Sebastian Lange, Felix Spanier
Particles ejected from the Sun streaming through the surrounding plasma of the solar wind are causing instabilities. These generate wave modes in a certain frequency range especially within shock regions, where particles are accelerated. The aim of this paper is the investigation of amplified Alfvenic wave modes in driven incompressible MHD turbulence. Results of different heliospheric scenarios from isotropic and anisotropic plasmas, as well as turbulence near the critical balance are shown. The energy transport of the amplified wave mode is governed by the mechanisms of diffusion, convection and dissipation of energy in wavenumber space. The strength of these effects varies with energy and wavenumber of the mode in question. Two-dimensional energy spectra of spherical k-space integration giving detailed insight into the parallel and perpendicular development are presented. The evolution of energy injected through driving shows a strong energy transfer to perpendicular wave modes. The main process at parallel wave modes is the dissipation of energy in wavenumber space. The generation of higher harmonics along the parallel k-axis is observed. We find evidence for a critical balance in our simulations.
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http://arxiv.org/abs/1209.0659
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