The Parametric Decay Instability of Alfvén Waves in Turbulent Plasmas and the Applications in the Solar Wind

Shi, Mijie; Li, Hui; Xiao, Chijie; Wang, Xiaogang

doi:10.3847/1538-4357/aa71b6

Cited by 25 publications

(25 citation statements)

References 43 publications

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“…The growth rate of Mode 2 is estimated to be γ/Ω i = 0.0022 in the interval 600 < tΩ i < 1100, smaller than the PDI growth rate in a quiescent plasma, which is γ/Ω i = 0.0088 (measured in Run 0, a simulation without background turbulence). The result confirms the reduction of PDI growth rate by turbulence found in previous MHD simulations (Shi et al 2017). Since Mode 1 and 2 are Alfvén modes, their density fluctuation levels remain nearly unchanged.…”

Section: Resultssupporting

confidence: 91%

Parametric Decay Instability and Dissipation of Low-frequency Alfvén Waves in Low-beta Turbulent Plasmas

Guo

et al. 2018

ApJ

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Evolution of the parametric decay instability (PDI) of a circularly polarized Alfvén wave in a turbulent low-beta plasma background is investigated using 3D hybrid simulations. It is shown that the turbulence reduces the growth rate of PDI as compared to the linear theory predictions, but PDI can still exist. Interestingly, the damping rate of ion acoustic mode (as the product of PDI) is also reduced as compared to the linear Vlasov predictions. Nonetheless, significant heating of ions in the direction parallel to the background magnetic field is observed due to resonant Landau damping of the ion acoustic waves. In low-beta turbulent plasmas, PDI can provide an important channel for energy dissipation of low-frequency Alfvén waves at a scale much larger than the ion kinetic scales, different from the traditional turbulence dissipation models.

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Section: Resultssupporting

confidence: 91%

Parametric Decay Instability and Dissipation of Low-frequency Alfvén Waves in Low-beta Turbulent Plasmas

Guo

et al. 2018

ApJ

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“…A complex mixture of compressible and incompressible fluctuations is involved in the solar wind turbulence, with compressible fluctuations usually as a minor but significant component. The compressibility of solar wind fluctuations usually manifests itself as a slow-mode nature (Burlaga 1968;Tu & Marsch 1994;Hnat et al 2005;Kellogg & Horbury 2005;Yao et al 2011Yao et al , 2013aYao et al , 2013bHowes et al 2012;Klein et al 2012;Zhao et al 2014;He et al 2015;Narita & Marsch 2015;Shi et al 2015Shi et al , 2017Wang et al 2016;Verscharen et al 2017). As the quasi-parallel slow-mode magnetosonic waves are believed to be strongly damped, e.g., can be damped to be less than 1/e of original amplitude within three wavelengths of propagation in the solar corona (Ruan et al 2016), the slow-mode-like compressible fluctuations have often been interpreted as pressure-balanced structures (PBSs; Tu & Marsch 1995).…”

Section: Introductionmentioning

confidence: 99%

Coexistence of Slow-mode and Alfvén-mode Waves and Structures in 3D Compressive MHD Turbulence

Yang

Zhang

et al. 2018

ApJ

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The compressible component of solar wind turbulence displays a slow-mode feature. However, the nature of the slow-mode fluctuations remain open. In this work, based on numerical simulations of the driven compressible magnetohydrodynamic (MHD) turbulence with a uniform mean magnetic field, we use polarization of the MHD modes to decompose turbulent velocity and magnetic fields into Alfvén modes, slow modes, and fast modes. The numerical results with different cross-helicity, plasma beta β, and Alfvén Mach number note that fast modes are a marginal component among the three decomposed modes, and the compressible component of the MHD turbulence behaves mainly as the slow modes. Both of the decomposed slow modes and Alfvén modes exhibit a Kolmogorov-like power-law spectrum and evident anisotropy, with wavevectors mainly distributing around the directions perpendicular to the uniform mean field. For the first time, it is found that the propagating slow magnetosonic waves as well as the non-propagating slow-mode structures are combined to contribute to the compressible fluctuations, and the propagating Alfvén waves as well as the non-propagating Alfvén-mode structures coexist for the non-compressible fluctuations. However, there is unlikely a one-to-one match between the identified slow waves and Alfvén waves, or between the identified slow-mode structures and Alfvén-mode structures. These findings provide a new perspective on our understanding of the compressible and noncompressible fluctuations.

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“…Specifically, it is likely that a critically balanced cascade with nonlinear interactions occuring on order the wave propagation time could disrupt parametric coupling between Alfvénic and slow-mode like fluctuations Schekochihin et al (2009). This idea has been touched upon in Shi et al (2017), in which reduced PDI growth rates were found in a turbulent plasma. Our future work looks to address the physics of parametric coupling in a turbulent plasma and to compare the growth of compressive modes through PDI versus their recycling through a turbulent cascade.…”

Section: Discussionmentioning

confidence: 99%

Density Fluctuations in the Solar Wind Driven by Alfvén Wave Parametric Decay

Bowen

Badman

Hellinger

et al. 2018

ApJL

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Measurements and simulations of inertial compressive turbulence in the solar wind are characterized by anticorrelated magnetic fluctuations parallel to the mean field and density structures. This signature has been interpreted as observational evidence for non-propagating pressure balanced structures (PBS), kinetic ion acoustic waves, as well as the MHD slow-mode. Given the high damping rates of parallel propagating compressive fluctuations, their ubiquity in satellite observations is surprising, and suggestive of a local driving process. One possible candidate for the generation of compressive fluctuations in the solar wind is Alfvén wave parametric instability. Here we test the parametric decay process as a source of compressive waves in the solar wind by comparing the collisionless damping rates of compressive fluctuations with growth rates of the parametric decay instability daughter waves. Our results suggest that generation of compressive waves through parametric decay is overdamped at 1 AU, but that the presence of slow-mode like density fluctuations is correlated with the parametric decay of Alfvén waves.

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The Parametric Decay Instability of Alfvén Waves in Turbulent Plasmas and the Applications in the Solar Wind

Cited by 25 publications

References 43 publications

Parametric Decay Instability and Dissipation of Low-frequency Alfvén Waves in Low-beta Turbulent Plasmas

Parametric Decay Instability and Dissipation of Low-frequency Alfvén Waves in Low-beta Turbulent Plasmas

Coexistence of Slow-mode and Alfvén-mode Waves and Structures in 3D Compressive MHD Turbulence

Density Fluctuations in the Solar Wind Driven by Alfvén Wave Parametric Decay

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