Alfvénic Turbulence in the Extended Solar Corona: Kinetic Effects and Proton Heating

By S. Cranmer, A. A. Ballegooijen. 2003

183 citations recorded by the source corpus.

We present a model of magnetohydrodynamic (MHD) turbulence in the extended solar corona that contains the effects of collisionless dissipation and anisotropic particle heating. Recent observations have shown that preferential heating and acceleration of positive ions occur in the first few solar radii of the high-speed solar wind. Measurements made by the Ultraviolet Coronagraph Spectrometer aboard SOHO have revived interest in the idea that ions are energized by the dissipation of ion cyclotron resonant waves, but such high-frequency (i.e., small-wavelength) fluctuations have not been observed. A turbulent cascade is one possible way of generating small-scale fluctuations from a preexisting population of low-frequency MHD waves. We model this cascade as a combination of advection and diffusion in wavenumber space. The dominant spectral transfer occurs in the direction perpendicular to the background magnetic field. As expected from earlier models, this leads to a highly anisotropic fluctuation spectrum with a rapidly decaying tail in the parallel wavenumber direction. The wave power that decays to high enough frequencies to become ion cyclotron resonant depends on the relative strengths of advection and diffusion in the cascade. For the most realistic values of these parameters, however, there is insufficient power to heat protons and heavy ions. The dominant oblique fluctuations (with dispersion properties of kinetic Alfvén waves) undergo Landau damping, which implies strong parallel electron heating. We discuss the probable nonlinear evolution of the electron velocity distributions into parallel beams and discrete phase-space holes (similar to those seen in the terrestrial magnetosphere), which can possibly heat protons via stochastic interactions.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/61c3a63b4ee3150fcaa34f29250a2f8f7dd360d8

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In Astronomy and Astrophysics

Citations in the corpus

On the Generation, Propagation, and Reflection of Alfvén Waves from the Solar Photosphere to the Distant Heliosphere (2004, background): “Cranmer & Ballegooijen (2003), following the general development of RMHD anisotropic cascade theory, assumed that the turbulence eventually leads to a state of complete mixing between the inward and outward modes, and thus U+ = U− = Utot/2.”
A Model of Turbulence in Magnetized Plasmas: Implications for the Dissipation Range in the Solar Wind (2007, background): “In the spirit of a long line of previous investigations [Hollweg, 1986; Isenberg, 1990; Li et al., 1999; Matthaeus et al., 1999; Dmitruk et al., 2001, 2002; Cranmer and van Ballegooijen, 2003, 2005; Cranmer et al., 2007], we briefly address what our cascade model predicts for ion heating in the so”
Electron and proton heating by solar wind turbulence (2009, background): “Possibilities are kinetic Alfvén waves [Leamon et al., 1998; Cranmer and van Ballegooijen, 2003; Bale et al., 2005; Gary and Borovsky , 2008], whistlers [Gary et al., 2008], and nonlinear dissipation in current sheets [Sundkvist et al., 2007], to name a few.”
DEPENDENCE OF SOLAR-WIND POWER SPECTRA ON THE DIRECTION OF THE LOCAL MEAN MAGNETIC FIELD (2009, background): “These two distinct approaches are now described in detail.”