Saturation and damping of collisionless plasma wave echoes

1969 ◽  
Vol 3 (4) ◽  
pp. 603-610 ◽  
Author(s):  
J. Coste ◽  
J. Peyraud
Keyword(s):  
Plasma Wave ◽  
Collisionless Plasma ◽  
Time Interval ◽  
Phase Mixing ◽  
Mixing Effect ◽  
Applied Pulse ◽  
Comparable Amplitude

We point out in this paper that when one increases the intensity of the second applied pulse or the time interval between the two pulses, the amplitude of the first echo saturates and multiple echoes of comparable amplitude appear. Moreover, we predict a damping of the echoes which is due to a phase mixing effect; that is collisionless.

Airy-like electron plasma wave

2016 ◽  
Vol 82 (1) ◽  
Author(s):  
Hehe Li ◽  
Xinzhong Li ◽  
Jingge Wang
Keyword(s):  
Plasma Wave ◽  
Electrostatic Potential ◽  
Collisionless Plasma ◽  
Propagation Distance ◽  
Basic Structure ◽  
Electron Plasma ◽  
Propagation Direction ◽  
Propagation Characteristics ◽  
Electron Plasma Wave ◽  
Airy Beam

In this paper, an Airy-like electron plasma wave is investigated in an unmagnetized collisionless plasma consisting of inertial electrons and static ions. Just like the optical Airy beam, the Airy-like electron plasma wave also has two interesting propagation characteristics: it has transverse acceleration and is diffraction-free, which display that the Airy-like electron plasma wave propagates along a curved trajectory and retains the basic structure for longer distances in the propagation direction, respectively. We give a numerical simulation for the electrostatic potential of the Airy-like electron plasma wave and show that, with the increase of the propagation distance, the electrostatic potential decreases in the propagation direction but increases in the transverse direction.

scholarly journals Phase mixing importance for both Landau instability and damping

2017 ◽  
Vol 83 (1) ◽  
Author(s):  
D. D. A. Santos ◽  
Yves Elskens
Keyword(s):  
Numerical Calculation ◽  
Degrees Of Freedom ◽  
Hamiltonian Formalism ◽  
Langmuir Wave ◽  
The Self ◽  
Phase Mixing ◽  
Mixing Effect ◽  
Self Consistent ◽  
Landau Instability

We discuss the self-consistent dynamics of plasmas by means of a Hamiltonian formalism for a system of $N$ near-resonant electrons interacting with a single Langmuir wave. The connection with the Vlasov description is revisited through the numerical calculation of the van Kampen-like eigenfrequencies of the linearized dynamics for many degrees of freedom. Both the exponential-like growth as well as damping of the Langmuir wave are shown to emerge from a phase mixing effect among beam modes, revealing unexpected similarities between the stable and unstable regimes.

Theory of Plasma Wave Probes in a Collisionless Plasma

1963 ◽  
Vol 34 (7) ◽  
pp. 779-781 ◽  
Author(s):  
William E. Drummond
Keyword(s):  
Plasma Wave ◽  
Collisionless Plasma

Phase-mixing effect in styrene-butadiene block copolymers

1987 ◽  
Vol 20 (6) ◽  
pp. 1421-1423 ◽  
Author(s):  
Alice T. Granger ◽  
Sonja Krause ◽  
Lewis J. Fetters
Keyword(s):  
Block Copolymers ◽  
Phase Mixing ◽  
Mixing Effect ◽  
Styrene Butadiene

scholarly journals Electron plasma wave excitation by beating of two q-Gaussian laser beams in collisionless plasma

2016 ◽  
Vol 34 (2) ◽  
pp. 230-241 ◽  
Author(s):  
Arvinder Singh ◽  
Naveen Gupta
Keyword(s):  
Laser Beam ◽  
Plasma Wave ◽  
Electron Concentration ◽  
Collisionless Plasma ◽  
Electron Plasma ◽  
Spot Size ◽  
Laser Beams ◽  
Plasma Parameters ◽  
Electron Plasma Wave ◽  
Ponderomotive Nonlinearity

AbstractThis paper presents a scheme for excitation of an electron-plasma wave (EPW) by beating two q-Gaussian laser beams in an underdense plasma where ponderomotive nonlinearity is operative. Starting from nonlinear Schrödinger-type wave equation in Wentzel–Kramers–Brillouin (WKB) approximation, the coupled differential equations governing the evolution of spot size of laser beams with distance of propagation have been derived. The ponderomotive nonlinearity depends not only on the intensity of first laser beam, but also on that of second laser beam. Therefore, the dynamics of one laser beam affects that of other and hence, cross-focusing of the two laser beams takes place. Due to nonuniform intensity distribution along the wavefronts of the laser beams, the background electron concentration is modified. The amplitude of EPW, which depends on the background electron concentration, is thus nonlinearly coupled with the laser beams. The effects of ponderomotive nonlinearity and cross-focusing of the laser beams on excitation of EPW have been incorporated. Numerical simulations have been carried out to investigate the effect of laser and plasma parameters on cross-focusing of the two laser beams and further its effect on EPW excitation.

