Evidence for monochromatic unstable Weibel modes in asymmetric counterstreaming pair plasmas

Tautz, R. C.; Sakai, Jun–ichi; Lerche, I.

doi:10.1007/s10509-007-9496-6

Cited by 14 publications

(6 citation statements)

References 44 publications

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“…General results on the filamentation instability have thus been obtained by Tzoufras et al 128 in the case of separable nonrelativistic distributions. Likewise, the Weibel instability has been investigated by Tautz et al, [129][130][131][132] who found that the unstable k spectrum may be discrete instead of continuous under certain conditions.…”

Section: -6mentioning

confidence: 99%

Multidimensional electron beam-plasma instabilities in the relativistic regime

2010

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The interest in relativistic beam-plasma instabilities has been greatly rejuvenated over the past two decades by novel concepts in laboratory and space plasmas. Recent advances in this long-standing field are here reviewed from both theoretical and numerical points of view. The primary focus is on the two-dimensional spectrum of unstable electromagnetic waves growing within relativistic, unmagnetized, and uniform electron beam-plasma systems. Although the goal is to provide a unified picture of all instability classes at play, emphasis is put on the potentially dominant waves propagating obliquely to the beam direction, which have received little attention over the years. First, the basic derivation of the general dielectric function of a kinetic relativistic plasma is recalled. Next, an overview of two-dimensional unstable spectra associated with various beam-plasma distribution functions is given. Both cold-fluid and kinetic linear theory results are reported, the latter being based on waterbag and Maxwell-Jüttner model distributions. The main properties of the competing modes ͑developing parallel, transverse, and oblique to the beam͒ are given, and their respective region of dominance in the system parameter space is explained. Later sections address particle-in-cell numerical simulations and the nonlinear evolution of multidimensional beam-plasma systems. The elementary structures generated by the various instability classes are first discussed in the case of reduced-geometry systems. Validation of linear theory is then illustrated in detail for large-scale systems, as is the multistaged character of the nonlinear phase. Finally, a collection of closely related beam-plasma problems involving additional physical effects is presented, and worthwhile directions of future research are outlined.

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Section: -6mentioning

confidence: 99%

Multidimensional electron beam-plasma instabilities in the relativistic regime

2010

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“…Instabilities of relativistic pair plasma beams have been already studied using kinetic plasma simulations (Silva et al 2003;Tautz et al 2007;Cottrill et al 2008;López et al 2014;Lòpez et al 2015;D'Angelo et al 2015;Shukla et al 2015). Only a few studies, however, have assumed relativistic covariant Maxwell-Jüttner distributions, and if so, they were mostly considered to be three-dimensional (Bret et al 2008(Bret et al , 2010.…”

Section: Introductionmentioning

confidence: 99%

Refining pulsar radio emission due to streaming instabilities: Linear theory and PIC simulations in a wide parameter range

Manthei

Benáček

Muñoz

et al. 2021

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Context. Several important mechanisms that explain coherent pulsar radio emission rely on streaming (or beam) instabilities of the relativistic pair plasma in a pulsar magnetosphere. However, it is still not clear whether the streaming instability by itself is sufficient to explain the observed coherent radio emission. Due to the relativistic conditions that are present in the pulsar magnetosphere, kinetic instabilities could be quenched. Moreover, uncertainties regarding specific model-dependent parameters impede conclusions concerning this question. Aims. We aim to constrain the possible parameter range for which a streaming instability could lead to pulsar radio emission, focusing on the transition between strong and weak beam models, beam drift speed, and temperature dependence of the beam and background plasma components. Methods. We solve a linear relativistic kinetic dispersion relation appropriate for pulsar conditions in a more general way than in previous studies, considering a wider parameter range. In doing so, we provide a theoretical prediction of maximum and integrated growth rates as well as of the fractional bandwidth of the most unstable waves for the investigated parameter ranges. The analytical results are validated by comparison with relativistic kinetic particle-in-cell (PIC) numerical simulations. Results. We obtain growth rates as a function of background and beam densities, temperatures, and streaming velocities while finding a remarkable agreement of the linear dispersion predictions and numerical simulation results in a wide parameter range. Monotonous growth is found when increasing the beam-to-background density ratio. With growing beam velocity, the growth rates firstly increase, reach a maximum and decrease again for higher beam velocities. A monotonous dependence on the plasma temperatures is found, manifesting in an asymptotic behaviour when reaching colder temperatures. A simultaneous change of both temperatures proves not to be a mere linear superposition of both individual temperature dependences. We show that the generated waves are phase-coherent by calculating the fractional bandwidth. Conclusions. Plasma streaming instabilities of the pulsar pair plasma can efficiently generate coherent radio signals if the streaming velocity is ultra-relativistic with Lorentz factors in the range 13 < γ < 300, if the background and beam temperatures are small enough (inverse temperatures ρ0; ρ1 ≥ 1, i.e., T0; T1 ≤ 6 × 109), and if the beam-to-background plasma density ratio n1/(γbn0) exceeds 10−3, which means that n1/n0 has to be between 1.3 and 20% (depending on the streaming velocity).

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“…It is then followed by a significant decrease and shift into a left‐handed polarized mode, where the shifting point in ℜ(ω) = 0 corresponds to the purely growing Weibel instability, ℑ(ω) > 0. This shifting point, however, corresponds to an isolated Weibel mode (Tautz et al 2006; Tautz & Lerche 2007a; Tautz, Sakai & Lerche 2007), because only at one single wavenumber is there an aperiodic Weibel mode. All neighbouring waves do have a real frequency part, however small, and thus propagate away with time.…”

Section: Numerical Solutionsmentioning

confidence: 99%

Counterstreaming magnetized plasmas with kappa distributions - I. Parallel wave propagation

Lazar

Schlickeiser

Poedts

et al. 2008

Monthly Notices of the Royal Astronomical Society

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Non‐thermal particle distributions of kappa type are frequently encountered in collisionless plasmas from space. The electromagnetic emissions coming from space are believed to originate in the counterstreaming structures of plasmas, which are ubiquitous in many astrophysical systems. Here, we investigate the dispersion properties and the stability of a counterstreaming plasma system with temperature anisotropies modelled by a bi‐kappa distribution function. The numerical evaluation of parallel modes shows growth rates lower than those obtained for Maxwellian plasmas, with a strong dependence on the spectral index of the particle distribution function. If all other parameters are known, measuring the instability growth time can provide a possible tool for the determination of the spectral index κ.

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Evidence for monochromatic unstable Weibel modes in asymmetric counterstreaming pair plasmas

Cited by 14 publications

References 44 publications

Multidimensional electron beam-plasma instabilities in the relativistic regime

Multidimensional electron beam-plasma instabilities in the relativistic regime

Refining pulsar radio emission due to streaming instabilities: Linear theory and PIC simulations in a wide parameter range

Counterstreaming magnetized plasmas with kappa distributions - I. Parallel wave propagation

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