Rogue Wave Events and Topological Defects in Unstable Dust Acoustic Waves
Ya-Yi Tsai (蔡雅怡)1*, Lin I (伊林)1, Jun-Yi Tsai (蔡俊毅)1
1Department of Physics and Center for Complex Systems, National Central University, Jhongli, Taiwan
* presenting author:Ya-Yi Tsai,
For nonlinear ordered wave, increasing driving leads to the transition to the weakly disordered wave state through amplitude and phase modulations, accompanied with the emergence of low amplitude singular objects, defects, where the amplitudes are null and phases are undefined. On the other hand, rare uncertain extremely high amplitude localized events, rogue waves, could also be generated. Whether rogue waves exist in unstable nonlinear gaseous acoustic type waves, their correlation with low amplitude holes (defects), and their generation mechanism beyond modulation instability remain open questions.
Dust acoustic wave (DAW) is a density wave with longitudinal oscillations of negatively charged dust particles suspended in weakly ionized discharges. In this work, by visualizing the 3D waveform and tracking the individual dust particle motions, we demonstrate the first experimental observation of dust acoustic rogue waves and discuss the above elusive issues in the dusty plasma system. It is found that rogue wave events tend to be preceded with higher density of surrounding defects. The 3D particle focusing effect caused by the tilted and ruptured waveforms surrounding defects, is identified as the kinetic origin for the rogue wave generation.

Keywords: Dust acoustic wave, defect, rogue wave