Low frequency modes in strongly coupled dusty plasmas

The influence of strong correlations on low frequency collective modes in a dusty plasma is investigated. The dust dynamics is modeled by the generalized hydrodynamics description. For the well known dust acoustic mode, strong correlations lead to new dispersive corrections, an overall reduction of the frequency and phase velocity and the existence of parameter regions where partial derivative omega/partial derivative k<0. A novel result is the possibility of sustaining a low frequency transverse mode-a dust shear mode-in which the correlation energy acts as an effective bulk modulus. The influence of ion streaming and collisional interaction with a background of neutrals on the modes are also studied and it is shown that the longitudinal modes may be driven unstable by ion streaming. (C) 1998 American Institute of Physics. [S1070-664X(98)03610-6].