scholarly journals Gravitational Landau damping for massive scalar modes

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Fabio Moretti ◽  
Flavio Bombacigno ◽  
Giovanni Montani
Keyword(s):  
Phase Velocity ◽  
Vlasov Equation ◽  
Landau Damping ◽  
Maxwell Distribution ◽  
Massive Scalar ◽  
Numerical Techniques ◽  
Damping Rate ◽  
Scalar Waves

AbstractWe establish the possibility of Landau damping for gravitational scalar waves which propagate in a non-collisional gas of particles. In particular, under the hypothesis of homogeneity and isotropy, we describe the medium at the equilibrium with a Jüttner–Maxwell distribution, and we analytically determine the damping rate from the Vlasov equation. We find that damping occurs only if the phase velocity of the wave is subluminal throughout the propagation within the medium. Finally, we investigate relativistic media in cosmological settings by adopting numerical techniques.

Analysis of Dispersion and Damping of Ion Waves in Plasma

1998 ◽  
Vol 53 (9) ◽  
pp. 747-750
Author(s):  
A.-A. Turky
Keyword(s):  
Phase Velocity ◽  
Plasma Frequency ◽  
Experimental Results ◽  
Landau Damping ◽  
Frequency Range ◽  
Ion Plasma ◽  
Damping Rate ◽  
Theoretical Predictions ◽  
Ion Waves ◽  
Analysis Of Dispersion

Abstract Experimental results are presented on the dispersion and damping of ion waves having a frequency range extending up to the ion plasma frequency. It was found that the Landau damping rate increases exponentially when the frequency of the ion wave approaches the ion plasma frequency ; while its phase velocity decreases slightly. The experimental results agree reasonably with previous theoretical predictions. The study indicates significant changes in Landau damping even with small variations in the wave velocity.

scholarly journals Ion Acoustic Peregrine Soliton Under Enhanced Dissipation

2021 ◽  
Vol 8 ◽  
Author(s):  
Pallabi Pathak
Keyword(s):  
Acoustic Wave ◽  
Negative Ions ◽  
Landau Damping ◽  
Ion Acoustic Wave ◽  
Multicomponent Plasma ◽  
Plasma Device ◽  
Ion Acoustic ◽  
Damping Rate ◽  
Double Plasma Device ◽  
Spatial Damping

The effect of enhanced Landau damping on the evolution of ion acoustic Peregrine soliton in multicomponent plasma with negative ions has been investigated. The experiment is performed in a multidipole double plasma device. To enhance the ion Landau damping, the temperature of the ions is increased by applying a continuous sinusoidal signal of frequency close to the ion plasma frequency ∼1 MHz to the separation grid. The spatial damping rate of the ion acoustic wave is measured by interferometry. The damping rate of ion acoustic wave increases with the increase in voltage of the applied signal. At a higher damping rate, the Peregrine soliton ceases to show its characteristics leaving behind a continuous envelope.

scholarly journals Fluctuation-dissipation relations for a plasma-kinetic Langevin equation

2014 ◽  
Vol 81 (1) ◽  
Author(s):  
A. Kanekar ◽  
A. A. Schekochihin ◽  
W. Dorland ◽  
N. F. Loureiro
Keyword(s):  
Free Energy ◽  
Kinetic Equation ◽  
Langevin Equation ◽  
Density Fluctuations ◽  
Landau Damping ◽  
Phase Mixing ◽  
Real Frequency ◽  
Fluctuation Dissipation ◽  
Damping Rate ◽  
Universal Expression

A linearised kinetic equation describing electrostatic perturbations of a Maxwellian equilibrium in a weakly collisional plasma forced by a random source is considered. The problem is treated as a kinetic analogue of the Langevin equation and the corresponding fluctuation-dissipation relations are derived. The kinetic fluctuation-dissipation relation reduces to the standard “fluid” one in the regime where the Landau damping rate is small and the system has no real frequency; in this case the simplest possible Landau-fluid closure of the kinetic equation coincides with the standard Langevin equation. Phase mixing of density fluctuations and emergence of fine scales in velocity space is diagnosed as a constant flux of free energy in Hermite space; the fluctuation-dissipation relations for the perturbations of the distribution function are derived, in the form of a universal expression for the Hermite spectrum of the free energy. Finite-collisionality effects are included. This work is aimed at establishing the simplest fluctuation-dissipation relations for a kinetic plasma, clarifying the connection between Landau and Hermite-space formalisms, and setting a benchmark case for a study of phase mixing in turbulent plasmas.

