Dynamics of interacting multiscale acoustic vortices in dust acoustic wave turbulence of dusty plasmas

Wei Shuo Lo^1*, Lin I¹

¹Physics, National Central University, Taoyuan, Taiwan

* Presenter:Wei Shuo Lo, email:loweishuo@gmail.com

Dust acoustic wave (DAW), associated with the longitudinal oscillations of negatively charged micron-sized particles in gaseous plasmas, can be self-excited through the interplay of dust inertia, screened Coulomb interactions, and ion streaming. It is a good platform for investigating and understanding the generic behavior of nonlinear acoustic waves through directly tracking particle motion and waveform evolution over a large area. Previous works have demonstrated that using the empirical mode decomposition (EMD) based on Hilbert-Huang transform, the turbulent dust acoustic waves can be decomposed into several intrinsic mode functions (IMFs) and viewed as a zoo of interacting multiscale acoustic vortices with screw waveforms winding around fluctuating worm-like defect filament. In this work, we experimentally investigate the dynamical behaviors of multiscale defect filaments in the 2+1 dimensional spatiotemporal space in the dust acoustic wave turbulence of a dusty plasma system, by tracking the Lagrangian trajectories of defects. It is found that with increasing mode number, averaged speed and lifetime of defect decreases and increases, respectively. Defect filaments of different modes with the same topological charge are entangled associated with the phase synchronization of their surrounding waveforms. How the defect filaments of adjacent modes wind around each other through their mutual interaction is presented and discussed.

Keywords: Dusty plasma, Acoustic wave turbulence, Topological defect