a1 Dipartimento di Scienze Fisiche, Universitá di Napoli, Mostra d'Oltremare pad 19, 80125 Napoli, Italy
We investigate ion waves in a plasma in the presence of massive charged dust particles, a common space-plasma component now known to exist also in planetary rings and comets. We derive an equation describing low-frequency electrostatic perturbations on a non-homogeneous background, where the inhomogeneity is due to a distribution of charged grains, each surrounded by an equilibrium statistical distribution of plasma particles. This model is then applied to propose an interpretation of some recent data from the Vega and Giotto space probes to Halley's comet the increase of the low-frequency electrostatic noise (ion-acoustic waves) in the region of increased dust.
(Received February 12 1988)
(Revised May 10 1988)
† Also at INFN (Sezione di Napoli), Napoli Italy.
‡ Permanent address: IFSI (CNR), Frascati, Italy.