Radiation from non-linear Weibel plasma modes

Tautz, R. C.; Lerche, I.

doi:10.1016/j.physrep.2012.03.006

Cited by 8 publications

(8 citation statements)

References 143 publications

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“…Weibel modes and their associated non-linear structures play a role for many physical effects. The relevant extensions of the Weibel instability, other instabilities including the Harris instability, and both their respective linear and non-linear aspects include (for an overview, see [9] and references therein): (i) relativistic factors (both with and without external magnetic field); (ii) coupling factors of the transverse and longitudinal wave behaviors; (iii) generation of magnetic fields from the currents; (iv) modification of Weibel-type instabilities due to a background magnetic field; (v) specialized investigations of beam-plasma interactions and counterstreaming plasmas; (vi) saturation of the Weibel instability by non-linear effects; (vii) particle-in-cell calculations to investigate Weibel-like instabilities; (viii) Weibel-like behavior in quantum plasmas; (ix) the combination of unstable plasma distributions and particle scattering properties; (x) and a host of ancillary factors including multiple species distribution functions that may be partially anisotropic per species or isotropic (but not for all species).…”

Section: Non-linear Extensionsmentioning

confidence: 99%

Cosmic-ray diffusion in magnetized turbulence

Tautz¹

2015

Proceedings of Cosmic Rays and the InterStellar Medium — PoS(CRISM2014)

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The problem of cosmic-ray scattering in the turbulent electromagnetic fields of the interstellar medium and the solar wind is of great importance due to the variety of applications of the resulting diffusion coefficients. Examples are diffusive shock acceleration, cosmic-ray observations, and, in the solar system, the propagation of coronal mass ejections. In recent years, it was found that the simple diffusive motion that had been assumed for decades is often in disagreement both with numerical and observational results. Here, an overview is given of the interaction processes of cosmic rays and turbulent electromagnetic fields. First, the formation of turbulent fields due to plasma instabilities is treated, where especially the non-linear behavior of the resulting unstable wave modes is discussed. Second, the analytical and the numerical side of high-energy particle propagation will be reviewed by presenting non-linear analytical theories and Monte-Carlo simulations. For the example of the solar wind, the impact of anisotropic and dynamical turbulence models will be discussed. In addition, it will be shown how further complications can be treated that arise from the large-scale magnetic field geometry and turbulent electric fields. The transport properties of energetic particles can thus be calculated for current turbulence models so that they withstand a comparison with measurements taken in the solar wind.

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Section: Non-linear Extensionsmentioning

confidence: 99%

Cosmic-ray diffusion in magnetized turbulence

Tautz¹

2015

Proceedings of Cosmic Rays and the InterStellar Medium — PoS(CRISM2014)

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“…Among other processes (e. g., Ryu et al 2012;Durrer and Neronov 2013), seed fields can be generated by plasma instabilities for example in the neighborhood of massive stars that ionize the surrounding interstellar medium (Schlickeiser 2012). A special class of such instabilities generates modes that purely grow in time and do not propagate-the so-called "aperiodic" modes (Weibel 1959;Tautz and Lerche 2012a). The fact that such modes can be emitted spontaneously even in unmagnetized plasmas (Yoon 2007;Yoon and Schlickeiser 2012; again underscores the validity of the process.…”

Section: J Triptowmentioning

confidence: 99%

“…Here, the maximum magnetic field strength generated by a special class of plasma instabilities-socalled "Weibel-type" instabilities (Weibel 1959;Fried 1959;Tautz and Lerche 2012a)-will be investigated by means of a parameter study. Such instabilities have been the focus of intense research for some time regarding both their linear and non-linear stages.…”

Section: J Triptowmentioning

confidence: 99%

Interstellar turbulent magnetic field generation by plasma instabilities

Tautz

Triptow²

2013

Astrophys Space Sci

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The maximum magnetic field strength generated by Weibel-type plasma instabilities is estimated for typical conditions in the interstellar medium. The relevant kinetic dispersion relations are evaluated by conducting a parameter study both for Maxwellian and for suprathermal particle distributions showing that micro Gauss magnetic fields can be generated. It is shown that, depending on the streaming velocity and the plasma temperatures, either the longitudinal or a transverse instability will be dominant. In the presence of an ambient magnetic field, the filamentation instability is typically suppressed while the two-stream and the classic Weibel instability are retained.

