Charge and mass fluctuations in dusty plasmas revisited

Charge and mass fluctuations in dusty plasmas are revisited by invoking ove rall conservation of charge and mass in the combined dusty plasma, includin g external sources. If electrons and ions lost to the grains are not replen ished, a stationary state cannot be achieved in the usual spherical probe m odel. For a true stationary state other charging mechanisms are needed besi des primary electron and ions currents to the grains. A general multispecie s model describes the physics transparantly, without getting lost in comput ational details or being tied to a particular charging model. The character istic damping of the dust-acoustic mode is described. Even in an open dusty plasma, where electrons and ions are injected, the broad conclusions remai n the same, as far as the damping of the dust-acoustic waves is concerned.