Premium
Parametric decay of linearly polarized shear Alfvén waves in oblique propagation: One and two‐dimensional hybrid simulations
Author(s) -
Matteini Lorenzo,
Landi Simone,
Del Zanna Luca,
Velli Marco,
Hellinger Petr
Publication year - 2010
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 - 10.1029/2010gl044806
Subject(s) - physics , instability , magnetic field , wave propagation , computational physics , shear (geology) , perpendicular , oblique case , mechanics , optics , geometry , materials science , mathematics , quantum mechanics , linguistics , philosophy , composite material
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.