Dust rotation effects on dust-acoustic surface waves in a Lorentzian plasma

Abstract

The dispersion relation for a dust-acoustic surface wave is obtained for the semi-bounded dusty plasma containing elongated and rotating charged dust particles. The plasma equilibrium velocity distribution function is taken to be Lorentzian. Dust particles are assumed to be cold. The results show that the phase velocity of the dust-acoustic surface wave propagating at the plasma-vacuum interface is suppressed by the rotation of dust particles in the case that kxλD≲1, where kxλD is the scaled wave number. In addition, the increase of the spectral index κ in the Lorentzian distribution function is found to decrease the phase velocity of the wave. It is interesting to note that the frequency of the phase velocity remains constant as the wave number increases. In contrast, the rotation effect on group velocity of the surface wave diminishes as the wave number approaches either zero or infinity, although the increase of the magnitude of angular frequency reduces the group velocity at all wave numbers. The influence of κ on the group velocity is discussed.