Alfvén wave evolution into magnetic filaments in 3-D space plasma

Abstract

Abstract Nonlinearities in space and astrophysical plasmas generate a set of magnetic filaments or bundles that have an incompressible sense of fluctuations and propagate highly obliquely to the mean magnetic field. Those filaments are caused by wave–wave interactions in which a large-amplitude Alfvén wave (or pump Alfvén wave) is disturbed by thermal, density fluctuations and collapses into obliquely propagating Alfvén waves at shorter wavelengths than the pump. Hybrid simulations confirm the filament excitations in the three-dimensional low-beta plasma. Alfvén waves develop into magnetic filaments on a time scale of about 300 ion gyrations. The filaments grow in a multi-channel way at various azimuthal angles around the mean magnetic field.

Keywords

• Space plasma
• Parametric instabilities
• Density fluctuation