Dust-charge fluctuation effects on surface dust-acoustic waves in astrophysical half-space dusty plasmas

We investigate the dust-charge fluctuation effects on the propagation and the decay of the dustacoustic surface plasma wave at the interface of plasma-vacuum in astrophysical half-space dusty plasmas. The dispersion relation for the surface mode is derived by using the appropriate plasma dielectric function. We found that wave frequency decreases as the dust-charging frequency increases as well as the dynamical wave number does. However, the damping rate of the surface wave increases with an increase of the dustcharging frequency and the dynamical wave number. Hence, the amplitude of the surface wave is found to be strongly suppressed with an increase of the dust-charging frequency. The increase of charging relaxation rate is found to suppress both of the real frequency of the wave and the damping rate of the surface wave in astrophysical half-space dusty plasmas.