Transition from thermal to turbulent equilibrium with a resulting electromagnetic spectrum

Ziebell, L. F.; Yoon, Peter H.; Gaelzer, R.; Pavan, J.

doi:10.1063/1.4863453

Cited by 13 publications

(17 citation statements)

References 17 publications

(25 reference statements)

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“…However, in some of the applications that have been made, it was shown that nonlinear effects continue to operate far beyond the time scale of the instability saturation and nonlinear mode coupling, to the extent that an asymptotically steady state, or quasiequilibrium state, of the turbulent system becomes of relevance. Specifically, it was demonstrated that plasma in such a "turbulent equilibrium" state can be associated with a background of electromagnetic radiation [30,32]. It was also shown that the long-range, asymptotic state of the turbulence is associated with the inverse power-law velocity distribution function called the "kappa" distribution [25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Weak turbulence theory for collisional plasmas

et al. 2016

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Plasma is an ionized gas in which the collective behavior dominates over the individual particle interactions. For this reason, plasma is often treated as collisionless or collision-free. However, the discrete nature of the particles can be important, and often, the description of plasmas is incomplete without properly taking the discrete particle effects into account. The weak turbulence theory is a perturbative nonlinear theory, whose essential formalism was developed in the late 1950s and 1960s and continued on through the early 1980s. However, the standard material found in the literature does not treat the discrete particle effects and the associated fluctuations emitted spontaneously by thermal particles completely. Plasma particles emit electromagnetic fluctuations in all frequencies and wave vectors, but in the standard literature, the fluctuations are approximately treated by considering only those frequency-wave number regimes corresponding to the eigenmodes (or normal modes) satisfying the dispersion relations, while ignoring contributions from noneigenmodes. The present paper shows that the noneigenmode fluctuations modify the particle kinetic equation so that the generalized equation includes the Balescu-Lénard-Landau collision integral and also modify the wave kinetic equation to include not only the collisional damping term but also a term that depicts the bremsstrahlung emission of plasma normal modes.

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Section: Introductionmentioning

confidence: 99%

Weak turbulence theory for collisional plasmas

et al. 2016

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“…We assume that the ion distribution is described by an isotropic Maxwellian distribution, with T e /T i = 2. We also assume that the plasma parameter is (nλ 3 D ) −1 = 5.0 × 10 −3 , and v 2 e /c 2 = 4.0 × 10 −3 , values which have already been used in analyses of the plasma emission without taking into account the presence of a Kappa distribution 34,36 .…”

Section: Numerical Resultsmentioning

confidence: 99%

“…The situation depicted in Figure 3(a) corresponds to the initial stages of the evolution, which is displayed up to longer time in Figure 2 of Ref. 34 . In the presence of a small Kappa population, the spectrum of T waves evolves as shown in Figure 3(b).…”

Section: Numerical Resultsmentioning

confidence: 99%

Weakly turbulent plasma processes in the presence of inverse power-law velocity tail population

et al. 2017

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Observations show that plasma particles in the solar wind frequently display power-law velocity distributions, which can be isotropic or anisotropic. Particularly, the velocity distribution functions of solar wind electrons are frequently modeled as combination of a background Maxwellian distribution and a non-thermal distribution which is known as the "halo" distribution. For fast solar wind conditions, highly anisotropic field-aligned electrons, denominated as the "strahl" distribution, are also present. Motivated by these observations, the present paper considers a tenuous plasma with Maxwellian ions, and electrons described by a summation of an isotropic Maxwellian distribution and an isotropic Kappa distribution. The formalism of weak turbulence theory is utilized in order to discuss the spectra of electrostatic waves that must be present in such a plasma, satisfying conditions of quasi-equilibrium between processes of spontaneous fluctuations and of induced emission. The kappa index and relative density of the Kappa electron distribution are varied. By taking into account effects due to electromagnetic waves into the weak turbulence formalism, we investigate the electromagnetic spectra that satisfy conditions of "turbulent equilibrium", and also the time evolution of the wave spectra and of the electron distribution, which occurs in the case of the presence of an electron beam in the electron distribution.

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“…In some of the more recent works, we have also considered electromagnetic waves into the WT analysis, and discussed the emission of electromagnetic waves by nonlinear processes, considering the paradigmatic case of the plasma emission, 46,47 and also the possibility of emission without the presence of a beam. 48,49 The 2D analysis provides information and insights that are not immediately available with 1D analysis. There are certain features such as the time scales of different nonlinear processes, which may be adequately addressed by 1D analysis; other features such as the angular distribution of the radiation by plasma emission, for instance, can be learned only through a 2D formulation.…”

Section: Introductionmentioning

confidence: 99%

Two dimensional kinetic analysis of electrostatic harmonic plasma waves

et al. 2016

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Electrostatic harmonic Langmuir waves are virtual modes excited in weakly turbulent plasmas, first observed in early laboratory beam-plasma experiments as well as in rocket-borne active experiments in space. However, their unequivocal presence was confirmed through computer simulated experiments and subsequently theoretically explained. The peculiarity of harmonic Langmuir waves is that while their existence requires nonlinear response, their excitation mechanism and subsequent early time evolution are governed by essentially linear process. One of the unresolved theoretical issues regards the role of nonlinear wave-particle interaction process over longer evolution time period. Another outstanding issue is that existing theories for these modes are limited to one-dimensional space. The present paper carries out two dimensional theoretical analysis of fundamental and (first) harmonic Langmuir waves for the first time. The result shows that harmonic Langmuir wave is essentially governed by (quasi)linear process and that nonlinear wave-particle interaction plays no significant role in the time evolution of the wave spectrum. The numerical solutions of the two-dimensional wave spectra for fundamental and harmonic Langmuir waves are also found to be consistent with those obtained by direct particle-in-cell simulation method reported in the literature. Published by AIP Publishing.

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Transition from thermal to turbulent equilibrium with a resulting electromagnetic spectrum

Cited by 13 publications

References 17 publications

Weak turbulence theory for collisional plasmas

Weak turbulence theory for collisional plasmas

Weakly turbulent plasma processes in the presence of inverse power-law velocity tail population

Two dimensional kinetic analysis of electrostatic harmonic plasma waves

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