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The Alfvenic nature of energy transfer mediation in localized, strongly nonlinear Alfven wavepacket collisions
Journal article   Open access   Peer reviewed

The Alfvenic nature of energy transfer mediation in localized, strongly nonlinear Alfven wavepacket collisions

J. L. Verniero and G. G. Howes
Journal of plasma physics, Vol.84(1), 905840109
02/01/2018
DOI: 10.1017/S0022377818000090
url
https://arxiv.org/pdf/1712.08751View
Open Access

Abstract

In space and astrophysical plasmas, violent events or instabilities inject energy into turbulent motions at large scales. Nonlinear interactions among the turbulent fluctuations drive a cascade of energy to small perpendicular scales at which the energy is ultimately converted into plasma heat. Previous work with the incompressible magnetohydrodynamic (MHD) equations has shown that this turbulent energy cascade is driven by the nonlinear interaction between counterpropagating Alfven waves - also known as Alfven wave collisions. Direct numerical simulations of weakly collisional plasma turbulence enables deeper insight into the nature of the nonlinear interactions underlying the turbulent cascade of energy. In this paper, we directly compare four cases: both periodic and localized Alfven wave collisions in the weakly and strongly nonlinear limits. Our results reveal that in the more realistic case of localized Alfven wave collisions (rather than the periodic case), all nonlinearly generated fluctuations are Alfven waves, which mediates nonlinear energy transfer to smaller perpendicular scales.
Physical Sciences Physics Physics, Fluids & Plasmas Science & Technology

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