Small scale solar wind turbulence due to nonlinear Alfvén waves

Abstract:

In the work presented here, we study the evolution of wave localization and magnetic power spectrum using kinetic Alfven wave (AW) and fast AW in the solar wind plasma. We derived the dynamical equations for these wave modes using two-fluid model and then solved numerically to analyze power spectra as well as wave localization at different instants of time. The ponderomotive force associated with the pump is responsible for the wave localization and these localized structures become more chaotic as the system evolves with time until the modulational instability (or oscillating two-stream instability) mentioned here, saturates. We observe steepening of the spectra as we go from inertial range to the dispersion range i.e. nearly k^-1.67 to k^-3.0. The steepening of spectra may be described as the transfer of energy from longer scale to the smaller scale. The formation of complex magnetic filaments and change in the spectral index may be responsible for the charged particles acceleration in the solar wind plasma.