The collision between two counterpropagating dust acoustic solitary waves in a strongly coupled dusty plasma has been observed. The measured velocity and width of the solitary wave agree with the solution of the Korteweg-de Vries equation derived by using the generalized hydrodynamic model. The two counterpropagating solitary waves of equal amplitude merge into a single pulse with twice the individual soliton amplitude and then pass through each other. The solitons suffer a small time delay in propagation after collision. The measured delay time obtained from their trajectories is also presented.

Dusty plasma with a nanometer size dust grain is produced by externally injecting carbon nanopowder into a radio frequency discharge argon plasma. A self-excited dust acoustic wave with a characteristic frequency of ∼100 Hz is observed in the dust cloud. The average dust charge is estimated from the Orbital Motion Limited theory using experimentally measured parameters. The measured wave parameters are used to determine dusty plasma parameters such as dust density and average inter particle distance. The screening parameter and the coupling strength of the dusty plasma indicate that the system is very close to the strongly coupled state.

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Dust acoustic shock wave is observed in a strongly coupled laboratory dusty plasma. A supersonic flow of charged microparticles is allowed to perturb a stationary dust fluid to excite dust acoustic shock wave. The evolution process beginning with steepening of initial wave front and then formation of a stable shock structure is similar to the numerical results of the Korteweg-de Vries-Burgers equation. The measured Mach number of the observed shock wave agrees with the theoretical results. Reduction of shock amplitude at large distances is also observed due to the dust neutral collision and viscosity effects. The dispersion relation and the spatial damping of a linear dust acoustic wave are also measured and compared with the relevant theory.

The oblique collision between two equal amplitude dust acoustic solitons is observed in a strongly coupled dusty plasma. The solitons are subjected to oblique interaction at different colliding angles. We observe a resonance structure during oblique collision at a critical colliding angle which is described by the idea of three wave resonance interaction modeled by Kadomtsev-Petviashvili equation. After collision, the solitons preserve their identity. The amplitude of the resultant wave formed during interaction is measured for different collision angles as well as for different colliding soliton amplitudes. At resonance, the maximum amplitude of the new soliton formed is nearly 3.7 times the initial soliton amplitude.