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

Yoon, Peter H.; Schlickeiser, R.; Kolberg, U.

doi:10.1063/1.4868232

Cited by 50 publications

(18 citation statements)

References 35 publications

(47 reference statements)

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“…Furthermore, the anisotropy index at ion beta 0.05 turns back at later times (t p > 1500). Whether this peculiar evolution is due to the thermal fluctuations (see, e.g., Yoon et al, 2014) or due to the numerical noise of the hybrid particle-in-cell (PIC) simulation (see, e.g., Jenkins and Lee , 2007) is a question we cannot answer in this paper. Nevertheless, there is no connection with the initial Alfvénic excitation imposed at the start of the simulation.…”

Section: Anisotropy Evolutionmentioning

confidence: 76%

Wavevector anisotropy of plasma turbulence at ion kinetic scales: solar wind observations and hybrid simulations

Comişel

Narita

Motschmann

2014

Nonlin. Processes Geophys.

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Abstract. Wavevector anisotropy of ion-scale plasma turbulence is studied at various values of ion beta. Two complementary methods are used. One is multi-point measurements of magnetic field in the near-Earth solar wind as provided by the Cluster spacecraft mission, and the other is hybrid numerical simulation of two-dimensional plasma turbulence. Both methods demonstrate that the wavevector anisotropy is reduced with increasing values of ion beta. Furthermore, the numerical simulation study shows the existence of a scaling law between ion beta and the wavevector anisotropy of the fluctuating magnetic field that is controlled by the thermal or hybrid particle-in-cell simulation noise. Likewise, there is weak evidence that the power-law scaling can be extended to the turbulent fluctuating cascade. This fact can be used to construct a diagnostic tool to determine or to constrain ion beta using multi-point magnetic field measurements in space.

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Section: Anisotropy Evolutionmentioning

confidence: 76%

Wavevector anisotropy of plasma turbulence at ion kinetic scales: solar wind observations and hybrid simulations

Comişel

Narita

Motschmann

2014

Nonlin. Processes Geophys.

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“…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.

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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

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“…favourable conditions (Biermann 1950), while both the Weibel instability (Weibel 1959) and the generation of spontaneously emitted magnetic fields occurs on much smaller scales, comparable to a few Debye lengths. Recent calculations by Schlickeiser (2012) suggest the production of ∼10 −10 G magnetic fields in protogalaxies due to plasma fluctuations (Yoon et al 2014). So, both the Weibel instability and plasma fluctuations can produce a magnetic field on small scales.…”

Section: Introductionmentioning

confidence: 99%

Magnetic fields in primordial accretion disks

Latif

Schleicher

2016

A&A

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Magnetic fields are considered a vital ingredient of contemporary star formation and may have been important during the formation of the first stars in the presence of an efficient amplification mechanism. Initial seed fields are provided via plasma fluctuations and are subsequently amplified by the small-scale dynamo, leading to a strong, tangled magnetic field. We explore how the magnetic field provided by the small-scale dynamo is further amplified via the α-Ω dynamo in a protostellar disk and assess its implications. For this purpose, we consider two characteristic cases, a typical Pop. III star with 10 M and an accretion rate of 10 −3 M yr −1 , and a supermassive star with 10 5 M and an accretion rate of 10 −1 M yr −1 . For the 10 M Pop. III star, we find that coherent magnetic fields can be produced on scales of at least 100 AU, which are sufficient to drive a jet with a luminosity of 100 L and a mass outflow rate of 10 −3.7 M yr −1 . For the supermassive star, the dynamical timescales in its environment are even shorter, implying smaller orbital timescales and an efficient magnetization out to at least 1000 AU. The jet luminosity corresponds to ∼10 6.0 L and a mass outflow rate of 10 −2.1 M yr −1 . We expect that the feedback from the supermassive star can have a relevant impact on its host galaxy.

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

Cited by 50 publications

References 35 publications

Wavevector anisotropy of plasma turbulence at ion kinetic scales: solar wind observations and hybrid simulations

Wavevector anisotropy of plasma turbulence at ion kinetic scales: solar wind observations and hybrid simulations

Nonlinear collisionless damping of Weibel turbulence in relativistic blast waves

Magnetic fields in primordial accretion disks

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