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

Abstract

With the diffusion approximation, we study the cascade and damping of Alfvén-cyclotron fluctuations in solar plasmas numerically. Motivated by wave-wave couplings and nonlinear effects, we test several forms of the diffusion tensor. For a general locally anisotropic and inhomogeneous diffusion tensor in the wave vector space, the turbulence spectrum in the inertial range can be fitted with power-laws with the power-law index varying with the wave propagation direction. For several locally isotropic but inhomogeneous diffusion coefficients, the steady-state turbulence spectra are nearly isotropic in the absence of damping and can be fitted by a single power-law function. However, the energy flux is strongly polarized due to the inhomogeneity that leads to an anisotropic cascade. Including the anisotropic thermal damping, the turbulence spectrum cuts off at the wave numbers, where the damping rates become comparable to the cascade rates. The combined anisotropic effects of cascade and damping make this cutoff wave number dependent on the wave propagation direction, and the propagation direction integrated turbulence spectrum resembles a broken power-law, which cuts off at the maximum of the cutoff wave numbers or the ${}^4$He cyclotron frequency. Taking into account the Doppler effects, the model can naturally reproduce the broken power-law wave spectra observed in the solar wind and predicts that a higher break frequency is aways accompanied with a greater spectral index change that may be caused by the increase of the Alfvén Mach number, the reciprocal of the plasma beta, and/or the angle between the solar wind velocity and the mean magnetic field. These predictions can be tested by future observations.

References in corpus (28)

• A weak turbulence theory for incompressible MHD
• Compressible Magnetohydrodynamic Turbulence: mode coupling, scaling relations, anisotropy, new regime and astrophysical implications
• Measurement of the electric fluctuation spectrum of magnetohydrodynamic turbulence
• On the Generation, Propagation, and Reflection of Alfven Waves from the Solar Photosphere to the Distant Heliosphere
• Simulations of MHD Turbulence in a Strongly Magnetized Medium
• Impulsive phase flare energy transport by large-scale Alfven waves and the electron acceleration problem
• A Model of Turbulence in Magnetized Plasmas: Implications for the Dissipation Range in the Solar Wind
• Kinetic Simulations of Magnetized Turbulence in Astrophysical Plasmas
• Scattering of Cosmic Rays by Magnetohydrodynamic Interstellar Turbulence
• Stochastic Acceleration of Electrons and Protons. I. Acceleration by Parallel Propagating Waves
• Alfvenic Turbulence in the Extended Solar Corona: Kinetic Effects and Proton Heating
• Wave damping by MHD turbulence and its effect upon cosmic ray propagation in the ISM
• Wave turbulence in incompressible Hall MHD
• Kolmogorov-Burgers Model for Star Forming Turbulence
• Weak compressible magnetohydrodynamic turbulence in the solar corona
• Spectral Properties of Compressible Magnetohydrodynamic Turbulence from Numerical Simulations
• The Generation of Magnetic Fields Through Driven Turbulence
• Stochastic Acceleration of ${}^3$He and ${}^4$He in Solar Flares by Parallel Propagating Plasma Waves: General Results
• Particle Acceleration by MHD Turbulence
• Stochastic Acceleration of 3He and 4He by Parallel Propagating Plasma Waves
• Damping of MHD turbulence in Solar Flares
• Particle Acceleration by Fast Modes in Solar Flares
• Stochastic Electron Acceleration in Shell-Type Supernova Remnants
• Stochastic Electron Acceleration in Shell-Type Supernova Remnants II
• Anisotropic weak turbulence of Alfven waves in collisionless astrophysical plasmas
• Wave Decay in MHD Turbulence
• Correlation between Flux and Spectral Index during Flares in Sagittarius A*
• Dissipation-Scale Turbulence in the Solar Wind

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• Plasmoid Ejections and Loop Contractions in an Eruptive M7.7 Solar Flare: Evidence of Particle Acceleration and Heating in Magnetic Reconnection Outflows
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• A Kinetic Alfven wave cascade subject to collisionless damping cannot reach electron scales in the solar wind at 1 AU
• Kinetic cascade beyond magnetohydrodynamics of solar wind turbulence in two-dimensional hybrid simulations
• Proton, Electron, and Ion Heating in the Fast Solar Wind from Nonlinear Coupling Between Alfvenic and Fast-Mode Turbulence
• Sources of the Radio Background Considered
• Ensemble Simulations of Proton Heating in the Solar Wind via Turbulence and Ion Cyclotron Resonance
• The dissipation of solar wind turbulent fluctuations at electron scales
• Resonance Broadening and Heating of Charged Particles in Magnetohydrodynamic Turbulence
• Derivation of Stochastic Acceleration Model Characteristics for Solar Flares From RHESSI Hard X-Ray Observations
• Non-modal approach to linear theory: marginal stability and the dissipation of turbulent fluctuations
• Stochastic Electron Acceleration in the TeV Supernova Remnant RX J1713.7-3946: The High-Energy Cut-off
• Relativistic particle acceleration in developing Alfvén turbulence
• Elementary Energy Release Events in Flaring Loops: Effects of Chromospheric Evaporation on X-rays
• Transport of Cosmic ray electrons from 1 AU to the Sun
• Kappa-Maxwellian electrons and Bi-Maxwellian protons in a two-fluid model for fast solar wind