Generation of intermittent ion acoustic waves in whistler-mode turbulence

S Saito,Y Nariyuki,T Umeda

doi:10.1063/1.4990443

S Saito, Y Nariyuki + Show 1 more

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https://doi.org/10.1063/1.4990443

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Journal: Physics of plasmas	Publication Date: Jun 29, 2017
Citations: 8	License type: cc-by

Affiliation: Nagoya University, University of Toyama

Abstract

A two-dimensional, fully kinetic, electromagnetic, particle-in-cell simulation in a magnetized collisionless plasma has been performed, demonstrating the generation of intermittent ion acoustic waves in finite-amplitude whistler-mode turbulence. The self-consistent simulation shows that ion/ion acoustic instability can be driven as a consequence of the nonlinear evolution of whistler-mode turbulence. The instability triggering the generation of ion acoustic waves occurs intermittently in several local regions. We propose that the nonlinear development of the phase-space density that drives kinetic instabilities must be analyzed with greater care if the dissipation of plasma turbulence is to be understood.

Highlights

Forward cascade in magnetohydrodynamics (MHD) turbulence plays an important role in the generation of plasma turbulence at scales smaller than the ion inertial length and ion Larmor radius
We propose that the nonlinear development of the phase-space density that drives kinetic instabilities must be analyzed with greater care if the dissipation of plasma turbulence is to be understood
We believe that this nonlinear response is applicable in explaining the underlying IAW generation observed in the solar wind and the quasiperpendicular collisionless shocks where whistler-mode turbulence develops nonlinearly

Summary

Introduction

Forward cascade in magnetohydrodynamics (MHD) turbulence plays an important role in the generation of plasma turbulence at scales smaller than the ion inertial length and ion Larmor radius. This small-scale turbulence, or alternatively kinetic turbulence because the MHD approximation is expected to be broken there, has been considered as an energy sink of solar-wind turbulence. The steeper magnetic energy spectrum suggests that the kinetic nature of the fluctuations involves different cascade processes from that of MHD turbulence Both kinetic Alfven and whistler modes are believed to be crucial in transferring the energy of fluctuations from ion kinetic scales to electron kinetic scales. These fluctuations are dissipated by wave-particle interactions at the kinetic scales

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