Evolution and Self-organization of Alfvenic Wave Packets

Evolution of large-amplitude Alfven waves, which are governed by the driven derivative nonlinear Schroedinger (DNLS) equation, is numerically investigated. Nonlinear evolution of left-hand and right-hand polarized wave packets is found to be drastically different. Left hand one, due to interaction with the driver, quickly goes into the chaotic state. In case of a harmonic driver, time for the onset of chaos, scales as 1/A; A being the amplitude of the driver. On the other hand, the evolution of right-hand driven Alfvenic wave packets shows interesting features like collapse, turbulent power spectra and coherence in chaos. Self-organization and pattern formation phenomena are also observed in our simulations.In case of right-hand wave, self organization takes place because of an impulsive source whereas for left-hand wave, continuous energy source is responsible for the generation of self-organized state.