The effect of negative ion population on dust acoustic wave propagation in a self gravitating Lorentzian dusty plasma

A theoretical investigation into the effect of negative ion population on dust acoustic wave propagation is presented in a self-gravitating dusty plasma consisting of electrons, negative ions, positive ions, and charged dust grains. The kappa distributed suprathermal electrons and Maxwellian ions are assumed. The inertial dust grain is assumed to have a variable charge which is negative or positive in the equilibrium condition depending on the population density of negative ion. A general fluid dispersion relation is derived by using continuity, momentum, and Poissons equations for electrostatic potential as well as gravitational potential. The analysis shows that the higher negative ion and suprathermal electron population favored the reduction of the decay rate when the equilibrium dust charge is negative. On the other hand, when the negative ion population increases, the equilibrium dust charge becomes positive. In this case, the negative ion and suprathermal electron population enhance the decay rate.