Experimental observation of ion-acoustic waves in an inhomogeneous dusty plasma

The propagation of a dust-ion-acoustic wave (DIAW) wave down the steep dens ity gradient in an inhomogeneous diffusive dusty plasma is experimentally s tudied. It is observed that the presence of the dust enhances the plasma in homogeneity. The phase velocity of the DIAW increases rapidly with distance and becomes supersonic. The interplay between the effects of the density n onuniformity and collisional damping results in the continuous transition o f the relative amplitude of the DIAW from damping to growth. The experiment al data are in agreement with theoretical prediction and confirm the import ance of density-dependent ion-dust collisions. (C) 2001 American Institute of Physics.