ION-ACOUSTIC-WAVES IN DUSTY PLASMAS

The properties of ion-acoustic waves in steady-state, unmagnetized, dusty plasmas are analyzed using fluid equations. Two damping mechanisms are investigated. The ''Tromso damping'' has been discussed in detail by researchers in Tromso (Havnes et al., Phys. Scr. 45, 491, 1992; Melandso et al., J. geophys. Res. 98, 13315, 1993) for dust-acoustic waves, and is related to the fact that a finite phase shift generally exists between the oscillation of the wave potential and the oscillation of the dust grains charge in the presence of the wave. The ''creation damping'' is due to the continuous injection of fresh ions into the plasma, to replace those which are lost to the dust grains. These fresh ions, produced by ionization of a neutral gas, do not share initially in the wave motion of the pre-existing ions, and thus lower the average momentum of the ion population.