Particle dynamics in dust acoustic waves and plasma bubbles of dusty plasmas

We investigate particle micro-motion in large amplitude self-excited dust acoustic waves (DAW) and pulse-laser induced dusty plasma bubble (DPB) with dust particle depletion in a dusty plasma liquid through direct microscopic visualization. In a DAW, particles oscillate longitudinally. The particle upward motion is decelerated and accelerated while entering and leaving the wave crest respectively. The uncertain dwell time of particle trapping in the large amplitude wave crest is the main cause for the melting from the liquid to the gas state with chaotic particle motion as the wave amplitude increases. The dust-dust interaction further induces velocity modulation. For the DPB, its downward propagation after the bubble expansion is due to the asymmetric particle response in the presence of the downward ion wind. The bubble travels supersonically. It induces DAW in the wake, which is then gradually damped through the background gas collision.