Parametric decay of linearly polarized shear Alfvén waves in oblique propagation: One and two‐dimensional hybrid simulations
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- Lorenzo Matteini
- Lesia Observatoire de Paris Paris France
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- Simone Landi
- Dipartimento di Fisica e Astronomia Università degli Studi di Firenze Florence Italy
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- Luca Del Zanna
- Dipartimento di Fisica e Astronomia Università degli Studi di Firenze Florence Italy
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- Marco Velli
- Dipartimento di Fisica e Astronomia Università degli Studi di Firenze Florence Italy
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- Petr Hellinger
- Astronomy Institute Academy of Sciences of Czech Republic Prague Czech Republic
説明
<jats:p>The parametric instability of a monochromatic shear Alfvén wave in oblique propagation with respect the ambient magnetic field is investigated in a kinetic regime, performing one‐dimensional (1‐D) and two‐dimensional (2‐D) hybrid simulations. The parallel component of the mother wave is found to be subject to a parametric decay which excites an ion‐acoustic wave along the magnetic field and a backward propagating daughter shear Alfvén wave, as in the instability for a purely parallel mother wave. At the same time, the acoustic wave generation supports the acceleration of a velocity beam in the ion distribution function, due to the non‐linear trapping of protons. Moreover, the instability leads to the generation of broad band oblique spectra of coupled Alfvénic and compressive modes with variable perpendicular wavevectors, and, as a consequence, the magnetic field after saturation is characterized by a strong transverse modulation.</jats:p>
収録刊行物
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- Geophysical Research Letters
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Geophysical Research Letters 37 (20), L20101-, 2010-10
American Geophysical Union (AGU)