LINEAR AND NONLINEAR DUST-ACOUSTIC WAVES IN NONIDEAL DUSTY PLASMAS

Linear and nonlinear dust-acoustic wave propagation in a non-ideal cla ssical dusty plasma consisting of electrons, ions and dust grains is i nvestigated by incorporating the van der Waals equation of state for t he dust component. For linear wares, it is found from the normal mode dispersion relation that the volume reduction coefficient enhances the phase speed of the dust-acoustic waves, while the molecular cohesive forces lead to a decrease in the phase speed. The relative magnitudes of the two contributions depend on the specific parameter regimes char acterizing the non-ideal nature of the dust component. In the high-tem perature limit, there is a net increase in the dust-acoustic phase spe ed, while near the critical point the phase speed is reduced when comp ared with that for the ideal-gas case. For large amplitudes, we discus s the existence of dust-acoustic solitons by deriving the exact Sagdee v potential. While supersonic solitons are found to be admissible in b oth the sub-and supercritical parameter regimes, subsonic propagation near the dust-acoustic speed is possible only for the supercritical ca se. For small but finite amplitudes, explicit analytical solutions hav e been obtained. A Limiting case of these solutions is also discussed.