H+, O2¯) ions, (H+, SF5¯) ions, (He+, Cl¯) ions and (Ar+, O¯) ions with different negative ion concentration and relativistic velocity.

scholarly journals Solar Type I Radio Bursts: An Ion-Acoustic Wave Model

1980 ◽  
Vol 86 ◽  
pp. 251-254
Author(s):  
A. O. Benz ◽  
D. G. Wentzel
Keyword(s):  
Acoustic Waves ◽  
Wave Model ◽  
Type I ◽  
Radio Bursts ◽  
Ion Acoustic Waves ◽  
Langmuir Waves ◽  
Ion Acoustic Wave ◽  
Ion Acoustic ◽  
Solar Type ◽  
Astronomy And Astrophysics

(paper submitted to Astronomy and Astrophysics)We propose a model for type I emission based on scattering of Langmuir waves by ion acoustic waves, which are associated with the evolution of the associated active region on the Sun.

Reflection of ion-acoustic waves from bipolar potential structures

1989 ◽  
Vol 41 (2) ◽  
pp. 243-255 ◽  
Author(s):  
Y. Nakamura ◽  
Joyanti Chutia
Keyword(s):  
Acoustic Wave ◽  
Acoustic Waves ◽  
High Efficiency ◽  
Ion Beam ◽  
Plasma Potential ◽  
Ion Acoustic Waves ◽  
Ion Acoustic Wave ◽  
Plasma Device ◽  
Ion Acoustic ◽  
Double Plasma Device

Reflection of ion-acoustic waves from the ion sheath in front of the separation grid in a double-plasma device has been investigated experimentally. The plasma potential φ of the source plasma was controlled relative to that of the target plasma. When eφ < κΤe, where Τe is the electron temperature, no reflection was observed. The reason for this is that ions are drifting towards the grid with the Bohm velocity, i.e. the ion-acoustic velocity. When eφ > κΤe the reflected wave consists of the ion-acoustic wave and the ion beam mode. The reflection coefficient for the ion-acoustic wave is about unity. This high efficiency is due to reflection of the ions themselves.

The Zakharov–Kuznetsov equation for nonlinear ion-acoustic waves

1992 ◽  
Vol 47 (1) ◽  
pp. 75-83 ◽  
Author(s):  
K. Murawski ◽  
P. M. Edwin
Keyword(s):  
Wave Propagation ◽  
Fourier Transform ◽  
Acoustic Waves ◽  
Kutta Method ◽  
Acoustic Wave Propagation ◽  
Initial Value ◽  
Ion Acoustic Waves ◽  
Ion Acoustic Wave ◽  
Runge Kutta Method ◽  
Ion Acoustic

The Zakharov-Kuznetsov equation is used to describe ion-acoustic wave propagation in a magnetic environment. An initial-value problem is solved for this equation on the basis of a numerical method that uses the fast-Fourier-transform technique for calculating space derivatives and a fourth-order Runge-Kutta method for the time scheme. Numerical simulations show that the disturbed flat (planar) solitary waves can break up into more robust cylindrical ones. Interactions between these two types of wave, and recurrence phenomena, are also studied.

Radio-auroral scattering at two closely spaced frequencies

1980 ◽  
Vol 58 (10) ◽  
pp. 1485-1491 ◽  
Author(s):  
I. P. W. Sinclair ◽  
P. A. Forsyth
Keyword(s):  
Acoustic Wave ◽  
Acoustic Waves ◽  
Ion Acoustic Waves ◽  
Ion Acoustic Wave ◽  
Individual Ion ◽  
Ion Acoustic ◽  
Wave Trains ◽  
Radio Frequencies

Two radio frequencies near 40 MHz and separated by 500 Hz were used to investigate the type of radio-auroral scattering which arises in ion-acoustic waves. The results confirm those of Haldoupis and Sofko who found that individual ion-acoustic wave trains have lifetimes of only tenths of seconds. In addition it was found that instantaneous signal amplitudes on these two frequencies were sometimes poorly correlated indicating the coexistence of widely separated ion-acoustic wave trains. It appears that the radio-auroral scattering region is typically large but within it individual ion-acoustic wave trains grow and decay rapidly. Significant periodicities were found in the signals and these are attributed to magnetospheric modulation of the auroral process.

Measurement of ion-rich sheath thickness by ion acoustic wave

1972 ◽  
Vol 8 (3) ◽  
pp. 321-330 ◽  
Author(s):  
S. Watanabe ◽  
O. Ishihara ◽  
H. Tanaca
Keyword(s):  
Acoustic Waves ◽  
Analysis Method ◽  
Sheath Thickness ◽  
Ion Acoustic Waves ◽  
Continuous Transition ◽  
Ion Acoustic Wave ◽  
Clear Cut ◽  
Sheath Edge ◽  
Low Pressure Plasma ◽  
Ion Acoustic

Measurements of sheath thickness in a low-pressure plasma are reported. The sheath is ion-rich and contains both ions and electrons; the sheath edge is taken as a boundary for ion acoustic waves. The thickness of the sheath is estimated from a frequency shift of the wave. Despite the actually continuous transition from plasma to sheath, a clear-cut sheath edge is observed. It should be emphasized that even a very small increase in thickness, such as 0·1mm, can be measured by this frequency-analysis method. The experimentally obtained sheath boundary is in agreement with the Tonks–Langmuir value as modified by Self.

Influence of High Frequency Electric Field on the Dispersion of Ion-Acoustic Waves in Plasma

1981 ◽  
Vol 36 (1) ◽  
pp. 17-22
Author(s):  
A. Turky ◽  
M. Čerček ◽  
R. Tavzes J. Stefan
Keyword(s):  
Electric Field ◽  
Acoustic Waves ◽  
High Frequency ◽  
Wave Dispersion ◽  
Plasma Stream ◽  
Ion Acoustic Waves ◽  
Ion Acoustic Wave ◽  
High Frequency Electric Field ◽  
Ion Acoustic ◽  
Frequency Electric Field

The modification of the ion-acoustic wave dispersion under the action of a high frequency electric field was studied experimentally, the wave propagating along and against the plasma stream. The frequency of the field amounted to approximately half the electron plasma frequency. It was found that the phase velocity of the ion wave and the plasma drift velocity decrease as the effective high frequency field power increases

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