KINETIC ALFVEN WAVES EXCITED BY OBLIQUE MAGNETOHYDRODYNAMIC ALFVEN WAVES IN CORONAL HOLES

Journal Article · Sun Jul 10 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/735/2/114· OSTI ID:21578385

Zhao, J S; Wu, D J ^[1]

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1. Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing (China)

Kinetic Alfven waves (KAWs) are small-scale dispersive AWs that can play an important role in particle heating and acceleration of space and solar plasmas. An excitation mechanism for KAWs created by the coupling between large-scale oblique AWs and small-scale KAWs is presented in this paper. Taking into account both the collisional and Landau damping dissipations, the results show that the net growth rate of the excited KAWs increases with their perpendicular wavenumber k{sub perpendicular} and reaches maximum at {lambda}{sub e} k{sub perpendicular} {approx} 0.3, where {lambda}{sub e} is the electron inertial length. However, for KAWs with shorter perpendicular wavelengths, the net growth rate decreases rapidly due to dissipative effects. The evaluation of the threshold amplitude of the AW implies that for KAWs with {lambda}{sub e} k{sub perpendicular} < 0.3, the relative threshold amplitude is well below 10%, which is easy to satisfy. In particular, when applying this mechanism to the case of a solar coronal hole containing a dense plume structure, our results show that KAWs with {lambda}{sub e} k{sub perpendicular} < 0.3 can be not only efficiently excited in the interplume region but also strongly dissipated in the dense plume due to the Landau damping.

• OSTI ID: 21578385
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 735; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ALFVEN WAVES
AMPLITUDES
ATMOSPHERES
DAMPING
ENERGY-LEVEL TRANSITIONS
EXCITATION
FLUID MECHANICS
HYDRODYNAMICS
HYDROMAGNETIC WAVES
LANDAU DAMPING
MAGNETOHYDRODYNAMICS
MECHANICS
PLASMA
SOLAR ATMOSPHERE
SOLAR CORONA
STELLAR ATMOSPHERES
STELLAR CORONAE
WAVELENGTHS