2010/09/24 by Eckart Marsch, ECKART MARSCH, Daniel Verscharen +1 · 15 citations
Physics and Astronomy · #Dissipation #Dust and Plasma Wave Phenomena #Electric field #Energy cascade #Ion acoustic wave #Ionosphere and magnetosphere dynamics #Longitudinal wave #Magnetic energy #Magnetic field #Mechanical wave #Plasma #Solar and Space Plasma Dynamics #Transverse wave #astro-ph.SR #physics.plasm-ph #physics.space-ph
paper · pdf · doi:10.1017/s0022377810000541
published in Journal of Plasma Physics 77(3), 385-403 (Cambridge University Press) · 19 pages, accepted by Journal of Plasma Physics, in press, Link: http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=7908294&fulltextType=RA&fileId=S0022377810000541
openalex publication_date 2010/09/24 · arxiv created 2012/01/13 · arxiv updated 2012/01/16 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Abstract Large-amplitude Alfvén waves are ubiquitous in space plasmas and a main component of magnetohydrodynamic (MHD) turbulence in the heliosphere. As pump waves, they are prone to parametric instability by which they can generate cyclotron and acoustic daughter waves. Here, we revisit a related process within the framework of the multi-fluid equations for a plasma consisting of many species. The nonlinear coupling of the Alfvén wave to acoustic waves is studied, and a set of compressive and coupled-wave equations for the transverse magnetic field and longitudinal electric field is derived for waves propagating along the mean-field direction. It turns out that slightly compressive Alfvén waves exert, through induced gyro-radius and kinetic-energy modulations, an electromotive force on the particles in association with a longitudinal electric field, which has a potential that is given by the gradient of the transverse kinetic energy of the particles gyrating about the mean field. This in turn drives electric fluctuations (sound and ion-acoustic waves) along the mean magnetic field, which can nonlinearly react back on the transverse magnetic field. Mutually coupled Alfvén-cyclotron--acoustic waves are thus excited, a nonlinear process that can drive a cascade of wave energy in the plasma, and may generate compressive microturbulence. These driven electric fluctuations might have consequences for the dissipation of an MHD turbulence and, thus, for the heating and acceleration of particles in the solar wind.