Dissipation of the Perpendicular Turbulent Cascade in the Solar Wind

Markovskii, S. A.; Vasquez, Bernard J.; Smith, Charles W.; Hollweg, Joseph V.

doi:10.1086/499398

Cited by 84 publications

(73 citation statements)

References 68 publications

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“…These effects are associated typically with coherent structures such as magnetic structures. Indeed, intense kinetic activity is often found in the general proximity to strong gradients, including not only magnetic, but also strong density and velocity gradients [16,[55][56][57][58][59][60]. In particular, Refs.…”

Section: A Energy Conversion Related To Coherent Structuresmentioning

confidence: 99%

“…The turbulence in most astrophysical contexts, on the other hand, is typically of weak collisionality, and frequently modeled as collisionless, and thus collisional (viscous and resistive) dissipation at small scales cannot emerge immediately. While various specific processes may contribute to conversion of energy from fields into random degrees of freedom, for example, wave-particle interactions (WPI) [16][17][18][19][20] and processes associated with coherent structures (CS) [21][22][23][24][25][26], are likely ingredients, but nevertheless an explicit dissipation function cannot at this moment be defined clearly for a collisionless system.…”

Section: Introductionmentioning

confidence: 99%

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Energy transfer, pressure tensor, and heating of kinetic plasma

et al. 2017

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Kinetic plasma turbulence cascade spans multiple scales ranging from macroscopic fluid flow to sub-electron scales. Mechanisms that dissipate large scale energy, terminate the inertial range cascade and convert kinetic energy into heat are hotly debated. Here we revisit these puzzles using fully kinetic simulation. By performing scale-dependent spatial filtering on the Vlasov equation, we extract information at prescribed scales and introduce several energy transfer functions. This approach allows highly inhomogeneous energy cascade to be quantified as it proceeds down to kinetic scales. The pressure work, − (P · ∇) · u, can trigger a channel of the energy conversion between fluid flow and random motions, which is a collision-free generalization of the viscous dissipation in collisional fluid. Both the energy transfer and the pressure work are strongly correlated with velocity gradients.

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Section: A Energy Conversion Related To Coherent Structuresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Energy transfer, pressure tensor, and heating of kinetic plasma

et al. 2017

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“…Since both the Kolmogorov and IK cascade timescales (∝ k −2/3 and k −1/2 , respectively) decline with increasing k (or decreasing spatial scales) more slowly than the periods of MHD waves (∝ k −1 ), the turbulence may be better described as spectra of waves at higher values of ks (smaller spatial scales), which play a critical role in the energizing of low-energy background particles. However, at such high values of ks one may be stepping beyond the MHD regime and must use more complex dispersion relations to take into account the kinetic effects and the anisotropy of the turbulence properly (Leamon et al 1998;Markovskii et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Cascade and Damping of Alfvén-Cyclotron Fluctuations: Application to Solar Wind Turbulence

Jiang

Liu

Petrosian

2009

ApJ

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It is well recognized that the presence of magnetic fields will lead to anisotropic energy cascade and dissipation of astrophysical turbulence. With the diffusion approximation and linear dissipation rates, we study the cascade and damping of Alfvén-cyclotron fluctuations in solar plasmas numerically for two diagonal diffusion tensors, one (isotropic) with identical components for the parallel and perpendicular directions (with respect to the magnetic field) and one with different components (nonisotropic). It is found that for the isotropic case the steady-state turbulence spectra are nearly isotropic in the inertial range and can be fitted by a single power-law function with a spectral index of −3/2, similar to the Iroshnikov-Kraichnan phenomenology, while for the nonisotropic case the spectra vary greatly with the direction of propagation. The energy fluxes in both cases are much higher in the perpendicular direction than in the parallel direction due to the angular dependence (or inhomogeneity) of the components. In addition, beyond the MHD regime the kinetic effects make the spectrum softer at higher wavenumbers. In the dissipation range the turbulence spectrum cuts off at the wavenumber, where the damping rate becomes comparable to the cascade rate, and the cutoff wavenumber changes with the wave propagation direction. The angle-averaged turbulence spectrum of the isotropic model resembles a broken power law, which cuts off at the maximum of the cutoff wavenumbers or the 4 He cyclotron frequency. Taking into account the Doppler effects, the model naturally reproduces the broken power-law turbulence spectra observed in the solar wind and predicts that a higher break frequency always comes along with a softer dissipation range spectrum that may be caused by the increase of the turbulence intensity, the reciprocal of the plasma β p , and/or the angle between the solar wind velocity and the mean magnetic field. These predictions can be tested by detailed comparisons with more accurate observations.

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“…The difficulty is to explain how the energy gets into the high-frequency waves: on small scales, the energy is known to be at lower frequencies (Howes et al 2006). Among the possible mechanisms for transferring the energy to the high frequencies (the sources of coronal heating) are reconnection (e.g., Matthaeus et al 2003), heat-flux-driven plasma instabilities (e.g., Markovskii et al 2006), and MHD turbulence (e.g., Matthaeus et al 1999;Chandran 2005). Rappazzo et al (2007) performed high-resolution simulations of MHD turbulence in a coronal loop described by reduced MHD equations.…”

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confidence: 99%

Alfvén Profile in the Lower Corona: Implications for Shock Formation

Evans

Opher

Manchester

et al. 2008

Astrophysical Journal

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Observations of type II radio bursts and energetic electron events indicate that shocks can form at 1Y3 solar radii and are responsible for the GeV nucleon À1 energies observed in ground level solar energetic particle (SEP) events. Here we provide the first study of the lower corona produced from 10 state-of-the-art models. In particular, we look to the Alfvén speed profiles as the criterion for shock formation, independent of exciting agent (e.g., flares and CMEs). Global magnetohydrodynamic models produce Alfvén speed profiles that are in conflict with observations: (1) multiple SEP events are observed with a single exciting agent, but most profiles are missing the ''hump'' required to form multiple shocks; and (2) few slow CMEs cause large SEP events, but most profiles drop very quickly, allowing all slow CMEs to drive strong shocks to form between 1 and 3 R . Simplified Alfvén wave-driven wind models have steeper profiles, but are still in disagreement with multiple shock formation. Only studies that include Alfvén waves with physically based damping are in agreement with observations. This implies the results of these one-dimensional local studies must be included in global models before we can study shock formation in the lower corona. Subject headingg s: MHD -shock waves -solar wind -Sun: corona -Sun: coronal mass ejections (CMEs) -Sun: magnetic fields

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Dissipation of the Perpendicular Turbulent Cascade in the Solar Wind

Cited by 84 publications

References 68 publications

Energy transfer, pressure tensor, and heating of kinetic plasma

Energy transfer, pressure tensor, and heating of kinetic plasma

Cascade and Damping of Alfvén-Cyclotron Fluctuations: Application to Solar Wind Turbulence

Alfvén Profile in the Lower Corona: Implications for Shock Formation

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