Dissipative Dynamics of Nonlinear Alfven Waves in the Solar Wind

Nonlinear Alfven waves, sometimes observed in the Solar Wind, represent the ponderomotive coupling of Alfvenic magnetic energy to ion-acoustic quasi-modes, which modifies the phase velocity v_A and caused their wave-front to get steeper. In the warm, collisionless Solar Wind plasma the resonant particle-wave interactions result in relatively rapid formation of quasi-stationary Rotational Discontinuities, which have been the subject of intense satellite observations and theoretical investigations, and whose emergence and dynamics has not been understood for a long time. We have shown that these discontinuities are quasi-stationary wave-form remnants of nonlinearly evolved coherent Alfven waves. In the long-term asymptotic, the resonant particles are trapped in the quasi-stationary Alfvenic discontinuities by mirroring forces giving rise to the nonlinear Landau damping and to a formation of a plateau on the distribution function, so that the linear collisionless damping vanishes. Using virial theorem for trapped particles, we analytically compute their effect on the nonlinear dynamics which is highly non-trivial and forces a significant departure of the theory from the conventional paradigm.