The Propagation and Anisotropy of Cosmic Rays. I. Theory for Steady Streaming

Wentzel, Donat G.

doi:10.1086/149965

Cited by 85 publications

(51 citation statements)

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“…Note that the backward waves are damped at the same rate than the forward waves are amplified. The original calculation has been done by Lerche (1967), Wentzel (1969) and used in the theory of cosmic ray transport by Skilling (1975), then by McKenzie & Völk (1982) for the excitation of turbulence upstream of a shock. Hereafter we will assume for simplicity ε = 0, the value of this parameter will be discussed in Paper II.…”

Section: The Resonant Regime Of the Instabilitymentioning

confidence: 99%

“…Often the turbulent field spectrum and intensity are arbitrarily prescribed, assuming that it has been built by the ambient medium independently of the shock acceleration process. However Lerche (1967), Wentzel (1969) have argued for a long time that the development of an anisotropy of the cosmic ray distribution function triggers an instability upstream of the shock. McKenzie & Völk (1982) have investigated the consequences of this phenomenon in the energy budget of the shock, in particular, with respect to the efficiencies of conversion of the kinetic energy into thermal, turbulent magnetic and cosmic ray energies.…”

Section: Introductionmentioning

confidence: 99%

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Turbulence and particle acceleration in collisionless supernovae remnant shocks

Pelletier¹,

Lemoine²,

Marcowith³

2006

A&A

102

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This paper investigates the nature of the MHD turbulence excited by the streaming of accelerated cosmic rays in a shock wave precursor. The two recognised regimes (non-resonant and resonant) of the streaming instability are taken into account. We show that the non-resonant instability is very efficient and saturates through a balance between its growth and non-linear transfer. The cosmicray resonant instability then takes over and is quenched by advection through the shock. The level of turbulence is determined by the non-resonant regime if the shock velocity V sh is larger than a few times ξ CR c, where ξ CR is the ratio of the cosmic-ray pressure to the shock kinetic energy. The instability determines the dependence of the spectrum with respect to k (wavenumbers along the shock normal). The transverse cascade of Alfvén waves simultaneously determines the dependence in k ⊥ . We also study the redistribution of turbulent energy between forward and backward waves, which occurs through the interaction of two Alfvén and one slow magnetosonic wave. Eventually the spectra at the longest wavelengths are found almost proportional to k −1 . Downstream, anisotropy is further enhanced through the compression at shock crossing.

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Section: The Resonant Regime Of the Instabilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Turbulence and particle acceleration in collisionless supernovae remnant shocks

Pelletier¹,

Lemoine²,

Marcowith³

2006

A&A

102

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“…A collection of particles with a high enough density cannot stream along a magnetic field much faster than the Alfvén speed because they generate magnetic irregularities that scatter them (Lerche 1967;Wentzel 1968aWentzel , 1969Kulsrud & Pearce 1969;Tademaru 1969). The growth rate of the instability at wavenumber k for isotropic wave generation is (Cesarsky 1980) …”

Section: Generation Of Turbulence By Cosmic Raysmentioning

confidence: 99%

Interstellar Turbulence II: Implications and Effects

Scalo

Elmegreen

2004

Annu. Rev. Astron. Astrophys.

308

157

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Interstellar turbulence has implications for the dispersal and mixing of the elements, cloud chemistry, cosmic ray scattering, and radio wave propagation through the ionized medium. This review discusses the observations and theory of these effects. Metallicity fluctuations are summarized, and the theory of turbulent transport of passive tracers is reviewed. Modeling methods, turbulent concentration of dust grains, and the turbulent washout of radial abundance gradients are discussed. Interstellar chemistry is affected by turbulent transport of various species between environments with different physical properties and by turbulent heating in shocks, vortical dissipation regions, and local regions of enhanced ambipolar diffusion. Cosmic rays are scattered and accelerated in turbulent magnetic waves and shocks, and they generate turbulence on the scale of their gyroradii. Radio wave scintillation is an important diagnostic for small scale turbulence in the ionized medium, giving information about the power spectrum and amplitude of fluctuations. The theory of diffraction and refraction is reviewed, as are the main observations and scintillation regions.

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“…This has caused controversies since the classical work by Parker (1965). CRs can induce and are influenced by two instabilities: (a) streaming instability (Wentzel 1969(Wentzel , 1974, widely discussed in the CR literature and frequently referred to as the source of the postulated scattering "slab" , i.e. with k B Alfvenic component, and (b) the anisotropic pressure kinetic gyroresonance instability (see Mikhailovskii 1975, Gary 1993, Kulsrud 2004 and refs.…”

Section: Modification Of Turbulence By Cosmic Raysmentioning

confidence: 99%

Properties and Selected Implications of Magnetic Turbulence for Interstellar Medium, Local Bubble and Solar Wind

Lazarían¹,

Beresnyak²,

Yan³

et al. 2008

From the Outer Heliosphere to the Local Bubble

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Astrophysical fluids, including interstellar and interplanetary medium, are magnetized and turbulent. Their appearance, evolution, and overall properties are determined by the magnetic turbulence that stirs it. We argue that examining magnetic turbulence at a fundamental level is vital to understanding many processes. A point that frequently escapes the attention of researchers is that magnetic turbulence cannot be confidently understood only using "brute force" numerical approaches. In this review we illustrate this point on a number of examples, including intermittent heating of plasma by turbulence, interactions of turbulence with cosmic rays and effects of turbulence on the rate of magnetic reconnection. We show that the properties of magnetic turbulence may vary considerably in various environments, e.g. imbalanced turbulence in solar wind differs from balanced turbulence and both of these differ from turbulence in partially ionized gas. Appealing for the necessity of more observational data on magnetic fields, we discuss a possibility of studying interplanetary turbulence using alignment of Sodium atoms in the tail of comets.

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The Propagation and Anisotropy of Cosmic Rays. I. Theory for Steady Streaming

Cited by 85 publications

References 0 publications

Turbulence and particle acceleration in collisionless supernovae remnant shocks

Turbulence and particle acceleration in collisionless supernovae remnant shocks

Interstellar Turbulence II: Implications and Effects

Properties and Selected Implications of Magnetic Turbulence for Interstellar Medium, Local Bubble and Solar Wind

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