Lagrangian-Eulerian dynamics of undulated dust acoustic wave
Ya-Yi Tsai1*, Lin I1
1Department of Physics, National Central University, Jhongli, Taiwan
* presenting author:Ya-Yi Tsai,
Dust acoustic wave is a fundamental low frequency nonlinear density wave, constituted by negatively charged dust particles longitudinally oscillating in the dusty plasma. Transition from the ordered plane wave to the weakly disordered intermediate state by increasing the excitation is a ubiquitous phenomenon in many nonlinear open dissipative media susceptible to modulation instability. In this work, we experimentally demonstrate the waveform evolution of the 3D undulated dust acoustic wave by direct monitoring and correlating the dust density in a large area and the individual dust particle motions. It is found that, through rupturing and reconnection of the undulated wave crests, induced by the spontaneous symmetry breaking of plane wave, defects with helical waveforms winding around, the irregular low amplitude hole filaments where amplitudes are null and phases are undefined, are generated. In addition to the longitudinal electric forces from the wave crest toward the trough, the additional transverse electric forces due to the curved wave front and nonuniform dust density distribution on the crest are the key factors to determine dust motions and in turn waveform and defect evolutions.

Keywords: dust acoustic wave