DUST ACOUSTIC-WAVES IN STRONGLY COUPLED DUSTY PLASMAS

Dust grains, or solid particles of mu m to sub-mu m sizes, are observe d in various low-temperature laboratory plasmas such as process plasma s and dust plasma crystals. The massive dust grains are generally high ly charged, and it has been shown within the context of standard plasm a theory that their presence can lead to new low-frequency modes such as dust acoustic waves. In certain laboratory plasmas, however, the du st may be strongly coupled, as characterized by the condition Gamma(d) =Q(d)(2)exp(-d/lambda(D))/dT(d) greater than or equal to 1, where Q(d) is the dust charge, d is the intergrain spacing, T-d is the dust ther mal energy, and lambda(d) is the plasma screening length. This paper i nvestigates the dispersion relation for dust acoustic waves in a stron gly coupled dusty plasma comprised of strongly coupled negatively char ged dust grains, and weakly correlated classical ions and electrons. T he dust grains are assumed to interact via a (screened Coulomb) Yukawa potential. The strongly coupled gas phase (liquid phase) is considere d, and a quasilocalized charge approximation scheme is used, generaliz ed to take into account electron and/or ion screening of the dust grai ns. The scheme relates the small-k dispersion to the total correlation energy of the system, which is obtained from the results of published numerical simulations. Some effects of collisions of charged particle s with neutrals are taken into account. Applications to laboratory dus ty plasmas are discussed.