Nonlinear effects associated with the dispersive Alfvén waves in space plasmas

Abstract

This paper presents the model equations governing the nonlinear dynamics of the dispersive Alfvén wave (DAW) in the low-β plasmas (β ≪m_e/m_i; known as inertial Alfvén waves) applicable to solar corona and intermediate-β plasmas (m_e/m_i≪β≪1; kinetic Alfvén waves) applicable to solar wind in Earth's magnetosphere. The pump DAW is perturbed by a low-frequency fast wave (FW). When the ponderomotive nonlinearities are incorporated in the DAW and FW dynamics, the model equations of DAW and FW turn out to be the modified Zakharov system of equations. Growth rate and threshold field for modulational (filamentation) instability have been calculated. The dependence of the growth rate on the perturbation wave number and the pump wave parameters (such as perpendicular wave number) has also been presented.