Semigroup representation of the Vlasov evolution

1998 ◽  
Vol 59 (4) ◽  
pp. 611-618 ◽  
Author(s):  
I. PRIGOGINE ◽  
T. PETROSKY
Keyword(s):  
Hilbert Space ◽  
Real Axis ◽  
Vlasov Equation ◽  
Spectral Representation ◽  
Decay Rates ◽  
Landau Damping ◽  
The Real ◽  
Rigged Hilbert Space ◽  
Time Symmetry ◽  
Friedrichs Model

The well-known van Kampen–Case treatment of the Vlasov equation leads to a spectrum on the real axis. In this paper we show that, by going to a ‘rigged’ Hilbert space, we can derive a spectral representation that is complex and breaks time symmetry. This leads to a semigroup description in which the decay rates due to the Landau damping appear explicitly in the spectrum. Moreover, we can then define an entropy. In this way, the relation between Landau damping and irreversibility is made explicit. The analogy with the well-known Friedrichs model is stressed.

scholarly journals NON-ABELIAN MEDIUM EFFECTS IN QUARK–GLUON PLASMA

2002 ◽  
Vol 17 (10) ◽  
pp. 1435-1447 ◽  
Author(s):  
JI-SHENG CHEN ◽  
JIA-RONG LI ◽  
PENG-FEI ZHUANG
Keyword(s):  
Quark Gluon Plasma ◽  
Kinetic Equations ◽  
Wave Interaction ◽  
Gluon Plasma ◽  
Landau Damping ◽  
Medium Effects ◽  
Third Order ◽  
Damping Rate ◽  
Nonlinear Landau Damping ◽  
Color Field

Based on the kinetic theory, the non-Abelian medium property of hot Quark–Gluon Plasma is investigated. The nonlinearity of the plasma comes from two aspects: The nonlinear wave–wave interaction and self-interaction of color field. The non-Abelian color permittivity is obtained by expanding the kinetic equations to third order. As an application, the nonlinear Landau damping rate and the nonlinear eigen frequency shift are calculated in the longwave length limit.

Nonlinear dispersion of surface waves in a plasma column

1984 ◽  
Vol 31 (2) ◽  
pp. 177-191 ◽  
Author(s):  
D. Grozev ◽  
A. Shivarova
Keyword(s):  
Phase Velocity ◽  
Surface Waves ◽  
Plasma Column ◽  
Fundamental Wave ◽  
Third Order ◽  
Ion Plasma ◽  
Wave Phase Velocity ◽  
Collisional Damping ◽  
Damping Rate ◽  
Symmetric Surface

The effect of the nonlinear changes of the dispersion characteristics of highfrequency azimuthally symmetric surface waves in a plasma column is investigated theoretically. Both (ω + ω) – ω and (ω – ω) + ω nonlinear interactions of the third order (in relation to the fundamental wave amplitude) are considered here. These two types of interactions influence the wave phase velocity and the collisional damping rate in opposite ways. When ω2Pi/v2 < 1, the contribution of the (ω – ω) – ω interaction is negligible and the (ω + ω) – ω interaction results in an increase of the phase velocity and a decrease of the time damping rate. When ω2pi/v2 > 1, both interactions are involved; the (ω – ω) + ω interaction associated with the ponderomotive force becomes more important, decreasing the phase velocity and increasing the time damping rate (ωpi and v are ion plasma and electron-neutral collision frequencies, respectively).

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