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“…These are millisecondand kilometer scales if the electron number density is ≈1 cm −3 . Accordingly, a wide range of theoretical (Medvedev & Loeb 1999;Brainerd 2000;Bret et al 2006Bret et al , 2010Milosavljevic & Nakar 2006;Tautz & Lerche 2012) and particle-in-cell (PIC) simulation studies (Sakai et al 2000;Honda et al 2000;Silva et al 2003;Jaroschek et al 2004;Medvedev et al 2005;Dieckmann et al 2009a,b;Vieira et al 2012) have addressed the instabilities of counterstreaming lepton beams and the formation of shocks in pair plasmas (Kazimura et al 1998;Haruki & Sakai 2003;Sironi & Spitkovsky 2011;Sironi et al 2013;Bret et al 2013) that are triggered when plasmas collide at a relativistic speed.…”

Section: Introductionmentioning

confidence: 99%

Particle-in-cell simulation study of the interaction between a relativistically moving leptonic micro-cloud and ambient electrons

Dieckmann¹,

Sarri²,

Markoff³

et al. 2015

A&A

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Context. The jets of compact accreting objects are composed of electrons and a mixture of positrons and ions. These outflows impinge on the interstellar or intergalactic medium and both plasmas interact via collisionless processes. Filamentation (beam-Weibel) instabilities give rise to the growth of strong electromagnetic fields. These fields thermalize the interpenetrating plasmas. Aims. Hitherto, the effects imposed by a spatial non-uniformity on filamentation instabilities have remained unexplored. We examine the interaction between spatially uniform background electrons and a minuscule cloud of electrons and positrons. The cloud size is comparable to that created in recent laboratory experiments and such clouds may exist close to internal and external shocks of leptonic jets. The purpose of our study is to determine the prevalent instabilities, their ability to generate electromagnetic fields and the mechanism, by which the lepton micro-cloud transfers energy to the background plasma. Methods. A square micro-cloud of equally dense electrons and positrons impinges in our particle-in-cell (PIC) simulation on a spatially uniform plasma at rest. The latter consists of electrons with a temperature of 1 keV and immobile ions. The initially chargeand current neutral micro-cloud has a temperature of 100 keV and a side length of 2.5 plasma skin depths of the micro-cloud. The side length is given in the reference frame of the background plasma. The mean speed of the micro-cloud corresponds to a relativistic factor of 15, which is relevant for laboratory experiments and for relativistic astrophysical outflows. The spatial distributions of the leptons and of the electromagnetic fields are examined at several times. Results. A filamentation instability develops between the magnetic field carried by the micro-cloud and the background electrons. The electromagnetic fields, which grow from noise levels, redistribute the electrons and positrons within the cloud, which boosts the peak magnetic field amplitude. The current density and the moduli of the electromagnetic fields grow aperiodically in time and steadily along the direction that is anti-parallel to the cloud's velocity vector. The micro-cloud remains conjoined during the simulation. The instability induces an electrostatic wakefield in the background plasma. Conclusions. Relativistic clouds of leptons can generate and amplify magnetic fields even if they have a microscopic size, which implies that the underlying processes can be studied in the laboratory. The interaction of the localized magnetic field and high-energy leptons will give rise to synchrotron jitter radiation. The wakefield in the background plasma dissipates the kinetic energy of the lepton cloud. Even the fastest lepton micro-clouds can be slowed down by this collisionless mechanism. Moderately fast charge-and current neutralized lepton micro-clouds will deposit their energy close to relativistic shocks and hence they do not constitute an energy loss mechanism for the shock.

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Radiation from non-linear Weibel plasma modes

Cited by 8 publications

References 143 publications

Cosmic-ray diffusion in magnetized turbulence

Cosmic-ray diffusion in magnetized turbulence

Interstellar turbulent magnetic field generation by plasma instabilities

Particle-in-cell simulation study of the interaction between a relativistically moving leptonic micro-cloud and ambient electrons

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