Electromagnetic fluctuations and normal modes of a drifting relativistic plasma

Ruyer, C.; Grémillet, L.; Bénisti, Didier; Bonnaud, G.

doi:10.1063/1.4829022

Cited by 15 publications

(13 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The present microturbulence also differs from the spontaneous turbulence associated to the thermal fluctuations of the plasma, as studied recently by Felten et al (2013), Felten and Schlickeiser (2013a,b), Ruyer et al (2013) or Yoon et al (2014), since the present turbulence has been sourced in the shock precursor by the anisotropies of particle distribution functions.…”

Section: Nonlinear Damping Of Small-scale Magnetostatic Turbulencementioning

confidence: 91%

Nonlinear collisionless damping of Weibel turbulence in relativistic blast waves

Lemoine

2014

J. Plasma Phys.

View full text Add to dashboard Cite

The Weibel/filamentation instability is known to play a key role in the physics of weakly magnetized collisionless shock waves. From the point of view of high energy astrophysics, this instability also plays a crucial role because its development in the shock precursor populates the downstream with a small-scale magneto-static turbulence which shapes the acceleration and radiative processes of suprathermal particles. The present work discusses the physics of the dissipation of this Weibelgenerated turbulence downstream of relativistic collisionless shock waves. It calculates explicitly the first-order nonlinear terms associated to the diffusive nature of the particle trajectories. These corrections are found to systematically increase the damping rate, assuming that the scattering length remains larger than the coherence length of the magnetic fluctuations. The relevance of such corrections is discussed in a broader astrophysical perspective, in particular regarding the physics of the external relativistic shock wave of a gamma-ray burst. IntroductionThe physics of collisionless shock waves has drawn wide interest, from pure theoretical plasma physics, starting with the pioneering work of Moiseev and Sagdeev (1963), to high energy astrophysics (e.g. Blandford and Eichler 1987), where it plays a key role in explaining most of the observed non-thermal spectra, and more recently, to laboratory high energy density physics, where collisionless shock waves are about to be produced through the interactions of laser beam-generated plasmas (e.g. Drake and Gregori 2012). At low magnetization -meaning that the unshocked plasma carries a magnetic field of small energy density compared to the shock kinetic energy -the physics of these collisionless shock waves is driven by the filamentation instability, also dubbed Weibel instability: this filamentation instability takes place in the shock precursor, where the incoming background plasma -as viewed in the reference frame in which the shock lies at rest -mixes with a population of shock-reflected or supra-thermal particles. This has been demonstrated by ab initio particle-in-cell (PIC) simulations, see e.g. Kato and Takabe (2008) for non-relativistic unmagnetized shock waves and Spitkovsky (2008a) for their relativistic counterparts, of direct interest to the present work. This filamentation instability and its various branches have consequently received a great deal of attention (see e.g. for relativistic shock waves Medvedev and Loeb

show abstract

Section: Nonlinear Damping Of Small-scale Magnetostatic Turbulencementioning

confidence: 91%

Nonlinear collisionless damping of Weibel turbulence in relativistic blast waves

Lemoine

2014

J. Plasma Phys.

View full text Add to dashboard Cite

show abstract

“…The evaluation of these quadratures by means of complex analysis techniques is extensive and quite involved, and will be reported in details in a separate paper [53]. The ω-integrated fluctuation energy density reads,…”

Section: A Fluctuation Power Spectrummentioning

confidence: 99%

Collisionless shock formation, spontaneous electromagnetic fluctuations, and streaming instabilities

Bret

Stockem²,

Fiúza³

et al. 2013

Physics of Plasmas

Self Cite

105

View full text Add to dashboard Cite

Collisionless shocks are ubiquitous in astrophysics and in the lab. Recent numerical simulations and experiments have shown how they can arise from the encounter of two collisionless plasma shells. When the shells interpenetrate, the overlapping region turns unstable, triggering the shock formation. As a first step towards a microscopic understanding of the process, we analyze here in detail the initial instability phase. On the one hand, 2D relativistic PIC simulations are performed where two symmetric initially cold pair plasmas collide. On the other hand, the instabilities at work are analyzed, as well as the field at saturation and the seed field which gets amplified. For mildly relativistic motions and onward, Weibel modes govern the linear phase. We derive an expression for the duration of the linear phase in good agreement with the simulations. This saturation time constitutes indeed a lower-bound for the shock formation time.

show abstract

“…To drive an instability of a particular eigenmode in a plasma, one needs to have a spontaneous emission of that particular mode as a seed perturbation so that the eigenmode can be amplified when the free energy (e.g., in the form of bi-Maxwellian or counter-streaming distributions) becomes available. In a series of papers, [30][31][32] a) Electronic addresses: yoonp@umd.edu; rsch@tp4.rub.de; and uk@tp4.rub.de general expressions for the spontaneously electromagnetic fluctuation spectra from uncorrelated plasma particles in unmagnetized plasmas have been derived, which are covariantly correct within the theory of special relativity. The general expressions hold for unmagnetized plasmas of arbitrary composition and arbitrary momentum dependences of the plasma particle distribution functions and for collective and non-collective fluctuations.…”

Section: Introductionmentioning

confidence: 99%

Thermal fluctuation levels of magnetic and electric fields in unmagnetized plasma: The rigorous relativistic kinetic theory

2014

View full text Add to dashboard Cite

Any fully ionized collisionless plasma with finite random particle velocities contains electric and magnetic field fluctuations. The fluctuations can be of three different types: weakly damped, weakly propagating, or aperiodic. The kinetics of these fluctuations in general unmagnetized plasmas, governed by the competition of spontaneous emission, absorption, and stimulated emission processes, is investigated, extending the well-known results for weakly damped fluctuations. The generalized Kirchhoff radiation law for both collective and noncollective fluctuations is derived, which in stationary plasmas provides the equilibrium energy densities of electromagnetic fluctuations by the ratio of the respective spontaneous emission coefficient and the true absorption coefficient. As an illustrative example, the equilibrium energy densities of aperiodic transverse collective electric and magnetic fluctuations in an isotropic thermal electron-proton plasmas of density n e are calculated as jdBj ¼ ffiffiffiffiffiffiffiffiffiffiffi ðdBÞ 2 q ¼ 2:8ðn e m e c 2 Þ 1=2 g 1=2 b 7=4 e and jdEj ¼ ffiffiffiffiffiffiffiffiffiffiffi ðdEÞ 2 q ¼ 3:2ðn e m e c 2 Þ 1=2 g 1=3 b 2 e , where g and b e denote the plasma parameter and the thermal electron velocity in units of the speed of light, respectively. For densities and temperatures of the reionized early intergalactic medium, jdBj ¼ 6 Á 10 À18 G and jdEj ¼ 2 Á 10 À16 G result. V C 2014 AIP Publishing LLC. [http://dx.

show abstract

Electromagnetic fluctuations and normal modes of a drifting relativistic plasma

Cited by 15 publications

References 42 publications

Nonlinear collisionless damping of Weibel turbulence in relativistic blast waves

Nonlinear collisionless damping of Weibel turbulence in relativistic blast waves

Collisionless shock formation, spontaneous electromagnetic fluctuations, and streaming instabilities

Thermal fluctuation levels of magnetic and electric fields in unmagnetized plasma: The rigorous relativistic kinetic theory

Contact Info

Product

Resources

About