Particle simulation of plasma heating by a large-amplitude shear Alfvén wave through its transverse modulation in collisionless plasmas

Abstract

We investigate the nonlinear dynamics of a large-amplitude shear Alfvén wave (AW) with circular polarization in collisionless plasmas by using a 2D3V fully relativistic electromagnetic particle-in-cell (PIC) simulation code. We found that when the amplitude, A = δB/B 0, of the shear AW is larger than A c = νth,i/C ωpe/kC ωpe/ωpe/ωce, the shear AW spontaneously becomes unstable for the modified two-stream instability (MTSI), resulting in the excitation of small-scale quasielectrostatic waves with electric fields parallel to a uniform magnetic field. We found that the electrons are heated mostly in the direction parallel to the magnetic field due to the quasi-electrostatic lower hybrid waves by the MTSI. Subsequently, the shear AW becomes unstable with strong transverse modulation, resulting in the excitation of ion acoustic waves that can heat ions. About 70% of the AW energy can be converted to plasma heating of both electrons and ions. The plasma heating time is within about 250ω ci-1, which is shorter than the collision time between protons and neutral hydrogens in the upper chromosphere. The obtained results could be very important for plasma heating of coronal loops in the upper chromosphere. © IOP Publishing Ltd add Deutsche Physikalische Gesellschaft.