On the Parallel and Oblique Firehose Instability in Fluid Models

Hunana, P.; Zank, G. P.

doi:10.3847/1538-4357/aa64e3

Cited by 25 publications

(25 citation statements)

References 43 publications

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“…The oblique firehose instability is not included in our model, both because it operates at~ k k and because kinetic theory is required for its correct description (Hunana and Zank 2017). Linearly, oblique firehose fluctuations grow faster than parallel firehose fluctuations (growth rate g b D + W | | 2 i max 1 2 , as opposed to 23 The linear mirror instability can be captured relatively accurately by the LF model that we use (if the equations are solved in 2 or 3 dimensions; see section 8 of Snyder et al 1997).…”

Section: Oblique Firehose Instabilitymentioning

confidence: 99%

Amplitude limits and nonlinear damping of shear-Alfvén waves in high-beta low-collisionality plasmas

2017

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This work, which extends Squire et al. [ApJL, 830 L25 (2016)], explores the effect of self-generated pressure anisotropy on linearly polarized shear-Alfvén fluctuations in low-collisionality plasmas. Such anisotropies lead to stringent limits on the amplitude of magnetic perturbations in high-β plasmas, above which a fluctuation can destabilize itself through the parallel firehose instability. This causes the wave frequency to approach zero, "interrupting" the wave and stopping its oscillation. These effects are explored in detail in the collisionless and weakly collisional "Braginskii" regime, for both standing and traveling waves. The focus is on simplified models in one dimension, on scales much larger than the ion gyroradius. The effect has interesting implications for the physics of magnetized turbulence in the high-β conditions that are prevalent in many astrophysical plasmas.

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Section: Oblique Firehose Instabilitymentioning

confidence: 99%

Amplitude limits and nonlinear damping of shear-Alfvén waves in high-beta low-collisionality plasmas

2017

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“…For the purpose of this paper we adopt the well-known CGL framework in which not only dispersion, but also heat flux effects are entirely neglected (Chew et al 1956). Despite these simplifying assumptions, the CGL model provides a good description of some effects due to thermal pressure anisotropy at the large scales, while a proper description of the dynamics at smaller scales would best require more sophisticated fluid models that include FLR effects (Hunana & Zank 2017) or even a full kinetic treatment. Ion-acoustic Landau damping may be modeled phenomenologically by adding an appropriate drag term to the longitudinal component of the momentum equation.…”

Section: Configurationmentioning

confidence: 99%

The Parametric Instability of Alfvén Waves: Effects of Temperature Anisotropy

Tenerani

Velli

Hellinger

2017

ApJ

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We study the stability of large amplitude, circularly polarized Alfvén waves in an anisotropic plasma described by the double-adiabatic/CGL closure, and in particular the effect of a background thermal pressure anisotropy on the well-known properties of Alfvén wave parametric decay in Magnetohydrodynamics (MHD). Anisotropy allows instability over a much wider range of values of parallel plasma beta (β ) when ξ = p 0⊥ /p 0 > 1. When the pressure anisotropy exceeds a critical value, ξ ≥ ξ * with ξ * 2.7, there is a new regime in which the parametric instability is no longer quenched at high β and in the limit β 1 the growth rate becomes independent of β . In the opposite case of ξ < ξ * , the instability is strongly suppressed with increasing parallel plasma beta, similarly to the MHD case. We analyze marginal stability conditions for parametric decay in the (ξ, β ) parameter space, and discuss possible implications for Alfvénic turbulence in the solar wind. arXiv:1711.06371v1 [physics.space-ph]

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“…The CGL marginal stability threshold arises at larger pressure anisotropies than those derived from kinetic theory(Klein and Howes, 2015;Hunana and Zank, 2017), which, combined with the limited relevance of a fluid theory to a weakly collisionless system, limits this instability's relevance to the solar wind.…”

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confidence: 99%

The multi-scale nature of the solar wind

Verscharen¹,

Klein²,

Maruca³

2019

Living Rev Sol Phys

336

285

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The solar wind is a magnetized plasma and as such exhibits collective plasma behavior associated with its characteristic spatial and temporal scales. The characteristic length scales include the size of the heliosphere, the collisional mean free paths of all species, their inertial lengths, their gyration radii, and their Debye lengths. The characteristic timescales include the expansion time, the collision times, and the periods associated with gyration, waves, and oscillations. We review the past and present research into the multi-scale nature of the solar wind based on in-situ spacecraft measurements and plasma theory. We emphasize that couplings of processes across scales are important for the global dynamics and thermodynamics of the solar wind. We describe methods to measure in-situ properties of particles and fields. We then discuss the role of expansion effects, non-equilibrium distribution functions, collisions,

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On the Parallel and Oblique Firehose Instability in Fluid Models

Cited by 25 publications

References 43 publications

Amplitude limits and nonlinear damping of shear-Alfvén waves in high-beta low-collisionality plasmas

Amplitude limits and nonlinear damping of shear-Alfvén waves in high-beta low-collisionality plasmas

The Parametric Instability of Alfvén Waves: Effects of Temperature Anisotropy

The multi-scale nature of the solar wind

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