Dust-acoustic double layers: ion inertial effects

Abstract

Space and astrophysical plasmas often comprise a number of massive ion components in addition to a tenuous, negatively charged dust component and an electron component. Stationary electrostatic double layers in a dusty plasma are investigated in a model which incorporates the effects of ion inertia rather than treating the ion components as Boltzmann-distributed (inertialess) fluids. On comparison with the inertialess theory, one finds considerably reduced double layer existence parameter regimes. Significantly, highly nonlinear double layers are ruled out when ion inertia is incorporated. However, in the restricted parameter regimes in which the inertial theory predicts double layers for small ion/dust mass ratios (~ 10 −15–10 −8) there is good qualitative agreement with inertialess theory. The reasons for these, and other, discrepancies and similarities are discussed.