Cooperative Quantum Phase Mixing Effect or Why the Continuous (He-Ne)-Laser Operates Without Inversion

1997 ◽  
Vol 11 (28) ◽  
pp. 1215-1229
Author(s):  
Vladislav Cheltsov
Keyword(s):  
Rotation Velocity ◽  
Phase Mixing ◽  
Mixing Effect ◽  
Energy Eigenvalues ◽  
Resonance Modes ◽  
Operation Conditions ◽  
Periodic Dynamics ◽  
Lock In ◽  
Nonperturbative Theory ◽  
Beating Frequency

Cooperative phase mixing effect (CPME) in the system of N-two-level atoms coupled to one and two resonance modes is described. Caused by irrationality of cooperative energy eigenvalues the CPME leads to quasi-periodic dynamics giving rise to superposition of states with both positive and negative inversions, so that the averaged inversion should be close to zero. To check inversionless operation of the continuous (He-Ne)-laser the nonperturbative theory of beatings in a rotating ring laser (RGL) has been suggested. The derived formula for beating frequency displays two states: with split frequencies of opposite modes and the lock-in regime. Comparison of this formula with the observed lock-in threshold rotation velocity has given the estimation (N_/V)~ (10-5-10-11) cm-3 as dependent on geometry and operation conditions.

scholarly journals Stimulated Raman scattering of ultra intense hollow Gaussian beam in relativistic plasma

2015 ◽  
Vol 33 (3) ◽  
pp. 489-498 ◽  
Author(s):  
Prerana Sharma
Keyword(s):  
Raman Scattering ◽  
Laser Beam ◽  
Gaussian Beam ◽  
Plasma Wave ◽  
Stimulated Raman Scattering ◽  
Collisionless Plasma ◽  
Vital Role ◽  
Higher Order ◽  
Gaussian Laser Beam ◽  
Stimulated Raman

AbstractEffect of relativistic nonlinearity on stimulated Raman scattering (SRS) of laser beam propagating carrying null intensity in center [hollow Gaussian beam (HGB)] is studied in collisionless plasma. The construction of the equations is done employing the fluid theory which is developed with partial differential equation and Maxwell's equations. The phenomenon of SRS is shown along with the excitation of seed plasma wave considering relativistic nonlinearity. The power of plasma wave is observed for higher order of HGB. The Raman back reflectivity is studied numerically for various orders of hollow Gaussian laser beam (HGLB) and the numerical analysis shows that these parameters play vital role on reflectivity characteristics. It is observed that the Raman back reflectivity is less for the higher order of HGLB.

scholarly journals Fluidization of collisionless plasma turbulence

2019 ◽  
Vol 116 (4) ◽  
pp. 1185-1194 ◽  
Author(s):  
Romain Meyrand ◽  
Anjor Kanekar ◽  
William Dorland ◽  
Alexander A. Schekochihin
Keyword(s):  
Solar Wind ◽  
Power Law ◽  
Collisionless Plasma ◽  
Plasma Turbulence ◽  
Magnetized Plasma ◽  
Landau Damping ◽  
Astrophysical Plasmas ◽  
Phase Mixing ◽  
Fluid Turbulence ◽  
Collisionless Plasmas

In a collisionless, magnetized plasma, particles may stream freely along magnetic field lines, leading to “phase mixing” of their distribution function and consequently, to smoothing out of any “compressive” fluctuations (of density, pressure, etc.). This rapid mixing underlies Landau damping of these fluctuations in a quiescent plasma—one of the most fundamental physical phenomena that makes plasma different from a conventional fluid. Nevertheless, broad power law spectra of compressive fluctuations are observed in turbulent astrophysical plasmas (most vividly, in the solar wind) under conditions conducive to strong Landau damping. Elsewhere in nature, such spectra are normally associated with fluid turbulence, where energy cannot be dissipated in the inertial-scale range and is, therefore, cascaded from large scales to small. By direct numerical simulations and theoretical arguments, it is shown here that turbulence of compressive fluctuations in collisionless plasmas strongly resembles one in a collisional fluid and does have broad power law spectra. This “fluidization” of collisionless plasmas occurs, because phase mixing is strongly suppressed on average by “stochastic echoes,” arising due to nonlinear advection of the particle distribution by turbulent motions. Other than resolving the long-standing puzzle of observed compressive fluctuations in the solar wind, our results suggest a conceptual shift for understanding kinetic plasma turbulence generally: rather than being a system where Landau damping plays the role of dissipation, a collisionless plasma is effectively dissipationless, except at very small scales. The universality of “fluid” turbulence physics is thus reaffirmed even for a kinetic, collisionless system.

scholarly journals Alfvén wave filamentation and dispersive phase mixing in a high-density channel: Landau fluid and hybrid simulations

2009 ◽  
Vol 16 (2) ◽  
pp. 275-285 ◽  
Author(s):  
D. Borgogno ◽  
P. Hellinger ◽  
T. Passot ◽  
P. L. Sulem ◽  
P. M. Trávníček
Keyword(s):  
Fluid Model ◽  
Collisionless Plasma ◽  
Density Perturbation ◽  
High Density ◽  
Alfven Wave ◽  
Larmor Radius ◽  
Plasma Parameters ◽  
Phase Mixing ◽  
Finite Larmor Radius ◽  
Dispersive Phase

Abstract. The propagation of dispersive Alfvén waves in a low-beta collisionless plasma with a high-density channel aligned with the ambient magnetic field, is studied in three space dimensions. A fluid model retaining linear Landau damping and finite Larmor radius corrections is used, together with a hybrid particle-in-cell simulation aimed to validate the predictions of this Landau-fluid model. It is shown that when the density enhancement is moderate (depending on the pump wavelength and the plasma parameters), the wave energy concentrates into a filament whose transverse size is prescribed by the dimension of the channel. In contrast, in the case of a stronger density perturbation, the early formation of a magnetic filament is followed by the onset of thin helical ribbons and the development of strong gradients. This "dispersive phase mixing" provides a mechanism permitting dissipation processes (not included in the present model) to act and heat the plasma.

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