Three dimensional particle-in-cell simulation of particle acceleration by circularly polarised inertial Alfven waves in a transversely inhomogeneous plasma

Abstract

The process of particle acceleration by left-hand, circularly polarised inertial Alfven waves (IAW) in a transversely inhomogeneous plasma is studied using 3D particle-in-cell simulation. A cylindrical tube with, transverse to the background magnetic field, inhomogeneity scale of the order of ion inertial length is considered on which IAWs with frequency $0.3{\omega }_{ci}$ are launched that are allowed to develop three wavelength. As a result time-varying parallel electric fields are generated in the density gradient regions which accelerate electrons in the parallel to magnetic field direction. Driven perpendicular electric field of IAWs also heats ions in the transverse direction. Such numerical setup is relevant for solar flaring loops and earth auroral zone. This first, 3D, fully-kinetic simulation demonstrates electron acceleration efficiency in the density inhomogeneity regions, along the magnetic field, of the order of 45% and ion heating, in the transverse to the magnetic field direction, of 75%. The latter is a factor of two times higher than the previous 2.5D analogous study and is in accordance with solar flare particle acceleration observations. We find that the generated parallel electric field is localised in the density inhomogeneity region and rotates in the same direction and with the same angular frequency as the initially launched IAW. Our numerical simulations seem also to suggest that the "knee" often found in the solar flare electron spectra can alternatively be interpreted as the Landau damping (Cerenkov resonance effect) of IAWs due to the wave-particle interactions.

Physics of Plasmas, in-press, September 2012 issue, final accepted version

References in corpus (8)

• Impulsive phase flare energy transport by large-scale Alfven waves and the electron acceleration problem
• Recent Advances in Understanding Particle Acceleration Processes in Solar Flares
• Radio Spectral Evolution of an X-ray Poor Impulsive Solar Flare: Implications for Plasma Heating and Electron Acceleration
• Wave-particle interactions in non-uniform plasma and the interpretation of Hard X-ray spectra in solar flares
• Particle acceleration by circularly and elliptically polarised dispersive Alfven waves in a transversely inhomogeneous plasma in the inertial and kinetic regimes
• Three dimensional particle-in-cell simulation of particle acceleration by circularly polarised inertial Alfven waves in a transversely inhomogeneous plasma
• A minimal model of parallel electric field generation in a transversely inhomogeneous plasma
• Physics of collisionless phase mixing

Cited by in corpus (13)

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• Three dimensional particle-in-cell simulation of particle acceleration by circularly polarised inertial Alfven waves in a transversely inhomogeneous plasma
• Kinetic Alfvén wave generation by velocity shear in collisionless plasmas
• 3D particle-in-cell simulation of electron acceleration by Langmuir waves in an inhomogeneous plasma
• The effect of initial conditions on the electromagnetic radiation generation in type III solar radio bursts
• The effect of electron beam pitch angle and density gradient on solar type III radio bursts
• Collisionless, phase-mixed, dispersive, Gaussian Alfven pulse in transversely inhomogeneous plasma
• Particle acceleration by sub-proton cyclotron frequency spectrum of dispersive Alfven waves in inhomogeneous solar coronal plasmas
• Electron acceleration from the interaction of three crossed parallel Alfvén waves
• Electron acceleration and small scale coherent structures formation by an Alfvén wave propagating in coronal interplume region
• Interaction of a spatially uniform electron beam with a rotational magnetic hole in a form of a Harris current sheet
• Kinetic heating by Alfvén waves in magnetic shears