Localization of circularly polarized dispersive Alfvén wave and effect on solar wind turbulence

Abstract

Solar wind turbulence at large inertial scales is well known for decades and believed to consist of Alfvén cascade. At scales of the order of proton inertial length, Alfvén cascade excites kinetic Alfvén wave, fast wave, or whistler wave that carries wave energy to smaller scales. Despite supporting the kinetic Alfvén wave cascade to elucidate the steeper spectra at the kinetic scales, we here present another model, the localization of longitudinally propagating dispersive Alfvén wave (DAW) with finite frequency correction to illustrate the same. Inclusion of this finite frequency in Alfvén wave makes them dispersive. In this approach, the dynamical equation of the wave in the presence of ponderomotive nonlinearity of the pump is obtained and then solved numerically to study the evolution of the turbulence. The ponderomotive force accounts for the coupling between the DAW and ion acoustic wave. Taking the adiabatic case, we have first studied the localization of DAW. To have the physical insight of the dynamical system, the equation is also studied semi-analytically.