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Nonresonant absorption of shear AlfvÉn waves
Author(s) -
Strauss H. R.
Publication year - 1991
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/90gl02047
Subject(s) - physics , chromosphere , corona (planetary geology) , absorption (acoustics) , magnetic field , solar wind , coronal hole , wave propagation , mechanics , nanoflares , computational physics , shear (geology) , geophysics , coronal mass ejection , optics , materials science , quantum mechanics , astrobiology , venus , composite material
Resonant absorption of shear Alfvén waves is thought to be a likely candidate to explain heating of the solar corona and acceleration of the solar wind. A difficulty with the theory is that the absorption process is slow. It takes a long time ∼ S ⅓ τ A , where S ≫ 1 is the magnetic Reynolds number, and τ A a typical Alfvén wave propagation time, for wave fronts to steepen sufficiently for absorption to occur. Moreover, heating occurs in a very thin layer whose width scales as S −⅓ . A faster absorption mechanism is nonresonant absorption by compressional viscosity, in a curved magnetic field. Heating is nonresonant and is not localized to a narrow layer. The effect could be quite important where the solar coronal magnetic field is strongly curved, in the chromosphere. It could also be important on open field lines in the upper corona, where the compressional viscosity is large. It might imply that a significant part of outgoing Alfvén waves are absorbed in the corona.